THE CONODONTA. and Evolutionary History of a Long-Extinct Animal Phylum. Morphology, Taxonomy, Paleoecology, WALTER C.SWEEL The Ohio State University

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2 THE CONODONTA Morphology, Taxonomy, Paleoecology, and Evolutionary History of a Long-Extinct Animal Phylum WALTER C.SWEEL The Ohio State University New York. Oxford CLARENDON PRESS. OXFORD. 1988

3 PREFACE Conodonts are common fossils. Almost anyone who deals on a regular basis with Paleozoic and Triassic marine rocks has probably seen a few of them. Through the last 30 yedrs conodonts have come to be of exceptional value in biostratigraphy, and they now have pride of place as index fossils in many parts of the geologic column. But conodonts are extinct and are unknowo to most neontologists. The sketchiness ofinformation about them in most texts on invertebrate paleontology may result either fiom the fact that they are microfossils that haye only lately come to be important as stratigraphic tools, or from the fact that nothing quite like them exists today, so their zoologic relations axe uncertain. In this monograph, I provide a summary of information about a group with which I have worked all my adult life. Charts that name conodont-based biozones and show stratigraphic range ofselected conodont species are included as Appendix B. However, I have purposely avoided a recap of conodont biostratigtaphy because it is constantly changing and cunent views are readily available in various other places. Instead, I focus here on the conodonts as a group of extinct animals, about which it is important to know as much as possible before assessing their distribution biostratigraphically. Of course, one takes considerable risk in attempting such a summary, particularly of a group of animals known only from its fossil record, because most of what I think I know about conodonts as animals is either conjecture or a highly personal interpretation ofa still-irnperfect fossil record. So, with the caveal that whal follows is only one way of viewing an important group, I ofer my account of the Conodonta. For their "witting" or unwitting contributions to what I believe I know about the fascinating gtoup of extinct animals described on the following pages, I am gateful to a long list of my students and faculty colleagues at The Ohio State University, especially Stig M. Bergstrijm, and to members of the Pander Society, an intemational group of exceptionally goodnatured "conodontologists" that has met frequently and infomally thougl the last 20 years to share infomation about conodonts, argue conclusions, and correct the misapprehensions of its senior members. Karen Tyler, faculty illustrator at The Ohio State University, drafted nea y all the figures from my very crude copy and assisted with labeling others. Dr. Jerzy Dzik, of the Polish Acaderny of Sciences, Warszawa, provided about half the stippled drawings of conodonts that gace various figures in Chapter 5- The anistry of tlrese two good friends is plainly evident in their work and is warmly acknowledged. I am also grateful to Sue Shipley and David Little, of The Ohio State University, for their help in completing various parts of the manuscript and illustrations, and to Mark Klefner, who graciously cornpiled information on the ranges of Silurian conodonts and assembled the Silurian chart in Appendix B. The Department of Geology and Mineralology generously assumed much of the expense of drafting and photogaphy. Columbus, Ohio February 1988 w.c.s.

4 CONTENTS l. Inhoduction l.l History ofdiscovery and study 1.2 Achievements 1.3 Pending problems Skeletal anatomy 2.1 Composition of conodont elements 2.2 Structure of skeletal elements 2.3 Shapes of element crowns Coniform crowns Ramiform crowns Rastrate crowns Pectiniformcrowns 2.4 Symmetry- and curvature-transition series 2.5 Skeletalapparatuses 2.6 Symmetry of elements, element pairs, and apparatuses 11 ll t2 t4 l5 t6 l8 t J. Whole-animal anatomy 3.1 The Scottish Carboniferous specimens 3.2 The Waukesha specimen 3.3 Histology of demineralized tissues 3.4 Summary Z 33 JJ 4. Taxonomy 4.1 Form taxonomy 4.2 Multielementtaxonomy Multielementmethodology 4-3 Multielement classifications 4.4 A revised multielement classification 35 J) 36 4l The major conodont groups 5.1 Introduction 5.2 Cavidonti and Conodonti 5.3 The Proconodontida (Cavidonti) and its families (Fig. 5.1) 5.4 The Belodellida and its families (Fig. 5.1) 5.5 OrderProtopanderodontida, new Family Protopanderodontidae Lindstrtim, Family Clavohamulidae Lindstrdm, Family Acanthodontidae Lindstritm, Family Drepanoistodontidae Fihraeus and Nowlan, l

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6 CONTENTS Silurian cycles Devonian and Carboniferous cycles Permian and Triassic cycles 6.4 Extinction 6.5 Iterativeevolutionarypatterns 6.6 Evolutionary trends Apparatuselaboration Apparatusreduction Elaboration of elements in P positions 6.7 Developmental slralegies Recapitulation Paedomorphosrs 6.8 Summary lx r r t42 t t46 t46 7. Paleoecology and paleobiogeography 7.1 Introduction 7.2 Mode of life, or habit, of conodonts 7.3 Ecologic models Thedepth-stratificationmodel The lateral-segegation model 7.4 Selected studies of conodont ecology Ordovician paleoecology of Cincinnati Region Mississippian paleoecology, western United States Paleoecology of Pennsylvanian conodonts 7.5 Ecologicgeneralizations Depth as a factor Ternperuture as a factor Nearshore and ofshore faunas Phyletic changes in ecological distribution 7.6 Paleobiogeography Late Cambrian and Ordovician paleobiogeography l-ater Paleozoic and Triassic paleobiogeography l5l t t t , The phylum Conodonta 8.1 A personal bias 8.2 Summary of conodont characters 8.3 Conodonts as invertebrates Arthropod and annelid connections Molluscanconnections Connections with other invertebrates 8.4 Conodonts as chordates The opinions of Pander Newberry, Hinde, Huxley and Myxine Macfarlane and the nemertinean connection t7l t7l r75 176

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8 The Conodonta

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10 1. INTRODUCTION With just a bit of preparation, almost any marine rock of Paleozoic or Triassic age, from al- rather large (and growing at the rate of about opment. The literature on conodonts is now most anywhere on earth, will yield to the patient investigator an assortment of phosphatic sible to explore every aspect ofconodont paleo- 300 new papers each year), so it will not be pos- microfossils termed conodonts. Although biology in great depth. But this book is not named and first described in 1856, these tiny intended as a comprehensive review for speciatists. It is an attempt to summarize current fossils were paleontologi curiosities until just a few years ago. Little was known of their geographic or stratigraphic distribution, and they who may well have been wondering why this knowledge of conodonts for the nonspecialist, were classified according to a mechanical system based entirely on shape. Furthermore, tant rn recent years. group of tiny fossils has come to be so impor- their relations to other, better-known animal groups were hotly debated. 1.1 History of Discov ry and Study Nowadays, conodonts are mentioned in most reports on Paleozoic and Triassic biostratigaphy, and their contribution is widely ac- paleontologist Christian Heinrich Pander dis- Sometime between 1833 and 1844, the Russian knowtedged. Furthermore, enough has been covered tiny, lustrous, toothlike fossils in learned about their anatomy, associations, and washed residues of Lower Ordovician and Silurian clastic rocks from Estonia, and on the patterns of development to make them the honest subjects ofa wide variety oftruly paleobiologic studies; Thirty years ago only a hand- rock collected within the present city limits of surface of at least one slab of Carboniferous ful of paleontologists claimed more than a Moscow. However, these microscopic fossils passing acquaintance with conodonts. Today, were not illustrated or discussed in print until more than 200 persons devote a major part of 1856, when they were described as the remains their waking hours to the study of these tiny of an otherwise unknown group of Paleozoic fossils, and only a few of the world's major oil fishes that Pander named Conodonten (conodonts in English). companies or geologic surveys are without at least one conodont specialist. The reasons for In the years between 1833 and 1856, Pander this paleontologic successtory are numerous, evidently gave a lot of thought to the tiny fossils he named conodonts. During part of that but they have to do primarily with the fact that the conodonts have proved to be as successful time, he had geat trouble with his eyes and was at solving biostratigraphic problems in the Paleozoic and Triassic as the foraminifers have he saw when he was able to study his specimens not able to use his microscope. However, what been in the interval from the Jurassic to the microscopically convinced him that he was present. looking at the teeth and jaws of a previously In this monograph I will introduce the conodonts; show how at least some of them may em analogue. Thus, in descriptions of speci- unknown group offishes, a group with no rnod- be reconstructed from the jumbled bags of mens in his collection he used terminology appropriate to the teeth and jaws of fishes, and bones by which they are commonly represented in the fossil record; and look at major some of that terminology survives today. features of their long geologic history, with an Pander's 1856 monograph not only provided eye to suggesting somelhing useful about their the first descriptions of the hard parts of a previously unknown group of animals and a name relations to other animals and about their pattems of deployment and evolutionary devel- for the group itself, but it also began debates

11 -uo3 e,{1 pu?.seqsg e^4lrrrjd Jo qleel se ueql Pass?p e^?q sluopouoc Jo sluopnls luecel ll?.tlrzau.,, teri eloj r JTIoI J pue uosuelg..ra? -pnls luopouoj rroqt ot uo4cnporlur eql ui 'sjrssojolsrrrr sluopouoc eluos ls?sl le l?ql eepr eql psjo^ --?J opulh :edeqs eru?s eql e are^\ leql sued pr"q peurjoj sluopouos lenp.t^pul 1?q1 eepr eqt pajo^4 sjoqlne leqlo lsour pue lspu?d 'es?q crulouox?l elsrdojdd? eql ol se (s.opurh Jo dnoj8 lu?lodur u? sb sluopouo3 qlr^l pu? s,jepu?d) suorurdo luejajrp oû osp pep pue ezruso3oj ot pour?jl stuepnls Jo ojppc ero/t\ eleql lnq,quopouorjo senluge crtolooz? pojnpojd osp pu?,{lsnorâjd ueeq p?q egl ol se suorurdo luajojrp,{u?ur,{iuo u?ql lou ela.r u^\od[ retleq rljnrn dnoje eql Jo se^rlel êql are\l 9Z6l i(q 'snq1 '(.,s,,aef -uesejdej ueru? lfsuued q8nojql u?rjrôpjo 'Kllererl) snqnp snqpufitlod pollleu ûeul InJlqnop,, eq qrrqa audl?tu ur pollnsej srql unossrl l l? sluopo 'sarcods luopouoo elsurs?jo snt?l?dd" -uocjo,(pnls e^$uelurjo I?lole{s seppcop oû pelelrur eqljo slueuoduroc s? eseqt 'rt6l pul,- Ip papj?bel epurh te6i ur ssojd unossrl ljo,qrsleûll 'oc?jrns slr uo sueturceds padpqs eql peqsrtqnd s,{?sse crt?urets^s Jo eunlo^ e 'sarpnls ^q luopouoj rleqj.lgon.c Jequrnu e pesodxe ecun?tr 1 uosuplg g pu? 5po^ ^RuoJeJrp Jo Jo u?iuoâ(i eql ur^rpj,unossrw Iuo{J al?qs ^lan {ceiq Jo qels?.sueurceds s.opurh Jo,{lrsJa^run aq] JO euo.sr l?ql.os?q Jrrrrouox?l oql lnoqe l? slsrsotoluool?d et?jqeue^ Jo rred?,{iumuoc eraa J?rluenuur lsour oql.ase$jo.slssoj esoql Jo fpnls aql dn ei?l ol slsdololuoal?d uec -ueujv raqlo pet?jnocuo leded 9Z6l lrerll teql J?oJc sr 1r 'sluopouoc lnoqe raqgng Eurql{uz eloj,r Jelsseg Jou rlculn laqlreu q?noqllv 'ecu?uoolur I?rlu?lsqns Jo se.a\ 9Z6l ur eprs Jno^ uo qcu A\er Jo turod tuejejrp Jeqt?r e {ool eq tnq 'suuuroj qsg elal\ sluopouoo leql Jepued qlr^l poe$e 'solels pelrun u.ielseorluou oql pub ep?uec ur u?ru tuno,{? se popelloc oq sluopo -uoc u?ruoêc pue u?nrôpjo lnoqe 6/gl ur sjed?d lsjg srrl Jo ouo eloj^r oq1(,epurh seuru -ua1 efuoeg.sr.uro^\ pqouu?jo dnoj6?jo s^\ef aql Jo 'qsnljorrr Jo qleal Jelnp?J eql,sureur -0J u?ec?lsruc gje^\,{egl lbql popnlcuoc slaqlo lnq'seqsgjo dnore lruqxo uejo su?d pffq ogl se ueql SurpffEoJ ur JepuEd qlr,{l paprs sjoql -1n 3uure11.eseq crulouoxel pue flrug? cr3o looz Jo redsrrr eql qloq ur rspu?d Jo eprs aql uo,(luug u^\op olrre3,(eql Jouq ui...slcg eql pelubrrca lou sr,jourje [BuJep elu?s -n",{u?tr eql ur ^q l 'seuruwe crsolooz nraql ot s? penurl selejd Jo 'qlnou oures gql ur Jncco l(?rx -uo3 olzqep o^lsnltuocur lnq,jeê.,tloh gleal esaql Jo spul{,{u?ul l?ql uo[rdo luol -?êjd erll l?ql...,, pepnlcuoo osj? pu?.dno$ 'qdbjtououj snourej srq ur ueql ^le^rl ]noqs eloj.{ eur?s oql ;o 1p fpessecau tou,segsg ropu?d leq^{ ol pepp" s?^\ enlll pue.seursou eûr -nc arsololuoopd s? papj?aal ojea{ sluopouoc -ruudjo seleld lerujep pu? qteel oqt ar? sluopo 9Z6I pu? gggl uee^{laq orun erlljo lsorl roj -uo3 lerll JerToq rreql pel4s JelssEg pue qr 'el?qs ln ''(tuqlssod e osl??8oou?t?qj uerddrssrssrw-ubruoêclou s?a{ al?utolp eql se qjns slrun IcoJ p?ajdsepr^\ Jo,(rldBJ egl t gl pecuhum,{lelque lou s? \ eq t?qt Jeolc sr 1r tnq,?jeuoa,l pu? -Eu?Jts agl roqdrcep Eurdlaq ui flrlqn elqaoprs selcods 99 popnlcur qcq,rl,pesodojd eq uorl?j -uocjo eq lq8rru sjrssojorcrr.u Jo dnoj8 srql 1?q1 pelset8ns pue,uorl?ru$salc -grsselo eql JoJ srspq eql se sueurrceds pnpr^ cueuoebjdns,lleu -rpur paluesejd,sluopouoc Jo ed?qs aql pjetar ol esoqc oh.sed?qs Jo serjeds pue?lauoa,,\eu,{ueru pequcsap Jelss?g.s.u luerejrp du?i'u Jo qleol pepnlcur e^?q lqerur pu? qrulrl 'O 'A slslaololuoel?d ue3ueurv eql,926i ui ^poq feqf Jeqloq.{\ Jo, oloqtuot'u etu"s eql JO I[? oje.{, 1?q1 qleol peur?luoc pnpr^rpu.suos?oj of Auorr -uls ejo,tpoq oql Jeqteq^{ eurrujetep ei'i1 JoJ lnq 'lq8u se^\ epurh ieuo lsnf lou,sorc lou plnoc eq 'dnoja l?ql Jo onboleue tur,rrl e -eos 1o acuasqe luojejrp lejelos Jo suolalols eql Jo secord eql ur '18q1 lno pelurod osle oq pu? strq,seqsg sluesejder snlqnp sn\oubqod Jo tdea Jo dnojs punxe ue 3Je^\ ^lprpu?3 sluopouoc leqt pepnlc -uoc sq poseq eq qjlq,!\ uo ueurrceds aql l?ql seer8? ouo,fueê q8noql uo,\o.lqe -uoj ssel lo erour ropued qenoqllb ueoq 'st luql ^ltuepguor sseq crurouoxel el?udojddp el?q ot ^ppol lno sujnl opurh.^lpcruorl eql.sed?gs lnoqe pu? sluopouoj Jo serlruse JrAolooz eql lnoqu luejejrp lpjeês Jo slueuodruoj plele{s p q funluec e ueql elou JoJ uo un.t ot eje/.r l?rl1 VJ-NOOONOJ AHl-

12 INTRODUCTION cur in that classification." They regarded the evidence for this statement, and for their further conyiction that conodonts are polyphyletic, as conclusive, but they put off describing that evidence until a later time. Unfortunately, that time never came. However, they did allude to the fact that their evid nce of the fish nature ofconodonts is the fact that some specimens are attached to a substance "... that appears bony but does not have the structure of ordinary bone." Branson and Mehl also joined Pander, Ulrich and Bassler, and all previous students of conodonts except Hinde in using the shape of individual "teeth" as the guide to their classi fication. That is, like their predecessors, they adopted form taxonomy. However, like Ulrich and Bassler, they thought it likety that speci mens of different shape functioned in diferent ways-some as teeth and jaws, others as body scales, and additional ones as denticles on sprnes. Between 1933 and 1950, the Missouri school flourished under the leadership ofbranson and Mehl, and the prediction of Ulrich and Bassler that conodonts might one day be of great use stratigraphically encouraged other American students to collect and describe these previ ously enigmatic fossils. As a consequence, the literature on conodonts-a mere 200 articles in the late 1920s-more than tripled between 1930 and It is not easy to single out any of these conributions as more important than the others, but it is not diftcult to identify those that introduced significant new trends. In 1934, for example, Hermann Schmidt in Germany and Harold Scott in the United States independently reported the discovery of clusters of morphologicalty different conodont elements on the surfaces of Carboniferous black shale stabs. Like Hinde before them, Schmidt and Scott regarded these natural assemblages as the more or less complete apparatuses of individual conodonts-an opinion that was roundly criticized by Branson and evidently accepted with great reservations by other students of conodonts. In more recent years natural assemblages have played an important role in the development of conodont taxonomy. In 1941, Samuel Ellison, a student of the Missouri school, and Roy Graves, one of his students at the Missouri School of Mines, jointly reported on a group of Pennsylvanian conodont elements they had collected from samples of the Dimple Limestone in Texas, which they had dissolved in dilute acetic acid. Ellison and Graves do not describe the "acetic acid method" they used, which suggests that they did not regard it as novel. However, they were evidently the frrst to use a laboratory procedure that, a decade later, had become routine in research institutions around the world. The significance ofthis is that prior to 1941, and for about a decade after, most collections of conodont elements had been assembled from shales and other readily disaggregated rocks, and carbonate rocks were generally ignored. However, as Ellison and Graves demonstrated in 1941, as Branson and Mehl reported in 1944, and as nearly everyone knows today, much larger collections of well-preserved specimens can be isolated readily from carbonates by dissolving them slowly in l0 to 15 percent acetic or formic acid. This, in turn, means that, unlike many other types of microfossils, conodonts may be collected easily and relatively inexpensively from both carbonate and siliciclastic rocks. Thus their distribution in stratigaphic sections of mixed lithologic type may be determined wilh considerable precision. The increased size of collections made possible by more widespread use of organic acids encouraged micropaleontologists interested in conodonts to broaden their studies through consideration of sections in which there were no shales or mechanically reducible clastic rocks. By 1959, conodonts had been collected in some variety from rocks that range in age from Late Cambrian to late Triassic, and there was one report of distinctive elements from Upper Cretaceous rocks in west Africa. Furthermore, conodonts were known from marine rocks in this time interval from six ofthe seyen continents. The stratigraphic range of conodonts had been considerably broadened through improvements in laboratory techniques, and geographic distribution had been extended and collections greatly increased in size. No longer were inyestigatorsatisfied with

13 -Inos qjnru JaUe papnljuoc,,tueu ec,ajnq -oss? lueunrer peuuoj l?qt sed,q cfoloqdjou -JetrAI Ur Sra{lo,{\ luopouocjo ecujejuoc Jpuoll -Erlolur ue I46I ui.os esje,l.rp Jo sluetuela Jo sdnojt olul,tlpu:a1ut Jo sj?e,{ g ur sluopouoj popr^rp 3q plnos soorlcsuoj ur esoql,{luouox?l leql palou uuoj oc?ldej plno, souolejoqq pjeês ul sjol?b4seûr lueuralenlnu.paqsrurul leql,{duapguoc pu? ûrouox?l,(lcuqnd -Ip ueqt uoe^rtreq sdbb crqdel8rtejls peplperd se pue ezrs I pue ulorlsereg BnS 6961 ut ul slujujelj aljljstp ',{lje3luouox?1 tlleql elen ^êj8 Jo suorljjjloj SV 'lpo8 alqput?upun 1Bâ pue e se ujes sb^l sdnolt luaunoej,{34uapr o1,{1a,rr1ce3'elqellns arour ^llej[jeld -Je posn eq tq8lru senbrurljol AuuetsnJcJo sed^l ^ll?cltolorq sp pepl?aej q8nogl 1 'seeetqluasse I"Jnleu lo,slueuelajo sjelsnjc uo pessq ûrouoxel e loqs ui.setseds luopo -uoojo lrupu?q e uegl ejorx Jo srsoueetp el?ud IPJrlsqels q8no:oq1 e ol peljefqns ele^\ sdnojt luerrncoj upnlôpro eql 6961 ui.,4eolourr.ujol se,'a ll 'clqd?jep?jtsorq s?.r stuopo -uoc ui tssjelur se Buo[ s? ^lu?uud pue,{lj?rrqda8rlejts e^ndujsep SursnJuoJ etuos pue seru,(uoufs xjldrloj.euol pereds flepl^l pue ur pjllnsjr,{riq^.a.rntelrueu IIEurs aje^l suorpojlo3 se Auo[ se'reâ^{oh.s0s6l aw,(q.{ruouox?l -on IeJTSOIoOZ Jo selnu eql qlp\ ecu?procc? rrrroj uerjepu?d Jo /benbep?ur ^lree Iml8olorq aql lujoj ol peuaêj JesrlJ?A\.seroads luopouo, e6 -urs Jo sasnlpndde lelelels eql se pepl?8 -er sdno:3 luorrn3ej Jo lequnu ^le)trt B suorlcelloc u?rchopro rraql urqtr.ar pegquepr,auop peq resrtle^.\ sv.urortspur.j pue âqt,jesrjiea\ 'epeu{cnh,{q peplo^",{peeu os epunf eq1 olur Suoypeeq pe8unld tae ls pu? urojlsejeg pu" sreqelt.996i ur pereedde t"qt slodar ui.sarpnls e^rlredsej Jreql Jo suoqres crl?tuels,(s eql ur utloj 01 pouoêj ureql.pezrutocer Jo JIV ^ruouox?l sdno$ lueuncaj aql Jo Jo srs q eql uo êql serceds? pesou8?rp ûe ^ll?npe pu? dels lxeu eql Ioot sroqtn? aseql JO ouou leql 'Jele,trog,lseJolul Jo sr 1I.SdnO$ luejncal Suzru8oreJ pue Euqsrlqelse ur lngesn aq lq8rur leqt,buelsuoc lernlcelrqjr? Jo eouepr e puorlrppe peqursap uollspul.j,j?ef etlles eql ui sdnoja luerncej rrrjoj slueuale elejisrpjo suorljolloo ur sueurceds qcrq^\ eutrrr -rjtep lqsrur Juo rljrrl,r EuJluJ Jql pelsrl rasrll?a\ 'uo4lppe ui.usunjrs ^q eql ruo{ suo4 -celjoc srl ur suorlsrjoss qrns euru pequssep resr[eia tg6t ui.$icol JrssEUI ruo{ slueurela alajcsrpjo suoncelloc ur sdnoj8 lueuncej qcns lajês pegrluepr Jpeu{JnH.:lourexo :oj.3g61 uj sle^jolur cqdejan?jls erlles eq1 ui soldu?s e^rsseo3ns ur ecua?oddeej q8nojqi suortprc VJNOCONOJ ghj -ojddb Uoddns ol se8?jqruoss? IeJnteu pug leê plno.r Jî l?ql lqnop Burss:ldxa,{q futouoxel rrroj Jo esn ponu4uoc ezrl?uorl?j ol elqrssod poolsjepun sluopnls snoues JJe legl Aurcurûo3 os ere^{ 'ZS6T ur sepoqu fq {pn1s luz8ele ue qlr/h pjidnoj.llojs pue lprrrjqjs,{q sreded oqt 1 gl pedsns.sluopouo. I Jo sluepnts luonbes -qns IIlo{J sesuod$r e^q?beu,{lealbi peloôrd e,\?q 01 Jo pojouar ugeq e Eq ol suaes )[]o.r\ s,apurh q8noqtlv lroi ^{en Jo u?ruoê(l eql ruo{ relsnlc peunsejd? Jo Srs?q etf uo (snq -np snqtdusfilod) sjrjjds p pjurbu pup pjsou -8"Ip ^llbnlje epurh pu",(urouoxbt rrsql JoJ soseq Is4uelod se sdnor8 qcns pereprsuoc qtoq epurh pu? Jepu?d,pelos,{pea{e sv.tloos Pue lpluqcs ^q t 6I ul pesrluapr se8elques -se IEJnteu oql rujoj 13q1 esoql Se rlsns slueuj -ole Jo sdnojs luarlncoj Jo uorlrsodr.uoc lnq suorrjrceds efjjsrp Jo,{Boloqfuoul lou sr eseq Jrr[ouoxsl Jr.[l,(uouox?l lujrlaljrunu ul.tutouox1t uau,t -aplqnw lo DD eql se pezuep?jeqc eq rqslur qrreesoj luopouos Jo fuolsq eql ur l? jelur sigj 'sje!?nb euos ur ol?qep lueputs eloôjd I[4s pu? IIJJ?eser luopouoc Jo suoq"punoj eql Iooqs leql sfsodord 01s0g6l alpprul aql ur pol ujecuoc srqj.eseq Jruouox?l eqljo lnoq? ureruo3 prp os.s096i,{lr?e pu? ^lrtrqelrns s0s6l aql q8norql suorljjlloj pjllofluoj_ll:^\ ^\JA.atreJ ^ll?jlqda8llejls.;o raqrunu aq1 sy Jlqde$p'Jls snojor[nu *"r, le ue{el ssldu"s Jear"l ^lasolc "n^r"rr:;:l;;: qcnu uo pelsrs -ur lsohl 'selbqsjo Burqse,n snouoq?1,{q pal?la -qrj sueurcadsjo srsqurnu reeeeur,{lereue8 eql tt w 7

14 INTRODUCTION 1950 era in the history of conodont research, I should mention that students of conodonts have been blessed more or less regularly with bibliographers, who have kept track of the literature about conodonts and have periodically assembled and published lists of it. Grace Holmes began this service in 1928; Robert Fay continued it through 1948, with a useful catalog published in 1952; and Sidney esh and Sam El- searching that multielement taxonomy was lison have continued with the published bibliographies of the conodont literature that are more desirable than form taxonomy for conodonts and was also attainable even in the absence of natural assemblages to support every chapter. In more recent years, the bibliography listed among the references at the end of this diagnosed species. A complete multielement of conodont literature has been updated annually in a supplement to The Pander Society's taxonomy is still not in place, however, and there are a number of workers who still prefer newsletter. At the end of 1987, my file included its much simpler predecessor. However, a revised version of Volume W of the now-vener- papers on conodonts. the titles of more than 7000 books, articles, and able Treatise on Inwrtebrate Paleontology (Clark et al., l98l) issued in 1981 (but written 1.2 Achievements largely before 1976) is couched mostly in terms of multielement taxonomy, and a majority of The study olconodonts is very different in the current reports on conodonts at least give lip 1980s from what it was in 1950, when I began. service to this more sophisticated mode of classification. In 1967 students of conodonts attending an international symposium on the Devonian System in Calgary, Alberta, were impressed with the fact that data provided by conodonts contributed to a very large number of the reports presented and with the difficulty they experienced in keeping abreast ofthe burgeoning literature and research interests of a rapidly increasing group of conodont students. To solve these problems, the group founded an informal organization, The Pander Sociery, open to anyone interested in conodonts and with the single purpose ofsharing information on current conodont research. Subsequently, The Pander Society has grown in membership to more than 250; has become the official working group on conodonts of the International Palaeontological Association: and has distributed an annual newsletter that includes reports on the research activities of members, addresses of conodont workers and, in recent years, current bibliographies ofthe conodont literature. The Pander Society meets annually in North America and at 3- to s-year intervals at various sites in Europe. In sorting out significant events of the post- For example, in the last 30 years interest in conodonts has again become international, For much of the time between 1926 and 1950, study of conodonts was largely an American endeavor; now there is active and increasingly well-informed interest in nearly every part of the globe. At a meeting of The Pander Society in 1985, the approximately 150 participants represented 31 different countries in Africa, Asia, Australia, Europe, and North and South America. Study has become international again, and there is also close coordination and an unusual degree of cooperation among students of conodonts. These achievements, perhaps more than any others, have enabled the rapid growth ofknowledge about conodonts in recent decades. As noted earlier, assessment of large, stratigraphically comprehensive collections on an intemational scale has also caused a shift in taxonomic base from the morphology of single skeletal elemenls to the composition and relationships within recurrent groups of skeletal elements. This has resulted in a taxonomy for conodonts that, while admittedly more complex than its predecessor, is probably closer to biologic "truth" than the form taxonomy of Pander, Ulrich and Bassler, and Branson and Mehl. Such a taxonomy is obviously a collective effort and, like any other, will always be ripe for modification and the subject for debate. Nevertheless, students ofconodonts now have the framework within which to make biologically meaningful statements about conodont paleoecology, biogeography, and evolulion. and that musl be regarded as an important achievement.

15 srql 'reê^1.oh'cruodlsu ]{llsour,(jqsqojd snql pup slrqou ele^{ sleulrue eql l?ql uorlses:ins requnj e sr suerurssds qsr1lo3s alalduoc ssel lo erour eql Jo uu Tr4 lueuruord eql,oslv ed s?^r ejrl Jo epotu tueururop eql l?qt uoq?c -rpur ub s? sarj"j el?qs-icelq aql ui sluopouoj JO ecue ncco UOUTIuOC eql pj?eoj ol gnuuuoc I prmar puonnqulsrp Oqt Jo selnlsej uro{ ejrl Jo epour Eururu.uatep Jo su?e(il urelj'x 2 pesodord la,{ se seq Juo ou pu?.(+rljo sjporx eseql Jo q3?e luasejdej eujos Jr lo) sja lio^{p uouoq Jo 'sjel?ou ^?ur 'sjerurrjrîs ejo^\ i(oql l"ql peqslq lse su?eur ou,{q sr lr lnq,euu?r.u ejel\ sejnl"ejc alui oql leql ursua3 ^la^rsnlcxe suees li,,(,e^rl sluopouos prp ejeqa pu? 'uorlsenb eql ^{oh,! ol sje^\sue e^rlrugep ou e^pq IIqs e^\ l?ql lno pslurod eq osl? pfoqs 1I 'eiuelleqj sr tr 'ulelqold E oq,{ljedord lou " Îurzuec srqt qenoqllv sdnoje luopouoc Jof?ru ^?Iu lsoru JOJ SOrUaSOI,tqd el?nleâ pu? ezrsaql -u,{s 01 ueê lr Sursn ur Jo srgl ur eseq el?p Jno Suueprsuot ur l?j os ^?,!1 lsojelur eplrj usoq seq arsql'13ê^{oh.pol?qep Sureq,tlluaun3 epou djeuoqnloêjo seuraqcs snou?^ eql el?n l ê ol aslo euo,(u?,{lj?eu ueql uorlrsod leuaq 3 Ur eq pfoqs 3^\ snqj.3rss?rjl pu? crozoelpd eql roj,tqd"rerlejtsorq pellojluoj l(losolc e pue,tluouoxel luejgruers,tllejrtolorq e Jo luaurdo {e ep polqeua wq leql as?q elzp a,rrlcefqo ue petqujosse e^sq sluopouocjo sluopnls.lsjrc 'tujtll lsil I ejeg :sretd?q3 ret?l ur surolqojd esoql ^lejju Jo IeJe -Aes ssajppe ol uors?jjo 0q IJr/r{ ojeql.spofqns Jo Joqrunu e uo popeeu $ uowurroj -ur ejour 'sjee^ 0 lsel eql ^lj?elc ur sluopouoj lnoq? e8pel^\odl Jno ur e3u,tp? prdh aql elrdsod suralqord 8ulpuJd C.I 'slueueârqce luaca.l tuorue qerq Iu?J uorlducsep pue fueôjsrp Jreql pue,e{rd eql u^,\op erxoj 0^?rl ol sluopouoc alelduloc JoJ seleprpu J Surculûoc lsou eql Jq snql ojb teql elou ot tuerclgns sr lr aroq : Jetd?qJ êql ur solor tuuj?ls aêq III^1 suoutdeds qsnlof,s eqj uu I?pn J tueuruojd e pve :(snxotqd -tttv =) ouolsotlpuotg elp.pjorli e^brluud eql Jo (seuolo,(ur ro) qcolq olcsnlu eqt Jo luecsruruoj ej" lpql semleoj pedsqs-uojôqc VJNOCONOJ AHJ pepnjcur eêq ol s(iiees t?ql {urul :stueut -ole luopouoojo o8elquasse IeJnlBu e sur?luoj leql p?oq snoqlnq 3 rill{ elnl"erc elllllllo,r 'eletuole ue ueeq e^?g ol sorceds uerlu?ur(i eql slrssoj oseqj.sluopouoo Aoldruoc ssel ^loqs Jo ejoru luosejdal ol uees lbql suau -neds IsJe os Jo pu?llocs ur s{col ^lojns uerlu?ur(i ul (9861 'qt$rs pue 'uos{rbic,s8itug.e8pu -ptv : 86I'e8plrplv pu?,uos{r?lj,s8itug),fueôjsrp luecej eql lsll plnoqs I sj?e,{ 0 lsed oqljo slueueêrqoe ^lurcuoc eqt Auoluv 'ebu"j ejnleledurel JepEoJq? JeAo elq?jedo sr pu?,{!snpur pesn,{lsnorêjd esoql u?ql a^rsuedxo ssel q3nu ^q sr poqlouj oql esneceq pu? set ro Iro uelal 01 q8q ool pel?eq uoeq e^?q $IcoJ qcrq { ur seejs EUL{Iluept ur spl? U esn?ceq uorlbroldxe ulnalojted ur InJosn tua^ sr qcrq^\ 'Qy)) xapul uo?pntlv jop) E pecnpojd seq e8u?qo srql Jo uoq?jqrt?c I?1 -ueru edxg'ffelc lelsfjc 01.uoqJ?cJo ssol oq1 qlbr '^leteurqf 'pus )c"lq ol u?[ojq ot apd uro{j sue{rep loloc eql pu?,pexg ^\olle^ sauoc -eq sluoruele tuopouoc Jo Jall"tu cru?3lo aql ur uoqj?c 'pourelurcut sr pue sosu ejnlpjodruel tuorqu? sv 'eurn Jo sqfual Eu le^ roj srltdep luejo.gp l? I"unq pasr?j ueeq o,\?q s{jor Sursolf,ue qjrq^\ 01 ^q ejnlaedurel eql pu? slueur -ele luopouocjo roloc aql uoo,tueq dqsuoqelal esolc eql sr (tl6i 'suleh pu?,urelsda,uretsde) djeôcsrp luerej lueuodrrjr i(ljelncru?d.z v Jel -duqj ur i([uol?u" I?lelels Jo uorssnjsrp eq]jo I?ep poo8? pue t Jetd qj ur pessn3srp sl.uopo -uocjo uorle3grss"lj aqljo u?d secuongur a8pa l rodi l?ql '0961 ecu$ euop {Jot\ uo psseq si eepel^\odl tuesojd Jno Jo qcnu lnq,9sgl ur sluopouoc Jo ejnlcnls leujelur eql lnoq? suo4e^jesqo 3lq?F?rrr5J etuos apeur lepued.,'ts ololuoeledojcrur,, Jo ellrl oqt seîes -uaql ol pe^resej tuol os JoJ e^?g oq.al sleqlo pup slsreolojejrururerog yo Auedruoc aql ol ssec -o? Eu pnje ureql peure8 seq leql auo oql pu" 'esjnoc Jo 'Alauolou lsol?eja eql peululle eaeq sluopouoc Jo sluepnts qcq^\ JoJ lueureârqce eql sr srqj tuolsrq rrsseul puu orozoal?d Jo spedse snoue^ eql Jo ses^pu? peugej i(ll?uon -decxa o{?u.t 01 elqrssod sr 1r qcrqa urqlr,r ^\ou IJor'aorrr?JJ e rrloj gcrq^{'seuozorq 0SI lnoq? olur e8e crsszua q8nojqt u?uqusj elq Jo $IJoJ ouu?ur pegllells opr^p 01 sleqd JEneJls -olq pelqsus s q sluopouoc Jo uonnqrjlsro

16 INTRODUCTION may not apply to all conodonts, and the elongate, prominently "tailed" hagfish (or slime References Aldridge, R. J., Briggs, D. E. G., Clarkson, E. N. eel), which many hold to be the nearest living K., and Smith, M. P. (1986). The afrnities of relative of conodonts, is a largely sedentary conodonts-new evidence from the Carboniferous of Edinburgh, Scotland. Lethqia l9(4), creature that spends most ofits life in burrows in the muddy substrate of relatively deep marine water. Clearly, we need to address the Ash, S. R. (1961). Bibliography and index ofcon t. odonts, Micropaleontology 7, 213- mode-oflife question intensively before we 244. delve further into heady subjects such as conodont ecology or biogeography. odonts from the Lexington Limestone (Middle Bergstrtim, S. M., and Sweet, W. C. (1966). Con- On a more mundane level, but nevertheless Ordovician) of Kentucky and its lateral equivalents in Ohio and Indiana. Bull. Am. Paleont. of signal importance, is the business offilling in s0(229),27 t-44t. a number of gaps in the current stratigraphic Branson, E. B., and Mehl, M. G. ( ). record of the Conodonta. Lower Ordovician Conodont Studies. Unlv. Missouri StudiesS.lspecies are well known in the high-latitude 300. faunas characteristic of European localities, but Briggs, D. E. G., Clarkson, E. N. K., and Aldridge, in North America there have been only a few R. J. (1983). The conodont animal. Lethata16, comprehensive reports, and these leave a number of important taxonomic and phylogenetic Klapper, G., Austin, R. L., Rhodes, F. H. T., Clark, D. L., Sweet, W. C., Bergstriim, S. M., questions unanswered. The Silurian is also a Miiller, K. 1., Ziegler, W., Lindstrtim, M., problem, particularly the part of it above the Miller, J. F., and Harris, A. G. (1981). Conodonta. I\ T rcqtise on I nvertebrate Pqleontology Pt erospathodus amorphognat hoides Zone. This (ed. R. A. Robison), Pt. w, Suppl.2, wlpart of the Silurian was evidently a time of W202. Geol. Soc. America and Univ. Kansas, major marine regression, with widespread shallow-water environments, evaporites, and con- Ellison, S. P., Jr. (1962). Annotated bibliography, 202 pp. ditions hostile to development of rocks from and index. of conodonts. Texas Univ. Publ. which conodonts might be extracted easily and 6210, 128 pp. - (1963). Supplement to annotated bibliography, and index, of conodonts. Texqs J. Sci. in abundance. Nevertheless, a number of very important events in the evolutionary history of 15, the Conodonta took place during the late Silurian, and we badly need well-documented col- Pennsylvanian (Dimple Limestone) conodonts -, and Graves, R. W., Jr. (1941). I-ower lections as the basis for frnding out what happened. Taxonomy of Carboniferous and ser. r4(3), l-21. of the Marathon region, Texas. Univ. Missouri School of Mines and Metallurgy Bull., Tech. Permian conodonts is in less robust health than Epstein, A. G., Epstein, J. B., and Harris, L. D. is that of earlier forms or that of most Triassic (1977). Conodont color alteration-an index lineages. Only a few studies have addressed to organic metamorphism. U. S. Geol. Surv. multielement taxonomy of Mississippian conodonts with conviction, and a few excellent re- Kansas PqleonL Contr. (Vertebrata) Aft. 3, 206 Prof. Paper 995, 27 pp. Fay, R. O. (1952). Catalogue of conodonts. Univ. cent studies suggest that there are major surprises in store for anyone who undertakes Hinde, G. J. (1879). On conodonts from the pp. detailed studies of Permian conodonts. I recommend these stratigraphic studies strongly. lurian, and from the Hamilton and Genesee- Chazy and Cincinnati group ofthe Cambro-Sishale divisions ofthe Devonian in Canada and Finally, we have probably reached the stage the United Statas. QuqrL J. Geol. Soc. London at which monographic studies ofthe taxonomy 35, 35r-369. and phylogeny of major lineages are in order. Holm s, G. B. (1928). A biblioeraphy ofthe conodonts with descriptions of early Mississippian To be sure, a number ofsuch studies have been completed, and my debt to them is plainly in species. Proc. U. S. Nqt. Mus.72, Art. 5,38 pp. Huckriede, R. (1958). Die Conodonten der Mediterranen Trias und ihr stratigraphischer Wert. evidence in Chapter 5. We need still more of them, and existing collections will probably be Palaod. Z. 32, l4l-l'75. adequate as the basis for many. Kohut, J. J. (1969). Determination, statistical

17 'dd.rads ea,l lqnj MnS 'lurl/.lte,loseuurl loag I Jo seunej tuopouof, usrcnop -ro reodn pu" olpplht eqj (996t).l.c.sreqe^l '901 -l 'Iv tlrsnjaapog saluosapuo7 ssag.qqy 'srnlrs sop ueluopouoj (?96l).H.o,rcsrllBld 'dd 901 '65 ttuoj.moapj sdsuox Mun 'sesue) ulels?e Jo (u ru"^1,{suued Jeddn) onolc eeu^l?qs eql ur uonnqulstp luopouojjo lorluoc plueruuojrûq -kl6i) H.d.Jelllg uo^.dd.zi.lrv e9 '89 Jo]d sltw llon S'n.sercads uprddrssrs -srhl pue ueruo^jc ubjuauv Jo suondujsap qll,r 'stuopouoc'slrssoj eirhlool eqljo uorlpju -rsselc v (9z6l) s u'relss"g pue,.o.g.qculn 'zl-62'1.âoj.luoal'j 'uty'n 21td {ruouox?l luopouot ur ldecqoc clreueb eqj (6961) ti S 'ru-'ojts8reg pue,-.lqnd.rads,t8oloa) _ slz-l1z,t 'fiaq 'sosudx '^run.(tf,eqxl I unj pu? lo(u -tijn) pjequreg 'pe) uplsdlo{ $a./14 lo JlssDltJ pud uotwdd swalqoq ftrypunog TtldotS -tlzris ui uetsdtsd lse^,'t 'sesueu snpul-suprl pup e;ueu lles eqljo sluopouoc crss"rrj lemo.i pu? uerured lsorrlroddl).(016i).j.i[,133^\5 's9t-8t?'8 'luoalpd t sluopouoc eqljo sdrqsuo4elor J?cl8olooz eql (t 6t).H,ttocs ir\ ' g I z' l u oo l D d Bu"queuu'snz -rn ur epunc-ueluopouoj (t 61) -"q"r69u8n-r9dt.h.lp[uqcs 't '92 'tuoaldd t so8elqrusssb luopouoc u?rue^l^s -uuedjo uoq"cgrsselc V (Z56l).J.H.C.sopoqu 'd.d 16'Stnqslalad g 'ss!,,ll pdlv 1tlloy sluel'ueule^noc usqcsn 1eq-qcsrssru rop sruols^s ueqcsunlrs sep oqcsrg uelrssoj rop erqdersouol{ (99SI).H.J rropued 'dd.)lro^,uopuo.j,uleprets 961 -ruv'rorêslg sluopouoj ^{en (?961).I^l.rugJlspur.I 'zw -Z6E 'Q)E? tuoaldd f (puerpul pu,^)tcnr -uex 'orqo) uor8eu qbuurjurj eql Jo 4er1s uerclôpjo Jaddn pu? elpprl ur sdnof luopo -uoc luaj.rncaj Jo uoqelejfuelur pue,sts,{leue VJNO(IONOJ :IHl- OI

18 2. SKELETALANATOMY For reasons listed toward the end ofchapter l, it is now clear that conodonts were primarily soft-bodied animals. Their only mineralized parts formed a cephalic apparatus, at least partly of epidermal origin, that probably functioned to grasp prey and aid in the intake of food. In most, if not all, conodonts, components ofthe exoskeletal apparatus were discrete objects that became dissociated from others on death of the animal. Although collections at various places in the world house several hundred more or less completely preserved apparatuses, discrete specimens are the ones on which most of our information about the Conodonta is based. Pander diagnosed lhe Conodonten in ieffis of the physical characters of discrete specimens. However, everywhere in his monograph except on the page bearing the diagnosis, he referred to the "teeth," "jaws," or "rernains" of conodonts and thus used that word both for the animals as a whole and for their hard parts. I am not aware that this dual usage of conodont has ever puzzled anyone, but tlre potential for confusion exists. In the rest of this book I will use the word conodont only for an entire individual ofthe Conodonta. The term "conodont element" (or "skeletal element," or just plain "element") will be used for discrete components of the cephalic apparatus. 2.1 Composition of Conodont Elements From what appear to have been rather primitive wet-chemical analyses, Pander concluded that the skeletal elements of conodonts are composed entirely of calcium carbonale (reinem kohlensaurem Kalk). L few years later, however, Harley ( I 86 I ) wrote that "...they are composed ofphosphate and carbonate of lime, the former, contrary to my expectations, the more abundant constituent." Hinde (1879), like most others, felt that most of Harley's specimens were not conodonts and continued to maintain that conodont elements are composed of carbonate of lime. He cited this evi dence to counter conclusions that the little fossils might represent a group related to annelids or "naked mollusks," whose jaws or radular elements are of purely organic composition. In 1926 P. v. Roundy reported that conodont elements "... appear to be a phosphatic carbonate of lime." Six years later Stauffer and Plummer asserted, without citing further evi dence, that "conodont teeth are probably chiefly calcium phosphate." Branson and Mehl seem not to have worried much about the chemical composition of conodont elements but, in 1944, one of their doctoral students, Samuel Ellison, demonstrated from X-ray analyses that the substanc inyolved is a member of the apatite isomorphous group. Because ofthis, conodont elements are relatively heavy (2.84 to 3.10) and are less soluble in acetic, formic, and citric acids than the matrix of carbonate rocks enclosing them. This is important. ofcourse. because it means that conodont elements may be extracted from carbonate rocks by prolonged soaking in such acids-a capacity that sets them aside from many other fossils-and they may also be separated from large acid-insoluble residues by use of healry liquids or other types of gravity separation techniques. The most definitive, and also the most recent, contribution to the subject of conodontelement composition is a monograph by Pietzner et al. (1968), whose studies led them to the following formula for the mineral matter of conodont elements, Ca, Naoto (POa)3.qt(COj)0.r6 Fo', (HrO)'.s5 They interpreted the mineral to be francolite, a carbonate apatite in which the OH and CO, ions substitute for phosphate and do not occupy lattice positions as they do in hydroxyapatites. Traces of at least 39 other chemical elements have been identified in various nlaces

19 pue qta4 qsg Jo 13rlt. elllun olmb leuu?ur e ur slueluele luopouoc leql lueeur s?q srql ^\aj8 'sjeqlo pu? ssojc oj ql/{roj8 Jo seurrl 1? ens -srl papunojjns ueeq e^?q lsnru.{i1uejgru -fts ^q tsoru 'pue fuesoluo q8norql JeAlEl -sersojd eurejeq sluaulele.uoqs ui.^[?ujelur ^lo^n eeuruj?l Jo uourppe (q1ae1 ur sz) tou.e?ur -urel Jo uoelsodde leurelxe ^q a,trsseccns qtnorql u^ror8 a^?q lsnur eloqz,r z se luauelo eq1,bu11g I?S?q Ol UIAOIC ruo{ SnOnu4UOC eq 01 eellaur -?l roj repro ur leqt lno peturod ssojg (096I '/56l) ssorc,{q sjeded Jo seuos e ur ote sjee,( 0 lnoqe tno lq8norq sen l?rlu?tsqns sr qcrq,{r 'lc J srqt Jo aru?rg[ers eql 'uorteurt?u]r go 1rq e lsnf qlf\ suorsuaurp eejql ui pozqe -nsh eq um pub.8lj I.Z ur suorsuaullp o.r1 ur u,roqs sr srql 'snonunuoc et? AurTIg l?spq pu? u/yrojc Jo eeuruel,uollces urql ur JeJ snr{l por -pnts stuauela plele{s elelduoc eqljo IIe ui.burfig l?seq tu?l -slsej ssel egl Icq suerurseds elejjsrp lsou 1"q1 pej eql suleldxe srql pue,el?j?des luotu -ele eql Jo slueuoduoc o,'q eql Îp"er qjrg \ euol? ssedleendjo ec?jjns e sr Suqlu lespq pue uaojj uao/{\leq oc?j[ns eqj.u^{ojr aql Jo esoql u?ql pozrflauru,tlosuep ssel pu? relcql aq ol pual 8ul[g pseq aqljo o?unxq leql ur,{iuer.uud JeJ -Jrp slueuodruoj o^r1 eqj 'slrefqo,(un esaqt Jo suo4cos urll ur pepoôj selnl?ej uo luoruruoc ot lsrg eql osl? s?^r oq^l,jepued su^\oj3 ^q JoJ pelou tr?j?-pet?urur?l ere qloq,,{geu -relul 'pesn,{foruuroc zrb 3u!ll{ lqsdq ploe u$o.tj surre'j, eql gclqd{ JoJ sued ljullslp oû Jo tsrsuoc stuelllole luopouoc pe^jes"rd-il"+-._ '8rJ ur,{lpcq?ruute,s?rp u^\oqs oj? sejnl;; IEJnpruls Jof?IAI'oJnpruls ptuolur ur JEIrrrJrs.lqelJeureJ ej? ôqt leqt el?clpur soenls Jo requrnu z ',{Eoloqtuoul l?ujetxe ur,{ilbeja fu?^ stuopouoj Jo slue{rlele plele{s oqt qanoqllv sluoualfl?lola{s Jo arntrn4s z.z 'posrej ueaq 0A3q $[3oJ 8u$olcua qcll.{r ol ejnt?ledruol eqt ol xopur alejnj3e ^lqoferrrej " sr slueuela luopouoj Jo roloc ern l?ql porsôcsrp useq s"q 1I.pexg sauoceq uoqjec arueejo Jreql Jo ejoru pu? erour pu? peleeq oje se,( enpe$ ue{jsp stueuale tuopouoc tbql êqt l3ej eqt loj elqrsuodsel sr IELr4"ur cru?blo pouelel sql.lueuela oql urgll^r pourelej sr r{crl,,rl 5lJo^reu?{ cru?ejo ue urql$ ejeid lool uo4?zrpleurur teql selej -Ipur pue uoqrsodruoj ur ctue8jo sr elnpnjls elecrlep sql 'sul?lliel lsoge pezrtaauruop 'elrae{ e 'prc? ouolqcojp,{q Jo uonnlos {po,t\,? ur r(l^lols pe^lossrp sr lusrrrete luopouoc?ji 'pe^r sluopouoc qcrq/'( ur serpoq lale^\ eql ur suo4rp -uoc SurleJfu alur ur ajupogru8rs elq"joprsuoc Jo eq ol oruoo,{lot?t e^"q (urnnu^poou''a e) eseql Jo euos pu? 'stuopouoc Jo sljed pffq eql ur...-. ll::q *lsso.erjo seuoz opr^r,{q perepioq sr qjrg r llrd pseq ' e s"q (g) ur -:ta1t-"_t euo oqljo teql seereq^\ lrêcles qlecruoreseq(v)urlueruoloaqt3ouno:csq1:ubipesssbrc,rrslue*elal,ropouoceleia-ruo3..1.7,aig ûlt VJNOOONOS AHJ, ZT

20 SKILETAL ANATOMY thus that the Conodonta were probably not fish, as Pander and many others have thought them to be. Elements of the cephalic apparatus of most conodonts were dissociated upon death by decay of the tissues that held them together in tife or by digestion ofthose tissues in the gut of a predator. In only a few cases have complete apparatuses been preserved. After dissociation most conodont elements were moved about with other sedimentary particles on the seafloor and that agitation was apparently sufficient in most cases to separate crowns from basal fillings. In any eyent, most collections of conodont elements consist entirely (or almost entirely) ofcrowns, and we have little or no information on the internal structure or extemal morphology of the basal fillings for most species. I suspecthat th basal fillings of a great many species, perhaps the majority, were only slightly mineralized-or not mineralized al all. They are mostly unknown as isolated objects in rocks that contain lots of discrete crowns, and they do not occur in any of the complete apparatuses that have been described, which however, only the first few lamellae overlapped basally to form a very tiny basal cavity, whereas later lamellae became progressively shorter than their predecessors as the crown grew larger. Basal cavities of crowns with features like this are termed basal pils, and the remainder ofthe attachment surface is described as a zone of recessive basal margin. In most parts of the crowns of typical conodont elements, lamellae are 0.2 to 1.2 pm thick. However, at places of accelerated growth in elements that grew laterally to form platelike structures, or toward the extremities of those that built elongate comblike shapes, lamellae may be as much as 5 pm thick. As noted previously, each lamella of a complete element surrounds all its predecessors. We can see edges of lamellae along the attachment surfaces of crowns- however. and outlines of some ofthem are cornmonly visible in transmitted light within the thinner parts of many crowns. Each lamella is built on a framework of organic material, and the tiny apatite crystallites that mi neralize this framework are oriented with their prism surfaces parallel to the direction of seem to have undergone little, if any, physical growm. distortion subsequent to death of the animals. In reflected light crowns of conodont elements are shiny and translucent. They are pale Whatever the explanation, nearly all we know about conodonts is derived from a study ofisolated crowns. not been heated above 80"C for any length of amber in color if they are from rocks that have Crowns ofconodont elements, like basal fillings, are internally laminated. In morphologi- reddish yellow to brown to black if they have time; otherwise they may range in color from cally simple forms, like the one in Fig. 2.1A, individual laminae are conical in shape, and the temperatures. Elements from some metamor- been held for any appreciable time at higher entire crown has the structure ofa nested stack phic rocks are gray, white, or even crystal clear. ofpaper drinking cups. In the conical specimen Evidently elements such as this have been of Fig. 2.1A, the basal filling is still attached. deeply buried and kept at high temperatures for However, ifthe two components ofthe element such long periods of time that they have lost were separated, the surface over which they even the fixed carbon responsible for the dark were joined would be that of a conical indentation in the abapical part of the crown. This rocks. colors of specimens from lower-temperature indentation is termed a basal cavity, and it occupies a part of the crown known as its b4se. formly translucent and ofthe same pale yellow- Thermally unaltered crowns rnay be uni- Note in Fig. 2.lA that basal edges of successively younger crown lamellae extend some- within them more or less irregular, fuzzy-edged ish color throughout, or one may distinguish what farther toward the basal maryin than their masses that are opaque and of whitish appearance. Crowns ofthe first type are said tobe hya- predecessors. Thus, the surface along which crown and basal filling were originally attached /irq those of the latter are tened albid. Many is completely enclosed within the base of the crowns have both hyaline and albid areas, and crown. In the element depicted in Fig. 2.t8, internal distribution of the white matter thal

21 -oe sorrrsu eql sepnlcur osle gcq^{.i.z olqej ur ue^ sr seuotelej ed"qs Jo uorlmgrssqc V 'seuoeol?c osor{l JoJ oî1 -dujsep eqt ol pu" souoeet"j ^toloululel odeqs lof?ur Eur -zru8ojej pue lno Euruos ol pmd eq lsnu uon -uolt? Jo I?ep poo8?,ûlouox?l luopouor roj srs?q tu?luud eql osp oje pue slueuelajo uon -cunj eqt ol. se eêq a^\ sanlc lseq eql. oje sed?qs asoqt esneceg 'sed?qsjo,geu"^ EursnJuoc pu? epl^r e ur lnoco sluourele luopouoc.aur?s eql qjnur aq,teru sejnleej l?ujelur lteql qenoqllv su,norj luaualg Jo sadeqs t.z Jo dn op?iu er" qcq^\,oeuetuel {Jrql leql?j Jo llmq eje sluourele rujojrluopojneujo su^\ojc eule^r{ eql l?ql 'Jeê,,l\oq,u^loqs oêq ser -pnls lusnbesqns 'seulojrluopornon Jeplo eql 'sluopouoc Jo dnojt alej?des,{fiecrurouoxel? luesajdej ol ue{4 ojel\ ejnpnls,,snojqu,, e^rl -Jurlsrp qjns qlll(r slueuela.e?ltourpljo peelsur sroqujo selpunq el?tuolejo pelsrsuoc elntcuts l?ujelur lpql ueerl ol stql peleldolur,teql 'surejeu u?elj Jo peelsur pe,{e{ gll,& salnl -r?{ rxjoj ol )pelq 01 puel $ltoj u ljrôpjo elpprw ruo{ lseq u1(ou)[ sluopoum Jo dnols ejo su^{oro eurj ^q,{lelalduoc lsouil? eqt leql lcej eql 01 uonuells pallpc IIew pue uosusrg 'sluopouorjo sauolsrq ejil eql Jo sejnlpej Surlartualur ur pu? -xe1 ur luecgrutrs ele snql pue IoJluoc ûouo cneuet Jo suorssejdxe pcls,(qd,(lejns lsourp eje,{iiejr -leuatoluo tujoj sasserrr eseql qcrq^l ur ocuenb -es eql pu" su^\ojc luopouoc Jo subd prqp ur sess?ru Jell?ur-eltq^\ Jo sed"qs e^rpunsrp eql 'uoqs ui 'slueurols eql pep"^r3d l ql sans -sll ern Jo lojluor lopun se^l spro^ JellErrJ-elrq^\ aql e^?el ol el uoqjec ro et?qdsoqd FurAuo er{l Jo euos Jo uonfuosej pue elled" eqt Jo uorlzzqplsfucs.r l?qt osoddns ot elqsuoseer sr ti luopouoc e Jo erurlejrl eql Euunp flpnpu8 ecqd {ool JeDerrr elrq^,\ ol e"urujel eurp^q,(ipu uojo uorsjeûoo l?ql sueas osl" lr ecurs 'seprluep pu? sdsnc Jreql Jo suortej prx? ol Peuguoc s?ej? prqle e^rpudsrp pue uql e^?q ro rell?tu elrg^r {c?t l?ql stueulolo peuuoj ^[aj4ue serceds Jo sdno laqlo,oslnoj JO.Jel -lelu elq^\ Jreql Jo uoqnqulsw eql ur sujell"d JEIrurs,{IosoJo.r\oqs,{For.uuroJ serjeds eures Jql Jo se8els crlauetotuo ejqej?dr.uoj lujsal -dej ol pespn f sluauele teqt onrl sselequeêu sr li 'ûrouoxel Jo,(EoTorq luopouoc ur ecuecgru. pnrporuoud Joplo eql ur pepnlcur eje sluopouot.uuojrluopoj -8rs slr pezrutruru eêq pue uorl?jellz fu?puo ^{ou -ces Jo llnsej s" su^{olc prqle Jo JeD"rrJ olrq r -nau ro 'snorqu s.hei I pu? uosuerg Jo sql pepreeej " o^?q sroqln" euos qanoqllv 'ernpruts puletur tuero.ulp teqla [q peqsmt û?iai 'ezlleur?j eurrc^q perelpun,tr.ag e 1sze 1e,tq -uqsrp dnoj8? tur,tnuepr ur l3euoc pejeôc s,(eal? ej? pue selcuuap pue sre,t Asql 'e" eruq leujelur Euqcel ^nuel?dd? se sluopo ^lleujolxe sdsnc u^lojc Jo suor8al plxe eql ur polejlueo -uoc rrrjojrluopojneu Jo su^{otc orn Eurqursap -uoc ojs Jon?ur ellq^\jo sessetu l?ql ur pelle oêq ^?ul HaW pue uosue:g qenoql 1? 'snql 's[oêl pelou ^luo(uutoc eq plnogs lr ',tlleurl.f[p?el alrnb sjnc luoje:urp 1? I?elq teql susud -co eae)i?ojq qorq^r Suop secqlns ssje^su?ll pelced ej? eellaurel Jo slueuoduoo snonuduor lsorup fueut,(q pessojc ele seej a{qpor oql Îesolo teql lee,ta: glnor8go srxz aql ol lalp -Jed seoelns uelorg.qu{ojbjo plqle aqr t?ql os uorlezlflelsfucer go seposrde srx? eql ot IoII? -JEd polueuo et? leql setrjl?lsftc e)lrjpoj,auol Suunp JeqloSol.{Duar?dde sejqrns qcns 'reqljnc JellEru ^reja elrq^\ tunlnsel eql ur peurel -aj sr Jalleu ourler(q I?u6uo eql ui secqjns I?l -s,{:c lggg oqljo uorlelueuo,ee11erue1 pureuo Jo uou?jelrlqo Jo Surrnlq pue loueu elrq,rl uljoj 01 uo4szlllblsdjjej elrdsop l3q1 pe^\oqs sluopouoj epquopojepued r\oj su,{rojc eql ur seere prqlejo (IL6l) relsez "Jo pue rxorlspur.i,tq sepnls '^lsurlselalq.u.rolc eqt Jo sued ourl?,4q,(lleurjoj Jo uouezlfl"lstucoj pouuoj ssere prqf Jo roll?ru elq^l eql l3q1 ^q el?crpul sdrqsuoneler aseql 'pal?ururq,tpcurlsrp pue ourp^q ej? l?q1 u,{'ojc egl Jo Er?d olur seoj? peur8reru-,tzzn; aql q8norqt f1era1e1 epe:b,taql lnq 'su^rorc eiiies eql Jo su"d eulle,{q ur snor^qo sr l?ql uorleurur?t aql {cbl leuput otlq^r Jo soss?i I 'oduqs l?feeur lo l Jueqds Jo seqrêo,{ud,{q pel erujed sr leqt elrlede eurjplsfuo FIaUU fue^ Jo pesoduloc sr lall ru alq^\ 13q1 suees lr 'ejnpulspjlln luopouo3 Jo selpnls lue3el uolc lepu?d Jo eurn eql 33urs sluopouoj Jo sluepnls pelsejelul seq su/.rojc plqp ur r011"ru elrq,ia eql Jo ajnleu eql 'serceds luopouoc etu s 3ql Jo sluoluele ui eur?s eql,{yreau ro arues eqt,tluo(uuroc sr sued prqp eq1 seqsrnturlsrp VINOOONOS AHI nl

22 SKELETAL ANATOMY t) TABLE 2.1. Shape categories ofconodonl elemenls Major shape category Coniform (simple cones) Ramiform (bars) Raslrate Pectinform (blades, plates, platforms) Primary divisions Geniculate Nongeniculale Alate Teniopedate Digyrate Bipennate Dolabrate Quadriramate Multiramate Stellate Pastinale Carminate Angulate Segminate Secondary divisions Breviform Extensiform StelLplanate Stelllscaphate Pastiniplanate Pastiniscaphate Carminiplanate Carminiscaphate Anguliplanate Anguliscaphate Segminiplanate Segminiscaphate Bisegminiscaphate Trisegminiscaphate plied to those categories in Volume W (Supplement 2) ofthe Treatise on Invertebrate Paleon- two categories (geniculate and nongeniculdte) Coniform elements are funher divided into tolosy (clafk et al., l98l). on the basis of the type of curvature. Seven Pander, the first to describe conodont elements, divided his specimens into two major nized on the basis of the number of processes major types of ramiform elements are recog- categories, einfache Zahne ax.d zusammenge' and their relationship to the cusp. Pectiniform setzte Zahne (i. e., "simple or single teeth" and elements are divided into five major groups on "compound or composite teeth"). That division is still useful, although it has been custom- primary processes. If pectiniform elements de- the basis of the number and arrangement of ary for many years to divide the "compound or velop platformlike lateral extensions, they may composite" category into two or three divisions be further described in terms of the resulting termed Ddrs, blades, and plates (ot platforms). shape ofthe attachment surface (planate or scaphate). Typical representatives of each of these In the shape classification adopted by Treqlr'Je authors, Pander's simple or single teeth are categories are shown in Figs. 2.2, 2.3,2.4,2.5, coniform (cote-shaped) elemenls; barlike compound or composite teelh are ramifurm (ray- terms used to describe features ofeach ofthese and 2.6, which also include information on shaped) element$ and blade- and plate- (or element types. platform) like elements are grouped together as pectiniform (comb-shaped) elements. Elements described in Table 2.1 as rastrate have Coniform crowns been regarded either as peculiarly modified Coniform elements, which are also known in coniform elements by some authors or as compound elements by others. They were not spe- "cones," are basically of conical shape. Pander the literature as "simple cones" or just as cifically identified in rhe Treatise classification divided elements like this into two parts, a of shape categories but are here regarded as a more or less expanded base, which encloses a separate category for descriptive purposes. subconical basal cavity (Ihe Cavitas Pulpae of

23 sluelllele urrojru?j Jo sod,q Jofuru ueôs 'sassajold lolapl PeIIIrel er? lueuelo rrrjojrur?j? Jo seprs eql ol as"q eql Jo suorsuol -ye pue lssajotd tohalud ue sr dsnc oql Jo sprs Jouolus arb Jo uoqcofojd IDsDq D sr l?ql ouo ',ssnotd nua$od E sr dsnc eqljo eprs 'rouelsod ro 'o^?tuoc eql qia\ snonuquos sr l?ql ssocojd v 'pluoz oq dsnc oql ol Jouetsod os"q eqljo uoruod l?rlt Jo ur8jzrx reddn eql pue dn xod? dsnc oql qllr\ 'slueurele rujojruoc se Jeuupru elll"s eql ur peluouo aje slueuele ujojrr[?ll 'atdln?ltuapd eq,{?tu sessacojd eiijos lnq 'saptmap ere ssajojd e uo suorl? es pnpr^rpul 'olejjos(,(lq?u?^ -ur lou lnq),{iuoluruoj erc se8pe Jeddn esoqa\ 'sassnotd rljro! ot dsnc eql urojj,{e,{r" pepuelxe ej" eseq eql Jo ssepa Jo sop$ eql Jo elorrj Jo ouo..'sjeq,, se z86i ejojeq ejnlslelrl luopouoc 0IIl JO qsnur Ur U?r\Ou)I 'Slueuiala rrjojrru?j UI sa$uj rarojnldy z t z 'sluauap runrluoj anttstp perjrr4 eq lqeru f,lfseq suortca:rp elrsoddo ur 1sr^{l lsqt eelsoc lerolq qlrir\ suuoj culeurru^se pu? 'stuerrrela (alolnnuasuou afop Jo) awln7ruas apld se pequcsep eq ga.tr lqerur e?lsoc l"rolu I snonsrosuoc qll{l slueurale rxrojruos l?suleur -u.il(s fll?jelqrq 'sldru?xe JoC slusuole rujoj -rubj roj posn surjel e qdutsep eql Jo JIrJosu^roJc ^[uo,'aou rurojruoj roj ezrlrln ot alqrssod eq [?lll tr t?qt lsettlns I 'p"etsul 'ejeq surel pozq"roeds I"uonlpp? asodojd ot fu?ssoceu oq plnoqs lr oêrteq lou op I 'el?crpur Plno,[ uorl -EogrsseJc adeqs plojo^\l e uegl xoldrum ojour sr dnort srql urqlr^r uon?ntrs cboloqfuotu ar{l 'lselle ud slueluela uuojruor qlya pe)ljo^l s?q oq,'a euo,{ue se 'Je a,y\oh 'dsnc eqt Jo aepo rouolsod er{l olul os?q 3ql Jo urtr?ur roddn eql Iuo{ uorlrsue4 qloor[s 3 sr ojeql sluorueje uljojruoj awlnnua8ua ur s?ejer{,r\ 'e[8ue elnj" ue ur dsnc eql Jo urtj?uj Jouglsod oql surof oseq eql Jo oepo Jeddn oql 'slueuolo rrljojruoc alo1ntua? ui peqsrn8uusrp are su/r\oro rurojr -ooc Jo sed,{l Jof"ur ot t ilao aypatj eql ui 'Z'Z'Erg ur potecp -ur ASolourrurol e^rlducsep eqt uaqt,{?ru euo ',{e,$ srql ui pelueuo su,{ioro ^ldde u ojruos oj 'lzluozuoq eseq sqljo o8po Joddn oql gll^{ pu? dn sdq Jreql qlld\ peluerjo ej? sluetuele uuojr -uoj'sgsodjnd e^nducsap rod 'saajtep snou"a ol po^jnc sr ro tqere4s raqlra sr leql six? EuoI e seq pue 'lrun eql Jo xod? eql ol sjed?l 'pqos sr qcqla '(azrrds' s,jepued) dsn, e pu? :(Jepupd 'sesue) Jo,{lrsJe run pu? cljeuv Jo ilercos lecrsoloec eql Jo /kolnoc.âolotuoslsd elerqeuoûl uo esupolf Iuo{ ur\rerpor lqgu uo ruejs?rc.su^\olc rulojruocjo sed l loferu o^rf eqtyo A8olouluuef pue uoqq uaug.1i3.b;g alelncruaouou atelnjrua6 iauroc leseqorelue urore 'u lessq llêc lgseq,euroc lesgqojelsod essq lo ur6js rl,addn alsos le.l eurj9c dsnc lo 'drl to 'rede VJNOCONOJ AHI 9I

24 SKELETAL ANATOMY l7 have been recognized. Names for these shape nally form-taxonomic concepts based on alate categories are listed in Table 2.1. Typical forms ramiform-type specimens. are shown diagrammatically in Fig. 2.3, which Tertiopedate ramiform elements also have a also includes some information on terminology. Alate ramdorm elemenls are bilaterally side of the cusp, but the lateral processes are posterior process and a lateral process on each symmetrical, lack an anterior process, but have not symmetrically disposed with respecto the a posterior process and a lateral process on cusp and the posterior process is commonly each side of the cusp. In some descriptive reports, alate ramiform elements haye been Digyrate ramiform elements are like alate long and conspicuously denticulated. termed "trichonodelliform" or "hibbardelliform" because the genera Trichonodella and, rical; only rarely is the posterior process well elements, but they are individually asymmet- Hibbardella (and several others) were origi- developed and denticulate; and lateral pro- Fig Ramiform crowns and their orientation. Tetus used to describe th m include the followns: ac = anticusp;ap: antetior process; bc = basal cavity;bp = basal pit;c = cusp;d = denticle; ilp = inner laieral process; lp_ = lateral process; olp = outer lateral proc ss; pp = posterior process; and zrm = zone ofrecessive basal margin. Diagrams rcdrawn from Trcatise on Invertebrate Paleontology, courtesy ofth Geological Society ofamerica;nd University of Kansas. ant + post quadrtramate dolabrate olp ta.l opodate ahlo

25 -IJJq. = q pup:^1o!nj _J:JIJnuJp = p :dsnj = J:?ur^lolloJ oqt JpnlJut ruj-ql equjsep ot pjsn surjej uorlslueuo rreql pue su^rolj olerlseu.r.z.t!d -?JeJ qlr^{.sua{ojc JulaUrUr,(S?,{lpnpr^rpur 'pesserduoc " eêq (r.e.erc) sluetllale elslls?u 'peuroc spl{ ald4sd,t prot'l^ eql pu? pezrueocej sb/(r euo roj poeu eql 6t6T ur parlsllqnd I uodar c4eurals^s? ur lnq 'sluoluela t4arts roj asrpatj oql ur pesodojd s ^\ rujel e^bduosep pnods on 'dsnr eql Jo urtj?r.u louelsod o^?cuot oql uo selruuep I?Jsês ol euo dolaêp AluourrfioJ lnq sluetllale tiijojrril"j IsJrd,g Jo soss$ojd eql ol elqej?duoc selnl3ruts {oel l?ql slrun ruiojruoo fljeorseq sft snllpubdeah pue.ourpo laqdtdd'durpoqlurynj,ourpopqopnasd,durp -opg ejoue? ap4uoporepued eqt Jo slueruela su$onapqsvv t..2 'slualuala uttolraot apwotlqnru parujel eq tq8ru (pore -ôcsrp eq reê,{us pfoqs) sossejord lnoj ueqt ejoru qll.t\ esoql s ejeg,tl,stuauala unltrad.t apuotupdnb se pequosep er? (l?jel?l o,{l pue 'Joualsod 'Jouelue) Îet?udorddp sessajojd JnoJ qlrn ^{ej asoql.oj?j ej" sessecojd fu"ruud eerql ueql ejou qll^l EuerrJele ujojnu"u.,{uouoxq lueurelorljnrll pu? Kurouox?l rrrjoj uea,{qeq uorlrsu Jl Jo J? Jelur eql ur penedd" luql $Fo,,l\ e^rldursep ur..tutoj -uuoporuoudoeu,, puz..uuojrluopouou^c,, peurjal ueeq osle e^?q uos s trl JO Sluau -efg 'sorceds luopouoc snoue^ Jo sesnlpj?d -oe lelela{s eql ur ed^l srql Jo slueuete ueeal -eq [SoToruoq olqeqojd oql ezrseqdue ol u?ql uos?ej Jeqlo ou JoJ.el"lntlue8 Jr s" poqursap ^{ou suuoj eqt JoJ tuau)p uttoltuot autqopp uorssejdxo eql esn ol et?udordd? eq lq8lt'u fl 'tc?j ui 'sserojd Jouelsod elefcuuep e Euheq ui sluourele ulojruoc elelnoruee uro+ JoJ -Jrp,(eql Îuo 'tcedsoj srql q.pedsp l?jet?l ur ped?qs {crd,{iuorullioc ej? pue ssecojd touelsod e e^?g stuauap unlrrudr aptqdpe ^lrro 'eteuueolq ural Iurlneu eq1 ;o,{1qrqz li? e qlr^r aseec ^llsjntelcueulou [r^\ ecncejd srgl l?ql pedoq sl tr q8noqlp 'sjed?d cu"ruets^s ouros ui..urloj -4uopol,{proc,, Jo..urJoJrlapoepulq,, peulrel ueeq e^?q sluaurole urjojrr[ej oleuuodrg 'o1?lnorluep" ss$ojd Jouotsod eqt pue ol"in rl -uep sr ssecojd Jouelu? egl (snpoutsttg pue uopouad Jo sorceds Jo sesntaedd? plela{s eql ur '3'e) ses"c,\lal B ui.urfueu dsnr aqljo uors -uelxe e{rle8uel} e Aq,{luo peluesardal sr pue sglcquep $lcel ssejojd Jouolu? eql,,(iuoruluoc -un lon ',{lfretq 'pelcouop sr ro 'se^rnj -(IIoc pu? ssecojd Jouelsod egl u?ql Jeuoqs ^luouj si ssecojd Jouolu" eql,sluer[gja ujjojrrrr J elpu -uodrq lsou.i ui.dsnc eql 01 lcodsej qlr,t\ uoqrs -od ur Jouelsod pue Jouelu? ej? qorqa{.sassec -ojd o^,u eêq.sflrruala uuofnud,r apuuadrg 'stueluele atej^8rp rujojrêjq loj suon -?u8rsap Jrutouoxel-urJoJ elo^t snllpu&ortuo -ug pue snqpuso8tz s?ereq^\,stuourele elej -,{3rp urjojrsuolxe JoJ ruloj ur pela -ajc ere^\ snpoqlodsopald ^ruouox?l plue snpopo -dsn} eql qlr^{ ajnlounfjo lurod eql le alnl? JnJ JorJ -elsod ro Jouolu? Jreql ur3eq qjrq^\ 'sessecojd lopoqs gcnur o^?q ol ^llproue8 pual Jellpl eql 'spue I"lsrp Jreql lz ro,(ljouotue tur - rno etojeq dsnc aql ^llouolsod uro{ pr" Uno,(lsnonrrds -uot puelxe,{foururoo 1eq1 sessecord pre1zl Suol aêq rorruoj eqj.slueuele eif-r^trp ulto! -hatq pue lanltsuatxa ueeûeq r{srneuqsrp ol InJosn etmb ll pug,s I leld?qj ur t?rll suo$snjsrp ui'sasnlejedd? ^lolloj luo{rrelerllnut snor -Je Jo slueuoduoc el?j,terp eqt loj.,urlojrql?u -eobueue,, pup..,urjojrql?ueo8,(2,,,.,rulojrluop -oq1edso1ca1d,,..'rurojrluopolno!, se qcns sujel sopnpur ejnlejolrl a^rlducsep 9rfl Jo auos 'sueunceds-ed,q ujojrrrrel alej,(ary uo peseq sldecuoj crruouox?l-urloj,{l[?ul8uo eja/ snql -ousouuoug pue,snqpu8o&tz,snpoqndsol -JaH 'snpolno ereue8 sq1 ssn"jag.suoqcejrp olrsoddo ur e,rrnc fluoruuroc lpr{l serlrue4 -xe Telsrp rl1l1'\ 'pedoleôp ow sessac ^lpnbeun VINOCONOJ EHT 8I

26 SKELETAL ANATOMY l9 tively deep basal cayity and a posterior maryin characterized by a prominent flangelike "heel" at the posterior end and, typically, a series of seyeral denticles between the heel and the tip of the cusp. A few rastrate elements lack denticles between heel and cusp apex and are thus superficially like geniculate coniform elements. A few others (e.g., the upper pat in Fig. 2.4) lack a "heel." Pectiniform Uowns In 1879 Hinde used the term "pectinate teeth" for comb-shaped conodont elements ofthe sort Fi9.2,5, Pastinate and stellate pectiniform elements, their scaphate and planate derivatives, and terms used to describe them. (See Fig. 2.3 for explanation of abbreviations,) Diagams redrawn from Treatise on Invertebrate Paleontology, courtesy of the Geological Society of America and University of Kansas. ant. -_ + post past nale post._ c I stelliplanate ant <_ - oost PoSl -_ - ant anl post. pastiniscaphate stelliscaphate

27 -eq ecejns lueurqcene eql pus dsno eql qt?eu -runced Fcrd,(I 'I U olqel ur pelsll ore sluoul -eq lld ps?q? ol pajnpar aq f?ur,(lr?j aqt ro -ele uuojrurlrod roj asudajj eql ur pesodojd :dsn3 aql qt?euaq spu?dxe q3rq^l srrrrej 'suoq?urquroc tuerajrp ur 'elerjdord ',$l^?j pseq aql Jo ^DuE3gruErs suorsuelxo olrtqenojl Jo -d" s? 'pesn eq pfoc lpqt spro,t\ /neu e lsnf -eaooja ur pasolcuo eq,(eu ecslns lueluqcel uo pes?q e^nducsep E ^rej asrêp ol -1? eql Jo suorsuelxe sessecojd esoql Jo sued elqrssod se^\ ^Solouruual lr'fuoeelm od?r{s Jofeu oleurs?jo rj^lol Jql uo 'slueu:ja ulojrtllej Jo sessejojd sluelj? se su \ojc Jo sedlt eseql TI? AurpJESoJ ueqt Jeq8rq pue possojdruoc,tll?jelel ej? sossec,(q'uorlrppz u1 snonqo,(solouoq l"ql sa{errr -ojd'sluourele ujojtuqced ssalurlojleld lsour l?qt E ur pequtsop eq pfoqs snqt pu? ui 'dsno eql luo{,terre puelxo l?ql sossecord sasnler"dde ^?,r lelale{s snoue^ ur suoprsod J?II JnoJ se,(ueu se ol auo pue lrd Jo,qrêc l?s?q? -Iurs perdncco? su.uojleld pu? 'sel"ld 'sapelq Jo xod? eq1 eôq? pelenlrs sr l?ql dsnj e Eur^Brl 13ql reelc elmb ueql s",r lr esnejeq sroqtn? ur Jelruns I[? eje suorsuedxe pralel e{llrrrjoj snol\ejd ^q -leld ro -elqd ]cpl l?qt su,rorc pod?qs-quroj ^q..suuoj1eld,, Jo..selqd,, poqqnp stueuela opnljur ol (.,ujojrurped,, lujoj eql 'sed^l aseql Jo slueluele eqrjcsop ot ui) ujr01 eqtjo uorlrugap peuapsorq I 'raê,ror{ pesn surjel aqljo eruos epnlcur osle qcrqa'r'z 'sluopouoj uo orljnlo^ aslpalj 186l etll ui p'de '9'Z '9'e 's8rj ur u.{rogs ele sluouela urroj 'sjoqlne luonbosqns,(q..sepelq,, peujel ûetu pue 'uourv Jo l"jlaoroec eql ^rorcos Jo,,t'ororuosled orerqoueûl uo ^sounoc ".,r".rr'iilrufl*?,fi''l,qliils ol pesn suuol pue'so^qeûep oleueld pu? oleqd"rs Jreql,sluouele ulojruncod eteurturec pue elqnauy_.9:i.a1i olsuitt rsc oleqoecsrurturec elelnbue aleueldrlneue e - sern6ll lte -.- d ur6jeut leseq a^rssacol lo euoz,ull2 ssaaord lerelet llepuoaes.dls ssejojd roualsod -dd ssacord lejalel AJeul ld -dld uljolleld_ld taal_r al.rluap-p duluc-lt euuea,ec dsnc-a d leseq-dq apetq-tq aôor6 leseq _6q Alrê. leseq,jq oteltns luetrlqcelle-se sseco,o lot,ralue.de aôor6 leuuecpe-6e VJNOOONOJ AHJ oz

28 SKELETAL ANATOMY 2l neath the processes may have a narrow medial groove that is flanked laterally by zones of inverted basal margin of varying width. Platformless pectiniform elements are divided in Table 2.1 into five major categories, depending primarily on the number and arrangement of processes. Stellate pectindorm elements (Fig. 2.5) have at least four primary processes, of which two are anterior and posterior. One or more of these processes may branch distally to form secondary processes. Pastinate pecliniform elements (Fig. 2.5) have three primary processes, which are anterior, posterior, and lateral in position. In pastinate components of the skeletal apparatuses of some Ordovician conodonts (e.9., Neomultioistodus, Multioistodus, Phragmodus, Pleclodina) the anterior process is commonly adenticulate and is represented only by a conspicuous flangelike rim on the anlerior margin of the cusp. Pastinate elements of this type have been termed "dichognathiform" in some of the descriptive literature because the genus Dichognathus was based on such elements in the heyday of form taxonomy. Carminate and angulate pectinifurm elements (Fig. 2.6) have two primary processes, which are regarded as anterior and posterior in position. The categories differ only in that the longitudinal axis of carminate elements is straight, or essentially so, in lateral view, whereas that of angulate elements is arched beneath the cusp. Carminate elements were commonly termed "spathognathodontiform" and trig Segminare pectiniform elements, their scaphate and planate derivative$, and terms us d to describe them. Upper sets ofdiagrams from Treatise on lnvertebrate Paleontology, courtesy of the Geological Society of America and University of Kansas. proccaloa brsogminiscophato trisogminigcsphots

29 -rp J?IrtIIrs i(1eso1c olur sru-ro; elei? cljlauul^se,qtqeiis Jo,(?^r ep?l8 slueluele alsl? lejulelx -ru^s ^q ',{?cdsuetjej?gj Jer{loue Jo esoql ^llejot lq pue edih euo Jo sluauele uoe^\leq uuoj fi uo4rsu?rl snonuuuoc lsourl? u? sr ajaql l?ql sjoôcsrp ueuo euo 'seuoeelm edeqs olul peuos ale slueuele rrrjojrrusr Jo suollcelloj sv sa!res uolllsubrtr-arnf^rnj pub -tr4ouru S t'z 'I Z elqej ui pelsrt sluaul -ola ulojrurpad paur:og1qd JoJ surel ZI eql ol peol (oleueld Jo slpqdecs) ecu.fns luourqt?l -l?jo ajnteu pus ( cle 'eteurlsed'elellets) sessec -ojd fu"ujud Jo luelua8uelje pue Jaqunu Aur -qucsgp srrrjel Jo suorleulquoc uisj?ur [Eseq e^rssecej Jo?el? Surpunouns peorq e pue lrd I"$q tunsrsum ec?.ljns lusulqoe e ue pu? sossocord "Jo o,'.\l [Iuo qtl\\ tueurele peuuojteld peqjj"un ue.lrluepr plll.o,f. apuoldtutrun)j uual eql s"ojaq^r 'apqddjsrulisod parxrel eq 'uol eql uo slu.ulele plnond eprsjopun ej4ue slr sardncjo leql elerq lop ro oleuuedrq oql olul reluoc eql ul slueur -olo etepodoruol ro el 8rp eqljo ^ror Aer'.' eql uo sluoruole olqv seraods ^q eper8 lqiu ps"q e pue sessejord fueruud eerql qli,,i\ ^lrl"c luour luopouoc eerql Jo sosnler -ele ujrojrud3ad paurroszld e stql'apudld -edde oql ur soues uoq$ueil-tul6rrtll,{s oql '8 2 't!d oq ol ples sr ocefns sql 'u l"u Ieseq e^rssaj -ejjo eeje luec"fp? p?orq e pu" dsnc eql qleau -eq lrd ps?q E Jo slsrsuoc ecejjns luaurqceue slujrujjj Jo JrnlPu J^tle^rosuoJ 3ql 'le^j^roh sql Jr 'Joênd.oH'apqdoJs aq 01 pl?s sr scejlns 'auop sluauele ssoql Jo qenorql sel' luetliqc"lle eql 'eprsjepun slr Jo lp Jo qcnul -ods cusuoeuoc Jo sosnl?j"dd? ^pnls eql qsrneu4slp serdnmo l q1 pseq snorc?dec z seq 01 llnrup sl 1r Pu? 'e^4e^jesuoc lujr!olo Jqr JI 'ojejlns ^lr^m luelllqjelle eql Jo Jd?qs ej? seues uollrsu?4-fu1alulli^s ^luoruluoc eql ur slueur eq1 01 eulpjocce pelueu eje sluetuolo urloj -ele Jo sed?qs 'sluopouoc lsorrl Jo snt?jedde etelduroc eql dn e{?u leql slueuele Jo sed.{l uaês ro xls aql Jo rnoj ro JJrql lsnf saajoa -ur seuss uorlnuu Jl-fulou.Iuj^s eql 'elnj e sv 'Iooq srql ur areq.$asle uaoqs ere sjeqlo snojeunu Pue '8'Z 'BIC ul sorros uodrsuell-futeluu^s pjaês ol"jlsnlf I 'stueurele elejcsrp,{iuo peluosoj -dej ale l?r seroeds luopouoc ^q Jo sesnl?edd? Ielelqs eql turlcn4suooar ur ecueuodurr l?jil -c?jd l"aje Jo eq ol ouroc s"q uonrusocej Jreql pu? 'lno pe{ro^\ ueoq e^?q solros Jaqlo flluonb -esqns sed,(l praês pet?jlsn[r pu? peq csep eq pue 'sauas uoutsuoti-li4aluurts tllns ezruso -c3r 01 lsrg oql send. (t96i ) urojlspurl solerpeu -relur creoloqdjoru snojeunu Jo srujoj el?rqqop ueê Jo eteuuedrq otur pocejl Ê^\ ^q eq 'ujnl ur 'as3ql 'sluou.iela alepedoruel Jo aler^8 ^"tu VINOCONOJ AHI -luqced el?uurtes pue 'olef8ue 'efuiu.u?j 'elpu"ld 'el?uols Jo sensofue peuljojleld ;urjql roj sulal eje ojeql'dn ^'\ou ujnl plnoqs êql Jr 'tnq slueuele ujojlurljod eseql Jo suorsja^ eleueld Jo ssolurrojleld eje ejeql 1?ql oj"^c tou ule I ssejojd Jouelsod ou pue 'sessecojd l?jelel o/al ro euo '^ll^?c ps"q daep'peojq E r0r.,i\ sluelliele peulojl?id or" qorqa 'suuoj tllns roj apqdnstunu8as l pue atm.ldojsrutw8asrq surret aqt etnpojtur I l Z '3r{ pu I Z elq?i ur pue 'oû Jo ssa3ojd l?relel a^?q osle l( ur sad,tl auros pue Joualsod slr " l? dsnc oql qlh\ 'ssecojd Jouelu? uz,tpo ar'zq 0'Z A.c) vuawap unllurlrad apulwsas 'Aurouox4 luarueleufu Jo sesofund eql JoJ paldep? Sureq se^\ ujoj Jo eeenauq eql ueq^\'s0/61 eqtjo ûrouoxel ernlejelrl aû ducsep aql ui..urjojrurpoldzo,, souo 91"lnBuP

30 SKELETAL ANATOMY in the symmetry-transition series may be of considerable help in distinguishing between conodonts that belong in differenl suprageneric stocks. Thus it is important to pay careful attention to the correct assignment oftransitionseries components during the systematic study A of any collection of discrete elements. In a few conodont species with apparatuses composed solely of coniform elements, it has been noted that positions in a symmetry-transition series may be occupied by elements that are variable with respect to longitudinal curyature. Fahraeus and Hunter (1986) have recently termed these variable gtorrps curvaluretransition series a\d have illustrated those they regard as characteristic of the apparatuses of Panderodus gracilis, Protopanderodus vqricoslatus, ajf,d Drepanoistodus sp. aff. D. suberectus. In the skeletal apparatus of Panderodus graciri, as reconstructed by Fihraeus and Hunter, four ofthe five components form a symmetrytransition series (Fig. 2.9). Specimens in row A offig. 2.9 are all bilaterally symmetrical, alate coniform elements, but they differ from one another by slight variations in curvature; specimens in row B. which are slightly asymmetric versions of the alate specimens in row A, also exhibit some variation in curvature, as do those in row C, which are otherwise even more asymmetric versions of elements in row B. Fihraeus and Hunter tius recognize five curvature-transition series within a skeletal apparatus that also exhibits a three- or four-member curvatur e-transilion seies of Panderodus Fig.2.9. The gracilrs (Branson and Mehl). Each of the five or six elements oflhe apparatus is shown to increase in curvature symmetry-transition series. Fihraeus and Hunter evidently conclude away fiom the plane ofbilateral symmetry. Inner lateral that each individual of Panderodus gracilis views had, on lefl; outerlaleral views on dght. Redrawn from F6hraeus and Hunter ( 1985). a skeletal apparatus in which there were five morphologically distinct components, each of which was represented by a six-member curvature-transition series. Thus there must have 2.5 SkeletalApparatuses been at least 30 elements in the skeleton of a We have thus far considered the composition, complete individual. Fihraeus and Hunter classification, and descriptive terminology for regard the nature and number of such curvature-transition series as features of potential ofconodonts. However, it has been known for discrete components of the skeletal apparatuses suprageneric value in conodont taxonomy. at least the last 50 years that in many conodonts, perhaps in all of them, the skeletal However. they do nol seem to have given se- ap- rious consideration to the possibility that they rnight merely be charting the breadth of morphologic variation within the particular populations thev samdled. paratus included elements of several different shape categories. Thus, in order to compare one conodont with another and to build a biologically reasonable taxonomy for the group,

31 ola^8lp urjojr.{arq ro 'eteuuedrq 'et"rq"iop ol luzuodurr sl lr 'aslpatj oql ur pelou sv perlcre eq.4pru qcq^{'slueuele (..urjojrllol?u,, 'Jr?d oleurs? ro) ped?qs-icrd Jo ll"d efurs e peldno ueqt ejou,{q suej?dde eql ur poluosejdej aje^\ -co Alpcrlsuep?Eqr sr uodrsod W eql ^q (suo4 3lrs le ssoql I ti ro fi u?ql te8je[ r{cntu -Isod qd pue?d eql peurjel eq,(eur ueeq û? e^pq ^dncco âql suortrsod tq8ru slueruele Jo lequrnu plol oql Jo) slueurele qd pu? ed peleu eql pue 'perr"d,(lq?isuouep tou snql pue -8rsep aq feru aseqj 'snlejedde qcbe ur esaql Jo sad,{l o^\l ere ojeqt 'elnl " s".pue alep s?^1 sod& aqtjo euojr l se r\ol s ueeq (sluoruole e^"q lq8ru requnu eql q8noqlf '(sluaurolo etej,t8rp uuojrsuelxe''t'o) slueuele uuojnx?l Jo sed,{l luorogrp ueês eql pezrleroods,{q lo sluourele uuojrurped,{q perd Jo qc?ejo rrzd euo) ^llec oloqtuour sluaurele elejrsrp tl tseel -ncao eje suoursod d se3?lquesse Ianlsu ui '01'Z'ErC ur S pue le papnlcur e^"q plno^\ snlpjedde elpjqruorurl 'tr^['d perellol er? qcrq,{r\.'seu-das elsldluof, E t?r,tlelrt sr tr snqj 'ed& cfoi -oeot?c ledrouud ean0 olur,{1peat peleredas -ogfuolu euo,(uejo sr?d JpJe os oq,(e['u elaql eq up3 setelquess? IUnl?u alalduoc,tq pelues 'snl?ledde ue tb E ur 'pu? sjr"d g8eurr-lourut -erdal sorceds lsorrr Jo sesnl?jedde I?lelels ui Jncco sluopouoo Jo snlel?dde l?lalois eql eql leqt p"j eqt uo,{[u?ruud peseq sr euaqcs t?qi 0I'Z '8rC Jo slueuodruoc eql Jo lsour 'sr l?qj sluauod ur,( ucu?ururejeprpel?jl -sn r eueqos eql SurpueuruoreJ i(q pepnl3 --Irroo lueuela-qojoslp ueles ueql ejoru eêrl,{puj snlej?dde letelels aejquror.urldes û"u -uoc PUE srql op ol peshep ueeq eêq l?qt suels^s oql Jo preles pessnosrp I as1nalj e\1, " leql sraq olou 01 eepr poot e,{lqeqojd sr li 'slueurela Jo ui 'snlbjadde sjdfl lu: oql uql[^1 suo4rsod snosolour -raglp ueês Jo snl?jedde ue -oq Surueu puz 8ur.,lrluepr :o3 eueqjs? oêq s?q qj?a ^ll?jrtoloqdjou 1?q1,{luo-ou?s 3ql oje slueuodtrro3? t lerrxao 's?sus) Jo,{trsle^tun pue EJueuV Jo,{ppos IpcFolooC equo,{se!noc,^sololuoel?d eterq -4il4,{ul uo esrlee{ ruo{ pevrporu pue u^relpeu.suorl -Isod roferu Aupeu8rsop loj urolsxs e seprôrd li :slueruelrjo sed^l snoue^ Jo suo[rsod lenpg aoqs Îelou ot popuolur tou sr deur eqj.snlsedalb elelqueul4das e ur slueuele JoJ uonqou leuortecol Jo euoqcs.0i.2.8lf, l,1l -+ps, +":. I I 5 "'l qs? es i + / n d qd ed -i;- 3 3?qd +ed lerlsruts VINOCONOJ IIHJ eql l3r{1 'Jsâ/rloq "{ldlur lou seop sasnl?j?d -de el"jqrueuqdes p q sluopouoc lueje.grp o^\l l"ql uoqeururelap ro /fteôjsrq 'pesn,{[apr{l eq ol tuuu eq sr peuobueur lsnf eql pu" 'lnjssaccns ueeq s?q aueqcs ^SolourruJel o^4ducs -ep srqt ebjet pue,{g 'pesodruor eje qjlq^r ^lejnd Jo sedr(l tuolliele purlstp êql -roru Jo requnu eql uo Supuadop ^ll?jrsoloqd 'seuoeel?c aqjqulauqdas pue'antquaulxas'atotquau -mbumb'aptquautuponb'aptqwauuj'aptq -uautq otar peputpqns eq fuo8al?o red?l oqt lew pue alotqwaullnut Jo aldtqwaulun s2 fldurs pequcsep aq sluopouoc Jo sesnlej dd? I?lala{s eql leql potse8:ins I'asuoatJ aql ai 'seuobslec:noj ro eelql ueql ejoru ou eaioaur saureqcs asoql 'u?d lsoru ogl Joc 'peluesejdoj sesnlujedd aql,tjrss"lc ol pelue^ -ui ueeq eêq serueqos snoue^ pu? 'JlEuts -?qojd s?î su.leded l"lelals lof ur Jo Jequnu ^lq aql leql peuluol J^Drl J^l.r.rrrsnlJ pasnl pue sasolquassd lonpu eseql urojc serlquess? Ieu uo pru?d lseel le lueseldel ol rrroes osl? JaueJ oqi tuourec ctl?qdsoqd,(q reqlasot pleq slueurele Jo sjelsnlj ur?luoj suorpelloc Jeqlo,{u?tu pu? 'peleôcsrp ueeq a\ou e^?q sasnl?l -edd? ololduoc ssal Jo ajour 00S u?ql elo]al '11a,r se 'ueq1 ro1.{soloululel sruos aq ol paeu llr^\ ejeql 'esjnoc Jo 'puv sasnl"j?dde lelole)s ol uoruuoc surelled eql Joprsuor lsnur osl e,$

32 SKELETAL ANATOMY ramiform elements or geniculate coniform trated diagrammatically in Fig. 2.1L In Lane's types. Elements in the three major positions in scheme, C/ass I symmetry is exhibited by elements that are themselves bilaterally symmet- the S series form a symmetry-transition series of the sort first recognized by Lindstrdm rical. For such elements (e.g., alate coniform or (1964). The Sa position is occupied by an alate ramiform elements) no pairs can be established, and it is possible that they occurred sin- coniform or ramiform element; the Sb position by a digyrate or tertiopedate element; and the gly in skeletal apparatuses or were paied with Sc position by a bipennate or dolabrate rami other individually symmetrical Class I elements. C/aJs 11 slrmmetry is a feature of indi- form element. However, the nomenclature just mentioned (and illustrated in Fig. 2.10) provides formal identification for just the midsented by approximately equal numbers of vidually asymmetric elements that are reprepoint and the two extremes in the S series. In "rights" and "lefts" in large collections of discrete specimens. As lane (1968) noted, the the apparatuses of many conodonts, however, there may be more than three morphologically bulk of known types of conodont elements apparently belong in this class. distinct components of the S series and, to describe and locate them, it may be necessary to Class III symmetry is exhibited by conodont invent intermediate categories such as Sa-b or element pairs in which the "right" and "1eft" Sb-c. In Fig there is also a position in the S series labeled Sd, which is occupied in some Fig.2.ll. Various symmetry classes reconstructed exhibited by elements typica.l of (I) R hipidognathusi (Jl\ Xaniognathus; septimembrate apparatuses by quadriramate ramiform elements. It is not appropriate to use Sd as the designation for inter- (llla) Eognat hoduii (lllb) A mory hoghalhus. mediate positions in the symmetry-transition series, as some authors have recenfly done, In most skeletal apparatuses the Sd position is not filled at all. 2,6 SymneFy of Elements, Elem nt Psirs, and Apparatuses It takes rrery little experience with collections ofdiscrete conodont elements to discover that, like components of the human skeleton, most of them corne in mirror-image pairs. The only ones that depart very obviously from this pattem are alate coniform and ramiform elements, which are themselves bilaterally symmetrical, and a few straight pectiniform elements that are developed in the same way on both sides. Indeed, it was not until almost 1960 that it became obvious that the right and left (or dextral and sinistral) mernbers of some element pairs are not exact mirror-image replicas of one another; and the incieasingly widespread practice of multielement taxonomy has led to the discovery that bilateral asymmetry was rather common in the skeletons ofat least certain groups of conodonts. Iane (1968) suggested that four major types, or classes, of symmetry could be recognized among various element pairs. These are illus-

33 pue sp"u?j ur'uetuoêc aqljo suorsl^rp el?qs lq8u lnq,fulo('ulu,(s EIII Jo II sselc oêq eeseqac pup uollrtrr"h eql uo+ pup'uppnlrs,{ltpjl,{eur slujrxeto qrns ecueq :snl l.?iqt,l?r"$',$;t;";",3"i;:"j,ti i":"^1513," Jiq*:errrs eqr ur srueuero qcns rerro qlr^\ -zss-ivsytt ' io1i" pat ea tuleuru^s AI ss?lj qlr.r slualuelo l?ql -uoi cos loag f UonO sureurej u?ej?lsruc elmrpul ol luerol$ns,(foruruoj eje sarcuonbe{ slr pu? poq-euoq ^{otpnl aqr uo (lggt).f '. olr"h palefq?l,sr legj.en8o^ olur erour pu? ejorr] 89-0t 't 'Z tuooldd euoj seq suorljallor etrel Jo srs,tpu? rrurouo f:;:w?"lff':t:{:fl!:;;.,i1"6:i)!!!- pojeedd?srp lir 1i"i,r"rri",,1. spq,, ^rebi?t fi-s fe :i ti,ii.ia'""t roj peeu eql pue'lecrleroaql K1uo sr ssejc 'tu1eul -uopouoj rep srseg erp roqn (/961)'IA 'ssoro -ur^s slql 'pozlusocej euq sv pezrusorej eq '68r-LLr. 'O/dgg ottuojb4 uoadpd Dpv uzc suorsrel l?jlsrurs pue prlxep qcrqr,r [q '8ur (Eleluopouoc'"ec luopocersro 'eor"luopojsp -ôq pre1e1 se qcns 'sejnleal rcer leqlslueusja -ued) sesnl?,sdde luopouoj auoc-elduls _Jtlos r"rr-tuia" rn"'nfr^rpur sgpnjcur qj rlt,fttaru Jo ued IEJAJIu1 :seues uoqrsugjl-jjnieajnj --l'."_: ' t,- t eqj (986I) U o '.roiunh pui ' a r 'sne?rqgc -ul[s 1l ssdl) e pezusocal osp (896I) ou?'i 'otl-g l '8I luoapd l'stuopo 'lejlsluls sfe^\i? uotsje^.,pep?lquou,, -uocjo uorlrsoduoc eqj (tt6l) rf'd S'uosIIIg eqt pu? IeJtxap s.{eale sr uorsle^..pepplq,,.arun pu' Ecua"'v."os 1o"e.aa sq7,ffi ;ll ;:Til:illfi:"H#:3"::::Jl,:"r"i::,1 '(EauElleosrl I) 11 t4 '(uosrqox y -puoapd awtqatn^q uo asuoatj ri {;ifi; Ienba '{lelerulxojdd? ur rncco suolsle^ oû oqj -uo3 (1861) I'V'slJleH pu 'J'f 'rellrhl 'lou sr lequeur lejlsruls eqljo leql seejeq^\ 'JI 'ru,o.j1spur.i ''t \e6elz'.f.),rolllw,applq snonrrdsuoc? se pedoleêp sr Jred "I H C TapoqU'-I U 'urlsnv ' C 'tjdd"tx eqljo requreur IEIxep oql Jo ssero.rd rouetu ''IAI S 'ruoissrag < J 'a 'tee^\s "l 'c 'Ir?lJ "..r.nrô11.ssssecord tu?puojss pu? fu'ru "qt sajuarajeu -udjo luauoeu?rs pue requrnu ur pu? eurnno ur Q?rquepr lou,{[alns lnq) lelrrurs ele Jrzd eqt Jo sjeqrueu (IBrlsrurs pu latxop Jo) Uol 'poqs{q?lse uaaq seq tr qrrq.{ pu lq8lr t?ql elon.(tt.z BtS) eldul xo tuel ui sluopouo3 6soql Jo luautdoloôp Jo ajii Jo -lecxe ue s? e^jes,sntjôpto sntlwu&oqdloluv epour eqljo uoq?leltue1u ur qlr,1a ll?ep eq uercnopro ete.i eqt Jo stueruale ed eleqdms ol arnl"oj Jeqtoue,{loJeru sr û? fulaulur,{sy fu1au -r11e1s,xeldtrroj oql.g96t ur ere^\,(oql ueql -ulfs l?rel?iq ruorg fllear8 pouedop oloq.{ A\ou snojetunu uour Alqeraprsuoc eje (eue-i s? Ierrrru? orll l?ql Jo peau"je,(lpculeuur,tse,{q qlij ssod paqqnp) d:leruur^s III ss?lj Jo ejenr slueuodruoc Joqlo lpql u?eu lou peeu,{leu? srqljo soiduexa.eruaun3jo-oj JrqdeJE uolalols eql Jo slueuoduroj ur?loc Jo,fulatx -rtej$ pue orqd?j8oea pu? ajuepunqe Jelrurs -u se lerel?lrq 'leê,,aoh 'l?cule('uru,{s,{q,(po.rred pur8uo u? Jo sued s? peqsllq?l -t [Iq uaeq e^?q lou lr{erur sesnlejedd? I?laleIS ^ll?ro -se eq uec pu? lcuuslp elrnb,{jpcr8oloqtuoru rreql ur srrpd gcns qll { sluopouoc 1?gl lse8 ej? teql sjequler[ pepu?q-uot pu? -lqeu se^lo^ -8ns ol ro-uorlelejdjelur u? qcns olur qcuol^r -ur Aleuru^s IJI sseic Jo ed{l puoces V,(e{uour e ot Jeedd? lqsrut,&teurur^s tulauw/k DIII ssolj dllerurufse ^lorql Jo ed,{l III sselj qfl/( srr"d luerllalajo ejualsue po8pa srql perujel (g96i) eue-i.^\oj eljrluep pu?q-uel l^\odlc?-^\ou eql fu1eurru,4s prelegqjo eueld eqt surofll?d ejo sleqrueu qloqjo ssecojd Jou eql Jo seprs elrsoddo uo ueoq e,r r{ ueql tsnul -olue a{rtop"lq eql lnq,(ii.z.brc) Aur^{oq IEra '^poq ro uoflo{s s.luopouoc e ur pat nlrs ueoq -1e1 ur sacuersgrp,4q pogrluepr ar? rred?jo sroq eêq,(eur sjred esor leêjeq \ 'sjr"d lueui -ureu pepu?q-uel pue -lqbri.socqjns Jeddn -elo Jo sjoqureu eusoddo 'pculeluru,ts rragl uo saljrluepjo alqnop e doleêp leql ^ror -l?iq sa^lesrrjaql oje^\ sluopouoj l?ql uorurdo ^llae slueuelo ujojlurl5ed eleqd?csrultrj r pe,rloq pleq,(ll?jeuae eq1 JoJ elqrsuodsor,{iueurud sr ele qcrq^\,snpqns snpolltdu&og Jo srred tueuala-luopouoj Jo,tuteruu,{s (II sselj ^llerelq III sselj Jo) e8?urr-joutul pa^jesqo,(fouluoc eql Jo uos auo Jo eldtu?xa ue sv.suos luele.urp 'pegduapr o^!jo pu? elqereprsuoj Jo tq8ls eq ajue eq louuec tsnl rred? Jo sjeqtllelll Uel pub -te.ulp eqj Je.Urp ^?ur slequleru ^lpcrtoloqdjorr] VINOOONOJ EHJ-

34 the United Stltes. Quafi. J. Geol. Soc. London 35, Lane, H. R. (1868). Symmetry in conodont element-pairs. "L Paleont. 42, Lindstriim, M. (1964). Conodonts. Elsevier, Amsterdam, London, New York, 196 pp. -, and Zregler, W. ( 1971) F instrukturelle Untersuchungen an Conodonten. l. Die Uberfamilie Panderodontacea. Geol PaloeonL 5,9- SKELETAL ANATOMY Pan-d'er, C. H. ( 1856). Monographie der fossilen Fische des silurische Systems der russisch-baltischen Gouvernemefis. Akad. lliss., St. Petersburg,9l pp. Pietzner, H., Vahl, J., Werner, H., and Ziegler, W. (1968). Zur chemischen Zusammensetzung und Mikromorphologie der Cor.odor]]!e[ Paleontographica, 128, ll 5-l 52. Roundy, P. V. (1926). The micro-fauna. In, P. V. Roundy, G. H. Girty, and M. I. Goldman, Mississippian formations of San Saba County, Texas. 2. U. S. Geol. Sum. Prof. Paper 146,5- Sr".t, W. C. (1979). Late Ordovician conodonts and biostratigraphy of thae western Midcontinent Province. Brigham Young Univ. Geol. SLudies 26, (1981). Macromorphology of elements and appa.atuses. Pp. W5-W20. ID Treqtise on Inverlebrete Paleontology (ed. R. A. Robison), Pt. W, Suppl. 2, Conodonta. Geol. Soc. America and Univ. Kansas, 202 pp.

35 qslltocs eql ruo{ suourrjeds puoqrppe 8ur -qfcsep(986i ''Ie te e8puplv) reded retq E ui ^poq aqrjo suorlod lusjejrp e^jesard osp '?la -uat lueregrp oml lsbel te luesejdej.. I"Jo^rnbe,, sz peg4uepr osl? ajaî suobelojd qcrq,,a 'sueurcads uellueur(i qsulms ^llueprê JnoJ eqj -rotur eseqt lng 'qsg pue snxoqdurejo (qrolq suaruljadsnorajluoqrbj rlsqlojs oql elcsnur ro) souroloîu eql qtl,,r\ I' pepdruoc eje.{\ puz..uorlelueu8es,, ^lpuorsrôrd lsetens ol uel4,{laû"lu5l Jeql?J ojea suorssejdurr '^toloqtuoul ur p4"rjosse pad?qs-a aw '(I' 8rC :9861'lE le s3!lfg) lsoru oq 01 uroes sluopouoc?j?d qcq^\ ^lesolc qlr^\ suerurceds qs! ocs aql Jo (e^qcn4sur lsotu 'sql?u8ole?qc eql uro+ ur luarajrp oql uns pu?) rsry oqr Jo t",tu"i:"j.:l]#"" elrnb osje se,.. ûroleu? smldltsotuopo 'l..ooq slql ur uo4ejeprsuoc Îlueprê ruo:; pellnuo sr dnore pue punq ejojeq lsnf uaurceds eql Jo uonjol tero pue l.uopouoc?jed B ueeq e^?q,{lejns Jo llnsoj? se sduqred ',(lroue$od palcelrp oq 01 plnoa 1r 'luopouo3 se,!\ (peu?u s?,,r{ uaurrjeds nedd? s.a lsoujjorjolue oqljo socrde uourceds ew se) snqdusotuopo " Jr 'Jo e,'aoh 'sluopouoc l?ql ur 'Jo e^roh {urul eql Jo Pue rouelu? roj Iopour Jllrroleu? IEJeusa? s? pojeprsuoc aql ol lsorrrje psalxe s nljnrs p3d?qs-a Jql,{lsnoue se^\ uoujrceds u?uqulec olpprw srql 'suelurceds qsrdors,fuelugrua?{j eql Jo euo ui 'eulu JoJ 'os stueurele ellluopoum Pepnlc 'Jouelu? oql 016u[urod s.a eql Jo secrde qlrar " -ui o^?q?urtuo lqtru?rqu.rntoj qspfg 'edeqs olq-/\ e^pq ot uaes eq qorq^\ Jo el?r{s ssesjng ^ snou?j eql uro{ el"roqdoqdot ut '(986I) F ra etplrptv,(q psqucsep Êur êql (Z' 8rC) pequ3sepun,{fnor,lord e ur suorsserdrur pe^jes suorurceds pe^josojd-lle^r ssel eojgl eql ur lcuq -ajd,(ljood tpqt pelse8ilnsujol,^{,{e^{uoj 9t6l -slp:joui ore sajnljruls JseqI'rouelsod eql ur 'oslv erag possncsrp lou eje 'srol?o prb {o1 edof l ql sejnpruts Jeln8eJr euos tuopouocjo dnoj8 (ljurlsp êqj pue) pezru Jo sju:s e sr qrrqa Jo Jprs Juo uo 'uorssjldtul -EoceJun,4[snorêJd lnq 'sluopouoj ^lqrssod lou ere l?euq lcu4srp? pe{reur sr {urut aql Jo sueurrjads esoql l?ql 'Jeê,$oq'oslo ouo,{joâ srxe eql 'raô1aoq ^q 'spjlql o,dl Jouolsod eql ui,{lt?nur^ Jo uorurdo eql sl 1I etepjoqrotuopo 'pue louelue slr Jeeu suorsseldlur J?eurl lourl -uoj runl^qd Jleql roj srsuq eql peuroj pug -srpul Jo Jred lell?edqns roj ldecxe sornl?ej JqsouEerp s{3?l (l 'trd) uourrceds pa^jeseld sluopouo3 eq ot ( 16I) llocs pue uotlel{ Aq lq8noql era,n EuuluoIAI ur slcoj uerddrssrssrl -lseq eq1 ur lurul eqt Jo pjrql rorjelu? eql txo{ suerurceds lpuoqrpp? Iereês ursuojsrld 'uu peuoddns-,{"r E ur elruolop ueunlls E r!o+ euo pue 'pupllojs 0q ot petertuatur sr leq^\jo serul sj? 'rorelsod 'qfunqurpe Jeeu (u?rddrssrssrl l) snojojruoq&c oq ol petpnf 'puo elrsoddo eg1 Jo urejeu euo J:^\Ol Jql Ur PJq Urql P UrO{ JnOJ 'SUetUI'JdS uo 'aqol crpqdec Jouetu? ue se pepj?8ar sr pup o^g $nt Jo slsrsuoc sluopouoc Jo snl"j"dd luopouoo elalduroj E sesolcue pue gos aql Jo ocueplê o^doefqo 'alou ûroleu? ueae euo t? uorsserdulr paqolrq 'snoqfq V opr^\ ( ur ',{urol?u? I?ruru?-eloq^\ Jo sldecuoc 80 0 ot t0'0) rulll 56'l pue 8l uee^\fq pue Suol eseq ol qcqr\ uo ef,ueprâ ljerrp el I ueoq ('ur 9 D ru['u S'0t sr (l '3U : 861 ''le te s8ilug) seq ejar{l '^pumer alrnb Iqun 'pup Z ratd"qc ur uourceds pe^resajd,{l4olduroc lsour ogl pequ3sop osoqt e{ll sluetuele Jrleqdsoqd 'ruroj ul elrllrrjo^\ pue 'pjssjd go flerrlue lsorulz dn apelx sr 'ro,\o^\oq'pro3ej ûll -uoj,(ll?jelq 'el"euole ere^\ sluoru?p{ e$ql IrssoJ rreql slerurue pjrpoq-uos )^{ rrro{j pepnjlsuocer sleujru? eql qloq 'Je e,,aoh stuopouoc t ql 'oluu lsru eql JoJ uraqt ^le8rel pasous? 'slcedse luejojrp legnd.oruos ur,{0uojudd? -rp Jepu d uoq^\ '99gI ecurs J?elc ueeq s"q 1I 8Z AIÎOJVNV'IVruINV-A'IOH,&\'g

36 WHOLE-ANIMAL ANATOMY 29 2mm Fig Clydagnath lls? sp. cf. C ca,rutbrmis. (A\ Cafiera-lucida dmwing of part; (B) and (C) enlarged vrews of head showing conodont assemblage in part (B) and counterpan(c). Specimen from "shnmp-band" in Granron Sandstones (Dinantian), Edinburgh, Scolland. Redrawn from Bflggs, Clarkson, and Aldridge (1983). Dinantian locality, these V-shaped structures are identified, with no further discussion, as "somites." This interpretation was obviously quite influential in the much more subjectiye discussion ofanatomy in the 1986 paper. even though it is in no way required by the evidence. Outlines ofthe anterior end are preserved in only one of the Scottish Carboniferous specimens (Fig. 3.1). Although this end is termed the "head" by Briggs et al. (1983) and Aldridge et al. (1986), there is no evidence in it ofa brain. The term cephalic lobe may thus be more appropriate. As noted previously, the cephalic lobe of the best-preserved Scottish specimen encloses a complete and apparently little distorted conodont apparatus, which permits the specimen to be identified as Clydagnathus'l sp. cf. C. cavusformis. In the only Scottish specimen to preserve the cephalic lobe, right and left components ofthe skeletal apparatus are superimposed instead of arrayed on opposite sides of a line of bilateral symmetry. It is thus reasonable to suppose that the cephalic lobe of this specimen is preserved in lateral aspect, that is, that the plane of the bedding approximates the plane of bilateral symmetry. The deep cleft at the anterior end of the cephalic lobe may thus mark the position ofthe mouth, and the position ofthe apparatus within the cephalic lobe may indicate the general position of a buccal cayity. If the entire specimen shown in Fig. 3.1 has been flattened

37 .rellg eql al?jrpur osp,t?rrj pue tujojruue^ I?mnq E ur unrleqlrde peleljr3 Jo selc?luel Jo repur?urar eql ol snlej?dd? ^poq Ielelqs elsldruoj JoJ suoddns e^rss d ssel Jo ojoru se pe^jes E sel?lej,(lsurjur uoc ualurjeds snolejruoq e^?q,{"u snq} pu? elqeôrutllr ^[uo ajeal,{eql -rec qs[lors po^jesejd-lssq eqt q8noqflv Jeqleq \ ro qleel pu? sjodwls s? pa^jos e^?q (186I ' 3'e) sred?d tue3 snql lq8rru pue etq"ôur ej9,,ir sntej?dde eqt Jo stueulele Jeqtaqa olur tqtrsur ou pue,pasod -ej l Jeês ur [ocrn,tq peulnsse euo eql qlr \ osp pue I/61 ur uossddel,{q ap?ul auo qll^l -x0 Jo lunrlaqlrde urqlr^\ pasolcue se/a snlel ejns?aur e8j3i ui seejae luotue8uelje lueualo -"dd? luopouoc eq1 Joqleqll ol s? uorldrruojur ou eprôjd suaunceds qsldojs ogt,uoqs ui.snl Jo uou?lardjetur sql 'p(iitu eqt Jo srx Suol agt qll^\ Ielpnd tou pue ot IerIJou ueeq e^?q -?Jpdd? xeldruoc t?qt ol?nl3e tsql saljsnu eql IIe^\,4?ur sex? I?urpnl uol reql tnq.pesoddo Jo lueuqje? Jo atrs 3ql s? pu? qleal pnsurj,{lluej"dd? eje^\ sejelns Jo sur8l u poleln3rl eql JoJ el Jlsqns snouie?[iu 3 p s? se^jes qjrq/( -uep JreqJ ',{Ieurur,4s lejelelrq Jo ouqd eqt 'saqsg8pq eqt Jo el?ld Fs?q eql 01 alqer?d Jo seprs al$oddo uo petenlrs pup sorjas S eqljo -ruoc ejnljnjls? Jo lu?uruoj eql se pelejdjalur ssoql ol Jouelsod ecu?lsrp eluos,{fueprâ ojo^\ eq rq8[u 1?q1 Suq ue Jo ecuosqe eql sr Suqz seues qd pu" aql Jo stueuoduroj ljal pue -znd ejour uaâ snleledde eql qlr^,\ palercos tqaij oqj,{lerluoôjelu? "d popejrp sur8reur -s? ojnleln3snu Jo uoq?crpur ou sr 3J0ql pu? olelnsuuep rraql qlh\ pelueuo ele,,ll snlejedde 'el?ld lespq? urelar ol sjeedd" snl"jpdde eql ur sl.ueluele eql Jo ouou,eldruexa JoJ.slallelu clleqdec eql ui slue(uele Jo seues S pue I I eql 1"q1,tle{rt suees 1r ueql 'eq lqtrur lr pelse88ns crurol?u? Jeqlo I?JeAas ol pedsel qlp\ olnur ( 861) T te s33pg s? 'ug lesrop e st lln oqtjo,(ieleunuojun sr lr 'oqol cll qd33 ogl uqtr,'(, uraj ur auo Suop elnlouls peuoddns-,{?j eqljr snl?jedde aql Jo uorleluauo pu? uoupnlrs pue 'ftleurl'u,(s lerolelrq Jo eu ld slr 01 leller?d.pu'rocsro euo*pues uoru'ro upnueur(r au, ",..0;9ot_gtJJl::."iff J;'ltX"P,":TJiffil#JJ:"Tr? H'Ii1t t VJNOOONOJ IIHJ 0t

38 WHOLE.ANIMAL ANATOMY ll The trunk of all four of the Scottish specimens is 1.2 to 1.8 mm wide and preserves evi- in every specimen representhe same organ or require that all segments ofthe axial structure dence oftwo distinctive anatomic features. The organ system. For most ofits length in all ofthe most striking consists of a series of V-shaped Scottish specimens that show it clearly, the structures, which were apparently situated on axial structure joins the apices ofthe V-shaped the sides of the animal and whose apices point structures ofthe trunk. No such relationship is anteriorly. In the most completely presewed shown in the anteriormost part of the trunk of specimen (Briges et al., 1983; Fig. 3.1) these the best-preserved specimen (Briggs et al., structures are rather indifferently preserved 1983; Fig. 3.1), however, and the axial structure and are confined to the posterior half of the in that specimen may not be continuous with, trunk. In the three more fragmentary specimens (Fig. 3.2) described by Aldridge et al. discontinuous pair of axial lines in the poste- or represent, the same anatomic feature, as the (1986), the V's are better preserved and may be rior half of the trunk. Aldridge er al. (1986), seen to extend nearly to the anterior end ofthe who allowed their interpretation ofthe Scottish trunk. The shape, serial repetition, and lateral specimens as primitiye chordates to restrict situation ofthese V-shaped structures are reminiscent ofthe myotomes (or muscle blocks) of that the double lines in the anterior parts of their survey of anatomic possibilities, suggest Branchiostoma (or "amphioxus") (Fig. 8.1) several specimens might represent some parts and of other chordates such as the hagfish or all of a nerve chord, notochord, or dorsal Myxine (FtE. 8.2). aorta. I suggest that one might also consider interpreting this pair of lines as the incomplete But chordales are not the only organisms that might yield such V-shaped impressions trace of a nemertine rhynchocoel, the tubular compression. For example, nemertines (phylum Rhynchocoela) such as Nectonemertesthe curious group of invertebrates store their cavity within which living representatives of (Fig. 8.1) are characterized by a long, straight eversible proboscis. Such an interpretation, of intestine, which bears numerous paired lateral course, would not rule out interpreting axial diverticula that might, on flattening and lines in more posterior parts of the trunk as compression, produce patterns similar to those traces of a gut with numerous lateral exhibited by various parts of the several Scottish Dinantian conodonts. Nemertines, of If the axial structure in the posterior part of diverticula. course, are pseudometameric but acoelomate invertebrates, probably derived from preted as a gut, it appears to have extended to the lrunk of the Scottish sflecimens is inter- flatworms and not known to have a fossil the posterior extremity of the tail in the two record. specimens that retain it (Figs. 3.1 and 3.2). The second feature recorded in various ways That would mean that these animals lacked a and with varying fidelity in the trunk of all four postanal segment, or true tail, features that are Scottish specimens consisls of a line. or a pair characteristic not only of chordates but of individuals in virtually all the deuterostome of subparallel lines, more or less coincident with the longitudinal axis ofthe body and extending from a point just behind the cephalic nemertine model, even with tongue in cheek, phyla. On the other hand, if one assumes a lobe on the anterior to the posterior end ofthe the problem vanishes. for in that g.roup-as in body. Aldridge er al. (1986) note rhat these most invertebrates with a complete digestive lines might represent a number of different tract-the anal end of the digestive tube is situated at the posterior extremity of the body. I structures. For example, they might be traces of a notochord, a nerve chord, the gut, a major agree with Aldridge et al. (1986) tbat anatomic longitudinal blood vessel, or a mesentery or interpretation of the axial structures of the septum dividing the body cavity into compartments. I agree that a gut is the anatomic feature suggesthat, in combination with other fea- Scottish specimens is inconclusive; however, I mosl likely to be represented by most of the tures, those structures might well tum out to be length of the axial lines in most specimens. as significant in reconstructing details of conodont soft anatomy as the V-shaped However, evidence available thus far does not structures

39 'suolrlrceds qs$locs oql Jo crlsueper?qt ujollsd ped?qs- oqljo uorlec -rpur ou sr orjqj lurul JqlJo srxe 6uol aq1 ol esre^suejl pu? lqercis eje souepunoq lueutes elqrssod ^lperrp s3 PeloJtuelul saul lui"j eqt '(/86I ) I? le qlrurs polou sv 'uou"luelu -tes l?u uo slsetllns 1?ql ^q uoweu{ esjo^suell 'onte^ ueql rerllo snp$ojlun snpolapudd Jo,turoleu? ipoq-uos oq1 uo uorl?rujojur Jsqlo aldrl fue^ seprôjd ueurlcods oql 'sluaullpos "r{so{nel\ tulsolcue eql Jo uorpsdr[oc uo,1?,!\ lusjejlp fua-/! e ui peuloj -ap ueeq eêq plnor\ snlej?ddu eql (suosrcods snorejruoqj?c qsqlojs eql qlrt\ es c eql ueeq e eq 01 sjeadds sd) pesseldruot,(llejelel ueeq 1l peh 'pessojduroc 'Ja) snplsurun snpodpuod ol elqelejej si IErrnu" eq1 eleclpul l?ql slueruole Jo pesoduoc sr'peuuojep uoeq lou ÎlueJedde s?q qjrq, d. 'snl?jbdde lelelqs eql '^poq oql Jo su"d Uos oql Jo se3"i pe^rasejd,(leleldluojul pue,(iluarejrpur qlr,$ uodercoss" ur slueuele UIJoJ -ruo3 Jo snlel?dde elelduoc lsourl? ue sopnlc -ur lew ( 't 8IJ) ueurlseds eltuls 3 si?lorq lerd Jo slueuodrxoc eql Euoluv 'ulsuocsll '?qse)lml {i Jo uo4euloc aepug uopu?jg u?u -nlrs eq1 luo{ sleurub pelpoq-gos fllusunuop Jo Elorq pe^jeserd,(?uoudecxe u" Jo slueu -odrljoo pequcsop yopuossenl) pue 's6bug 'oin)iii I'9861 ur pereedd" lbqt sred?d o,{u ui uaurlrads sqsa{nel\ aql Z' s?^\ eql l?ql slsasitnsnl"ndde ^ll?jlueôsjop Ûeul8uo pe^les -ejd eql ^poq ur sluaurale Jo uou?lueuo aqljo uou? 'uorp?duroj -Jeprsuoc'eJouxequnc I Jol?Irq JO pu" Ipunq ot Joud l"q/(eulos peuolsp eu Id eql 01 puuou eueld "fuleuur^s e ur passaldulot oje se^r ro elelduiocul sl (I' 'ElC) uelurceds 'e^4 uour3eds?qsjin?a\ eiil Jo lunjl snons[uoj eql pu? eqol JrJEqdoc oql 'os s?^r srql JI 'sixe -culsur lsou llls pu? 'pequcsop-tslg eqljo ui8 -ftrli louolsod eql 1?q1 lsotbns feru qslqr\ Jo purpnlr8uol s.purrus eql Jo epis qcee uo euo los,4lj?elc sr ug Fpnm on J0q1o eq1 u?ql epis 'se^pq posoddo o,!\l Jo pasoduoc,(lleurtuo auo uo.(irouetu? JeqwJ puetxe,(eql q8noql s",r\ snl?j dd? ero leql salejipur uoq.elueuo j? ',4poq eqtjo sur8j?u qloq uo Jncao s,{el ug srql leql lseesns (t86t) e8pfplv pu? 'ssilug peullcur,{y:ogelsod 'uoqs 'po^leseld sr 'qlllls rouelsod oql ol 8uqulod sdn leql eql ^poq Jo pue roualsod aql qolq,'a ul ueurrjeds qll,r\ pue lunrl s.ueurcods eql Jo l?qt 01 esjs^ reqlo,tluo oql q euo ppnm E f,lqlssod lsotu -su?rl s3x3 Suol Jraql qll^\ pjtujllo JJE snlplbd -Jouelsod eql 'sug oû Jo 'ug Peuoddns-,(eJ -de crt?qde3 eqtjo sluorxele IrrJoJluoc I I aqj 'eleurs,( eurtuo uejo sluau8es snonu4uo3slp 'q16uol /r\ou Jeqlro oq ol peledjelut Alq?uosEal ejb l?ql purtuo u,rou)lun Jo ue(ulseds " Jo {urul eql sduls aler?des o/'u se^resejd lesjop se (t86i) Jo u?d rouelue eql pub aqol JrlsqdJJ :ql slues 'p 1e stbug pslordrelul urtu?u eql (l -erdej pue elrxolop snoa3ellrej? Jo qels E Jo '3rC) oseqljo euo ^q u1 fpoq eql Jo pue rouolsod etpe ue{ojq oq} l? urlg crlrlsd? 'uql? s? pe^res eqt epnlcur suerurceds qsplocs 3ql Joi,![tE - d sr '8uol uru tt lnoqe si uaurljeds qsal -ns^\ eql {f86t 'eepfplv pu" 's8ilug'qllurs lunoluel"d pl?d o^"q ol ur00s qjrq^l ol êql {/861 'pu l3ug'rerserlcqc' pl.i pooûoh srllg poqslqnd'( po 'o8pup!v) stuopouo) Jo [Solorqorrlrd tuo{ uolsslulod qlr^r pocnpoldox ulsuocsl^\ 'Etlsolne^\ ^q l? itot-riuirog uopuerg ueunls eql uro{ sntd$onun "ipug snpoapuod Jo uoulcads paaroserd A erued v ' ' '3!d VINOCIONOJ AHJ

40 3.3 HistologJ of Demineralized Tissue WHOLE.ANIMAL ANATOMY Fdhraeus and Fahraeus-van Ree (1987) have identified cells, fibrous material (thou8ht to be at least partly collagen), and luminae ofvarious shapes in scraps of demineralized tissue derived from the pectiniform elements ofsilurian specimens of Ozarkodina confluens. Cells of vanous types have been identified; some are relatively large, with nuclei 3 to 5 pm across and long dimensions as much as 20 pm: others are smaller, contain numerous nucleoli, and have a strongly eosinophilic cytoplasm. Luminae, which have the form of irregular spherical spaces, and single and branching canals, are related by Fihraeus and Fihraeus-van Ree to the irregular frothy spaces within conodont elements that have been termed white matter. Flbrous matter is sparsely distributed among cells, occurs in bundles and, for the most part, lacks nuclei. Some is dense, basophilic, and apparently associated with elongated sinuous cells. The fibrous matter without soft-bodied animals with a slender, vermiforrn body a couple of inches long that may have been either laterally compressed or dorsoventrally depressed. The anterior end of the slender, elongate body is developed as a distinct cephalic lobe in known Silurian and Dinantian specimens and includes the apparatus of mineralized elements by which conodonts are best known. The slender trunk is divided into serially repeated transverse structures that occur on either side of or surround an axial structure that may representhe gut, a notochord, a doral aorta, a longitudinal septum or mesentery, or some combination of these structures. The transverse structures, which are V shaped in Carboniferouspecimens (but not in the Silurian one) have been compared with the myotomes (or muscle blocks) of amphioxus and fish and thus taken as evidence of body segmentation. Those interpretations are not required, however, and the transverse structures might just as well representhe paired digestive nuclei is considered diverticula to be collagen. Fihraeus that characterize many acoelomate and Fihraeus-van nemertrne Ree emphasize the fact worms that and, as such, indicate only onty 20 to 25 percent pseudometarnerism. of the tissue fragments The posterior end of two they studied is collagen, whereas of the flve collagen known accounts for the entire matrix whole-bodied fossil conodonts ofmost is other types bluntly aciculate, and its margin of mineralized tissue. They also point bears traces out of ray-supported that finlike structures the large number ofcells in on one demineralized or both conodont tissue indicates sides. Linear axial structures extend that it "... is not to the posterior bone margin in bolh specimens. or dental Ifthese tissue as we know it," represenl because bone traces ofthe gut, the Carboniferous "... is either totally non-cellular with an conodonts extracellular matrix largely may not have had a postanal segment, consisting ofcollagen.. or true tail.. or, in cellular bone, it is dominated The by bundles five whole-bodied fossil conodonts now ofcollagen with the occasional 'trapped' known osteocyte." They go raise almost as many questions as they provide on to state that the demineralized conodont tissue of their study is answers. It is a comfort to know that the skeletal also unlike that found in apparatus is apparently associated with living inarticulate the cephalic lobe, for most ofus had concluded brachiopods or mollusks. They do not exclude from seat-of-the-pants functional analysis the possibility that primitive vertebrates might that this would turn out to be the case have formed such tissues, nor many years do they fule out before the famous Scottish specimens were the possibility that the tissues they studied discovered. It is also no surprise represent a "... unique that approach to the biomineralization." specimens indicate an elongate, vermiform shape, since that is a shape common to mobile aquatic animals. However, even though the skeletal assemblages included in the wholebodied fossils seem to have been only slightly 3.4 Summary distorted by compression, they all apparently Existing evidence on whole-animal anatomy is lack basal bodies, and it is not possible to determine how they may have been related to sparse but may be taken to confirm the conventional wisdom that conodonts were prirnarilv muscular systems or whether they were com-

41 'dd 08t 'relsoqcqc 'poo^uoh sr[a (esptrptv 'f 'U pa) stuopouoj lo [SopqoaDlDd vr bll -16 sluopouoc pltuopojepu?d Jo ernlsellqjj? snlercdde aql pue 'VSn 'ursuocsld\ Jo u unl -rs Je,rol eql uro{ lerurue ruopouoj v (t861) 'f d'e8pupn pu? ''D g q 's8:lug 'd 'I^t 'tilitus 'dd 16'Srnqsn@d 1S 'ss!,,ll ptdlv l8tuox 'slueweure^noo ueqtsrl 1Eq-qcs$sru Jop surols,(s ueqosunls sep eqtslj uelssoj rop eqd rsouo} I (9S81) H J 'repued 'dd 08I 'relsoqjrqc'poo,$roh srlla lesplrplv t d'pe) suopouo) lo l6optqoa0l -oj ui06-ll IErurUe luopouoc eql ur luetllele?d oqljo uotpunj pue urod 086I)'S'U' ocin 's8-8r'ii 'g'res'uopuot ')os 'toy sudtj Tl4d 'vsn 'u$uocslld Jo u?un lrs Ja,$q-I aql uo{?lolq pe^.lssejd flpuoqdec -xo A{ou V (q9861) - Pu '-'- ' Lt L-gt L '8ZZ aruaps 'Etorq perpoq-uos ueunlrs V (es86l) 'f Fop -uessonl){ pue 'C A (I 's8ilpq 'C 'O 'cltnllhl 'dd 962'tlt ndod 2ads 'utv JoS 'pad (sepoqu I lh'ji pe) l8olooz ealdd tuopouoj ur 99-lf 'eu?luol^l 'Juolseur-l qclnc JBsg sql uro{ sleulrue iuumq-luopo -uoc ( t6i) 't H 'ttoc5 pue "C A\ 'uoltew 'ezl-lol 'v 0!?qp7 sluroj r?lluls w pup edft D apoapng Jo sesntbrpdde luopo -uoc ur lueue8uru? lueluelg (lt6l) "I 'uossddef 'd O8I 're$eqclqj 'poo.rroh sua (o8plrplv f )d'p.) siuopouoj Io tsoptqoadp{ ul 0l I-90t (ueuntis'eluopo -uoj) saanlluoj D apoap?ra Jo slusurele uuojl -urljad peurjl crpjo xuleru enssll UoS (/861) 'g C 'eeu ue,^.-sneerq?c pu? "g 'I 'sneejqec ' ZZZ- 66 t' 6l t3 o p tao a D P d' erqr,jl]loj qsrlug Jo eleqs sss8rng aqt uro{ albroqdoqd -oj u?uqruec V (9161) S 'slrrot{,t?/ruoc ^leu vl -l 'gl DrDqpT 'leutrue tuopouo, eqj (t86 I ) f 'd 'o8plrplv pue ) N'E 'uos{relj ''C a ( 's?ilug 't6z -6LZ '$)6t olwllai 'pueqocs, 'qarnqurpg Jo snorejruoqjes egl uo{ ecueprlo ^lou-sluopo -uocjo senrulg oql (986I)'d'I I'qlllus pue '111.1 g'uos1:e13 "C A C 's33ug'f U 'ebpgptv sojuorejau 'eluopouoj eql Jo uo4rsod srt"uels^s aql ol padsoj qll{\ suorsnlsuoj uo f,dtejlpur pu? snl?jedd? Jrt?qdal eql Jo uo[ljunj JLll Jo suonelejdjelul Jno uo a8urdur srellpru eseql V ',(li -A?c leccnq ^OcoJrp eql uqtrli{ sflcod Ieleqllde ui pele -nlrs Jo unlequde lbccnq ui pasolcue,{leleld VJNOCONOC EHJ-

42 4. TAXONOMY 4.1 Form Ta-xonomy Pander's classification ofconodonts was proposed largely In Chapter l, I pointed as a means of giving order to the out that Christian Pander, who discovered and named conodonts. systematic description of specimens in his collections. He made no attempt to give it profound wrestled in his 1856 monograph with the choice oftaxonomic base. He wrote (my biologic meaning, nor did he use it as the rough basis for discussing eyolutionary development translation): or addressing other biologic questions. Evidently the classification was to serve only until We don't know what sort of teeth we have before us; wheth r they belong to the jaws, the palale, the lips or discovery of more complete specimens made it the tongue; whether each particular shape conslitutes possible to determine if all elements were morphologically alike in the body of a single indi. sufficient basis for establishmenl ofits own genus or species; or whether different forms could have come from one and the vidual, same body. or if the body of the same individual might have had an array ofmorphologically different elements within it. In the absence of a living analogue, and unable to answer the questions he raised about Although Harley, Smith, Hinde, and Hadding contributed to conodont taxonomy be- function or anatomic position or about morphologic monotony or yariability of elements tween 1856 and 1926 by describing discrete elements of distinctive shapes as genera, no in the same body, Pander chose an admittedly utilitarian classification based on shape of individual elements. This approach to the classiries seems to have been made until 1926, when further consideration of suprageneric categofication of biotic groups is sometimes termed, Ulrich and Bassler published their influential rather pejoratively, form taxonomy. taxonomic scheme. As you will recall from earlier discussions in this book, Ulrich and Bassler To begin with, Pander assigned coniform elements in his collections to an informal category stated their firm conclusion that conodonts termed "simple teeth" (Einfache Zahne), and represented not only the teeth, but also the dermal plates of extinct groups of fishes. In addi- ramiform and pectiniform elements to another, termed "composite teeth" (Zusammengesel.ztetion, and probably rnore significantly, they also Zahne). The s.imple teeth (Fig. a.1) were then concluded from their studies of recent fishes further divided on the basis of cross section, that, except for the fact that they may occur as into 7 categories, which Pander described and right and left mernbers ofa pair, all teeth in the named as genera. Finally, each of these was mouth of the supposed living relatives of the subdivided on the basis of cusp curvature into conodonts are essentially alike. Thus they groups regarded as species. Composite teeth in wrote "... each kind is characteristic of some Pander's collections were represented by 7 obviously different mophologic categories. among professed complete codfidence that a classifi- particular genus and species." In short, they which he recognized 18 species on the basis of cation based on the shape ofdiscrete elements, features such as mode of denticulation, presence or absence of carinae, angle between prologic relationships. a form taxonomy, was a true expression ofbiocesses, character of platform extensions, and In their 1926 paper Ulrich and Bassler ignored the one genus (Periodon) proposed by the like. Altogether, then, Pander recognized and named 7 genera in each major category Hadding in 1913, but distributed all the others (simple and composite teeth) and, collectively, known at that time, and 15 new ones, among 4 56 species, all based on an analysis ofshape, or suprageneric categories described and named form. as families. Pander's "simple teeth" category

43 ecej?rd olur lnd 1ou se^{ lnq Jepu?d -uud Jo repro lcuqxo ue se sluopouoo er{l poug -sod? s" pezrueocal osle s?,^^,\ ',{urouoxel ^q ^lrtqrs uuoj -ep IqoIAI pu? uosu"rg tt6l ur lnq '(eprqaue^ 01 e/\rlsruelle ue 'ûouox?l luouraleqfl^tr unl,tr{d 'sacsrd ssep eql Jo) IluopouoC ss?13 ûtouoxsl luauolalflntr -qns aql ur sluopouoc papnlcul uosuerg 8 6I tr Z't ui 'luoserder ol lq8noql ejoa\,{eql sorceds pu? ejeuet eql Eurueu pue SursougElpu? slueur '(ralss?g Pu? qcu -ele luopouoc Jo sed^t u,,l\ou)lun {njo 1?q1 ur t lo auleqcs s.lqel l pu? uosuejg turqucsep ol suorluoll? Jreql ^lsnolêjd petoâp ul g qll { pereduoc) /I paflol sseh pezru IqeII Pue uosuerg ^lebjbi t?61 pue [6J uee,4aleg -BooeJ souotel J cueue8bjdns Jo Jequrnu ^q eql 'qleel lou 'seleld puuap se polortuelur leql os sjrfuejqns olur p:pl^rp aje^l(spplluopejend qcrq^\ 'sluaruele ujojrurped poujjoj -oqleusopi Pue'e?pnuoporuoud'o?pquopoel -leld uo paseq sercods pu"?joue8 lle pepnlc -oj) seqrur"j 3erql 'pu?q Jsqlo eql uo 'sjopjo -ui rellel eql :sedegsnolr"^ Jo slueluale rujoj -qns ssoqt ozrutocar lou pip flluenbesuor oq,r -rudcod ssoluirojl?ld pue stuaulele urjojiuej 'ss?i{,{q luelsrxeuou Jo luecuiuersui se pap$8 roj PelceJe eje,ld esaquo o./irllsjg eql 'aeprqlbu -er ar3,r1 sau ojrluopouoj pu? sourjojrluop -t{iod pue'e?prurpououd'(ezplluoporuoud -ornon sjopjoqns aql ezusotej o1 pesn HeI I :01c0J) oeplpoluoud serlrurej 3q1 olul popr^rp pue uosuejg 1?q1 ojnpruls l?ujelur Jo sejnl?aj seat fuo8el?r..q1oal olrsoduroc,, sq pue '(o?p eql 'serlurej I olur pepr^rp se,r qjtq,t (ept -rluopooetsr(i uejq o^?rl plnor{s qjtq^l) e?pt -JoqdotuopouoJ aql) repjo ol8urs? ol pous$ -poo"tsrc eql se peguuepl f eujoj se^\ -se ojea\ sluopouos Jo ejeve? Lvl 'sseh uaqllla ^truej ^q ^lejrlue lsolup uollrj \ 'eunlo^ puosjed,(lq8q t"ql ui '2961 ul pejp.edde \3{t4u\'{8opj 'suorlces ssojc gql Jo lq8u oqr ol seuq iêoq oql SuolB -uoal0d aptqauaûj uo astloatj oqljo A\ arlrn seulllno pjelq ur u,roqs ej pu dsnt oql Jo ejnle^ 1oA ur errroe slr paqceej {lojns slueujele elejc -rnc uo poseq eje \ sorcods slolceleqc cueuo8 Jofeul 5q1 -srp'pnpr^rpur Jo sedeqs eql sepcrpur eull Jo srs?q eqt uo leluozuoq qtuojo Pue 0q1 le uollcos ssolc aqf sorceds pue ereue8 euoc-oldtuls s.ropusd 'I't '3!d sluopouoc Jo uorlssgrsselj Ieclueqseru eql ureql pauroj leql qsg eqljo eqt pedselc e^?q ot lqenoqt oref\ qcrqnd ^{?f 'saprsrepun ellqsnol 'deap,{le^n?lal qtl/( slueluole snojqg,{q procer lrssoj eql ur peluasardal er" ^ll?ulalul 'oldrue -xo roj 'a"pquopoeloc eql ol pou8lsse sjeue8 eorqt eql eluoq ueeq a^?q ol tqanoql are^\.{eql qcrq.{ uo rruer,nef eql. pu? r{teol ped?qs,(fnou ^ eql uee,{rleq dqsuon?lej pesod -dns eql Jo srsbq oqt uo serlrrjej s? peuuap sou -o8elec olur pednoj8 eral, ^ lv6l ur uaou{ seuo ped?qs eql 'qleet qsg eq ol lq8noql ^FuereJrp ojo,t\ sluauele û"ru luopouoc osnmeg'ajnl -cruls I3UJ91Urc errrel E e^?q leql sluour -ele f,q peluesajdej ej" qcrq,t\'ejeuea SuIurzI[oJ aql roj peqsrtqelse se,l^ sor[jojrluopouoj rep -Joqns gql seojeq^\ 'ornloruls l?ujolul snorqu (e^pq 01 tq8noqt ejea\ Jo) eêq slual'uolo esogr( Jauet uercrôplo T pepnlcur seurojrluopoj -nen JopJoqns eqj 'ejnlcruls pujotrur ui Jeiurp sluetusle esoq^\ sluopouos JoJ peqslq l$ ejo^t (seuuojrluopouoc pue saurojlluopojnen) srepjoqns o,!u eql 'sjepjoqns z pu? sellltrr"j g o1.ur pelquressere,$ qcq^\ 'ejeueb, pequos -ep pu? (srpuoqdotuopouoj oql) seqsg a^nr VJ,NOOONOJ lhl- 9t

44 TAXONOMY 37 until 1879, when Hinde employed it for a species from the Devonian of New York. In the "multielement" way of looking at things, the skeletal apparatus ofa conodont is made up of numerous parts, not necessarily all alike in morphology. The base for taxonorny is thus a group of elements that can be shown, or can reasonably be inferred, to have occurred together in the body of an individual conodont. An apt analogy, ofcourse, is with the vertebrate skeleton, which consists ofnumerous morphologically different parts. Hinde (1879), the first to practice multielement taxonomy, based his concept of Polygnathus dubius on an assortment of elements and an essentially complete "natural assemblage" is preserved in the head of the Scottish "conodont animal" discussed in defail in Chapter 3. So, since at least 1934, there has been no good reason to defend a form taxonomy for conodonts as a natural one. The practice persisted through 1962, I suspect, because most students of conodonts wer more concerned with biostratigraphic applications than with biologic taxonomy I Multielement methodology The major difficulty with putting a general scheme of multielement taxonomy into practice for conodonts has been the fact that "nat- partly exposed on the surface of a slab of black shale. He took physical proximity on the shale ural assemblages" and fused clusters are relatiyely rare and are not uniformly distributed slab to indicate original association, although the name he chose for the first species to be diagnosed in a multielement sense suggests that able to most systematicists are jumbled assort- stratigraphically, whereas the collections avail- he was not completely convinced that all elements came from the same individual. ponents of several different multielement ments of elements that may have been com- Other, more convincing "natural assemblages" of elements were described indepensented by natural assemblages, a means must apparaluses. Thus, except for species repredently in 1934 by Hermann Schmidt in Germany and by Harold Scott in the United States. collections of discrete specimens were origi- be devised for determining which elements in The assemblages available to those paleontologists are all from Carboniferous rocks ofabout Perhaps the most instructive way of reconnally associated in the same skeletons. the same age and are made up of about the structing the skeletal apparatuses of conodonts same types of conodont elements. Because the from large collections of discrete elements is a composition of Schmidt's and Scott's assemblages is closely similar, and becauseach had was applied as early as 1958 by Huckriede, who basically empirical method. This procedure several specimens of sirnilar or identical composition, chance association was easily ruled odonts certain forms occurred more or less reg- noted that in his collections of Triassic con- out, and the assemblages were described and ularly with certain others. From his observation that certain types of ramiform elements interpreted as the skeletal remains of individual conodonts. E. B. Branson and Mehl (1936) were regularly associated with one or the other and C. C. Branson (1957) attempted to dismiss of the two most common platformed pectiniform elements, Huckriede proposed that the Scott's specimens as coprolites, but Scott replied (to Branson and Mehl) that "... it would " Conodonten-Satz" (literally, conodont-set) of be strange indeed to find a group of animals Gondolella navicula (the platformed pecriniform element) includes a pair of angulate pec- with such a balanced diet that the excretal material would consist time after time ofone pair tiniform elements (refened, then Lo Ozarkodina of prioniodids, one pair of spathognaths, one tortilis), a\d ramiform elements that were included in 1958 in 9 form species assigned to 6 pair of prioniodells, and approximately four pairs ofhindeodells." form genera. Huckriede compared the association he recognized empirically with natural as- There are now more than 500 "natural assernblages" of conodonts known from Cambrian, Devonian, and Carboniferous rocks, al- and Rhodes (1952) and evidently noted agreesemblages described by Schmidt (1934, 1950) though not all have been described and ment in at least major features. He applied similar reasoning to a reconstruction ofthe ",Salz" illustrated. In addition, fused clusters of elements now and then appear in acid residues, of Polygnathus tethydis, with results that are

45 x X X XX X X XXXXXXXX xxxxxxxx XXX XXXXXXXXXXX XXXXXXX XXXXXXXXX XXXXXX XXXXXXXX xxxxxxxx XXXXXXXXXXX 'uetllrmds 5uo rseet le,tq eldu4s ul peluesardar = x rtorv X I st I I I OI I soldues sodil lueurola saldwos 0I ut sadlq tuawala SI Io uon qu$id, I t g'i{vj, 0l 6 8 L 9 s, E z eq lq8rur leql slueuala Jo 'sjalsntc Jo 'sdnoja JO JJUJJnJJO-OJ JO luolxj Jql JO ldjjuor e olqa leql ur El?p ruo+ Surdoleôp ur pelsojolur eq plno^\ lsrurouoxsl lujuralenlnti.i eqf'sald -urps 0l ur slujrr.rjlj luopouojjo sedfl luej rp s[ Jo ecuejjncco eq1 sezrjerur]ns I't alqel 'urnuiiuiut se,+r Eut1.to,r,r J 1eql elecrpur sejnl"ej esoq/,( slsoj tuo{ ej? PUe Sr roj erues eql Jo,(ueru opnlsur leql saldu s Jo Jeqrunu e8jel,{lq"uos gj? qlr \ 8ur {?ep sr Jole8qseûr eqljr, luo )ljo,{r sejnpef,ord eseqt l?ql pufiu ur ldel eq pfoqs ll qtnoql 1 'ê^ms Jeuq E quo,r ele senbruqcel tuuol -snlj :rfl Jo sjjnlp+ l?jjuac sjrceds esoql Jo sosnl?jedde eql ui slueruelejo sjr"d pue slueur -3le uea/$laq sollsl l?cueunu egl 01 se SUoIS -nlsuoc ouros qceoj ol 'ejorujequnj'puz serc -ods lueurelorllnur luenldsuoc Jraql olul ssunq sarcej Jo ledur,\ojd se pepj?eej oq lqsfr lpq^{ epr^lpqns ol s3s?j auros ls?el le ul Jlqrssod eu?ceq tr l?qt lfsoj orn qlh\ '1oeA\S pue urolls -8Jeg pue 'sraqa^\ 'resrll?l[ 'epeu)lcnh Jo spo -qleu Fcurduro aql JoJ sejnpacojd IDcrueqcorrJ polntrtsqns 'lceje ui 'sercads tuopouoc Jo sesnleftdde êql lelele{s eq1 s? pelepô eq lq8ru] leql sdnojb luorjnoer al?iosr 01 slduiauz ur slueuele elejrsrp Jo suorlcolloo otr?j ol 'sluelc tsoru (^luenbesqns luelxe etuel? 01 pu") 996I ot roud 'sr leql isepjrc luopouoc ur sleqllde aj01a sorueu u,{ro reql l?ql PunoJ uoos lee,,irs pu? rug4s8jeg pue sraqala 'ecrlcerd slqt 8ul -ldop 'sluelliele Jo sdnor8 lueuncal esaql {q paluaserdar ^g sabads eqt JoJ 3sn ol se(ueu 3lq? -lr?a?,{ueu eqljo qcq^\ SululuJelep UI pa,{\ol {oj era^r atnplluau.ron lnrsolooz lo salny louou?utaluj oql pue 'selceds Jo seêeluas -ardej erll se peleojl,qll3rtdxe ojo.r\ (resql ia Jo..sasnlpndd?,, eqt 'epof{.nh Jo a49s eql) pezrusooej,{aql sdnoj8 lueuncoj eql 'Jeê^{oH 'stuopouoc uercrôpro reddn pu? elppll I Jo suoncelloc egjei JroqlJo srs,{leu" c(uouoxsl ur rasql d\ pu aped[rnh pasn pcurdure eur"s oql AllErluesse ^q poqdd? ^Solopoqlaur (9961) lee,rs pue uro4serog pu? (996I) sroqa^\ 'suual Srurouoxsl-IuJoJ I"uouue,\uoc ojour ur poqrrtsop ejo^\ qd?lsouour srq ur pajeprsuoc ^l31 uiuin eq stuopouoc u?unlrs aql 'Jeê -aoh 'serceds luopouoc.lejnl?u, Jo suolelels olqeqord sql s? rueql pezueotej pue,.sesu"jedde,, sdnort asoql Peulsl ^lffelc 3H 'sluopo -uoc u"unlrs Jo suoqcolloo etrq slq ur slueur -ale Jo sdnojt lua[njej azrutocat ol poqleur I?curdule eqt posn osle (?96I) Aepol _reslll3,4a--^ slsruo -Ueoc urs fueulq tuerejrp uo peseq 'spo -uox31 lsolu,{q pe,(oldruo ouo eql si ojnpejojd -qleur ^tu?i tuuelsnlc snoue^ peltdd eêtl (ZL6l) srql 'slepoul Jluroleue se pj^ras leql sjaptq Jerllg uo^ pu" '(0/6I) 10e,'.\S '(6961) tnqo) -uosse lejnleu u/(oullle,r Jr.ll Jo slujuodluoj ilsbot oql ol 'use qll,lr,(lperlp pejeduro3 aq pfoc slequleul -rsnqluo rltr,r pel$jt lou se,tr,t('uouoxel ^3s posr^ esoq^{ sdnojt lueuncej lcrulsuocer ol slusluals -er sq1 ur serceds pu? ejouet ol perldd? sgrueu elarosrp Jo suorcelloc e3ru1 qlr,n fluellurej slq eql Jo pu? eseq crurouox?l eql Jo uoisiaej Joferu E pu?-suralqojd qdejerl?lts e^[os ol Jo Jsn JeJUrduJ Jpsrll 'uotls ut 'apju{tnh 'sjoqlne leqlo os prp sluopouoo porpnls oq,{\ slsreololuoopd Jatel sl?a^ pelels osoql ol Jelrurs,(lasols ^q û?iu VJNOOONOC AHI

46 IAXONOMY 39 TABLE 4.2. Jaccard cofficients for element-type pairs from Table 4.1 Type 1 l t) I l0 ll t2 l4 lf J0?1 78 1t _ 88?0 60 7l t00 6't ? ? t s i{ot? Decimal pornts omitted:"100" = 1.00;"50" = 0 50, e1c. -,:tr l t considered to represent the skeletal apparatuses all possible pairs ofthe 15 element types whose of various conodont species. Several different distribution is given in Table 4.1. Note that coefncients have been developed for use in stating the degree ofassociation between two enti to a high of What we need to do now values of those coemcients vary from a low of ties, and each student has a preference for one is rearrange the data oftable 4.2 to reveal clusters of element types more closely related to or another. Kohut (1969), for example, used an index of affinity developed by Fager and each other than to other clusters. This may be McGowan (1963), whereas Von Bitter (1972) done in several ways. Kohut (1969) chose, in employed the Jaccard coemcient. Clusters derived from the data oftable 4.1 are essentially matrix itself, as I have done in Table 4.3, by effect, to rearrange the similarity-coefficient the same whichever similarity coefiicient is rnoving the highest values in each row and column to the diagonal median of the matrix. Von used; so, because they are easier to calculate than Fager values, I have derived Jaccard coefficients for all possible pairs of the 15 element weighted pair-group method to develop a den- Bitter (1972), on the other hand, used the un- types in that table. The Jaccard coefncient, as drogram that graphically displays the relationship between pairs and clusters of pairs of used by Von Bitter, may be given as element types. I have derived the dendrogram _a J=a+b+c of Fig. 4.2 from the similarity-coemcient data of Table 4.2. in which a is the number of samples in which In both the rearranged matrix of Table 4.3 both the element types considered occur, D is the number jn and the dendrogram of Frg. 4.2, note rhat there which one of them is present are three well-defined clusters ofelement types. alone, and c is the number of samples in which Two of these clusters include six rnorphologically different types of elements, whereas one only the second element type occurs. Obviously, ifthe two types ofelements do no1 occur has only three. Furtbermore, both the rearranged matrix and the dendrogram reveal the together in any ofthe samples available J : 0; but if each of the two is represented in every same three clusters, which may appropriately sample that contains either one of them, J = l. be identified as recutent groups. Ofcourse, ifj = I for a pair of element types, In a multielement view of the conodont we must consider the possibility that those element types were originally parts of the same omy if their components also exhibit several world recurrent groups are the basis for taxon- skeletal apparatus, even though they may differ other important features. For example, if a recunent group is to be interpreted as the skeletal greatly in morphology. In Table 4.2 I give the Jaccard coemcients for apparatus ofa conodont species, one might rea-

47 -o tr. sjaaot I a lt t 8 E tt 6 I 9 -ot ' elqejjo xuleui pesuerreer oql ur pue ereq reedde sjolsnlc orues oqf t ql ' elon Z t elqej uro{ senls^ pleccej sed^l tuewolejo sdnor8 uoe^qeq suonel Surlndep ue$olpuop.2.t.3!d V 'suonenl$ leql le u^{odi seeelquoss? û?ru ui uobneo qtla pendde I?Jnl?u eqt uro+ eq osp lsnur uoddns eulos qtv'i 'pepueluoc(696i) tm{o) IcllspJe^ siit 'uoqs ui sutsuler lelolo{s Jrorll '1S"O eql ur polnquluo3 qorq.yr ot sluour pelsrxe aaeq lqtru sulell"d Jaqlo teql fl$qls -uojr ue fj?luerurpes ^llbnlueâ eql âq1 ur Jo sercads luopo -sod eql,(uep pfo,r 'Jeê^{oq'sluopo -uoj auros Jo {uoaoluo eql ur ibuulsuoc qcns -uoc IIE JoJ uorlrsodujoj ^lareu snlejedde ur,&fuepl lsuete pelejedo slueê t"qt r?ep,{l3urs?erjur uo gjuelsrsur qsrêls sluopouos JoJ slepoul euroceq seq lr ecurs'sarcods luopouoc ejo snlej clluol?ue e^rpafqo AIuo eql se sjdof iueuj -?dde eqt s? dnoje lueuncej e SunoJfuoluroJ roj pa^res o^?q l?ql sot?iques$ [EJnleu eql uoueluc lereue8 e s3 orlej ro {uej ui asoql 01 tueudoloêp IeJauet pu" requnu loddns ol linjsrp oq ^cu?lsuoc plnoa lr 'JoAoA\oH'per ur elqereduloc slueruete Jo u? opnlcur ol -Pnls aq spuol?ur ubrcrôpjo eql rllo{ peûep u,yroqs aq u?3 dnort lualnjer ^?lje?jo sluguodrrjoc sretsnlc p uesejdej-lseq aql IpJo ejnpej " se^{ JI InJdIaq osp sr ti 'ezrs ur abu?jeirurs e pu? Iu?J ur,{cu?lsuoc lue grutrs ^lforlsrl?ls leql :flrêt 1eseq pu" ece3rns lueurqc?1e Jo lueur elalsuoulap ol alqp se^r oq puv 'sarjads luopo -doloêp Jo epolx pcpuepr ro JeFurs e :.,Jal -uoc EJo snlh?dd? I?tele{s eqljo sljed pojeprs -tetii etrq^\,, Jo uounqulsrp pue ojntdlnjsorc -uof, eq 01 JepJo ur ou?r ro {u?j ur Jeqloue euo -rur pc4uopr Jo Jelrur6 e :ejnpnjlsorcru pue ol drqsuortelar JBlntar ouos osl? pfoqs uollelncduep dnor8 ^\oqs Jo epou I?J[uePr Jo Jelrurs e luolncej slueuodr.uoc eql leql 'erull e.,\.?q ol slueuole lueuodruoj slr Fadxe,(lqeuos "Jo '.re '0S 0 =..01,,:00 I = <{00L, :pouuro ueeq a^bq slulo<i leurlsed rrloy'{ r r 00r,s0s II. IL TL LS _ 0t0 0f0s09- btq9999sbb8lol- 0r 0s 0s 0s 0r 0r Z 6Z ft 67. 6a t t9 0t 05 - nt nv 8/ 0r EE tv 8f ft 09 L9 8L 0L zz ee f cc 8 99 L9 09 0r. L. 8t 88 - zz EE ff 8 99 L9 09 0L rt 8t 88 00r zz EE ' U r 00r - ZI OI I L IT ed^t 7 SI 7l OI fl I 6 9 I L 7 2 a\qoa uo{ uualcsaot ptntoflo xltrotu pasud oav 'E V A'['.JVJ, VINO(ONOJ 3HI 0t II 8 I bl

48 TAXONOMY MultielementClassifications ment or redefinition ofcertain categories eslablished in that volume. Personal prejudice dic- Ljndstrdm (1970) compiled the first classification of conodonts that recognized recurrent tates others. Thus the classification adopted in groups this book and discussed in some detail in Chapter 5 wilt appear, at least superficially, of morphologically different element types to be as the basic taxonornic units. Conodonts quite were grouped into 2 orders (Westergaardodinida Lindstrtjm and Conodontophorida Ei- different from that in the Treatise. Some brief comment is thus in order. chenberg), with the latter (the "conodonts First, I have become increasingly skeptical as proper") to the amnities and relationships of further divided into 8 superfarnilies the tiny, (Distacodontacea, weakly phosphatized fossils Panderodontacea, Chirognathacea, Prioniodinacea, Prioniodontacea, termed protoconodonts and paraconodonts and lumped together Bryantodontacea, in the Treatise as the order Paraconodontida. These superficially Gondolellacea, and Polygnathacea). These major groups were defined, conodontlike insofar as possible, forms are quite in mullielement terms, different in internal structure as from were the families into which they were the ones described in Chaprer 2, for which divided. Bengtson (1976) has provided Altogether, Lindstraim was able to assign a total the general term of73 genera more or less confidently to "euconodont." Although Bengtson has shown one or how paraconodonts another ofthe 2l families he recognized. might have evolyed from protoconodonts, The neither he nor taxonomic scheme outlined by Lindstrbm (1970) anyone else has yet documented the steps obviously influenced the one by which euconodonts might have developed by authors ofrevised Volume W developed from paraconodonts. Szaniawski (1982), on the ofthe Treatise on Invertebrate Paleontology (Clatk et other hand, has demonstrated that conical al., 1981), which was written between l97l elements of one and 1976 but was not published of the protoconodonts (Phakelodus until late tenuis) arc essentially identical in jntemal Treatise atjlhots included alt conodonts in structure a to the grasping single class of a phylum spines of modern anow worms Conodonta and followed Lindstrdm in assigning the animals I re- such as Sagitta. Thns, Phakelodus tenuis, a protoconodont, may well have been an early repregard as "true conodonts" to one order (the Conodontophorida), which included 44 sentative of the phylum Chaetognatha families distributed among 9 superfamilies. The 179 or of some now-extinct group closely related to the genera chaelognaths, of "true conodonts" recognized were and not a conodont at all. diagnosed, insofar as possible, Szaniawski (1987), whose careful histologic in multielement studies are certainly important terms and described in in this regard, continues to hold the terminological scheme described in Chapter 2 of this that the proto-, para-, and book, euconodonts (i.e.. the which was developed specially fot lhe Treatise. Paraconodontidand Conodontophorida of the Treatise classification) form parts of a single evolutionary lineage. He does not regard the Conodonta (in which he would 4.4 A Revised Multielement Classification include the Paraconodontida) as chaetognaths, At the time ofthis writing, skeletal apparatusesdespite considerable histologic similarities, but of species that represent more than 100 genera as representatives of a group that developed have been recognized from natural assernblagesfrom a common ancestor. It is my conclusion, or fused clusters or have been reconstructed which is further developed in Chapter 8, that from recurrent groups identified in large collections of discrete specimens. For the most part, natha are similar but divergent groups, all pos- the Conodonta, Paraconodonta, and Chaetog- the classification adopted in the Treatise provides a satisfactory framework within which to general radiation of major structural plans that sibly of phylum rank, that developed in the assess relationships of the species so reconstructed or recognized. However, discoveries biosphere. characterized the Cambrian history of the since 1976, when the f,"eat,se manuscript was It would be an unjustified extrapolation from essentially complete, dictate some rearrange- Phakelodus to assign all 15 genera included by

49 -rxes Aq pazualc"j?q3 sercoos luopouoc $pnlc rurojruos 'po^\oxnjun lnq 'Peleuls -ur rapro eej?l sql sro\tne asuoatj Jo eex ^lpjetel - qleueqod eql,{llertuesse sr ejeq Û"rcgrns Jo sesnlej"dd? elsjqlrr3tuqlnu ro -run llnq l3q1 sluopouoj Jo erjujs 0z roj pe \olloj arrreqss ^lrruejredns eql Jo epurpo{ftzo aql peqsllq"lse sr eprluoporepu?dolord eql sjep 'JJpJO Srql Ul apnljul I sjllrrrjbj s eql ur HJuaS -Jo e^g olur pepr^rp $ luopouoj ss"l3 oql t eausocej I 'suruq Jo suorsuelxe e{quuoj 'usruoôo JqlJo pu3 Jql.{q -l?ld dolaôp suoqrsod d eql ur sluorxolo plp l3urlxa,40uejedde s"'r lnq 'PeJeôcslp lej snql repro eql Jo,irolsrq eql ur el?t :solcluap lseplo eql 'ee? u?uqure3 el?.l Jo sluopouoc elqeed qll,{ las pue lsnqoj eq ^luo ol puet slueur sepnjjur ss?lj JqI uon?jjjsnonjtdsuojul -elg 'suoursod d eqljo qloq Jo euo ur sluourele pu" pe63?rjo,4luo slsrsuoc flueulolsnc er"j/ lp urojlêrq Jo urjojrsuelxe qllt\ sesnl"l Îlsoru uo4?lncrluep pu? 'slueruala Jo ses?q eql puo^ -?dd alerqureu4dos 01 -Ixes llnq sluopouoc -eq le,fue^ puelxe eprurpouolrd?ec?qleusojrqj ^lej?j 'podoleêp Jr 'sossoc -ord sabrêc I"s"q deep q1v'\ sluetxele (Pel?ul.s 3q1 ur sroqln?,,rllrr{,{q pepnljur ÎrurE#edns?Jouea eql Jo) qloouls pesodruoc JO oiiios Sapnlsur OSIE pue aslpatj ^Heo,'a,(Iuo sesnlersdd? [?lele{s elpjqureurlllnur ^lprcfnsjo 01 -lun aql Jo?ocslleloPuoc pu??ecsllepjeqqrh ^ruouoxet sell e^"q sercads tuoprêj '"p4uoporepu?d pu" -rruqredns eql seurquoc Eprurporuoud eqj sprluoporuoud sjepjo aql se pogrluapr eleq."plluoporuoljd seuo8alec rueue8?jdns ur papnlcul eje^\ qjrq^r aql Jo solru?j snoue^ ur ejeuet gt roj ec?ld 'a"pqlapoleg pu"'eeplllesuv'o?plluopoe(d? punoj eêq I 'Jerlle3ol[Y '?prurp seqrurq eql ol pu" EeJ?ulqsruJnc pu? eec?l "{[e^!cedsej -oljezo pue?p luopouojojd:ql ol pausrsse -uopouocord sarlnuqjodns aql 01 uoq"cgrsse[3 erp qcrq^\ '(o?pduopoqledsorsld pu a"p4uop asudatj elql ur pausrsse sluopouos e^luurud -o8^d) sdnoja Jeqto oû epnlrxe I pu? '?ecel Jo sjeuee gl epnl3ur 'nuopr^?j ss?13 eql Jo -uoporelsrc aql ol sroqln",srrdatj Aq peuers '?plllepoleg pue?prluopouosojd srepjo eqj -s? (e?pquopolsro eq1) dnoj8 lu?uodurr ue '[z] atq li ui epnltul osle I 'leê,{\oh uorl?cglsselc astl -elrcê fpeerp seu?u dnort-rapjo ej? (eplulp -oajj atll Jo eersluoporuoud,tlrurejuedns eql -o{r?zo ' prluoporuoud) gcrq^r Jo z roj 01 lueluoj pu? edocs ur Jelrurs sr dnols luopo 'slapro, otul pephlp JeqUnJ ej? qjlq/t\ ^luo 'Iluop -uoc Jofeur srql 'pe^recuoc snql sv suonrs -r,tec puu [1] rluopouo3 'sass?lc Z olur pepll -od d eqtjo rdoq Jo euo ur ssoleue peuuojleld -rp sr stuopouoj eql 'Jeê.{oq'areH epuoqdol neql Jo slueurels el?u4s?d epnljur pue elejq -uopouoj JepJo arlt sz asrpary oql ur pednoj8 -uaurldos Jo -rxas eje leql sesnlaed aje,$,{eql lnq 'qcols Jof ur tuejojrp Joql?r -de lelele)s qtp\ stuopouoc ^llecrs?q sepnlcur ojeq pesod o,r{l luesajdar ol J?edde sluoruela q3ns uo peseq -ojd uod"cgrss"is aqljo?pquoporuofd aqj 'u?ruoêo 3q1 olur lle,{r pj?!\dn 93u?J pue $[coj u?nrôpjo Je^\o-I ur lsju readd ' pquoporapu?dolold eql ur {Jo1s l?jlsecu? u3 ruo{ Pedoleêp,(lorns qcrq^\ 'sepquopojepu?d sernssg ro snaojjnj IEurp -nlr8uol snoncrdsuoc pezuapercqc 'sluaru -ejj JI?JISPJ pu? rr.rjojluoj ^q pjtsêjxe JO SosnleJpdde l?lelels el?jqureurnburnb ^ldjjp ol -rq e^rlsuusrp llnq eptuopojepued eql ur PepnlJur?Jaue8 luopouoj 8 aqljo sgrcads '4uopouoJ aqljo srop -Jo rjqlo IJE Jo srolsjjus Jr.ll sjpnljur xlqeqord sluopouos 3ql Jo dnors roferx srql sjarllo,ral Jo [? orrjej sdocs ur pacnper Pue saqr " -(uejljedns Jeqlo ot ^q sjoqlne a,r/tra{.{q peutrss" ejeues Jo requrnu E Jo rejsu?jl r(q potueur -3nE'uorlpJgrsspl, asuoatj eql Jo Eoa?luopor?l -src oql ej? iseqt 'ued lsour oql roc 'slueualo YJ,NOCONOJ :IHJ sercads pu? EJauaC JrsserJl oql Jo pue fue^ ero lllun 4eJls ourj?ru ezuapej?qc pue s{301 ueuquej Jeddn ur lsrg Jeedd? Z ratdeq) ui pequosap ejnljn4s e{illllopouo)na arll rllrtvl slueruelo uuojruoj pezd?qdsoqd,tdnols 'ss IJ elsj?des e s? pepje8ej lseq eq,ttqeqord IILI stuopouoiend eqf '(1861) Dls^{eruezs Jo esoql s? qons 'sorpnls arntnj q8norqt poqsllqplse eq uorlceuuoj ^teuugep " plnoqs {ooq sql ui uolssnjsrp uro{ ureql PJllrr!o Jêq I 'slujtljij luopouojnj qlr,4\ surjoj pue sluopouojej?d eql ujj^lteq uolljeuuoj ollugjp ou IJA se st JJaql osnbceg 'sllelep crsololsrg ur sar6olouoq lejnl -retuo3 pu? Jourur pue uuoj FuJelxe ur fluellrurs ^lu"d peorq e;o srseq aq1 uo.(jeretll eluop -ouoj erll ur srrrjoj o^rlrurud aseql opnl3ul 01 pegusnfun,{11enbe sr 1r lnq 'eq1eu8oleeq3 aql ol EprluopouoJ?led eql ur sjoqln? a'sllra4

50 or septimembrate apparatuses u,ith carminate and angulate pectiniform elements (or their platformed analogues) in P positions. The ozarkodinides, which appear to have been the most diverse of all the conodonts, did not appear until late in the Ordovician and persisted into only the earliest part ofthe Triassic. At present, this is the largest conodont order, with 55 genera distributed among 12 families. Chapter 5 is devoted to a description of the principal components of each of these conodont orders and to a discussion of the distnbution and geologic history of these groups. A synopsis of the classification followed here is also included as Appendix A. Apparatuses of typical species of many conodont genera are illustrated at appropriate places in Chapter 5, and illustrated discussions of additional species are to be found in the Catalogue of Conodonts (Zieglel 1973, 1975, 197'1, 1981 ), of which four volumes have been issued to date, References Bergstrom, S. M., and Sweet, W. C. (1966). Conodonts from the I-exington Limestone (Middle Ordovician) of Kentucky and its lateral equivalents in Ohio and Indiana. Bull. Am. Paleont. s0(229), 21 t-441. Branson, C. C. (1957). Comment on the Moore/ Sylvester-Bradley "Parataxa PlaL" Bull. Zoo l. Nomencl. 15, 169. Branson, E. B. (1938). Stratigaphy and paleontology ofthe Lower Mississippian of Missouri, Panl. Univ. Missouri Studies l3(3), l , and Mehl, M. G. (1933). Conodont studie^s number l. Univ. Missouri Studies 8(l), 5- -, (1936). Geological afrnities and taxonomy ofconodonts, Geol, Soc. Am. Proc. Abstr. 1935, , (1944). Conodonts, pp , pls. 93, 94. ln Index Fossils of North America (ed.. H. W. Shimer and R. R. Shrock). Wiley, New York. Clark, D. L., Sweet, w. C., Bergstriim, S. M., Klapper, G., Austin, R. L., Rhodes, F. H. T., Miiller, K. J., Ziegler, W., Lindstraim, M., Miller, J. F., and Harris, A. G. (1981). Conod,onta. h Treatise on Invertebrcte Pqleontology (ed. R. A. Robison), Pt. w, Suppl. 2. Geol. Soc. America and Univ. Kansas, 202 pp. Eichenberg, W. (1930). Conodonten aus dem Culm des Harzes. Pa ldonl. Z.12, l' Fager, E. W., and Mccowan, J. A,. (1963). Zooplankton species groups in the North Pacific. S cience 140(3 5 66), TAXONOMY 43 F6hraeus, L. E. (1983). Phylum Conodonta Pander, 1856 and nomenclatural priority.,sl,sl. zool. 32(4), Hadding, A. (1913). Undre dicellograptusskiffern i Skane jdmte nagra liirmed ekvivalenta bildningar. Lunds Univ. Arsskr., Avd. 2 9(15), l-90. Harley, J. (1861). On the Ludlowbone-bed and its crustacean remains. Q. J. Geol. Soc. London 17, Hass, W. H. (1962). Conodonts. Pp. W3-W69. In Treatise on Invertebrqte Pqleonlology (ed. R. C. Moore). Pt. W. Geol. Soc. America and Univ. Kansas. Hinde, G. J. (1879). On conodonts from the Chazy and Cincinnati group ofthe Cambro-Silurian, and from the Hamilton and Geneseeshale divisions ofthe Devonian in Canada and the United States. 0../. Geol. Soc. London 35, Huckriede, R. (1958). Die Conodonten der mediterranen Trias uod ihr stratigaphischer Wert. Paldont. 2.32, l4l Kohut, J. J. (1969). Determination, statistical analysis, and interpretation of recurrent conodont groups in Middle and Upper Ordovician strata of the Cincinnati Region (Ohio, Kentucky, and Indiana). J. PaleonL 43(2), Lindstrom, M. (1970). A suprageneric taxonomy ofthe conodonts. Lelhaiq!, 42' Pander, C. H. (1856). Monographie der fossilen Fische des silurischen Systems der russisch-baltischen Gouvernemetts. Akad, Wiss. St. Petersburg,9I pp. Rhodes, F.H.T. (1951). A classification of Pennsylvanian conodont assemblages. J. Paleont. 26, r. Schmidt. H. (1934). Conodonten-Funde in ursprunglichem Zusammenhang. Pqliiont. Z. 16, (1950). Nachtrage zur Deutung der ConodonteL Decheniana 104, I l-19. Scott, H. W. (1934). The zoological relationships of the conodonts. J. Paleont. 8, Smith, J. (1907). On the occurrence ofconodonts in the Arenig-Llandeilo formations of the Southern Uplands ofscotland. Truns. Glasgow Nqt. Hist. Soc., n. s.7(3), Stoll, N. R., Chm., Dollfus, R. Ph., Forest, J., Riley, N. D., Sabrosky, C. W., Wright, C. W., and Melville, R. V., Secretary (1964). Intemational code of zoological nomenclature adopted by the XV International Congress of Zoology. Int. Trust Zool. Nomencl.,Londoq 176 pp. Sweet, W. C. (1970). Uppermost Permian and Lower Triassic conodonts ofthe Salt Range and Trans-Indus ranges, west Pakistan, pp h Stratigraphic boundary problems, Permian and Triassic of lvest Pakistan (ed. B. Kummel and C. Teichert). Univ. Kansas, Dept. Geology, Spec. Publ. 4. Ulrich, E. O., and Bassler, R. S. (1926). A classification ofthe toothlike fossils, conodonts, with

51 'eluopouos arll Jo suorsr^rp luecurusrs sselc elsproqj eql Jo uo$i^rp e s? pop.lesej se,$ leql se pezrusocej Je8uol ou eje posodord oje^{ ^llm(uouoxel Ioql qcrq^\ ([uopouoj sselcqns),tuo8elec dnors-ss lc roj seuosolec eql lnq..'seluopouoj,, s,ouelrejael,,\l " JoJ 8f6l) uosuerg Iq parnporlur sp^{ rluopouoj or!?u eqj J Jo sur,{uou,{s rorunf ore sotueu osoql 'roqf8o1 uo{"i 'tt6l q lqehl pu uosusrg Iq spunojs lernlcrun uo salon posodojd seuuojrluopouoj pue seuuojtuopornon srep -Joqns oql 01 'osjnoc Jo 'serldde elues oqj sluopouoc eql Jo uorldcgrsselc posrêj,{tii ul pasn sorueu Jeurpro 'dd Snn 'ue8 aqljo ûe Jo u. uou,{s rorues e pejeprsuoc oq louuec ll os <re -11U5' 8unvuotlq Jnqs8o4aI aq Js, Uoqaz 1 a 4 q?s eldoq'sluopouoa IJe pepnlcur,,se1uopouoj,, '!. t ]o^ 'sluopouocjon8ojel?c (I86I) - s.eueirejr?i I (eluopouoc 'eper) soluopouoj ropro 'dd tlg 'uea ue Jo (ejeld ermsqo B ur) lesodojd qtl{ sjeo,{ -ltrrls' 8ury pudtl q Jn q s 30 u a A a q r s. u D q l a z! a aq J s, dq tuoquoqcrg peledr.que ÊDlrturs ( Z6I) euplrejiew reqt?. 1oA.sluopouocJo enaop.le3.(trct) - petou u03q eêq plnoqs lr 'uos ar sitb rod plp llji s? 'dd tot 'ueb pelerodo illuolsrsuoc oêq srolrpo atudarj t(lleraluaa -nnls' 3 u ry puo q r! Jn q sa D Ua /l a W s, u D qt a z I a q r S serueu dnojs-lopro ol puolxo lou seop,(fljoljd qsnoql? Z lo^'sluopouocjo ansol?l?c (St6l) - {V 10 6I) tuequoqcq,{q reded ejncsqo ue ur posod 'dd tos 'u?fllnls '3u rypuotlqrnq -ord orueu E 'EpuoqdoluopouoJ roprc oql urqlf uorlej -ssouaa aqjs,udqlazla$qjs g 'l Io 'sluopo -g$selt aslloarj aql ur psurnsqns ele i eluopouoj oql -uoc Jo ensol4ec ( 16I) 'pe "M 'JeFetZ JO UOrl?JgrSS JC pesraor Ur SrOprO oqr JO / IIV Z 'EZt-t'V nnd uds '^lns'pad 'spunojs eues ^ru oqt uo etu ol olq4docreun 'uulw 4oseuu\ IJO S?un?J luopouoj ueijrôp sr 'rapued 01 pequcse oq qjrq,{r 'RleluopouoJ Jo Jesod -ro reddn pu? olpplhl eqj (996I) C I'sreqsll[ -ord s.sne Jq-eC {0t61'tu.quoqJrg'epuoqdoluopouoC '901 repro xo) JeJsuEJl pelceuoj,{jfessecauun pue roalord -l '1, qjstoluapog satrupsapudt 'ssall 'qqv -rln u" sr (I861 ' p r. YelJ) asudaq aql ut pozlusocel 'sinlrs sep uetuopouoc (t961) H O etuopoooj urnl^qd oqljo ssqs ol3u6 eql roj pesn sluop 'soi-i ilesl[eâ '65 'q!ruoj 'luoalpd sudx -ouoj eueu eql 'lno polurod seq (t86i) sneuqbj sy 'sesus)i ujels?o ^lun Jo (u?rup^1,{suued Jaddn) '(v96t 'llots) a topuawon lwlsoloozlo salnf, louoltou dnoro eeu,reqs eql ul uolnqulsrp tuopouocjo -./rtrr oql Iq dnors srql Jo seureu 01 popuelxa lou sr Iorluoc pluoruuorrûq (Z16l) 'H 'd 'renrg uo^ -roud leql lcej oql olrdsap eloq peldope sr lr os 'uorsr^rp ^1r ' 9-l dnors-ssela s roj posn eueu lsrg eql si tluop '(Zl)Bg rord snl/{ tdn S n 'selceds u Iddrssrs -ouoc s.uosu?rg ^ljeuroj 'espol,rou)l lseq eql oj secsh -srw pup usruo^jc uecuawv Jo suondujsap ûrjo vt NoooNoJ ahj

52 5. THEMAJORCONODONTGROUPS 5.1 Inhoduction In Chapter 6 I look into general features in the eyolutionary history of the Conodonta. Before attention can profitably be paid to such airy matters, however, some attempt must be made to characterize the major conodont goups, illustrate their typical members, and point out tbe features that provide internal unity for each group and those that indicate their relations to other major groups. As noted at the end ofchapter 4, my concept of the Conodonta is limited to the group discussed collectively as the order Conodontophorida in the Treatise (clark et al., l98l). shallow basal cavities, which were assembled by evolved members of most orders into elaborate sexi- to septimembrate apparatuses with complexly denticulate ramiform elements in S and M positions and a varied assortment of pectiniform elements in the two P positions. The stratigraphic range of the Conodonti is from Upper Cambrian to uppermost Triassic. Although the Cavidonti seem to have appeared a bit before the Conodonti in the Iate Cambrian, the latter diversified almost explosively and were clearly the dominant conodonts throughout the history of the phylum. There is currently no evidence that the Conodonti Here, bowever, that group is elevated geatly hs Teridontzs) are descended from cavidont (e.g., Proconodontus) ancestors, which in taxonomic status and treated as 2 classes, Cavidonti and Conodonti. These are further di- might suggest that the Conodonta are polyphyletic. The possibility remains, of course, that vided into 7 orders: the Cavidonti into Proconodontida and Belodellida; and the Conodonti the Cavidonti and Conodonti were derived independently from ancestors in the group assigned to the order Paraconodontida by Zreainto Protopanderodontida, Panderodontida, Prioniodontidd, Prioniodinida, and Ozarkodinida. /ise authors. At present, however, there are reasonable structural grounds for being skeptical about affinities between paraconodonts and 5.2 Cavidonti and Conodonti conodonts and, on those grounds, I have omitted the Paraconodontida from this discussion The conodonts I assign to the class Cavidonti (and from the Conodonta). Answers to all of are distinguished by thin-walled, smoothsurfaced elements, primarily these basic questions are surely lurking in as yet coniform, that formed unimembrate to quinquimembrate undiscovered or undescribed collections from apparatuses, Cambrian rocks. most of which apparently lacked structures in either of the P positions. Cavidonts made their debut in the Late Cambrian (as Proconodontus) and persisted (as Belodella 5.3 The Proconodontida (Cavidonti) and Its Fanilies (Fig. 5.1) and. Dvorakia) into the Devonian. The Conodonti, established by Branson Species of Procozodontus (Fig. 5.2), founding (1938) as a subclass of the vertebrate class stock of the Proconodontidae and the oldest Pisces but here regarded as a class of another conodonts known, built an apparently unimembrate skeletal apparatus composed of phylum, includes the bulk of the Conodonta. This large and important stock apparently originated in Late Cambrian forms assigned by faced, hyaline coniform elements that harre relatively large, de ply excavated, smooth-sur- Mifler (1980) ro Teridontus. Typically, these subsymmetrically oval transverse sections and conodonts formed longitudinally striated elements, mostly with relatively short bases and The marginal keels of some elements are keels on the anterior and/or posterior margins. mi-

53 lvorrnoco lacuo3.s.) \=--4./ ô1 ^r.t ^r.a """t ^""t- ^."t.'>""'a..*,.'"t',"t lvcttnooonolo 8d 4S- 'Z\ lvcrr Nooo t l]xaui _ lvotrnooocad I oo J o c) z tsdvc - 9, (n c - t z m z t z 'oppnuopolsdec pue 'eeprtlesuv'!eeprllopolog oql sopnl.ur eprllepoleg repjo eqj eep4uopos,{d pue,eeprluop -o extug 'eeprluopol[pjoj'oepquopouocold eql sepnlcur plluopouocord ropro oqj.ltuoprêj oqi.i.s.3!d -rrr?j? sr Jeglo er4lt :snpolsrcotquoj Jo lueuod -ruoc I?lele)s el?lnjruatuou or Jo ensolouoq pol"fcrluep eql sr euo '.uoqs ul elsue alnc? ue qlia dsnj oqt surofreqlo eqljo lsgt s?ereq^\ 'annj qtoours p ul dsnt oql surof Juo Jo ssej -ord rouelsod erb l?ql ur [lu?urud JeJrp sluoru -ele elerq"lop eseql seljpuap I?Je^3s reeq luq1 sess$ojd Uoqs olur lno u^\djp ej? Sedf,l luaur -ela pale^?cxa i(ideep qloqjo suraleu Jouelsod eql lnq (sasnl?redd" elejquleurrq,4q peqsm8 -uq.srp osls er (Z S 3H) senads snpol/tpto) 'IJOIS I"JlSetU? perrjnsejd eql 'snfl,r opouorog Jo luzurele culalu -ul(s? eql 01 J?lltuls sr reqlo eqt pue ^lesojc el?lntlua8 puu pel A?cxe.{Ideap sr ad^l lueru -ele euo qcnl^\ ui snlejpdd? el?jqrrjeurq e llmq (Z'S '3rl) snuqlun snpotstoolquoj eepuuop -ol,tproj eqt s? I'S 8rJ ur pelquasse eft 'repusd Îrruq snporlpn) Jo sarsads praâs oql pu 'Surpue-J snqpusopd1j Jo serceds uarodi o/$ aql '(rel[il I) snjuqwoj snpo$tootqud) 'uerjrôpjo,tlj?g eql otur e8?eurl aql ponuquoc pu? u?uquej lselq eql ur per?edd" '(6961 'rellln) sntuopouojotd ur popnlcur Allzureuo 'snluopo -uo)og 's{ao.r aeugr.u?c laddl] ur i(luo pezuso -cej st 'e?pduopouorojd eql Jo Jequreu e^r1r -tuud oqt 'snuopouo)otd dsnc lueq,(l[elet?l E pu? oprs suo uo euuec e glua leqlo eql 'uorljes ssojc lbjuleurul{s? qlya ed,q euo 'sluoru -ele ujojruoc elq-snluopouuo.td prqle Jo sesnl - r?dd? elerquraulq tllnq teql sprtuopouoc -ord roj (086T) rellrw,(q peqsrtq4se sea,\ qorq,{l '(Z'S 8lC) snuopouojog paui\eds snluopo -uo)otd 'ln.qep u?uqur?c el.i slr Jsue uoos 'sluoprêc aql Suoru? ezrutocej I l"ql JepJo puojos eq1 'epqlepoleg eql Jo JotruaSold osle se{. sntuopouojold leqt (lseol 1? 'slu ot) sote3 -rpul teqt sejnl ej eql Jo auo sr ujetl?d Jo uos srql pue '4elJes,{Ir?InAe!r roqlej pue.{[elnu VJNOCIONOJ AHI

54 THE MAJOR CONODONT GROUPS Polonodus F ryxellodontus Cambrooist odus lapetognathus Proconodontus E oconodontus Fig. 5,2. Elements typical of species assigned to various generu of the Proconodontida. iform version of the geniculate component of en with Proconodonlus in a single family, although this would surely complicate diagnosis Cambrooistodus apparatuses. Miller (1980) suggests that Cambrooistodus and Cordylodus of the Proconodontidae! developed independently from Eoconodontus. The two known species of Iapetognathus Ifso, it might be better to include all three gen- (Fig. 5.2) are represented in Early Ordovician

55 -penb IepruIBJAd oql esneceg seloeds snpouol -rdrjo sesnl"ddd? eql ur lueuele olerpejq aql (ueq1 raydrurs qcml qtnoqlp) ol paleler -sod pu? el?rp?rut sr serceds snpostd Jo tueuj ^lqrs -ele Surl^1ejds raqlo eqj 'sel5eds snpouolod Jo luelxele eteqolupenb eqljo sessaoordjo Jred JorJelu" eqt lsnf 01 sno8opue,(duejedd pue elbqolrjl,{flsrrssq sr setoeds snpostrd Jo sntejed -de eql ui slueuole esopou,{["jgrns '8uq^\ads eql Jo ouo culeurur,ts? sr '(lg6l 'lb ra Ir?lJ ui) ujojls8jag etepedoruel paulet 'Jerllo eql :l?juleurur^s ^q,tfielatqrq sl 'ol"lu?jupenb se pequosep eq reur qjrq^{ 'sluau.iele esaqt Jo auo sur8j?rx rnoj ro oejrll uo sloe)t pe1"l -njquep,tlelnurur Jo palelles,{lsnonirdsuoc -ui qtl^l slueurole lpprur"r^d pel?êjxo,(ldeep eje qcrq^\ Jo o^\l pue snpouolo{ Jo sluour -ala paqoj-earql pu" -moj eql qll,,tl snosolouoq oq ol EeddE qjrqa ^llecrs?q Jo o/al. 'sluaur -ele urrojruoj pet A?cxa rpoglpolu,{ji?rc -eds Jo sesn1eledd? A"Jqueurup?nb ^ldeop tlmq l?ql sercods u?i'rôpro elpprf{ ^ljbe S Jo t sepnlj -ul '( 86I) uerls8reg,{q Ielep ui possnrsrp ueeq s?q qcrq \ '(e'9 'Ac) snpos,td ^nuocer 'sujurrjjds,(ueu fue uo peseq sr JeJ snql pequcsep serceds eql Jo guou lnq 'snl?jedd? el"jqruaurq? u?ql eror.u pedoleêp srpouolod Jo serceds,{u? teql 1e,{ s? ecueprê ou sr ejeql serceds snoue^ Jo slueuelo ui seuo fu"lprsqns olur epr^ -rp,(?ur soqol fueurud aarql oql qenoqlp 'elplp -?Jul,{IlecrsBq sr od^t pelueurpujo -r aro(ii Jeqto eql 'snue8 eql Jo l?crd,{l ^lj?lneel se8pu esopou cl4uocuoc Jo ujeued eql pu? '^Jlou -elsod oû pu" potcejrp oû,soqol JnoJ sdolei\ep ed& ^ljouelue lueurela euo 'sapou pu? sa8pu petnqulsrp ro setpu esopou culussuoc Jo Jeqlle ^ljeln8eur uiioj 0q1 ur luouteujo ec?j -Jns r?eq pu? dsnc puqslp e Icel lpql sluouole rujojruoc pale^"txo,(ldeep 'turt^{?jds Jo sed^l o/al. Jo pesodrrjor sesnl"jedd patujoj l?ql sarc -eds f ls?el te sepnlcur (Z S 4{) snpouolod 'uotlsljdjelur s.jollrl I rrrjguos euoz snalold u?rcrôplo flj?g aql uro{ sueurroods puoelppejo aldnoc ejo suorletsnf ( 86i) s.{lz(i sa8pu r?lneeljr uuoj ot peurof ej l"ql sepou petnqrrl ^lpnbe -slp,{[l?feejjr fq pelueureujo ecqljns e qlk\ lueuiele rujojruoo pele^?cxe dldeep? sr lse8-8ns sqdh8oloqd tuecel eloul (0961) s,rellrt{ qcrq^l 'uoulrceds eteldruocur elsurs e JoJ (S96I) uorlspurl pagsrtq?fe se$ snpojuan ^q VJNOCONOC IIHJ, 'snpojuan pue snpouolod JaJor os[? I qrlq r ol 5lcots sftlljo sjeqrueur pue eqljoj *prtuopos d eql pot?erj uro.4sereg (1861' le F l.relj) astpatj e\l ui 'snpojuan ulôul-anlrt eql Jo [e^\ [q sdbqjed 'quopr^bj oql Jo lcols swuopo axtul eqt ot pe]xler ere snpos(lj pue snpouolod ueriôpro eppuî 1?q1 Suuse8ilns ur ( 86I) uro4s8reg pue ( 861) {zo 1{\oUoJ I 'l S 'elc ui pelerrpur sv 'll?s Jo urere e gll,t\ ue{el aq lsnu I'S 'trg ur fgu crleururejaerp ul{oqs snuopo axtrl Jo esuuj eql snql (sttpoj -uan Jo Ker( ^q sder.ljed) \.ols snruopo axtul eqt Jo so^rleûep elqeqord s pretoj I qjrq^\ 'o?prluopot,4d oqljo serceds u? luesejder IIe^r s? lqftru suerurceds aseql ^ljbe eunuatjv uje -lsa1(jo uorlsrrloj ubnf ues (u?rchopjo uqs lnq) roeuno^ qcnur eql Iuo{ suerxrseds ^ljeg Jo reqrjdnue snruopo axfui otpeu8rss? -uel seq (tz6 T ) IF?tueS 'reô,t\oq :4erls ^ls^rl?t uerc -rôpjo les"q rrro{ oje srrrjoj $elljdg peqsrl -q?lse uooq te,{ tou seq snluopo axtutr Jo etupr ^Tu'IJg crqd?$lrl?j$ eqj-'snleredde sn opol pxtul ew ur tols J I eqt 01 peuersselaq sr 1r os 'uon$od S,(ue ur lg ol ruees lou saop xade pepunor,{lp?orq E qlr^l lueurole pedeqs-uellru 'pesserduroo V 'ur8j?ur Jouelsod elelncrluep,(lepnlc E o^pq,(bur pue pesselduoc f l?letel sr uoqrsod cs eqt ol u8rsse I luauialo aqt qjrgx, ur seues uonrsuel-fuleuur,{s e ncunsrp B rrrjoj sod,q tueurolo oqt Jo eajql 'eurle/(q,{llbcrs?q eft 1"(o sluelliele urrojruoj pejsfns-qloorus 'pal?êcxe ^ldeap Jo sosnlej?dde plolels elejq -ruerrlup?nb \nq sauopo axtq Jo 'aa? sarjeds u"isr opjo lseqrcojo $[cor ur peluesardaj sluopouoj luopr^"c paju"^p ajorx aqljo ouo pu? (I'S '3rd) e"prluopoflexac eqtjo requeur elos eql J?J snql '(2 9 er.l) swuopolpxttl Jo ro1 -secue eql osl?,{llueprê se1(\ snluopouo)otd 1no pelru aq louueo uorl?zru?ejo elejqueujrllnur u os 'Jeê,{roq'uorlzu?A lprlu?lsqns ltqlqxa s?srr8 -uadatd'i 01 su8rss? eq suounceds eql elejq -rrjeurrun su^\ snl J?dd? eql leql sepnlcuoc snr0 pu? tuourele snqpusopddl Jo ed,4l alsuls e,{iuo sezrusooej (9961'uofuraelg pue 'tur -pus'i 'êuoc) Surpue.I Jouolsod tou 'lpjelel si sluouele snqldusoladol Jo ssecojd pel?lnrq -uap eql 'sr l?ql 'uoqelueuo ur rejrp -J?dd? lnq snlereddz snpo{pto) oql Jo sluau ^llue -odruor et?rq lop alqncuea eqt lseeans lbrll Euoruele rrrjojrrrrej,{q elejls (ubrcopeuejl)

56 THE MAJOR CONODONT GROUPS riramate and tertiopedate elements of the Pygodus apparutus form a partial symmetry- has not yet been reconstructed. Walliserodus coniform elements, but the entire apparatus transition series, they are reasonably assigned species (Fig. 5.3) had quinquimembrate apparatuses composed of keeled and costate coni- to S positions. The sprawling character of the other two elements is like that associated in form elements, one a symmetricat form with other conodont species with P-position elements, hence they are assigned to those posi- an occupant of the Sd position. Dvorakia (Fig. anterior and posterior keels and interpreted as tions. That also suggests, ofcourse, that the two 5.3) differs from LValliserodus pintarily in that known elements in the apparatuses of Polonodas species might atso have been occupants of ently lacked elements in the Sd position. Belo- apparaluses of its two known species appar- P positions, although obvious elaboration of della, name giver of the family (and the order) the apparatus in the evolution ofpygodas from (Fig. 5.3), includes species whose skeletal apparatuses are similar to those of Walliserodus Polonodus may merely haye made room for additional positions. but are distinguished by S elements with finely denticulated posterior maryins. Species of Ansella (Fig. 5.3), principal genus 5.4 The Belodellidand Its Families of the Ansellidae, (Fig. built quinquimembrate skeletal apparatuses with a geniculate coniform s.l) In Fig. 5.I (and in the classification outlined in element in the M position and an S series of Appendix A), I include three closely related elongate, deeply excavated, surficially smooth groups of conodonts (Ansellidae, Dapsilodontidae, and Belodellidae) in a newly established ularly serrate posterior margins. Elements in rarniform elements with adenticulate or irreg- order of the Cavidonti for which I propose the the Sa position have three keellike costae and name Belodellida. All the conodonts assernbled are triangular in cross section; Sb elements in this new order formed quadri- to quinquimembrate skeletal apparatuses composed of gins and a planoconvex transverse section; Sc have sharp anterior and serrate posterior mar- typically thin-walled, smooth-surfaced coniform elements with \'ery deep basal cavities. the apparatuses of most known species but elements are like those in the Sb position in Those elements commonly have distinct anterior, posterior, and lateral keels or costae that of species, have no posterior denticles or are ofbiconvex cross section and, in a majority develop fine, needlelike serration or denticulation in the apparatuses of several species. The apparatus of Hamarod.us (Fig. 5.3) ap- sertatlons. The central stock of the Belodellida is the parently had a geniculate coniform M element Belodellidae. Treatise arolhors assigned,s/a1o-andus, Belodella, Coelocerodontus, and Walliser- a quadriramate element with a few anterior a symmetry-transition series that included odus lo this family. I add Dvorakia (Klapper and lateral denticles in the Sd position, and laterally adenticulate alate, tertiopedate, and do- and Barick, 1983), which was described and named after the Trcatise was published. The labrate elements in the Sa, Sb, and Sc positions, better-known belodellids formed quadri- to quinquimembrate apparatuses of slender, deeply excavated, smooth-surfaced, basically coniform elements, ornamented by longitudinal keels and costae. The latter bear minute serrations in several species but are undenticulated in others. The oldest belodellids are included in Slolodus (Fi$.5.3), which Lindstr6m (1955) erected for conodonts with deeply excavated coniform elements with three or four asymmetrically disposed longitudinal keels or coslae. Coelocerodontus (Fig. 5.3), which may not be distinct from Stolodus, includes symmetrically costate respectively. Typical of the Hamarodus apparatus, however, are a pair of deeply excavated, laterally compressed elements with serrated postero- and antero-basal margins. Evidently these elements occupied P positions. Affinities of Hamarodus arc anything but clear. Elements assigned to the S positions are surely not exactly like those in comparable positions in Ansella, which also lacks elements in the P positions. But Ansells also lacks features that would ally it very obviously with any other major group of conodonts, including the Periodontidae (Prioniodontida), where it was assigned in the Treatise (Clark et al., l98l). Thus I follow

57 -srp eql polecrplrl ifeels $ snpoltsdde q]lt drqsuorlelej ^q e lnq 'Jollel eqt Jo sesnler"ddb ur u^rou{ er? slueurelejo sedfl oi$lîuo olefcru -ea eje ( 'g '3r{) serjeds snpolr,ssr8r Jo sesnler -"dd? ur slueruele IAI seejeqa 'slueuele l I el"i -njrueeuou qll{\ sesusj?dd? olejqrxeurljpenb poruroj ( 'S 8r.J) snpolrsdd1 Jo serceds 'urejeru rouolue eql ol luecefp? uorlelueuj -?luo anbrlqo e^rlcurlsrp 3 llqqxa l?ql sl.uour -ole rrrjojruoc possojduoc,{lprelsj'pel?êcxe,4ldeep Jo sesnlujedde plelels pourroj,{trur?j ^\eu srql ur pepnlcur "Jeue8 or'dl 3rl1 Jo selc -ods 'oepnuopofsdec oql 'KlurEJ,{deu? ot.szp -opssaq pue snpol$do1 uerss" I I's '8rc ui '(8unu.!\ s.{izc JO 3rU[ Jql le pausu uasq I,upELl 'JslnoJ Jo 'qch?r r) o asuy o1 pol?ler aq l]4ercr snp -otdutoh l"ql uofsesilns ense ( 86I) s.{lzc.w eq lueuiole ulojruoc elelnorue8 :u^\oulun rrpolrs$ rjo slueuelejo uorlsro-i ed pue 'qd 'L I 'cs ^"tu 'qs,{q po,l olloj 1q3u uo slusu.rele (ps Jo) S :saurl pluozuoq,{^peq peurof sesnler"dde û"jr'sluoluole etejqulou.rulnru Jo sluouodruoj sprllepoleg oqljo snolje^ ol peu8rsse serceds Jo lecrd& ^q sesnleftdde pue slueuel:i 'E'S'3f.{ "reuo8 tnruoporattolaoj tnpnt tah VJNOOONOS AHJ

58 THE MAJOR CONODONT GROUPS JI tinctive pattem of chevron-shaped ridges adjacent to the anterior margin. At present, BeJselodus is known only from Ordovician rocks. Dapsilodus is also represented in the Ordovician, but it is probably best known and most typically represented in Silurian strata. 5.5 OrderProtopanderodontida,New This division of the Conodonta includes most of the conodonts that built uni- to multimembrate skeletal apparatuses composed of longitudinally striated, laterally unfunowed coniform elements. Expressly excluded are the panderodontide conodonts, a goup that built apparatuses of coniform and rastrate elements with deep lateral furrows; and the oistodontids, whose apparatuses include pastinate coniform (or "acodontiform") elements in an array of coniform types that is otherwise typical of the Prioniodontida. With the exceptions noted, the Protopanderodontida is the major conodont group identified in the Treatise as the superfamily Distacodontacea, which was based on the family Distacodontidae of Bassler (1925). Unfortunately, no one knows much about Distacodus Pander, 1856, whose types are presumably lost, or about the Distacodontidae, based on it by Bassler (1925). Consequently, I suggesthat Distacodusbe regarded. as a nomen dubium ar.d. that it not be used as the basis for any suprageneric taxonomic units. The name Protopanderodontida, although a mouthful, is taken Fi9.5,4, The Protopanderodontida and Panderodontida. The families Protopanderodontidae, Clavohamulidae, Acanthodontidae, and Drepanoistodontidae make up the Protopanderodontida. The Panderodontida consists of the single family Panderodontidae. z 9 o G PROTOPi AN \* s z CLAVOHAM DREPANOISTODONTIDAE

59 ,{q pel?j dosnql sr eruajncco lsjg sll 'u ruo^ -de et"rqureurq e tllnq (9.S.Erg) 9961,reyg4 -oo eql olur pj",'.\dn setuej pue s{3oj u?rcrôp snpo$ojouon -ro raddn ur sj?edde snpopauoopnasd,(lg6l) Jo sercads plql, se pequjs -ap snqt pue elrq,{ e8nols peuodej ecuern33o u r3rôplo alppq4l ro^\ol ^q snopruoue u" roj tdecxe.snuee ere ^ljedord ^lelelduroc lsourp teql uortces ssorc I?cqdrlle,(pqErls 01 r?lnf, eqljo JrlsouS?rp,t ercadse oje eseql pue,selrq -rrc Jo slueurele rrrjojruoc pouqcel l?q^rauos Jo l3eje Jo snl?jedde el Jqrleutrun p peuloj -uep T?ird? e{rlepou eojrll ot euo doleâp osle snpopauoopnasd Jo slueuele lnof eql.^jiejr 'sepuuoporopuedolord lseplo eq1 sepnl3ur -8o1oqtuour relurrs esrûoqlo tnq,tslg qclq/*\ '(9'S '8lC) 0g6I 're rw snflopual eqt ueql ',tjrurej oql Jo sjequreur pazl JepuaTs ejoru pu? JeJlerusr ed^l luauele Joqlo -prceds to paju? pe aroru ur se8pu Jo,eelsoJ eql :,(U?crd? ue{crqt l?qt slle^\ s"q pu" lnots pue uoqs sr ad,{l lueujele euo.socqlns 'e"uu"c purpnlreuot pe{leut aq,{?i'u 1nq,{lr q100rxs -urej eqljo stequaur ^q rsldrurs aql ui peluetueu qlr \ sluaurele urojruoc prqp,pel?^ -JOUn eje SIUoUOIO ^le^q?ler JO SeJsd.SeCqlnS paleuls -ecxe{1dsep Jo snlaedd? Ielelels el?jqujorrj,{leug qlr^{ sluauela uuojruoc el"lnjruotuou -rq e seq tl6l 'lrdea(jq snpopauoopnasd 'plqp (^le^rsnlcxe su?eur ou.lj^jl JuJueB eql le ^q 1nq) Jo sosnter?dd? I?lolols elelquralu4lnru ^ll?rrdfl ot -run uorlhbdos trjeu socueta.ulp lq8rts eql ejns lou we '.snponuozotuas peurroj sluopouo, eseql.eepnuopodoloss pu? pup- snruopual lgeey\t -eq alerperujelu srness snpopauo,peugep 'e?p4uoporepuedolojd,eeprluopoloeuo.aep -nuopuel seljluej eql ur sjoqtn? asuoatj iq fllusrrnc sv eelsoc purpnlrtuol esjeoc JeqleJ pepntcur sluopouoc ere srql ol peu8$sv ',t\ol A\aJ e rrrroj eruos pu?,elnl? JnJ dsnc ^lrluz; rununx?ut Jo lurod oql l? ur8jeru Jouelsod 'utq.tlspa!1 aqt uo uorl?tuepq adpruopoapuvaolota,tlt?.l! tr{8ls e J?eq f?ur sluetuole 1 g g assqj 'uorpes ssojc l"cndrtle,tpqtqs o1 :e1nc -JI, Jo slueuole uuojruoc prqp,lnols Jo pesod -Iuoc ejeî sesnl?jedd? esoq^\ serceds luopouoc sapnlcur (S'S 8lC) (I86I,puerg pue uofurqta,{q psugepe: s?) 5g6l,ruorlspurl snpopauo 'ur8wru Jouelsod ogljo spjrql o1r\1 I?tsrp oqt 3o Jeqlou? Jo eprs ouo uo Jo,uo elsoc ^ro!?u 'fueqs B qlr^\ lnq serced sn /I,/op!tal Jo esow a{i sluaruete urjojruo3 prqle Jo snlered 't s 'EId ul,{llmupuiuru]t?ip u^roqs ere epuuoporopu dol -ord eqtjo leue8 ledrouud eqtjo sdrqsuorlelej paunsejd pue uorlnqulsrp crqder64erls eq1 'eep4uop -ojepuedolojd eql.sesnl?j?dde lueuele -rrrjojruor qlr^t sluopouorjo [lrurej o^rljurlsrp lsolu pub tsetr?l eqljo otq?u eql uro{ ^lqeqojd 'eep[uopolopuedolojd aqljo eleuo8 ereuo8 ol peugnse peugrsse serce( serceds Jo l"crd^l sasnleledde pue sluauelg 's's'6id tnpoao4 snuo.otl.,. A.t.p.{ttots.nPot.cu.dotot4 VINOCONO]:IHJ

60 THE MAJOR CONODONT GROUPS a considerable stratigraphic interval from the components of multielement Tropodus Oneotodus, its closest morphologic relative, comptus, tbe type species, as form species of and this suggests that ancestry and possibly familial assignment of Pseudooneotodus may be there is still uncertainty a'bout Tropodw in Paltodus a\d. Scolopodus, which suggests that elsewhere. Lower Ordovician circles. Species of Semiacontiodus (Fig. 5.5) built bimembrate apparatuses. One elementype is bidovician rocks by a number of species previ- Semiacontiodus, represented in earliest Orlaterally symmetrical, anteroposteriorly compressed, and has a posterior indentation or ancestral to the long-ranging Early Ordovician ou sly assigned to I contiodus, was probably also costa flanked by posterolateral costae; the other stock named Glyptoconus by Kennedy (1980). element is asymmetric and has a costa on only The only species of Glyptoconus (Fig. 5.5) that one side. Sometime early in the Middle Ordo- has been adequately described, G. quadraplicallas (Branson and Mehl, 1933), has a multi- :"ician, Semiacontiadzr gave rise to,s/ auferella (Fig. 5.5), whose species formed a bi- or trimembrate apparatus that differed from those ments that have only slightly expanded bases membrate apparatus of hyaline coniform ele- formed by Semiacontioduspecies in that the and slightly recurved cusps that are quadrate in basal part of the finlike lateral costae is distinctly notched. Dzik (1983) suggests that grooves on the lateral and posterior faces. cross section and bear prominent longitudinal Semiacontiodus was also ancestral in the Middle Ordovician to Scabbardella (Fig. 5.5), of the Protopanderodontidae was development A particularly important event in the history whose only known species formed a bimenbrate apparatus of strongly compressed ele- stock named Utahconus by Miller (1980). Spe- in the earliest Ordovician of the short-lived ments, one type of which is essentially syrnmelrical and has anlerior and posterior costael brate skeletal apparatus of albid elernents, one ctes of Utahconus (Fig. 5.5) formed a bimem- the other is asymmetric and more broadly costate on one side than the other. form) coniform element. Utahconus probably ofwhich is a primitive pastinate (or acodonti- Shortly after Sezlacontiodus made its debtjt was ancestral to RossodrJ, the oldest described in the very early Ordovician, it apparently member ofthe Prioniodontida. Utahconus may spawned a stock of protopanderodontide conodonts characterized by a multimembrate aptidae, another of the protopanderodontide fam- also have been the ancestor of the Acanthodonparatus of albid, costate, and noncostate coniform elements. Landing, Bames, and Stevens 1982) is similar, but its elements may bear ilies. Parutahconus Landing (in Fortey et al., (1986) have recently coined the generic name small nodes on the base and along the lateral Variabiloconus for the best known of these conodonls, V. basslui (Furnish, 1938) (Fig. 5.5). In costa. Fig. 5.4 I suggest that Variabiloconus may have been ancestral to Protopanderodus (Fig Family Clavohamulidae Lindstom, ), a long-ranging stock of Ordovician conodonts This family was established for a small group with a bi- to trimembrate skeletal apparatus of bizarre protopanderodontide conodonts that composed of albid elements with prominently formed unimembrate skeletal apparatuses of sharp-edged posterior and posterolateral costae. In the very latest phase in the history ofthe nodose, or spinose. Species of Hirsutodontus albid elements that are surficially granulose, Protopanderodus stock, the upper margin ofthe (Fig. 5.6) built apparatuses of Teridontus-like base was extended posteriorly and came to support a single large denticle. nodes at the base. The basal part ofcomparable coniform elements that developed spines or Species of Tropodus Kennedy (1980)(Fig. elements of Cldvo hamulus (Fig. 5.6), however, 5.5), like those of Protopanderodus, formed spread laterally to form a hemispherical multimembrate apparaluses of deeply excavated symmetrical and asymmetrical coniform of Serratognathus (Fig. 5.6), on the other hand, mound with a nodose upper surface. Elements elements, all of which bear three to firre prominent keellike costae. Repetski (1982) describes symmetrical structures with a knifelike are anteroposteriorly compressed, bilaterally lower

61 eq plnoqs lnq elsjquaujul ro -rq se poqucsap ^lq?qord,tluouiruoc sr t?ql snl?jedd? IElalols e peq (g's 'fii) snpo$rouodat( Jo sercods 'rolsocue oql s? eeprluopoqlue3v eql Jo req(irelu ^la{q raqlo eulos ro outpoqjuln snessns JeppJerlc srqt pu?.peujnlut Jo 'peueueu eq slueurale es ol?te ^0q8rls Jo urej?u lewq eqljo ^"ru luau8es roustue eqj.suou -Isod d eql ui sluetllelo el?fcruetuou el?lsoc -Iq dnols pelerluojojrpun ue pu? Î"culaurur^sEJo 'uoqrsod tr I eql ur lueluele rrjjojruoc alef -crue8 e^rlcuuslp?'seues uolrsuell-fuleuut,{s ol9lduroj? rnl1(t snlej?dd? elelqueulrnburnb e s?q 'eepbuopolsrou?dejc eql Jo {colslooj 3ql se,{\ qch,r '(g S '^C) npotlod 'seuo8al?c ^Tluer?dde JUeuoAEJdns ed,{l aql s? elqe -lms lou sr snql pup' untqnp ûbjo uaulou e se peplee -ej lseq s snpnd$lc. 'Jeâ,roq.Joldegc sql ur rerljba pelou sv'gz6l'lalss?g e"p4uopocblsr(i elueu 0q1 pesn e^?q sjoqlne AuEur qjrq^\ JoJ sluopouoc opuuopojepuedolojd Jo dnojs lu?l -Jodrur uejo ajoc eqt uljoj snpo$touddate pue 'snpo$lotod 'snpoudd lueurele]j;lnlu Jo sodeds 916[ 'udit$on snaul!?i pud appltuopolstouddato tltutol r'g g 'uedrôpro egl 01 Peuuuoc sr eqj 'snuoe eqljo crtsuep?jeqj sr teql qjlou ^lrur"j e^rlcuusrp e rrjjoj 01 AJpJE^\ur poduruj sr seraeds outpotpt r/n Jo sluaurolo pculaurur{s,{ erelelrq eql Jo ur8lerx I?s"q eqt Jo lueu8es Jouelu? u? s?ejeq,rl 'ur8jeu louelsod oql EuoI? sopoujo? doleêp.eldrldxe JoJ ^{oj 'seloeds snpoqudj /Jo esoql ^luourujoc 'srt,t! Jouru,(Iuo ur reqloup 3uo tuo{ Jo,grp e?puuoporou?cv eql ol erag peusrss? sarceds Jo slueuelg ',tlur?j srqtjo roqueut s3,{lelbjedes polsq lou sr ecueq pue (tg6l " 'll..rzq) Duryoq.tln Jo seljeds?jo snl rcddp egljo lueuodujoj? ueaq 3?q 'Je e^loq 'snpopudjs Jo sell'eds rrrjoj adfl Êt,rJ eqj 'uttolnuopopudjs se ueql ot rejel 01 lue$eûoc sr 1r os 'Jenel aql se qcns sluau -ele roj snpopuozs snues uuoj eql peqslq?l -se urorlspur.i 996l ui'ep$ euo 01 susdo snql qjrq^\ 'es?q oql 01 lredssr qlr,{ pals!{l $ dsnc aql lnq'lelrurs sr Jaqlo ^llejelq eql :surfueu Jouelsod pua louetuz dj?qs s q,{luoruuloc pu? 'lmulelxu s fll?lelqrq,pessejduoc sr lusuele auo 'eule^q ro prql" ele leql sluorrjele urjojruoc elefcruesuou ^plea,n Jo s5snl?led 'oepnuopoqlurrv eqljo E ueb ol pou8rsse sodads Jo lecrd,{l slueuela.l.s '61tr -d? plale$ el"rqr erurq peurjoj zle -ue8 asoqt IIEJo solceds (f ^TleJrs"q.S.Aq) snpo adlns /ilq?qord pue 'snpouddd.toj '(L'S 'elj) snp -oqrudry'q's'trl) Duryoqrqn '(1'9 '?rg.) snpo -nutoj'(l'g elic) snpouddat1 sepnljur.e3uop -merd seq o?p[uopoqlubcv erreu eql qcrq^{ roj '?pnuoporepupdolojd eql Jo uorsr^rp slql 016I 'wolrspur7 aoptruopotltudjv!(ltwo! F S S 'sepou pec?ds ^lasolr uoqs Jo s,rol snojsrunu qlr^\ ar?j Jouelue u? pu? ulsjeur 'oeprlnureqoêlj eql Jo Eroue8 ol peu8rsse sepeds Jo lptrdll slueuelg '9.S.trJ snqteu6oluras snluopotnsrth snlnureqoêlc VJNOqONOJ!IHI n9

62 I THE MAJOR CONODONT GROUPS 55 of recessive basal margin at the anterobasal corner. Nongeniculate elements that form the symmetry-transition series in the apparatus of Paroistodus species tend to develop bases whose upper margins are drawn out posteriorly. Dzik (1983) and Stouge (1984) have bolh suggested that this process became denticulated in the youngest species of the genus, P. horridus (Barnes and Poplawski, 1973). Patotsrodus Fig. 5,8, Elements and apparatuses typical of species assigned to genera of the Drepanoistodontidae. 5.6 The Panderodontida Species assigned to this distinctive division of the Conodonta are distinguished by tri- to septimembrate skeletal apparatuses composed of longitudinally striated, taterally furrowed coniform or rastrate elements. The latter are basically coniform types but have a few denticles along the posterior margin ofthe cusp. In only a few apparatuses (e.g., that of Plegagnathus) are denticulated parts of any elements drawn out into distinct processes. In my opinion the major diagnostic feature ofthe Panderodontida is the distinctive longitudinal fissure or furrow that is developed on one or both sides of every element ofthe skeletal apparatus, and I have excluded from the order all ofthe conodonts whose elements lack indication of this feature. This means, of course, that my concept ofthe Panderodontida is considerably narrower than that adopted in the Treatise. In the narrow sense adopted here, the Panderodontida includes Panderodus, Parapanderodus, P s eudob e I o dina, B e I odina, C u lum bodina, P legagnat hus, Parabelodina, and Neopanderodus. Pseudopanderodus (l-anding, 1979) is excluded because the ostensibly latest Cambrian coniform elements on which it was based have subsequently been determined to be representatives of Panderodus that were somehow mixed into collections from much older rocks. The oldest panderodontide species known had apparatuses composed of furrowed coniform elements, and it appears likely that they were ancestral to species of genera such as Pseudobelodina, Belodina, Culumbodina, and Plegagnathus, whose skeletal apparatuses were formed entirely of rastrate elements. Conse- considered quinqui- or even seximembrate. An essentially erect, nongeniculate element with equally concave sides and sharp anterior and posterior margins occupies the Sa position. Sb and Sc positions in the transition series are filled by regularly recurved nongeniculate coniform elements, which are flatter on one side than the other and commonly have basal margins that are diferent in conformation. M elements are geniculate coniform elements, commonly with long cusps and much shorter bases. P positions were evidently occupied by subsymmetrical nongeniculate coniform elements with an acutely angular anterobasal corner and sides that are almost equally convex. Certain species of Drepanoistodus attained an essentially cosmopolitan distribution in the Ordovician, but the genus became extinct at the end ofthat period. Paroistodus (Fig. 5.8) species had a bi- to quadrimembrate apparatus that included a symmetry-transition series of laterally costate nongeniculate coniform elements and a geniculate coniform element in ihe M position that quently, at first blush, it would seem feasible to characterislically develops a conspicuous zone assign panderodontide conodonts with appa-

63 -$dd? sercads osoqtjo snlej?ddeql.e8s uerc -rôpjo alppr,,{,{jpe Jo $lcoj ur petuesojdel erc snpodpudddtdd Jo sercads l"uonlppv [ (3961) 1re13 pue uo1 -Surqlg pue 'oenots'dls,["ldod pu? seujpg sarnau ui alqrsr^ flftalc sr.r\ollnj eql Jo uorlrs ^q -od eql ur urfueur ps?q eql ur r{4ou e 'Jeê^roq :luau.iele srql Jo sejn8g II? ur ejnjsqo sr ep$ leql l?qt elou ol tursnrue sr 11] '"lsor roualsod -pnu aql Jo ur8r"ui Uel eqt Suop ouo s?g,{ljealc 1r tnq 'suort?4snll peqsllqnd ur e " ^\ormj IJ?l ol sreedde 'sniutawut{,r, d Jo pjrd,{l sr qcq,{ luotuelejo od,q JaU?l eql.srxp touel -sod-jouelu? eql ol prulou eueld e ur pauell"u,{lsnoncrdsuoc sr l"ql luaugle rrrjojruoc Juleu -ur,b? u? pue :qsoc rouelsod eql Jo sprs euo uo AlolnJ? rllr/a lueuole rrjjojruoc Iecu ^luo -leuru^sqns'jepuels? :^\ounj snonordsuocur -suprl,(lluajer lnq It6I ur uosrtla pue so ejc ue,tq eprs Jeqlre uo pejeptoq Elsoc Jouolsod snpt.tts snpouodate se pauruuolop sueu ppojq e qlll'a lueurele rxjojruoc elble 'peleuls ^q '(9861) luesirc pue )tizc rlrou ErlopodJo ueunls aq1 tuo{ sr sluouralc stlporap -rrd Jo Jolsnls pasnj e\i snporapuod pue snpodpuod -rrrd Jo sosnteledde oqljo leord,{t sluoruelg.6.s.8rd snqpusoudn!' ol pelojsuejl s?^\ saneds l qj ( 16I ) Dts,r"ldod pue seur"g Aq s,?/.r pruutso snponpuddototd Jo sed^l eqt ap?u ere.{\ qcrqnd 'slueulalg urjojruoj'pe,rt\ojjnj,{lsnoncldsuoc -ui lnq 'pet"uls ^lsnoncrdsuor Jo sed^l eerql 1s"01 lejo posodruoc snter?dde u? qlua soroods Jeqloue [q (euoz ee^g) uercrôpjo,{lleg eql ul relel peulof se^\ snlou$ snpotapudddrdd 'ecq rouelsod eqt ur deep e oêq uon ^{o[nj -ces ssojc JelncJrJJo surjoj pue'suorlzrjls l?urp -n1 uo1 eug leeq sod/g gloqjo secelns auo3 el?lnjruo8uou Julaujlu,{se ue leqlo eql,uon -cos ssojc JElncJrcJo euoc elelnjruatuou pe^jnc I ruec?jt'repuels '3uo1 E euo 'sluotuole [ujoj -Iuoo prqp,tqee,n,{po Jo eurp^q Jo snl?jed -d? plele{s el?rqueurrq? p"q (6'S 'trl.) snlouts 'd '0g6l) eenots iq snponpuoddrdd ot parjej -rceds uo (?96I) {leij pu? uofurqte,4q pespq Alpurpnlrtuol? papnlcur pue et?jqureuul sedads? 's?rrr.{3 snpodolojs Jo seffitueserdor ls?el le se^,\ l?ql snle[dde ue p?q ( /61 se pepre8er uoeq oêq sluopouoc 'Dls/A?ldod pue seull"g) snn4awulko snpotap oseqj (ouoz rajnlaq) ^luouuloj u?rcrôpro fll E eql -uodo.tdd tern e?ou (996I ) tu?8tuc pu {tzc.aue ur fue^ pejeodd? e?pquoporepu"d eql ol olq"rejer ^lr"e eq ot urees 1?q1 sluopoum lsaplo eqj s tr roj eruoq pooa se le\l sel]leuj snpoap -udddtod " Jo sorceds qlr^{ uouluoc ui sluelxelo 016I 'ruoltspu17 appttuopotapudd tltwdl J 9 9 auos senqs 111?q1 p-j 0rl1 pu? luoporapusd B,{lerns sr lr leql eur pecurûoo seq suo4cel 'se8l?lue dnoje Eurlzznd srql 1o3 elq?lr?ê ui sercedsrqljo suoturceds,{ueru Jo etpel^1ou{ Jno se paprlrpqns eq ol Dodxo I agljo uoneuruexe tnq'peuousenb aq osle,(br.u qcrqa 'epprluopojopued eq1 'fiulej elsurs? ol lueluuftss? teqj (996I) 1ue8Aq pue 4zq,tq snpodpuoddtdd Jo g^rleluasejdej?p[uopojepupd repjo eql ur pazueocel,(nuel e sb pel?ejl -rno serceds II? u8rss? I '^lluonbesuoj.crlal. qd ',{Duecer lsolu 'pue (tg6l) e8nols,tq szpo4 -uorotuas ot pautrss?er '(6261) ulo4stuog fq -f1od eq p1no,lr stuauole l?telels elprls"r qlr^\ sluopouoc eprluoporepued loj peteojc,(iruq? lew pije 'DplnJruap DutpopqufiJ Jo Jolse'ue,t1a1q eq1 sr 'slueurala ptele{s ele4ser qlrr'r serc -ads E tou 'tuaoqssdq snpoapuod ler41, eu ot s1se3lln sql 'DplnJuuap d Jo stueruele et?rl -ser egl 01 lesrluepr eshljoqto el? leql slueur -ele uuojruoc pe,,llolnj Jo snlel?dd? ue p"q rlcrr4[\'ruaotls8dq snpoapudd qlr,tl u?rcrôp -JO al"-l eql ur ees eqt pej?qs 'sluaurele elejls"j e^nourlsrp ÛerJq Jo snlel?dde te qllt^,d DI -n)nuap DutpolaqDt d s3 qrns sarseds 'sr lsqj 'e8beurl Jqel,{qdouoru e dn eleur lou,(elu sesnl -ej?ddp,{luo-e1ej1sel qlr^\ sepeds l?ql eêtl -eq ol uos al sr ejeql 'leê,'.\oh 'peul?u -un le,{ s? 'Jeqloup 01 slueuele ^lruej al?jls?j Jo sesnl?ftdde qll,$ esoql pue 'oeprluopojepu?d eql '^lrurej auo ol sluerxela urjojruocjo sesnlej VJNOOONOC AHJ

64 I THE MAJOR CONODONT GROUPS ently contained only two types of slender coniform elements, both of which exhibit a "panderodont furrow" (or a pair of them) on the posterior face. The basal cavity ofthese elements seems to be somewhat deeper than that in elements of P. asymmelricus blot m\ch shallower than cavities in elements ofyounger panderodontid conodonts. Panderodus (Fig. 5.9) made its debut a bit later in the early Middle Ordovician (Llanvirnian or Whiterockian). According to Ldfgren (1978), the apparatus ofthe earliest species, P sulcatus (Fahtaeus), had a birnembrate apparatus ofslender (or "graciliform") and laterally compressed (or "compressiform") coniform elements that are longitudinally striated and have basal cavities about one third ofthe total element in length. Elements of both types appear from Liifgren's illustrations to be slightly bowed, and the distinctive panderodont furrow is situated on the outer, or convex, side. Later Ordovician s pecies of Panderodus were determined from large collections of discrete elements to have had quinquimembrate skeletal apparatuses (Sweet, 1979), and this is also the case in fused clusters representing Panderodus unicostatus (Branson and Mehl) from the Early Silurian of Podolia, which were recently described in detail by Dzik and Drygant (1986). Although certain of the elements in the apparatus I reconstructed in 1979 are nearly bilaterally symmetrical, they are furrowed on only one side and were described only as "similiform." Jeppsson (1983) reports that there are truly symmetrical forms in his collections of Panderodus elements from the Silurian of Gotland, and a few have also been discovered by Britt Leatham, one of my students, in the large collections on which I based my 1979 reconstruction. Thus it is appropriate to conclude that the apparatus of fully evolved species of Panderodus was probably seximembrate although, as Dzik and Dryeant (1986) note, distinctions between elements forming the S series are commonly difficult to make. Panderodus ranged through the Silurian into the Devonian, but information on the species represented is sketchy. Indeed, specimens are illustrated in only a few reports on Devonian faunas and Silurian forms have received less than adequate taxonomic treatment. The youngest members of the Panderodontidae are late Early and Middle Devonian species ol Neopanderodus, which apparently had apparatuses like those of better-known species of Panderodus but composed of furro\ped coniform elements whose sides are marked by longitudinal striae that are more prominent than those of Panderodus elements. The oldest rastrate elements known are from early Middle Ordovician rocks of about the same age as the ones from which the earliest Panderodus elements haye been collected. Opinions vary as to the genus represented by these elements. but I regard them as specimens of Belodina. Later, better-known species of,be- Iodina (Fig. 5.10) formed trimembrate apparatuses characterized by three different types of rastrate elements, which are separated primarily by differences in their radii ofcurvature and the number of denticles on the posterior margin. One element lacks posterior denticles and is formally coniform. In 1979 described a sequence of species of Belodina and noted that in younger and younger Ordovician strata denticulate rastrate elements become more numerous and coniform ones proportionately less so. However, one Late Ordovician species, B. calcipromin ens, is known only from large coniform rastrate elements of the sort once included in the form genus Eobelodina. Although specimens assignableto Belodiru are known from rocks of latest Ordovician age, none has yet been recovered from the Silurian. Pszudobelodina(Fig. 5.10) has a quadrimembrate skeletal apparatus composed of deeply excavated, laterally furrowed, posteriorly "heeled," anterolaterally costate rastrate elements. Three ofthese element types are bowed to the unfurrowed side and form a symmetrytransition series; the fourth, which may have occupied either the M or one ofthe P positions, is straight or is bowed slightly toward the furrowed side. The oldest Pseudobelodina known to me is an as yet undescribed species from Middle Ordovician (Blackriveran) strata in North America. Although elements of this unnamed species are all denticulale rastrate forms and thus morphologically similar to comparable elements in the apparatus of Belodina species, there is no coniforrn rastrate (or "eobelo-

65 -rp pu? lueurdolaôp.rraqljo euic? eql peqceoj o^?q 01 tllaos sesnlej?dd? lualuole-elells?j qlr \ sluopojepu?d eql Jo eluos pue snpoapudd 'dnor8 TertseJue IEcrEol lsou aqt peteprsuo3 eq lsnu qcrq^l 'oulpolag popnlsur sluoporepued tuerodruetuoc.uercrôpjo al?-i eqt Jo (u?rue -pa) ljed flffa oql ui lnqap str epeu] tr ojeq^\ '?cuerrjv quon ur ueql u?rcrôpjo ueljeqls eql ur rort$e lrq E pej?edde AIq?qoJd snues eql 'sou?joduoluoc slr lo snuet eql lnoqd uo4?rx -JoJur peqsrlqnd IIlo{ snohqo lle 1? tou ere out -poqwryn) Jo sul,uo.setels c4euo8oluo lsel?i eql Eunuessldol slueutala ur tuesq? r{lelalduoc eq pu?.unaojtjaô eje seljrluep ssoql Jo lsour êur êql 'sluetuole e8sls-rll,rojt Jelq ur :loeq eql Surpnlcur 'urej?ur Jouelsod aql Jo lsoul AuoI" saljrtuop eêq gll.\oj8 Jo see?ts,(feo luesej -qer leql slueulela aprs pe^{o njun erll pj?^{ -ol pa^{oq qloq.sed t o,$ljo stuoulele alejls?j elasortlnrll ro.paprs-qloous 'poleeqjo snlerpdd? ^lfurpnlrtuol Telolels ot"lquoulq z peq '11 lordralur I s? '(0I S 'E]g,) DurpoqrurynJ 'sasnlej?dd? plelels elejqulelulxes Jo -rnbunb e^?q I[? serceds osotqt^,snpoapudd uro+ r(puep -uedapu pue pedoleêp Dutpopqond pue snqpusosald ^lperp nql lcedsns I ecueh.twao.u -sdnq mponpudd snoeuelodueluoo Jo t?gl ol pelelej sr snlel?dde DulpopqD.tod ^llejreologdlour arll..tno pelurod ^losolo eêg I s? ^p eji? 'pue Durpopqopnasd ro Dutpopg tufua_euol ojour Jo seoeds Jo asoql ur peledrcrlu? lou el? sasnlej"dd? JreqI.sluopouoc luopolapuzd eql li" Jo sosnl?jedde,tluo-etejlsej et?roqele lsour eql l[nq outpolaqd]dd pue snqpu8d&ald 'slueuele.uuojruoc e13[n34uep3 lou 'alejlsej peteoq elb 1?q1 sluouodujor qll^l lnq mpofipuod lo leql 01 r lrutrs,{lp?orq snl -?JEdd? elhqr.ueurrnburnb? paujoj,?ouo(uv IIUON ujelso^t ui $[JoJ uerjrôpjo Jeddn uro{,{luo u^{o(dl osp,(01.9.b:.i{) Dutpopq -zlrd'seuos uonrsub4-fuleuruj,{s? ujjoj l"ql seuo pelelnrnuop,{telojcsrp.el4soc eejql pue 'epis pe/yrorjnjun oqt 01 pe^\oq ^lt?jolel euo 'eprs po^\ojjnj eql pjeltrol pe^\oq euo.slueuj -ole elejlspr lcuq.srp,{flec oloqdjour a^gjo snl -"Jedd" plele{s e s q.e3ueurv quon urelsa,n ur 4el1s u?rsr opro JeddIl ruo{ re snql u^\odl sr gclq,r\,(0i.s Etg) snqpu7o&al4 ^luo 'u"rcrôpjo elpprtr l eql ur lerljee qjnu I.'ols snpotapudd eql ulo{ peleul8uo oêq feru qcrq,rr 'oulpopg uro{ lou pue snpoap -u0d wo$,([pojrp pedoleêp Durpopqopnasd leql lr {uql I,,{JluenbesuoJ.slJor erues ^le{rt eql ur peluosejdej eff qcrq/h,ossatdu,toj.b pue stsuatoluour outpopg Jo esorllpue sersods ' aurpolaqopnasd srrll Jo slueruele ueoûeq ujoj uj uorl"patjolur sr eleql qjrq,{\ ur suorpelloj uaos lou e?q I pue,luourele (,,r.ujojrurp 'oeprtuopolapued eqtjo EJouoB snoue,r ol peu8rsse sarcods Jo lecrd^l sesnlerbdde luaqrojo-oldrlsex.0i.s,i!j VJNOCONOJ AHJ 89

66 THE MAJOR CONODONT GROUPS versity in shallow, tropical, or subtropical seas. 5.7 The Pdoniodontida Dzik, 1976 Panderodus itself has a somewhat more cosmopolitan distribution, but it seems largely to This major division of the Conodonta (Fig. have been replaced in higherlatitude Ordovician faunas by Drepanoistodus and, farther ofthe P positions in the fundamentally sexi- or 5.1 l) includes conodonts in which one or both poleward, 14 alliserodus. Specialized panderodontids, with rastrate-element apparatuses, by pastinate coniform or pectiniform elements septimembrate cephalic apparatus are occupied were orimarilv low-latitude forms. or their platformed equivalents. In a few spe- Fig.5.ll. Ordovician and earliest Silurian families and genera ofthe Prioniodontida. Later Silurian and Devonian redresentatives of the order are shown in Fis a s e e t a i I I? i 3 a PERIODONTIDAE I AA I I I\ l POL s fl\ il\ I I I J a! e il Ip l. noi il\

67 tnntaou tta$euoatuanf 1tl6 I ) rlsetues u'io4 stuavrele sn tou&ouon[ s?ur^\sjc lo reprluopolsro Jql Jo BJeuoB snoue^ ol peustss? sercsds Jo leard,{l sesnleredde pue slueurrl:i.zi.s!d snt"redde letele{s et?rqureumburnb ot -up?nb? qtl{i sluopouoc epnlcur I srql ui ^[[uej 016I 'urqttsputt a0pltuopojsto tltwo! I l.9 ',{ua3ol^qd luojejrp Dqlel e pelsea8ns s?q (tg6l) sne?lqec pue.r?el3 lnq Suq u? sr spuuopourr u ruoêo pu? u?unlrs relel pup sprtlopousr u?rrnlrs-prhl ot fljeg pu? u?rcrôpjo uae,{rleq dqsuouelal eql 'Jeê^roq'e"puuopouJl oql Jo uorssnjsrp ful ur polou sv snuet peueuun u? luesejdel -qojd pue snqnusslqalad uro{,tlluepuedepur ^[qe pe uap eje,ti opnlcuoc (?g6i ) uesaelo pu" SJeq -pues, ^rcqt,,snpou4,, Jo serceds upruoêc elsl praaes Alqeqord er? ep[uoporuoud tsetuno^ oqj '$[cols e^rl3urlsrp Jo roqurnu e ol pllssc -u? aq 01 r?edd? pu? sacuojjnmo uersrôpjo Je^\o'I pelu0rrjnjop{le^\'p eldsepr^\ peluos ^q VINOCONOJ 3HJ, -erdej osl" eje ser3ads ese\l.mporcqdu1 Jo,,snpo)v,, ol sloqlo {q peusrss? ueoq e^brl feql lnq '(ZI'9 '4J) npoduj ur ejoq pelqrxoss? oje sesnl?jedde plele{s Elrrurs qlr,t{ seneds re8uno,{ f,rqarts erreqrs pu? ^lesolo,u rl,erl?llsnv 'EoJo)I'?cueurv quon ur serlrle3ol snojorrj -nu 1e 06? uercrôplo {ljse JO $[coj ut peluesej -der,(fouuroc ere qolq,!\ '(ZI'9.tru.) snpossoy 01 (0861) uofulqla pu? Dlsledou,(q pautrs -se oû gql aj? snlejedd? IElelo{s epnuoporuoud ^Dueunc e qtl,a serceds lsaplo eqj 'slueurole el?unsed go uorlecgrpour crlaua8 -ol^qd Jo crleueeoluo qtnolql uesue e^ q ot (perejur,(lqeuoseej lo) u^{oqs eq u?j tnq elel -n8ue Jo eleurluj J,{IputoJ aj? l?ql slueluele urojrurtcod,tq,,tlunl?tu t? ts?el le,perdnrco aj? suoqrsod d sjeqlo [eje,\es uj.suon$ -od IAI Jo S ur parujoj uaeq e^?q ol ruaes sluoru -els pozrl?reurur ou 'soprluoporuoud pezrlen

68 THE MAJOR CONODONT CROUPS 6l Protopttoniodut Oisaodus Fig. 5,13. Elements and apparatuses typical of species included in three genera ofthe Oistodontidae. of coniform elements, of v/hich one (P) is pastinate (or "acodontiform"), one (M) is geniculate (or "oistodontiforrn"), and the rest form a symmetry-transition (or S) series, which, when completely differentiated, grades from an alate ("acontiodontiform") element in the Sa position by way ofa digyrate (or"paltodontiform") Sb element to a compressed, laterally unornamented nongeniculate ("distacodontiform") element in the Sc position. Conodonts with such apparatuses have been included in Rossodrs Repetski and Ethington, 1983, Acodus Pander, 1856, Tripodus Bradshaw, 1969, Diaphorodus Kennedy, 1980, Oelandodus Yan Wamel, 1974, Protoprioniodus McTavish, 1973, Oistodus Pander, 1856, and probably Juanognathus Serpagli, 1974, but it is not clear to me just how many genera are really represented. Rossod?rs (Fig. 5.12) may not have a fully developed symmetry-transition series, hence its two known species seem primitive. (On the other hand. the "acodontiform" P elements and "paltodontiform" Sb elements of Rossodas may be so similar that they have not been distinguished). Furthermore, if the skeletal apparatus of the tlpical species of Juanognathus (Fig.5.12) includes a geniculate coniform element (Serpagli was not sure about this), Juanoqnathus is probably a senior synonym of Rossodzs, as noted by Repetski and Ethington. Tripodus (Fig. 5.12) and Diaphorodus are based on different, but probably congeneric. species; hence I regard them as synonyms. There will probably always be uncertainty as to how Acodus (or many of Pander's genera) should be interpreted in a multielement sense, so I recommend that Acodus be consigned to the list of nomina dubia and that we go on to more important things. Oistodus, Protoprioniodus, and Oelandodus, all shown in Fig. 5.13, include species whose skeletal apparatuses are composed entirely of geniculate coniform elements, which nevertheless exhibit an array of forms closely similar to that in the apparatus ofspecies ofrossadzs and Tripodus. ln lhe Treatise Bergstrdm expressed the opinion that further work might show these three genera to be synonyms, and I can see no very good reason (aside from the geniculate nature of their coniform skeletal elements) to refer them to a family separate from Rossodzs and. Tripodw. Consequently, in the schematic classification in Appendix A, I group all these genera in the family Oistodontidae (which has priority over Juanognathidae), btt rcfer Oistodus, Protoprioniodus, and Oelandodus to a subfamilv Oistodontinae: Rossodus and Tri-

69 'eeprluoporuoud eqljo erouo8jo IEctdIt seraods Jo sasnleredde pue sluatuala,ri.s.a!tr osle sr ejeql qjrqa ur pu? sessejojd " pel?ln3rl -uep olur lno u^\ejp ej? sluer[3le Jo sursj?u q3rq.i{\ ur snlej?dde Fl.elo{s al"joqele ojorll leqndeuos E ur,(lu?rxud Je.urp qcq^\ rrro+ 'snpodrtj Jo sluepuecsep lsojrp êql elp.jep -u?d snporuor.td 01 pejlejsj,sluopouoj oseql 13ql J3e[3 Sr[eos 1I 'slueutele eleuejupenb pu? 'e1"p 'al"pedoruel,el?uuedrq sepnljur l?ql seues uorlrsu?j1-fu1ouul^s E,{q suobrsod S pu? :ssecojd JorJolu? el Fcluep 'el?auola ue qtl/.\ luelliolo lulojrrrr?j ^lelnurut eleu -uedrq B tnq.snpodt.tj Jo lueuole J I urrojruoc ^fleruroj elelncruat aq1 erlq luaruale ue,(q uorl -rsod I I eqt :sossocold olelnclluep oejqt qtl^\ s]uel'uelo e1eu4s?d pjrluepr,{ eclaoloqtuo(u,(q pardncco eje suo4rsod d oû eql qrq^{ ur snl?jedd? Flele)ls otejqrueulryes qlr^\ sluopo -uoc gje lnqep slr epzvr snpodttj qcrq \ ul ouo eqt eôqe lsnf euoz u?rcrôpro eqt ul ^lleg SZ6l tafspg a?pttuopotuottd tl upj Z.l g '(luatuele rrjjojruoj elelncruo8 e) Jeqlou ol slrutp? ^\ou aq q8noqlp?ouuop.h Jo tueujele epurs e [I(Jo poqursap Dlstedeu.uoDrppe ui.\ao$ o a -potisth le}rd,tt eql Jo sa^q?luesejder lsrg aq1 rxo{ u?rirôpro oqt Jo qcnru pel?j -edes sr ll esng)aq ^ljea snqpusoudnl Jo snpodr.tj ^q reqlra ruo{ lueurdoleêp,luepuedapur ue sluosejder aouuop 'H s.dtsledeu ^lrm l?qt ojqrssod osle sr li 'snpodtu eq IIe^\ se lsnf 1q8ltu 1co1s [?4soJu? eqt llq'snqpusouonf Jo lu"puo3s -epesed apottsrh,{oqs I IT'S 3rl ui.sessej -ojd rouolsod pue Joualu" Jrer{lJo sufleur oql uo solcquep elnuru doleêp 01 (s)uonrsod d eql ur slueuele roj,{juepuet Juauo8ol,{qd eql st DlppolisrH Jo rep?jeqc Sulugep pdrcuud eqj 'e?pquopotsro eqtjo ortsuolcej?qj sed& luoru -ele Jo IInJ eql slrqqxe pu? elerqureur -rrlbsrnb Ê!? sr D apousr]? Jo serjeds J?crd,q Jo snl -ejedd plele{s eql t?qt sal"jrpur uorl?urojur.t, eu sql 'pu?punoj^r0n Jo uotl rlroc peeh elq?i u"rcrôpro elpprru eql ur snuee oqt Jo uorleluouncop roqlnj ^lree peprôld s"q (t86i) e8nots pub'seroods uerchopro,(lwa.4jj"e fue^ e peqrrjsep pue petlleu seq (Zg6l) D{sledau 'uonlpp? ui.serceds uercrôplo elpprlî lejeêsjo snl?jedd? plele{s eql uo pue 5lJo$ snorjnc srql urqlh{ uo 'serc -ads DlppottsrH Jo.{ueSoluo ûe8ol,{qd eql uo uotl?uuoj -ui lzuorlppe peqslqnd s?q (Zg6I) enbr HrI{ ',{puenbasqng eepqteusopldrqa Alrru?J oql ol ournlo^ 1?r ur pojjejej s?a (zl.s.3rc) srjjeh D apottsth 'uellu^\ s?a\ asunatj atll eluu eql l? IEcrSol peuoes leql suoseel JoC 'Eprluoporuoud eql Jo {3olslooJ aqt tuesojdej,{1erns'ezpquopolsro,(lrlubj eql s? Jeqta8ot uolel 'rlcrq^1?jeuae eseql II Jo sarj -eds ur e^reojed I ujeu?d l?lele{s ur esolc eql sazrs?qdure eueqcs srqa.aeurqleuso ^luelrurs -uenf,([[u Jqns e ot (snllpusouoni' Jo e^\eû -ep olqeqojd e) DlppottslH pue snqpusoudnl' pue :e?urluopoduj,{lrtu-"jqns e ol snpod V.JNOCONO] AHJ

70 Amo.phognathus Fig Elements and apparatuses typical ofspecies assigned to genera ofrhe Balognathidae. greater degree of morphologic ditrerentiation in groups of elements that represent a phylogenetic series ofconodont species referred to Bal- the S series. Prioniodus (Frg. 5.14) developed phylogenetically through a succession of similar, bio- distinguished from those of Prioniodus by mortoniodus (Ftg.5.l5). Species of B altoniodus arc stratigraphically useful species in the Early and phologically different pastinate elements in the early Middle Ordovician, and in rocks a couple two P positions of their skeletal apparatuses. of zones above the one in which it first appeared, spawned a new lineage, assigned now subgeneric significance by several investigators, Although this is regarded as of no more than to Oepikodus (Fig.5.l4). In species ofthe latter, others have pointed out that Baltoniodus appeared a bit later than Prioniodus and also the skeletal apparatus consists of Prionioduslike pectiniform elements; a geniculate coniform M element; and a symmetry-transition secies of Tripodtts and not from Prioniodus. probably evolved directly from a younger speries of quadriramate elements like the one in However tbis may be, Baltoniodus is the universally acknowledged ancestor of Amorpho- the Sd position of Prioniodus. gnathus, which appeared in a somewhat later part of the Early Ordovician and ranged, Family Balognathidqe Hass, 1959 lhrough a succession of distincive specjes, to Beginning in Lower Ordovician rocks just the end of that period. above the ones in which Prioniodus is fitst recognized and extending upward into Upper Orhaps the best-known and most widely distrib- Species of Amorphognathus (Fig. 5.15), perdovician strata is a succession of recurrent uted members of the Balognathidae (Balogna-

71 snl"jeddv 'snor^qo lou aj? sjolsecue Jealc 'os uaô :..4EJquraurlco,, flrul 1ou pu" uorlrs -od l I eql ur 3rgfuourp eq l(?ul snleffdd? oql 'od"qs leplur?j,{d Jo sluourala (IIJoJ -ru?r el?.rq?lo pue ^l,r\ojl"u 'elepedoruel'olel? leuorl -?p"r8relur,{llmrtoloqfuour Jo seues S ue pue :suodrsod I J ur slueuele el?uuodrq Jo Jred E pue eterqelop Jo ll?d p :uorlrsod d puoces aql ui sessecord polqnrquep oau qll^r Eueu] -sle et uqspd o{qep?iq:uoqrsod ^luo ouo ur sosset -ojd palencquep earql qlh{ slueluole oleuus?d epnlcur '(S l's tuj) mqpustrlrout"g Jo sercads o,{\l s? (0861) seuj?g pu? 'u?l^{on'ualc?lccw pelarfuelur 'slueuiele u?rorôpjo el?.i Jo ^q sad^l e^rtcu[srp lqerejo sdnoj8 lugjjnceu 'e3" $[coj ul papjocej?unq luopouoc opnlrleltseqarq û?jo eql ol xapur ue eq,(?ur'sees JeJodqns ui pelrsodep.(lqeqord are^\ t?ql $[rol u"rjrôpro ele.j rrro{ u^\od[ sr \an]rn 'Dutuopotll8rs' teql tsejol -ur turss?d uzql ejoru Jo i(frsum sr lr qtnoql l? 'uolssncsrp JequnJ lueru ol u,rdou)l qenoue llatyi ouuuopoltr8ds rold snpoxa4uoj Jeql -len (2861) souj?g pue s$perjain snwopo 'e prqleusoleg eqt ol pau8rcse ereuo8jo serj -ror\. Jo ru,{uou,ts Jorues? ^lq?qojd sl'( g6l) -eds Jo cusuelj Jeqc stueurolo lu]ojrurped '9I'S 'tld urotsereg,{q palcnrlsuocej se 'qorq^\ (gi's '8lC) rejdnel Durluopo rsds snue8 tueuleleq lnru eq1aeprrpzueopg eqt ot rejer osp I '9I S etelqurjurq perl 'ArC ur psl?rlsnll pue T I S 'ErC leql sluopouoj qlr.r Surl?ap Jo oeprqleuso erar\ ea{ peôqeq 1 pue urorlstreg '9961 ur leg er{t ur pepnlour os[? s 'snqtdusoqdtoutv snqpusosapoqy peqsllqetse e^\ ueq1,!\'urolls Jo osoql (uro{ JeJIp lnq) elquresej l"ql Eueul -8reg,(q pejedejd uorl?cu$selc astpatj eq! -ela el?qdecsruus?d Jo slsrsuoc snlej?dd" elaq rn pellle sr tr qcrq \ qlr^l' 'snqtdusotldtowv Jo -ruourrun esottr^..'nl:ruo8nd snpoxaldwoj luspuecsap? sr snuee eql,{le{ll ejoru sr lr '(9l S 'AIeIrl SJOrrr 'el1) ue e si II S '8rC snqjdusosapo?yjo Jolseou? eqt sz snporu ul I $qt snqpusosap -a{r8r seguuepl (t861) sneerq-?c qtnoqllv -ot1y pue snqlousoqdtouy ^1oqs ueer':l.?3q drtlsuo]4el 'dno$ tuopouoc lu?uodurr sql,{q peôrqc? -0J osolc aql uoql 'es"c eql sr l?qt JI 'paqsqq?l uollsuuaje.grp Jo elceuurd eql lueserdej -se s?.{i snuo8 aqt ueq,$ otp sr"e,( 0Z pezq?nsr^ snrll pub eprluoporuoud Jql lle Jo sjsnlejed e/,a euo elerquraurq oql Jo peolsur snl -de xelduroj tsorlr eql peq seoeds snqpusolld -?J?dd el?jqureunrldos Jo -rxes E seq snqpuso 4OUy..'utroJ\aopopqurelt pue.,r[jojrql"u -sapoqy ftqt pue 'elqsqsrnbunsrpur oje mqpus -Soqd:our?,, petujel ej? ejnl?jelrl lueuelgrllntu -osapoqv pue snqpusoqdnlutl Jo sluouela Jeplo eql ur qjrq,r 'slueurele oleqd?jsrun (I I uoê illqrssod pue) S f?ql tcedsns,4aou oa\ -s?d pf,utaurur,(se,(1pre1elq 'purlsrp,{?jr snql'ja eqljo e^rpuesrp $ueurela peurjoj -8oloqtuou perdncco era,{ suo[rsod d -l ld oql "l Icel lrrg 'snqpusol4rowv Jo asotfl o^r1 oql pu ^q stuauele (,,uuojr1uopoloq,, Jo) elquasej 1?ql sluauale rrrjojrursj epnlcul osle alepodoruet e!?zrq ejoq uorlrsod I I oql q3rq,r l"qt seldul?s euros u rnxxo snqpusosapoqu Jo ur 1nq 'snl?jedde snpotuo og oql ui seceld cusuep?j qo sluel'uel el?urlsed eql'reê,{ioq J?IuIIs ur esoql 01 elqejuduor slueluele rruoj 'sluepnts Jno rel?i polqurass suorloelloc -ItrrEJ popnlcur suo[rsod S eql qcrq.r ur sesnl ui'stuoluele (..uuojr1uopopque,, ^q Jo) el"ur1sed -uedde letelols elerqruaurrldes'el roq lo p q IeJuleuruj^s,(U?Jolellq'pelted Jo sesnl?j?dde '(snwdusoqdnluv Jo [u,{uou.{s Jorunt e s sm.lt VINOOONOJ AHJ

72 THE MAJOR CONODONT GROUPS 65 stucture is, in many respects, more like that of Prioniodus than Baltoniodus species, but the species most proximate stratigraphically is an unnamed representative of Baltoniodus (Savage and Bassett, 1985; Orchard, 1980). Consequently, in Fig. 5.11, Gamachignathus (includ.- ing Birl<sfeldia Orchard, 1980) is included in the Balognathidae and shown tentatively as a descend.ant of B a It o ni o dus Family lcriodellidae, new I interpret lyiodella Rhodes, 1953 as the stem of an important prioniodontide stock that probably also incltdes Pedavis Klapper and Philip, 197, Sannemannia Al-R.awi, 1977, and Steptotaxis Uyeno and Klapper, In the Treatise all these genera were included with Icriodus and. Pelekysgnathus in the Icriodontidae, primarily on the basis of obvious sirnilarities in the Pa elements formed by their species. Many of the other elements of the apparatus are different. however, and the differences are sumciento raise reasonable questions as to the relationship belween l%iodella and its probable derivatives and the primarily Devonian Icriodus-Pelelqts gnat hus complex. Thus lcriode//a and its kin are here set aside as a new family, the Icriodellidae, the relationships ofwhich are shown in Fig Basically. the icriodellids have a quinquimembrate skeletal apparatus in which the Pa element is pastinate in the apparatus ofthe oldest species known, pastiniscaphate those of later forms, and stelliscaphate, with four processes, in apparatuses of the youngest species known. The Pb element, in apparatuses of the Icriodella (Fig. 5.18) and Pedavis (Fig. 5.18) species for which it is known, is a pyramidal pastinate element with three sharp edges that are adenticulate or only weakly denticulate. I interpret the "coronellan" element in the apparuttrs of Steptotaxrspecies (Fig. 5.18) as an occupant of the Pb position, primarily because it is related morphologicalty to the pastinate coniform (or "acodinan") elements assigned to thal position in apparaluses of various icriodonts. The apparatus ofthe only known species of Sannemannia is unknown, M elements oflcriodella, Pedavis, and proba.bly Steptota-xis are bipennate or even pastin- ICRIODELLIDAE DISTOMODON T IDAE -/a/ Fig Silurian and Deyonian P oniodontida. ate, wilh adenticulate or faintly serrate edges. In apparatuses of species of lcriodella (Fig- 5.18) the occupant ofthe Sa position is a deeply excavated, pyramidal alate element with minutely serrated lateral processes, whereas elements in other S positions are pyramidal tertiopedate units that are closely similar to the Sa element, but asymmetric with respect to disposition of their lateral processes. S positions in the apparatuses of Pedavis species, however, are filled by elongate, prominently costate structures that apparenlly are nongeniculate coniform elements in the Sb and Sc oositions

73 e-ff-# 'sepfllspoucl aqljo Iecral l serceds Jo sosnleredde pu sluou.r.lx 'gl.s.3!d shopad Jo uo4eausp eq pfo,r lfsej ftolc souo eql Jo lecrdi(l uoueuuojuoc oêq 'Jo s eql 'esec sql ur euop orea\ leql JI slueuele " -^\oq 'sar3ods osoqljo sosnpj?dde aqt ur slueu ed ur seuu"frrns ol lq8re^\ tsel?eje pepjocce 13 Jeqlo (9861 Joqrsrg) stôpad Jo esoqt JAEII sluopouoj Jo sluepnls lsorrl 'sdlqs 01 JeFrIrs eru l?ql slueruole el?qd -uoqplej crleuasol,{qd turssess? ul luopourol -Ecsr[a1s,(q ^TqalJeurer pardncco or? -srp,(ljpelc oj? suogrsod S pu? Jo uerjnl 'ni 'qdjo slued -rs Je^\o'I eql uro+ serceds "ll"jlsnv I?Je esjo sesnle:sd -ncco perunsejd 1"qt lftq 'shdpad Jo serceds Kq -de eg1 ui suortrsod ed sepoujo s.{or el8urs Jo peu oj osoql ol esolc fue^,{llmrtoloqd:our srz rrroj aql ur sr uowfcrtuep lnq 'J?[ mpowotsle ot (996I) Joqcsrg,{q poutrss? sert -rurrs ej?,rllasar,sad Îlu3prê oruuouauuds Jo stuewele -odsjo sluourele?d teql palou i(p?ejl eêq I ed ',{ljouelu teqîetxos popeuop,{luoruruo3 'o apoujl Jo esoqt tllolj luarejrp alrnb eje l?qt (seuo pra1e1 eqt) omt pu? selcrtuep.re srtdpad Jo slnerrrola s pue 's?.1rpadjo osoql Jo olqnop e qlft\ euo lseol le 'sassejord elei uro{,{lq?reprsuoc ^\oj JeJrp stxrrotdars' Jo sluaut -njnujp rnoj qll,{l sjrujruls elbqdejsrllats? -ole ed-uon eepr1uopouol er+ Jo snqwu8sblal sluerrlele ed qsrq&r ur sesnlereddz,{q peqsrnb -a7 o1 peu8rsse {leur8uo ojea serjads clls olce -J?gc erour slr Jo ul?ilec qenoql ueô 'l(lrlu?j -uusrp or? (gt's 'ttg) srarpad Jo serceds 's3lj4uep srql ol srxotofiats tfrrss ol uorsrcep purqaq uoqs osp $ EuruosEer J?TrurrS 's?drpad Jo ^tu Jo,{1or alqnop? sj?eq pue ssecord rouatsod eql u?gl Jetuol l?q,$auos sr slueujelo pourjoj l?ql 01 J"lrurrs,(lesolc sr sorcods u^\odi ed Jo ssecojd JorJelue eql 'taêtôtf'o apoujl,(1uo slr Jo tueurela?d aqt esn?ceq pepnljur sr Dluuotaauuos 'sorjeds u^\ou) slr II? Jo sasnl Jo serceds Jaqto II? ui ssecojd Ieretq elsl -ncquepe loqs -EJ"dde ur suoqrsod W pue 'qd 'ed eql ot uers " pu? 'salouuep Jo s,{oj elsurs qll{\ sossocojd Jouelsod pue Jouelu? lenbeqns -se I sluaurele ueealeq esolcjo esn J 'dsnc pprruej,td '^qqnts? s?q lueluele?d el"un -eq oeprtlepoujl eqt u D ^luelrurs apouzl qlila pepnlxur -s?d aql 'paqucsop rej snr]i Dnapoull Jo ser.eds s'[ slndpad'esprluopoljcl pue'eeprluopourol lseplo eqt 'tl61 'djueh puu nooqaqs ll 'urolls -sic'e"p$opoucl eqt Auouls 1no pelecjed e^?q -pul'l xojaofi o apol./4 Jo sntejedd" eqt ui 1 eraua6 eqt Suolu? sdrqsuonelar orteuetolfqd 'uoucas ssol' l?lncjrc,{?duesse JlqrssodJo Jaqunu? JlsJrpur I LI S 3ll ul Jo slueurela rrjojruoc ele{nrrue8uou'el?lsot" 'snpoulolsr(j,{q perdncco,(lq?urnsejd ora^\ suonrsod S (8I 'S ol ueql peuftss? s?q (986l)Joqcsrg pu?'e?pp 'fic) serceds stxdtotdats ui 'uonrsod ES aql ui -uopourolsrq eqljo sebods snou?a fq pourroj sluelllele alerq?lop elelnjrluep,(ljouelsod lnq VINOCONOJ 3HI

74 THE MAJOR CONODONT GROUPS Rotundacodin6 Distomodus Fig Elemenls and appamtuses ofspecies typical ofgenera assigned to the Distomodontidae. ftom Distomodus or some other genus of the theless, I indicate in Fig the possibility Distomodontidae instead of from lcriodella. thal Pedavis, whose familial assignment is not To my mind, the prominently costate elements all that certain, might be the point of origin of that occupy S positions in apparatuses of Pedarls species are equally difficult to derive from Latericriodus and the lcriodontidae. either the Icriodella ot Distomodus stock and Family Dislomodontidqe Klapper, I9EI may thus be regarded as the features that distinguish Pelavis. Thus, if one considers the remaining elements (Pa, Pb, M), similarity is Distomodus, Rotundacodina, and Coryssogna- Conodonts assembled here and assigned to greatest between Pedavis and lcriodella, and thus have abasrcally quinqui- or seximembrate that has guided me in assigning Pelavls to the skeletal apparatus in which ramiform components tend to have short, weakly denticulate or Icriodellidae. Broadhead and McComb (1983) argue from adenticulate processes, and the Pa and Pb positions are occupied by stelliscaphate and pas- comparison ofthe Pa elements of Itte Silurian Pedavis and those of latest Silurian-earliest Devonian Latericriodus woschmidti that the latter The latter character provides a link with other tinate elements or their reduced derivatives. may have developed from the former by neoteny. Although that is an attractive idea, non-p of the Distomodontidae in Late Ordovician prioniodontide conodonts and suggests origin elements in the apparatus of L. woschmidti balognathids such as Gamachignathus ot (Fig. 5.20) differ substantially ftom those in apparatuses of Pedaws species and, in the absence There is some ditrerence ofopinion in the lit- Sagi odontinq. of information on the ontogenetic development of the latter, it is difrcult for me to see tomodus kentuckyensr Branson and Branson erature as to the apparatus composition of DiJ- how S elements of the supposed paedomorph (Fig. 5.19), type-species ofthe stem stock, and (L- woschmidtl) might be related to earlier ontogenetic stages ofancestors in PedavtJ. Never- omy and phylogeny. The apparatus this afects interpretations of familial taxon- recon-

75 '1rJO JOUolue SSoCOJO-Jolur I snql 'Suuodruoc pug I leql ecueprê uoqs /fia^ eq ol suerursads pel?jfnllr I?JeAes puonnqutslp Jo,{poq 8ul,{{or8 pu? pquelsqns ur sreedde sjeql pue pus JorreluE eql 1? ffeelj E uo pas"q /aou sr (986I Soqcsrg 'E e) sroqlo sr dsnc aql 'pueq Jeqlo eqt uo 'sluelxela.rz1l,1,(q poloddns pue JsdooC petmo^pe sarc -ousosstto) ui 'pue ro elsod eql 1? dsnc eql -eds-ed,{t eql Jo snlaedds eqt ^q Jo uorlorulsuoc qllll 'el?gd?csurureos oje snuet lsqljo sar3eds -er 'reê,lroh'woluotst(j lmrd{l e se polojd,tq peuroj slueuele Bd nq 'snqpu8sbppd -relv sl snrqnp DulpoJopunptr Jo sorcads e JI i(luo esues luosejdej slueuele asaql?ql pelset Jo l"ep poot? e{er[ sluelun8j? s.uossddof -8ns seq uossddof slodej snojeunu ui '.ffiq 'y461 ur [qd:n11 pue -np DurpoJDpunJo{ Jo slueuejj ed pjgrldurs Jeddef) petcutsuocoj snlejedd?,srcua[4jnl qcnur eql uro{ peûap uaeq e^?q,{lrs?o 1q3[u -u l 'e eq! ^q Jo sluauodruoj peurojl"iduou eq1 l?ql llos? Jo ssocord IeJelel pedoleêp,{food ot esolc,fua^,(ilm oloqdrolu ej? leql sluorx e rllr^\ slueluele uuojrurlced el u4s?d pojnp -olo uuojrrrruj popnlcur -er eft eseql'peqrrrsep uaeq eêq (6I'5 AId) ^lluar?dde lnq slueur -ele uuojrurl3ed peurjolqd.{u? pe{jel e^?q snqpusossttoj Jo slueruole ed eql ol srrjsas 'snpoulots!(i ui sepnlcur eq qclq,ll.eup4uopofcl ^luo eql '(6I'S tld) (sepoqu).flrqrp outpoidpunlov Jo lcots lujls$u" s? leq lseq eqt 'uorurdo fru ur usunlrs JeAuno,(Jo snl?rcdd? eql l?ql setou eq 'sr pu" u?rjnlrs aqljo pue oql ol se8uer Dutpoj 'ler{unc'sssn}pjedde luejejrp elmb osrûeqlo -Dpunpv,{uetoeu,(q peqsllduiocce,{q pozuopedqc '$lcols epnuopoluoud tue 's$oqdjouropesd Jo eldu?xe ue eq,(?ur ^lqrssod suorl -Jeigrp o,1dl ur pedoloêp slueru -rsod o,{rl gsogl ui sluguola Jo uorlscurtdurrs -eie d a]{]{-d apolrrl ^lluapuadepur lpqt slse8itns s8uabljnt cqeueeol,(qd,(le^rtcedsej'sluourele rsrojruoc -udl O toj (516l) JedooJ,{q pelmo^p? ouo el?uus?d pu" al"urlsed eldturs oje suoqrsod arll se qjns uolljrulsuojjr E leql 'otdulexj JoJ qd pue ed or{1 (n osolq..l frq'snpouotslq Jecld^l 'salou uossddof 'uodrsod d puoces eql ur luour Jo esoqtjo luecsruruer er? (6I q '49) mlqnp g Jo snl?redd? eql ur slueuele ln pue S 'snpour -3le ol?qdecslllels e tnoqlra\ ouo 'si teqt '.{qd -Jntr J pu? reddeix,tq paprutsuo3ej Alpur8uo -ols?o Jo Iecrd& oq ot loot (6t61) srcuallinurl snpou.toiste Jo snlejedde oql uossddef serceds ew 'snlqnp ÔuelEdde Durpo1DpunloYsroJord (6/61) uossddof 'suos ar lereês roc ol le]lseju" se/;t. snpoutolsre 'ijot 'ssunsj luopouoc u unls qlr/t\ -sq str ui olel ^nuarcdd? pu? 5lcolua^\ aql ur AIr?e lje Suqeep sroqln? lsoru,4q srseq NW uo snporu 'snqpuz - -orsro ol parajej uojq s?q pu? suorlrsod I -ojpdh se pogrtuepr fleurtuo esoql s? q3ns pu? s eql ur slueurele rujojrrrr?j e\ri-snpouol sluerxela ed pauuoj 'rfueôpu?l'i oqt ur Jelel -srcr fua^ s?q qcq,{ 'resrwa' saptotltous1nots aiuii e euol? elll?c qcrql( 'pjlqt eqt pug snqpusotpog luouraladlnur Jo uollsrulsuooej :(0zpnlepoFcl) sr1.dpad Jo i oloqdrour eql (9/6I) redd?i) pue Icrrreg aql uo luepued peledrcuu? l?qt stuourolo aleqd?csrtlols-ep,{ireelc sl 'reê,r1oq'astdatj oql ur oepduop rnq Jeqtoue :DutpotnJ se pegltuepr "d,(lpureuo -ourolsrq eq7 pue snpoutolsr( qloq Jo srsoutu ed& eqt Jo stueurela ed pedojeêp (qju?jq Iec -Ip s,rodd?d{ 's rlnga 1DurpotnJ sarjeds rujoj -rd,{t eql) qsnq srqljo r{ruerq euo,l'q SldJo oqt se (/t6i) uosuerg pue uosuerg fq pequcs ued ro^{ol eqt ur..qsnq,, z se snpouolsl(i Bur -ep euo eqt qll lueurele el?qdecsrllets uours -ueqc srql petpcrpur e^pq I pedoloôp seaee -od d puocas eql ur sepnljur tnq,{qdjnw pue -uq praês ^q {rots eql Jo fuolsrq,tf?e,(je^ eql roddelx,{q popn4suocej ouo eql ol srelncrued ui 'uedjcolue A l(lj?e eqt olur po8u?j pue ueunl JofeIII slr ur l?lrurrs sr \a\l 'slsuatljnlual -rs oql Jo Suruur8eq eqt 01 asolj Jo te lnqop slr 'O JoJ snluedde a"jqrrrarurxes e pelqurosse epeuj snpou.totste 'paqucsap lsnf s? peaar^ 'pueq roqto oqt uo '(S/6I) redooj '(snsuddxa 'stujrujle JlEr.ld?JsllsnqpuSor.poxg rewl) osuddxa LD apouotpttj -lpls el\-dutport7l perdncco s"1{ uontsod?d serceds uuoj aqt se (8961) peojxed pu IIoJIN eql qcrq { ui snleftdd? ^q plole{s el?jqrueujrxes pequjsop lueuele et?unssd er?zrq oql uoll e qlud serceds Jo dnoj8? s? 'sr terlt :61'5 3rd ^q -rsod d egl ur sepnlcul pue ol"rqueulnbulntt ur pelerlsnlll leuuer! Jql ut snpourotste sl (tr6t) I pu? reddet) Aq petrruts '3Jd ^qtuni VJNOCONOJ AHJ

76 THE MAJOR CONODONT GROUPS Family lcriodontidae Miiller lnd Miille\ follows but note that lcriodus in this sense is 1957 almost surely polyphyleti.c. ^fhat is, I- angustus and, I. angustoides. both wilh the segminiscaphate Pa elements typical of luiodus, have Included in this family are Latericriodus Mtller, Icriodus Branson and Mehl, been shown by Klapper and Ziegler (1967) and 1938; two apparently distinct goups of species Carls and Gandl (1969) to have evolved at different times from different ancestors in assigned to Pelekysgnathw '[homas, 1949, Antognathus Lipniagov, 1978; and an as yet unnamed genus, recognized on phylogenetic Serpagli (1983) has demonstrated that Lateriuiodus. grounds by Sandberg and Dreesen (1984) and the apparatus of Latericriodw woschmidti, based on a group of late Devonian species previously refened to luiodus 5.20). A bisegminiscaphate pectiniform ele- founder of the genus, is seximembrate (Fig. Icriodonts are characterized by a basically ment occupies the Pa position;a pastinate, lowpyramidal coniform element the Pb position; a multimembrate apparatus that includes bi-, trior merely segminiscaphate pectiniform elemenls in the Pa position. If there are elements "acodiniform") element the M position; and a more compressed pastinate coniform (or in other positions, they are an assortment of morphologically intergradational series of rather variable coniform or only weakly denticulated ramiform elements. Sa, Sb, and Sc positions, respectively. Klapper alale, tertiopedate, and dolabrate elements the Weddige and Ziegler (1979) advocate divi and Philip (1971), however. did nol recognize sion of Icriodus s.l. into two groups ofspecies, homologues of the S-series elements of.l. one that formed bi- and trisegminiscaphate Pa woschmidti in the apparatus of Z. Iatericrescens elements, and one with segminiscaphate Pa elements. For the first goup they used the generic membrate. Thus, ifz. woschmidti and L. l^ter' (Fig. 5.20), which they concluded was bi- or tri- name Latericriodus (Miiller, 1962), for the latter, Icriodus (Branson and Mehl, 1938). I foleage, a feature in the evolution of that lineage icrescens did,, indeed, form part of a single linlow weddige and Ziegler in the summary that may have been the loss ofs-series elements. Al- Fig Elements and apparatuses ofspecies typical ofthe Icriodontidae /!-^/Jn <$-<:/-{/-9,4 UVVV Latericrioclus woschmidti

77 sluourele eleqdecsrurru8es pe \oj-oejql eql ^q Jeqlra l?ql ftelc suees /Aou 1r 'eld(iiexe Joc 'pe^los eq 01 ur"ruej,{u38ol^qd pu IUOPOUsr ur SUJOIqOJd SnOJeUrnU 'elmrpur ^ruouox?1,{eru s{jeu3j JOUd Se 'Je,\e,trOH., SI$SOJ xepur,, ueruoê(j s? snorx4 euo3eq aûq sluopousr pu? 'serjejorq u?ruo^3o Jele,{{-^\o ui,{wrr "qs -qd"r8q"jls lu?uodurr ej eeprluopoljtl eql 'a"pquopou3l eql Jo Aolsrq 3ql ur slueê et?l poreprsuoc i(0uec -er eêq (t86i) ueseero pue Sraqpu?s pue :snpou)i lo se?eeljl I ueruoêq elpprw ur sulel -led tu?uo4nloê eqrrrsep (6161) relberz plde e8rppa^\ pu? (fr6l) oelppoln '.snpouruap-j Jo,tuotsq eqt ur slueê Jetel leq.{\euos pejeprs -um e^?q (r961) reltarz pu redded{ :seqrupjq snpou)j 2^\eûap ot^7 pue snpolljuald7 ueru -oêc lserlj?e ur sujed?d crleuesol,(qd crs q lno polro^\ e^?q (696I) Ipu?c pue slrej 'slusruuojrûj 13uoo8 -el euq sredr{ri 01 uonnqulsp Jreql ur pelculs -aj fpuer?dd? eja,,rl ser3ads ueruoâq elrl o^\1 slr lnq (u/(\odl lou en srulfiusojuy Jo suol4elzj pue ursuo aoleq Jo eôqe tuo{ pe,&el^ s? eurl -lno ped?qs-j u? pue sessejojd I"Jel"lolelsod,4qqnls ^llpculauruj^s? e Srull'uSotuy ulôut,(ljood eql êrl Jo sluoruele?d eteqdecsruru8es '(IleqlJo ouo roj elq?i?a?.{nuojedd? sr (6161 'ê ec) snpouahl)nog'$icols luopoujr e8?ls-elel osaql JoJ sarli?u cueue8.reu eleejc 01 elqelrs -ep eq.{leteurrlln fl pfoqs euo lsnf lou 's,,!lor olcrluep aarqt e^?q lnq 'el..\-s qtdu8sblalad oj? 'sal3eds oseql Jo lsoru JoJ u^\odi seuo eql 'slueruele ed 'snqpusst4apd urqtl,{{ sa8 e ^luo -ul[ luejejrp oû ur sjoqu]orrj pue eq 01 p els -ui lq8noql rlrq snpol.tjl ot peu8rss",{pueunj seroeds ueruoêc ale-i a^s Jo dnoj8? Jo Joq -rrjorrr euo Jo snl?jedd" eql ur lueruale (..uuoj -quopolsro,! Jo) rujojruor elpln rue8 e pegd -uepr osle eêq (t861) uosaalo pu Sreqpu S 'ubrcrôpjo oql u?ql Je8uno^ sijoj ruo{ pauoder eq 01 eqljo euo 'lueruejo(..rrrjojrl ^\ej -uopolsro,, ro) uuojruol el?lncruot e sapnlcur os[? 'dnoj3 u?ruoêc ol?.l-elpplhl eql Jo Jeq -ureur l?jtua3 pue sodeds ed,& eqt'(02's '8lC) snpulput djo snlej?dde oqt 1"qt pouodar ues -oerc pue SJeqpu?S 'raê^\oq '.t86l ui uorlej? -des qcnsjo uoddns ur ecueprê orsoloqdjout aldrt " uaeq s?q ejeql '^nu$el lnun 1nq ereuee VJNOCONO] EHJ tueragp ol seneds snt4pu8st\alad Jo sdnoja u?ruoê(i etrl-elpplw pu? eql SuureJ -ar pelsessns eêq sjoqlne l?jeês ^lr?e 'de8 Jrqd $ -r1ejls aqtjo esn"33g serceds-ed& eqt'snpuq) -ar d sepnlrur l?qt dnor8 ueruoêq ote-l puz slppqatr e urorj de8 JrqdpJBrt?Jts olq?r3erdd? u?,{q pel r?des ej? sarceds u?ruoêc,{lffg eseql 'suorlrsod S ur uorloes ssojc J InJJD All"uuassa Jo slueluela uuojruoj el"lnjruetuou pu? 'suoursod n (^lqeqord) pu? qd eqt ut ûu. slueur -ele(..u?urpoc?,, ro) rujojruor e1?urlsed 'uorlrs -od?d eql ui slueluele eleurul8es pe/t\or-gj8urs qlr^\ sesnter?dd? pauroj /I g '*J ar,.snql -ou8st4apd,, ol pou8rsse serceds u?ruoêo pue xaput snpou)l tsrg ^VeE aw Jo peeqe IlaM, pue QtprLuq)sotl/. 7) snpou) -uajoi Jo e^rlelueserdej lsjg eqt Jo p?eq? trq epll.l e \xapul djo t[joj eql ur) usunlrs lselel eql ur per?edde (0Z S 8lC) snqtdu8stuppd,, edpueje,, u^\o sll oq,tetu lr lnq 'cqel^qd,(lod eq lou Kern snpoltjl snqj isluarlialo olpqdeosrurur8es ^luo ei\-snpoujl pardncco ej? suorusod ed sesnl?jedde ^q esoq^\ rn serreds l?rgês peull.eds snqnubsbl -alad 'O861) uaseero pu? Sraqpups ot turproc -c? 'ueq,tl u ruoêc ele.i aql ur Je{rrql ueê eurmoq told egj srolsoru snqnu8sblapd utojjloa'snpou)j utorj poûap ueeq e^ q,4brx snrypussblapd Jo ser3eds euos lseol te leql slse83ns 1r esn?coq 'asjno3jo'sum8ulur sr srql 'slueluele d-uou Jo rejrurrs? saq 'sloor JeSuno,{ leq^leuros ^ ur peluesojdor '?,{Zr,rJ snqwu8sllalad leqt polou feql..'ruro;rur -po*,, are qorq^\ Jo II? lou 'slueluela ujojruo3 elq?u?^,(harq Jo dnor8 e 'u^\od[ szpo?.rrl lse -plo e\t'rlsdupdq 7Jo sntpr?dd? eql ui popnlj -ul (LL6t) tured pue uoueueqc 'reê^{oh 'sluetliala rljojruoc IupnuEJ^d ro eleunsed,4un,{ilsou]jo lueuruossb ue pu" sluoruola?d el?qd -etsrunx8ss Jo pels$uoc tunsanualdl sflportj -ua1o7 Jo 1eq1 e{i 'serjeds snpou)l Jo sntejed -d eql l"ql eejs? sroqln" Jaqlo lsour 'snpol.tjl snue8 uroj eqt peseq (8[6I) IqeI pu? uosu?rg qclq^\ uo sluerrjele eleqd?csrurutos oq1 Jo.tlerrluo peuuoj (02'S '31{) srrleredde snpouij ue peleco^p? (Zl6t) IouAIng q8noqllv '?teuei - lueje.up ol serceds ol/\l eql AuuErss? ejnt -cellqcj" snleedde ur secuejejrp esaql ^q ezru -8o3or ol elq lejejd oq lq8ru lr '^leûuulet

78 which species of luiodus have customarily been identified or the single-rowed segminiscaphate elements taken as typical of Peleldysgnathw may have been produced independently at different times in different lineages. Also, origins of the family are by no means certain. While I do not claim to have special insight into the ancestry ofthe icriodonts-or even the clairvoyance that would be required to make a monophyletic unit out of this family-i suggest that a derivation of Latericriodus woschmidti from Rotundacodina dubius explains tlte char acters of more of the Lateriuiodus apparatus than does a derivation from Pedavls. Pending badly needed additional information on Iate Silurian conodont faunas, I submit that this is a more straightforward route than is the one by way of Pedavis, whose own origins are yet to be amdlv documented. THE MAJOR CONODONT GROUPS ' Family Polyplacognathidae Bergstrdm, 198t I-ate in the Early Ordovician a species of the Amorphoqnathus group (Balognathidae) was apparently the progenitor of a stock of prioniodontide conodonts characterized by a reduced, bimembrate apparatus of bilaterally asymmetrical stelliplanate and pastiniplanate Klapper and Murphy (1974) suggested that Icriodus sensu lato mlght have evolved from Pelekysgnathus index, but they found no specimens that would bridge the gap in morphology that separates Pa elements of Lateriuiodus woschmidti and P. index. Nicoll (1982) re- elements. Recunent groups of such elements are the basis for recognizing a succession of species of Eoplacognathus (Fig. 5.21). These species have been of considerable biostratigraphic utility in rocks primarily of early Middle Ordovician age. The stock seems to have garded Rotundacodina dubius (Distomodontidae) as the most likely ancestor, and Broadhead and McComb (1983) regard Latericriodus Ordovician. died out, however, early in the late Middte woschmidti as a neotenous derivative of Pedavis. Fihraeus (1984) suggests derivation of Eoplacognathus seems to have giyen rise to an During its early Middle Ordovician heyday, Pedavis from Distomodus, in which presumably he included Rotundacodina dubius. I re- refers to the genus Cahdbagnathus (Fig. 5.21). important line ofspecies that Bergstrdm (1983) gard the neotenous route suggested by Broadhead and McComb (1983) as unlikely because lrke thai of Eoplacognathus, is composed of a The bimembrate apparafis of Cahabdgnathu\ it was devised primarily to explain the origin of pair ofstelliplanate and a pair ofpastiniplanate the Pa elemenls of I. woschmidli from those of pectiniform elements. Howeyer, those of the Pedavis latialatus, and it thus ignored other elernents in the apparatus, which are surely not pairs, whereas those of Eoplacognathus are bi- Cahabagnathus apparatus form mirror-image the same in the two species. On the other hand, laterally asymmetrical and have more simply there is substantial similanty between non-p ornamented upper sides. elements in the apparatuses ofr. dubius and L woschmidti, as Serpagli (1983) has shown, and the remote ancestors of R. dubius certainly Fig,5.21. Elements typical ofthe apparaluses ofspecies assigned to genem ofthe Polyplacognathidae. built scaphat elements comparable to those of L. woschmidti. (Of course, the scaphate elements some of them built were even closer to those of Pedavis, which I ally to Iuiodella because of greater similarities in M and Pb elements.)

79 01 euo r?eq leqt sessecord pedoleêp flljurlsrp ejour qlr/r\ lrq snpotjuo)dtdld Jo sarjjds IPJJ -ês eqljo asoql ot ueld ur l"cquepr slueurele eulp^q.tlo8reljo suolale{s qlr/( sercedsjo uors -s$cns e,(q peurol se,r\ mpouunodld '(uertcorelrq^\) Ûeuq u?rcrôpro elppqî oqljo u?d 1ser1:ee fra,r. eq1 ro '(uelxeql) uunrôpjo,4ljeg u?cuell]v quon eql Jo u?d 1so1?l oql ui 'luspuacsap si (roqtre Jr) r{cq^\ pue rolsejue sr (.reqfre gr) qcq,{ JeelJ lou sr lr os '\snpqap J pue slsoq -l1.atq'd Jo ru:o3 sqt ur) Jeê,iaoq 'otuq eur?s '(/861) JenEg uro{ Oep oql lnoq" l? r?edde snpoduj pue snpoqund -[uopolsrotlnl l eqt Jo loquou e 'sruljou3ouqjorcla7 -./atd'drqsuo4elej esolj E slsottns qorq.{ 'srxpod Jo sntecdde lelele{s oql Jo l?rrd.& stueuola. Z.S.3H -r.u Jo t?ql aii qcnur,fto^ flsnor^qo sr ujeu?d srqj sauas (S) uoqrsuejl-i4euru^s pet"ilue '( Z S tlc) snqlduso qroiat '\ao$ -JaJrp,(lotelduoc? r[joj ol snpol lueruele urojruo3 elei? pejredun,(iq?urnsejd e urofl?ql stueruele -stolqnwoan-snpolluo)onld eql Jo e^4eûep pejnpoj uuojruoc elepodoruol pue el?uuedrq e eq,{?ur li uoursod trai aql u! tueuele Jo sjr?d pu? u? peicei '(nd stueluele et"lncrue8jo red B,(lluoJedde snpo$toulnw Jo senads '(qd 'Ed) sluauele ot?unsed J?lruns -od.{l eqljo snl l?dde l?lelels eql esnbcaq (ZZ S 'fuj) snpotstoufiutoai(r ot ejeq pejlajat oj? Jo sjr?d o,{\l sopnlcur qcq \ ^llejrsoloqfuour 'sluoruele uuoj tnq sroqln? tsorlr,{q snpo$io\ftl4t ar ped,rj.or? -ruof, aurp,{q [llueuruop uaeq Jo,{euE eterqueur eêq sorcads eseqj 'selcrluep -Ixes ol -mbumb? sr snxeld mpoiuo)dtald eldurrs T?Jaês 'stu tllele d pue'i,{ 'cs'qs,ropq po^{o oj'^{or qcee Jo oolle slueruels es oeprluopolsronlniî ^q Oql ul pepnlc -ur EreueS Jo sarcodsjo l crd& sesnleleddv.zz's.ttd ilawpl,alo'.tquagol.nptlll uj eql ur seroads 3o snlzreddz I?lelels eqj 'ruûou^s Jorunf B {luieuec lsourp sr '6961'rederN snpouosttj 'tl6i 1arrclA UEL snporysuouj u?ql JorlrBa epecep p lsourl? lnq 'puno],{ snporuoudoauog se J?e,{ eues oql ur pesodojd s?,r qcrq, \ '(ZZ S '3H) (996I) sur?h pu" srrr?h Jo snpouuor -DDid esn I 'uorssn3srp sllfl ui 'snpolluojdnld Jo 'snpotuoudoauog Jo'snpof8uDuJ ol sro\l -ns snolr?,r peuejej ueeq s?r{ leql ser3eds Jo dnort e $,{Iur?J ^q 1u?uodur srqljo ulels eql,961 'stttoh aop4uopolstot nl1j tltwoi g'l'9 VJNO(ONOJ IIHJ 'suaqrs Jo u"rsrôpjo elpprw eril uo{ srujoj u^lou)l,(q pa g eq,{erii du8 er{l 'rs]retnoq:snqpusndqog ÎJood ar rolsacu? prtual -od.(u? uro{j ',{ll3orqd?jeoee pue,{?cqdzra -nej$ qtoq 'psl?losr t?q^\euros,{pueuno sr sns -outdt' d'sluewele urjojrurl3ed aleu?idruds"d pu? ateu?ldllelsjo srred oeerur-jourur sopnlcur l?q1 sntejsdd? I"lele)ls at?rqueurq e,tq pezu -AoceJ sr pue uercrôplo ejpprtr l elel aqt ur ejurôrd lueuquocprl^l umuelllv quon aqljo e^nourlsrp sr'snsorudt d 'sorcods uîodllloa\ ^lrro asoq^\ '(tz S 'EtS) snqpu8udldtlod or IEIsacu? osl?,tlq?qojd s",r\ szry'tousojdldot

80 THE MAJOR CONODONT GROUPS whose best-known species has a bimembrate species with apparatuses in which the Pa position is occupied by an angulate pectiniform ele- apparatus, was probably also derived from an early species of Neomultioistodus (e.9., N. clypaas) by simplification of elements in the P po- often repeated observation that, in large samment (e.g., P. tenuis, P. florida) because of the sitions and by loss of elements in the M and S ples from a succession of late Middle Ordovician populations, the denticulated lateral pro- positions. Lower Middle Ordovician (Whiterockian) cess of the 'dichognathiform' Pa elements strata in North America also yield two recurrent groups of dominantly hyaline elements fuses with the short, adenticulate anterior pro- rotates gradually anteriorly and ult.imately that are identical in plan to those by which I cess to produce an element in younger samples recognize species of Pteracontiodus, Neomultioistodus, and. Multioistodus. but with shorter noted in 1972, this sequence of events results that is formally angulate. As Bergstrdm and I cusps and longer processes, which bear numerous white denticles. These groups record two Jor group of dominantly post-ordovician in a type of apparatus that is basic to the maclosely related species of Paraprioniodus (Fig. conodonts herein identified as the order 5.22). The older species (P. costatus) apparently Ozarkodinida. had a geniculate coniform element in the M position of its skeletal apparatus, whereas the M evolutionary step such as development of the Because il is unfortunate to have a major position in the apparatus of the currently Ozarkodinida buried taxonomically within a unnamed younger species is occupied by a genus, I suggest that Plectodinabe reserved for dolaurate (or "cyrtoniodontiform") ramiform species like P. aculeala (FiE.5.24) with pastinate Pa elements, and that those species with an- element. Pteracontiodus rznges, in the form ofat least gulate Pa elements be transfered to another one unnamed species, into Middle Ordovician genus, which I will identify here only as rocks well above those dominated by the other "Plectodina." members ofthis family, but apparently was not The problem with Aphelognathus is just the ancestral to other conodonts. Dzik (1983) reported that, in a manuscript then (and still) in gnathushas an ang)late Pa element and is thus reverse. That is, the type-species of Aphelo- preparation, he and I might consider Pcraprioniodus, a Pteracontiodus deriyative, as the prioniodontide) conodont; the two species with appropriately an ozarkodinide (instead of a ancestor of the important Ordovician Phragmodus.For vaious reasons, however, that now genus (1. gigas, A. kimmswlckensls) will need pastinate Pa elements now assigned to this seems unlikely, and Phragmodus is shown in a new generic assignment, or can be accom- Fig as a possible descendant ofan as yet unidentified species in the Tripodus complex Family Plectodinidae, new modated temporaily in Pleclodina. Thtts, in Fig. 5.11, I show the range only of Plectodina sensu stricto. Species of " Plectodina" and. Aphelognathus with angulate Pa elements are included in the ozarkodinide family Spathognathodontidae, whose content and strati graphic distribution are shown digrammatically in Fig PleAodina s.s. (in the form of P. acalea- In this new family I include prioniodontide conodonts wilh a sexi- or septimembrate skeletal apparatus that includes a pastinate (or "dichognathiform") element in the Pa position, an angulate pectiniform element in Pb, a dolabrate or bipennate element in M, and alate, di vician, and specimens representing a host of /orzes) almost made it to the end of the Ordo- g).rate, and bipennate ramiform elements in variable (and largely undescribed) species are the Sa, Sb, and Sc positions, respectively. common in samples from low- and intermediatelatitude Middle Ordovician rocks. Since about 1969 I have assigned conodonts with such apparatuses Io Plectodina Stavffer The Plectodinidae seems also to be the best and Aphelognathus Branson, Mehl, and Branson, taken in a multielement sense. However, I known species has a unimembrate skeletal ap- home for Scyphiodus (Fie. 5.25), whose only have also assigned to those genera a number of paratus that consists of an anguliscaphate pec-

81 aql reô.tluol.ld leels s"q (eeu4uopoluou,{j,tlruejqns se'696i) ss"h ^q tr uo pos?q eep -rluoporuor^c,tlfu?j eql ^nq 'snpousdtqd Jo uûou^s elqeqojd e smlt s\ snpotuotti) 'sn Iu -8oc mpoutsotrq4 10 slueurele t{ oql tuasejdej leql sueurcods uo psseq Klqeqord set' snpotuol -rdj snua8 rujoj s,jejnsls Jo serceds-ed^l aql esneoeq fj"ssecou sr srqj 'e?prluopouo!^j,{irrrej eqt ot DutpotuoLtg pue snpou]sotqd?raue8 eql JaJaJ ejer{ I '^lsnouels,tur l"q^\ouros 696J'ssoH adp1uopotuout) qlu0l 0['l'9 'snlbj?dde olerqueurun 'pecnpal doleêp ol auo er pue " luolliala u[ojrurtced psurroglqd ^luo doloâp ot (snsoutot snlpu8nd4tlod setn reqlo eq1) u6uo uecuelllv qljon Jo sluop -ouoc epuuoporuoud o^{l Îuo Jo euo -Jedd? se,!\ snulud snporydtzs sur8uo eleurl ^llue -sed Jreql IJ?ur ot lesjo lzurpnlr3uol lq8ls aql,(luo urplar s$otdj,ale snporqdhs ojnteu sngl 'sat?ls crlouasoluo Jelq,{le^rssecJns Eurluas -ejdej slueuale ur ecsel?oc sossecord Jouelu? pue l?relq l?ql lnq '(..uuojrq1eu3oqclp,, Jo) al? -uq.sed ej? se8?$ qlrnor8,{fee.{re.t 8ut -luasjrd ^lj?ep suaurrjeds leql perjôjslp l '(2861 '1oeas)?toI?C qtnos Jo uoueuuod Sedruur^\ eqt rrjo{ sluetud:ela snponldtjs Jo uobcouoc ',{uetoluo ui 93qs el J e Suquesolder slueurals Ed Jo s^{ol^ Jeddn pu" Iulel J ele sern8g o \l Joddn eqi 'solltuue cueuos9jdns ol enlc Iedrcuud oql sr oibls Is'luoudoloêp slql l slueuelejo ejnlsu eleuqsed eqj a8e$ a$ougsoluo IIJEo fuo^ e 8uI -tuoserder lueuele uejo sr ojn8g Je,,rlo.[ leeplulpopold) sntuud snpotlldbs lo lpcrd,{l sluouele ea 'SZ'S 'Eld efupl ejo,{pnls luecar E ui 'squ,{lasre^suerl padjuuoj sjlorluepjo s^\ol IJIIETBd ^q eelql sjejq leql ql8uel errr?s eql lnoqejo ssecojd roualsod e ruo{ tes.uo,tpqttls st 1eq1 ssac -ojd rouelue ^lleurpnlduol etlepblq qlt^\ luourela ulojrurl " 'sluouola pd pue'qd 'I I 'cs'qs po,{olloj 'lq3u uo sluoulelo es (eeplluopouou(l) trtpoluditg ptje snporus1,trld pu9 '(eeprupotceld),??porrald ^q ol psu8rsse sorcods Jo lecrd^l sesnlej dde pue sluouolg 'tz's 't!d VINOCONOJ IIHJ 9L

82 THE MAJOR CONODONT GROUPS family Phragmodontida eslablished by Bergstrtim in orginally pastinate form, that reduction is not either developed by phylgenetic reduction ofan Phragmodus (Fig. 5.24), characteristic of documented by extant collections. low-latitude Middle and I-ate Ordoyician faunas, has a distinctiye seximembrate apparatus in which the P positions are occupied by 5.7. I 1 Family Rhipid.ognathidae Linhtriim, pastinate (or 1970 "dichognathiforrn") elements, the M position by a dolabrate (or "cyrtoniodontiform") or geniculate coniform element, and the emognathus, Appalachignathus, Rhipidogna- ln the Treatise Bergstrom assembled Belg$ro- S positions by the "phragmodontiform" ramiform elements distictive ofthe genus. The latdognathidae, which was assigned to the Prionthus, Carniodus, ar^d Histiodella in the Rhipiter, which include alate, tertiopedate, and iodontacea (the Prioniodontida of my taxonomy). Following publication of new infor- bipennate types, all have a terminal or subterminal cusp with smooth sides or with a sharp mation on Histiodella, which I have cited in costa on one or both sides and a long, arched, Section 5.7.1, I feel rnore comfortable assigning denticulated posterior process at the crest of that genus to the Oistodontidae. Also, Carniodus is out of place here, because the sexi- which is a major denticle that may rival or exceed the cusp in size. membrate skeletal apparatus ofits only known In 1972 Bergstrdm and I included Piragmodus and Plectodina in the family Cyrtoniotinctly denticulated processes in one P position species has a pastinate element y/ith three disdontidae and speculated that these genera, and an alate element with a long, denticulated which dominate Middle and Late Ordovician posterior process in the Sa position. Because conodont faunas in the North American Midcontinent, originated rn Pfioniodus. lt now paratus of any other rhipidognathid species, I neither ofthese characters is a feature ofthe a[f seems more likely that the prioniodontide plan feel that Carniodus should be reassigned. The of the skeletal apparatus in species of these only prioniodontide group in which Carniodus three genera is indicative of a common, but could be accommodated is the Balognathidae, probably not direct, origin. Thus, in Fig. 5.1 I I but there is little morphologic resemblance between most of its skeletal elements and those show Prioniodus, Phragmodus, and Plectodina as heterochronous deiyaliyes of Tripodus. formed by typical balognathids. Furthermore, With some reservations I also include Bryantodina (Fig. 5.24) wtth Phragmodus in the Cyrdovician balognathids by a considerable strati- Siluian CarnioduJ is separated from the Ortoniodontidae. Bryantodina has an array of graphic gap. Consequently, I follow Bischoff ramiform elements in S positions that look (1986) in assigning Carniodus 1o the Pterospathodontidae (Ozarkodinida), whose numerous very much like the distinctive "phragmodontiform" elements of Phragmodus. However, P Silurian species built apparatuses that included positions are occupied in the apparatuses of strikingly similar P elements. Bryantodina species by carminate and angulate Genera that remain in the Rhipidognathidae pectiniform elements that are quite diferent include species with tri- to septimembrate skeletal apparatuses in which P position(s) are oc- from the pastinate P elements ol Phragmodus and cannot be shown at this time to be either cupied by structures that are fomally angulate ontogenetic or phylogenetic mod.ifications of or carminate pectiniform elements but are allied morphologically to the "acodontiform" P such elements. In favor of an association with Phragmodus,I note that in the apparatus ofp. elements of Tripodus and olher slem pfioniodontides through possession ofa distinct rib or cognitus one of the pastinate elements is replaced phylogenetically by an angulate pectiniform one that retains a clue to its pastinate an- be marked on the basal margin by a conspicu- costa on the outer face ofthe cusp, which may cestry in the form ofa riblike offset on the outer ous boss or lappet. In short, those elements face of the cusp. No such ofset ornaments the may be regarded as very simple pastinate ones, outer face of either P element in the apparatus in which no sharp edge or denticulate process of Bryantodina typicalis, however; hence, if ever deyeloped along the anterior edge of the

83 ? pu? sessecojd l?jolel pel"fclluep,(lalnulur -StqrDloddv Jo srol.seouv (92'S Brd) sensoloru 'uoqs e^bq slueuodruoc rujojrr.u?j eql qcrq^\ ul -oq JEaJJ os[? Jru ejjql qcrq,,tr ul euo lnq'snsuat seuos s ue pu? :s$cojd Jouelsod el?inclluep? -xa snqidusoluaoltsstag Jo letlt u?qt elejoqele u? qlh,r 'sluetuele w (rujojrluopolq ro) elaq Jroru sr leql snl?ndd JEtalJIs? seq snqloubltl) -?lop:,.rurojruo1,, Jo 'pelslû,(lsnontrdsuoc si -oldddv Jo setoeds uîou)l pue 3d,{1 eqj qsrq/{ Jo euo 'slueurale d ujojrurpad elqneu? Îuo '9e s qlr,{ 'snl"j?dde pleja{s elejqluolulxes e sbq 'trc ur pele4snllr ej? qcrq,{rjo sluouoduoc eqt 'otoalnjo 'd 'uopouad Jo sal3ads-ed,4t er{i 'sq"j?dd? alejquleuul e lou '4?Jqlueuues 'saurl luejj.urp lsq,rleuos tuo[3 E JA?g ol pereôjsrp uaaq osle seq's{jol ueu peîoê tpqt {co1s uercrôpjo -n S-plur rno+ pu" 'uedu^\ sea\ Ldox asudatj Îluonbesqns {IJ?g ellles oqt Jo sogcu rq tuesejdej ejeueg eurg eql l? essc eql se^l u?ql EJuerIIv qlon o^\t eqt Jo serceds l?ql ( 86I '4zq 'uo.rt Jo usrcrôpjo olpprlî eq1 ur J0^1ol qcnu Illo{ -Jq'I) serpnls tuecej rrro{ suees u esneo 'EurqJ Jo u?rcrôpjo re ro'i eql uro+ -aq lnq 'snue8 Jeqlre 'uo uob?rujojur ^lelrl ^\ou,{\eu crseq peloder ueaq seq qcrr{nr 'snqpusoptdtqy Jo 'qllxi ecuouedxe l?art eêq I esn?ceq lou 'flr 'sjssajojd polelnjn -urej eruss eql ur pepnlcur ojeq al? '^laîpads -uep '!oqs pue dsnt pullslp e qtl,{ -ej 'eepuuoporuou^j pue e?prluopoljed eql (sluaulelo ^lsuusds qs pu? d Jo) luauale peaoq pue ot asuoatj eql ur peu8rss ere,{ qcrqâ '(LZ S :ssocojd Jouelu" pel"fcrtuop 'tuol s seq lnq 'Arc) Dulpo4lozo.trlI\t p'de (17, 9 'EIJ) uopolnd seplluep Jouelsod s{j?l t?ql luaurale n el"u 016I'tuoltspulI adplluopouad qtwd{ -uedrq :ssecojd Jouelsod? slcel leql lueluele ZJ I'9?S st"l"'ot"rxl"d'pessojduro3 -u? u" qlh{ 'snl?l?dde elejqujorllul ^ljouelsodolel,( ecrseq 'l I'S '3!J ur lellsecue s" pagpuepl " euo s?q '"urqj Jo uercrôpro re,,i\o'i oql ujo{ oslb eql sr lr os 'el?ujrxojd lsolu snue8 eqt sr teql 1nq'ltaots snqlousopldlqf, ^ljecrqde$nells ^\ou u^lou{ '(92'9 'ali) snqldusouao4stuag eql ('eepnuopoued oql Jo Ued u/$ou[ ur snor^qo lold eje snqjou ui slsue 'esjnoc Jo 'uod"nlls relrurs ^lllu?j y) 'dsnc ûe 'sluetllole sd pue 'qd 'I I 'cs 'qs,{q Uol or p5îolloj lq8u uo slueu -ole es (tt6 I ) T to rrl.o.ll:sajeg $otj sn puslttjdtdddv Jo esow '.(t L6 I ) rf"d$s wot! sn lousouautcsog Jo sanr -3rl eepqleusoprdrqx eqljo EJeuot Fdrcuud oarql oqljo sorceds Jo l?crd& sesnleredde pue sruouelg '92'S'tld sntltauooutaorrs6taa YTNOOONOJ AHJ 9L

84 THE MAJOR CONODONT GROUPS long posterior process that is arched, laterally ers. The stratigraphic (and probably phylogenetic) predecessor of P. aculeata, P. flabellum, compressed, and surmounted at the point of maximum geniculation by a denticle that is had geniculate con.iform, not anteriorly denticulate dolabrate elements in the M position, wider and conspicuously longer than the othand the ramiform S elements were apparently neither so profusely denticulated nor so conspicuously arched as those in comparable po- Fig, Elements typical of the skeletal apparatuses of species assigned lo th PeriodoDtidae. Top elements sitions in the apparatus ofp. aculeata. An even in each row Pa, followed downward by Pb, Sa, Sb, Sc, older species of Periodon, which has not yet and M elements. been named, is represented in the Proteus and Elegans zones of Jamtland (Ltifgren, 1978) by adenticulate alate elements interpreted as occupants of the Sa position and by adenticulate pastinate (or acodontiform) elements. The latter, and the "tortiform" angulate elements that evidently replace them in the apparatuses of younger species, are the elements that indicate that Periodon and the Periodontidae belong in the Prioniodontida. Ofcourse, the distinctive S elements ofp aculeata ar;ld P. Srazdri, the species of Periodon that I know best, are also gederally similar to those of Phragmodus, and this led me in the heyday ofform taxonomy to sug- Eest lhat Periodon might be an older name for Phragmodus- I no longer hold such a view. Species of Miuozarkodina, such as M. flabellum, tbe type-species, have quinqui- or seximembrate skeletal apparatuses in which the rounded anterior margin of pastinate (?) P elements is not developed as a process and the short, anteriorly deflected lateral process commonly bears no more than a single denticle. M elements are geniculate coniform structures, and S posirions are occupied by alale. tertiopedate, and bipennate elements with a long, straight posterior process. According to the vielvs just summarized, Periodon ernerged ftom roots in eady oistodontid populations by development of a highly differentiated skeletal apparatus in which processes of component elements gradually became longer and more conspicuously denticulated. As in the presurnably ancestral Oistodontidae, P elements never differentiated into conspicuously pastinate structures, but S elements became distinctively arched and denti culated. In Microzarkodina development was apparently similar. but the posterior processes of S elements are not arched, M elements develop no anterior denticles, and the feature I interpret as a lateral process in P elements remained short and bore only a single denticle.

85 'esrulp ot Jo sepnuep pue dsnt Jo suoreej -uoud Jofeur Euour? suoqelar perejur pu? uorl plxe eql ol laqlre peuguoc 'sel'eds I?JoAes Jo -nqutsrp lejodruej 'eee t$seul lsaleljo $lcoj slueurela ur 'pup lunoru? Jourur Jo l(luouluroc ur sfssoj s" punoj er? pue eepllolopuoc aql sr rel"ur otrq^\ pue :e{qeod pue elercsp,{[?c ur pepnlcu ar? qorq^{ '(D a ts!w)?luopouoj -qsuepa?qc ejb selcuua(i { ecrsologfuolu aql Jo sro^r^jns lsq eql oj" tse8uno,( s1i :(eep FuorlepaSrelur pue 'ezrs ellles eql Jo 'lnols -qteu8ojrqc) uopojudttg ol pau8lssb surjoj eq ot puel snteredd? eql ur slueuala Jo sod l uercr opro,tf?g ej" se^rlsluosejdoj uaou)l ue^os Jo xrs y'suoursod d o.trl oql ui slueur lssplo sll 'ejeuoe It pu? sar[uej s sepnltur -ele el"r^erp ulojrsuolxe o^dcurlsrp,{lqeq?prurporuolrd aql 'pe^recuot os sy'eplurpol sepnlour pue slhqureruddes Jo -rxes sr l?rll -uoud lapro aql riljoj ol pourof ejerl ej? qcq,{r snlej?dd? crpqdec pezrlaeuru?,(q pozuep? '?aieuolopuoo pu? Be3"Ilepleqq rh serlruej -Jeqc eje Bprurporuoud repro 3r{l Jo sluopouos 'pecnper ro 'petdep?'poglpolu,(gzrcsds ueaq a,req sesnleredde l?telels Jreql se ldecxg '82'9 '3rg ur pezueruruns eje slcols crjouet eprurpor -Jedns eqt ur pepnlcur eje,yuquoferu E lnq '?pn -uoporuoud eql ot sror{lne asrldatj Aq petfits -s3 ejo^r ejoq popnlcu sluopouoc aql Jo ^\ej v ^ron 'Gplulpoluolrd aql 8'S 'eprurporuoud tr.lljo serlruej pue aeuao.82.9.t!j ]VOIHlVN90AIHJ o a o I s o 5 ) I w N A/ I d w a I d J V I d I VJ.NOCIONOJ AHJ 8L

86 THE MAJOR CONODONT GROUPS fuzzy-edged clouds that are irregularly distributed through cusp and denticles. Species of a thal bears several denticles on its upper margin tends downward to form a distinct anticusp few early genera (Chirognathus, Curtognathus) and is thus a true anterior process. It seems unnecessary to invent a new morphologic term and of at least one Triassic one (Parachirognathus) formed elements with little white matter and thick lamellae that are mineralized by be described as a quadriramate structure with for such an element, which (if need be) might apatite crystallites whose prism surfaces are a short, adenticulate posterior process. oriented parallel to the direction of growth. Ancestors of Erraticodon (and thus the Such elements tend to break as if they were internally fibrous, and Branson and Mehl used reasonable to rcgard Eqaticodon as the plexus Prioniodinida) are not known, but it is surely this feature to distinguish the order Neurodontiformes, Middle Ordovician seas of North America. from which Erismodus evolved in the shallow It is also a characteristic ofthe Prioniodinida Species of Erismodus (Fig. 5.29) differ from that there is little difference in size or basal those of Erualicodon primarily in that the Pa morphology between the distinctive digyrate components of their seximembrate apparatuses elements assigned to the two P positions, the lack a denticulated anterior process (but retain ramiform elements that occupy M positions, and those that make up the morphologically conservative symmetry-transition series. For this reason, diferent authors have assigned comparable elements of various species to different positions in the apparatus, with the result that homologies are not always obvious. I will attempt to be unirbrm in the following discussion (and in the classification in Appendix A), but my yiews do not always coincide with those of other authors Family Chirognathidae Branson and Mehl, 1944 Eqaticodon, the oldest known chirognathid and the most ancient member ofthe Prioniodinida distinguished thus far, appeared late in the Early Ordovician, when it achieved a very wide biogeographic distribulion E. patu Cooper (Fig. 5.29), the oldest (and best-known) continent waters in which early Eru'smodus developed. Later species, such as E. quadridacty- /as, may represent forms adapted to the more normal conditions that probably characterized Midcontinenl seas later in the Middle Ordovician. The bizarre Chirognathus (Fig. 5.29), represented in the shallow, tropical waters of the species, is distinguished from other chirognathids primarily by features ofthe curious elemenl cies, is allied morphologically to Erismodus, Nofth American Midcontinent by a single spe- I assign to the Pa position. At first glance that from which it differs primarily in a skeletal apparatus composed of elements with a scarlike element appears to be pastinate (or "dichognathiform"), and its association in the same attachment surface skewed to one face, an alate apparatus with a Pb element that is an extensiform digyrate (or "oulodontiform") element, M element with denticulated anterior and pos- Sa element without a posterior process, and an and thus typically prioniodinide, might be terior processes. Cutlognathus (in which I incltde Trucherognathus and Polycaulodus) is taken to suggest that E. patu straddles the boundary between the Prioniodontida and the also a Iikely derivative of Erismodus,butits apparatus has not yet been competely recon- Prioniodinida. Closer inspection, however, reveals that the distinctivepa element of E. palu structed and, like Chirognathus, it is not likely is also basically an extensiform digyrale element, but the anterobasal part of the cusp ex- a bosslike anticusp), and bipennate M elements lack denticles on the short posterior process (and thus have sometimes been described as "falodontiform"). The oldest species of.erismodus with which I am acquainted are represented by typically "fibrous" or "neurodontiform" elements. However, the skeletal elements of later species (e.g., E. quadridaaylus) have more white matter and commonly break like other nonfibrous types. This suggests to me that "fibrous" histology may somehow be related to the probably quite unusual condilions that obtained in the shallow, very warm Mid- to be on the "main line" ofprioniodinide evolution. These two genera are significant, how-

87 08 'pequcsep uoeq lou se.q.o aproqqlh Jo ]lua:uliele ed eq.l slueuolo ed pue'qd 'I I'rs 'qs uel eql pjeaol po.rolloj 'tqbu eq1 le ore sluoeole es sasnleredd ^q lls ul'(o aprdqqth'dutpoluoltd'snpol O) eeprutpor -ioi1pue(tnqniion4s'mpowsug'uopocrpll3')oepqleusorqjequoiecrd,{lsorcedsjososnlereddv'62'5'8!tr tttt. ^"t.tt^,^ "nqteu6otlr.lj slppteqqth

88 THE MAJOR CONODONT GROUPS 8l ever, in being the primary "fibrous" conodonts platformed pectiniform elements in P positions and thus the nucleus of Branson and Mehl's and started to experiment with ontogenetic or Neurodontiformes. phylogenetic reduction in the development or mineralization of elements in various apparatus positions, the Prioniodinida remained Family Prioniodinidae Bqssler, 1925 conservative and development produced no startling modifrcations. Oulodus (Fig. 5.29), the oldest prioniodinid, seems clearly to have evolved from Erismodus, Devonian workers have not yet dealt in detail with the Prioniodinida, but Klapper and as Schijnlaub and I suggested in In the apparatrus of O. serralrs, the type species, there Philip (1972) have demonstrated that the apparatus of Hibbardella angulata (FiE.5.29), are extensiform digyrate (or "oulodontiform") elements in both positions, only minor patches type-species oflllbbardella, differs from that of ofwhite matter in any element, and a dolabrate Oulodus primaily in that the alate Sa element (instead of an anteriorly denticulate bipennate) of the former has a denticulate posterior process, whereas that of Ou /odrs has a stubby pos- element in the M position. These features, and scrappy evidence from Ordovician rocks in tenor process that lacks denticles. For this reason the assembly of elements from the upper northeast Oklahoma (Amsden and Sweet, 1983) ofa possibly slightly older species. suggest that O. seryatus may have been somewhat (Norris, Uyeno and McCabe 1982) has recently Middle Devonian of Manitoba that Uyeno specialized, since all potential ancestors in Erismodus have an extensiform digyrate (or Hibbardella, instead. referred to Oulodus may represent a species of "prioniodiniform") element in the Pa position, Murphy and Matti (1982) have established and this pattern is repeated in all younger species of Oulodus. However this rnay be, the plan Devonian species, which had a seximembrate the genus Erika (Fig.5.30) for a single Early ofthe sexi- or septimembrate apparatus of Oulodus is cleally anticipated in those oftnjmo- in both P positions, a breviform digyrate ele- apparatus with extensiform digyrate elements dus and. Erraticodon. its ancestor. and there can ment in the M position, and a symmetry-transition series that includes alate. extensiform di- be little doubt about close relationship. Oulodus qutchy adapted to the probably rigorous conditions in shallow subtidal parts of apparatus of Erika divarica, the only species gyrate, and bipennate ramiform elements. The late Middle Ordovician seas, in which its species were soon established as ecologrc hall- Oulodus and. Htbbardella; however, the M ele- known, is sirnilar in many ways to that ofboth marks. With enlargement of those marginal ment is not much like that formed by species zones in the later Ordovician, Oulodus also increased in diversity, and its evolutionary de- a posterior process and thus difers from any of either genus, and the alate Sa element lacks velopment is recorded in Late Ordovician and other prioniodinide conodont with which I am Early Silurian strata by a succession of chronospecies that is of considerable utility in Iate According to Nicoll (1980), the apparatus of familiar. Ordovician biostratigraphy (Sweet, 1984). Late Devonian specres of Apatognathus (Fig. Pristognathus, represented by a single, shortranging Late Ordovician species, is closely re- genus with the Prioniodinidae in Fig The 5.30) is also prioniodinide, and I include the lated in apparatus architecture to Oulodus and element typical of Apatognathus in form taxonomy was apparently an occupant of the M clearly belongs with that genus in the Prioniodinidae. position. Several Silurian species assigned either to Sparling ( l98l) has also concluded that the Oulodus or Delotaxis (which I include in Ozl apparatus ofat least one Middle Devonian species of Prioniodina (P. tortoides) (Fig. 5.29) is odus) cany the Prioniodinida through the Silurian into the Devonian but proyide evidence closely comparable to those of Oulodus and of very little change in basic plan or diversification. In the Early Devonian, when sonle of in morphologic features such as style of den- Hibbardella in element tlpe and number and the dominant ozarkodinides began to develop ticulation. Sparling's discussion suggests that

89 oql tse8itns ot procor peqsllqnd eq1 ur enlrt sr pu? (9161) potlo ueeq eêq '8961 ejeql 'ejeq dnoj8 srql o1 1r usrsse I pue '?piui 'peorxsid snqnu?dpqrudt ^qron ^q Jo serjeds rujoj -poruoud eql Jo leporu lsjeuea erit slu sntfidu8 EuuueseJdeJ slueuole elu?u elqelr"ê lseplo -opolx luelfuelal4frur 'p4jn4suocoj lsnf sv eqt eq ot suees '896I 'peolxeu snlpusopdlx 'I'ueqt peuerss" (J861) p?ojxeu qclq^\ ol qorq,r roj snue8 lueurelelllnu.r pjo serteds tuau suoursod qs aql ueql selr,eds snqpusopdlx Jo -etuoc luosojdal ler{l sdnoje luarlncej ITJJoJ sjsnlejedde eql ur suonrsod pardnjjo eêq ol ourpouosrt pue 'snporuoudoan 'o apnqqlh r(lelrt ejour ere D adpiusow Jo selceds uuoj 'D adplrubdi4[ 'snqwusopdlx Jo sercods uloj s pezruto3ej,(lsnorôjd slueruela ldqt lsoe8ns s? pegrluopr,{fnoherd stueuolo (@tddlssrs I tnq 'sortods.tn?trusopdtx Jo sasnlz:edde eq1 -sr] I) ueuelsoqc 1?q1 suodel (186I) p?orxau Jo uonjrulsuojjj srq ul sluaurole d eziusojej '?purpoiuoud lou pp (1861) peojxed snpoluottdoan Jo sarr eql Jo &otsq crozoeled olq eq1 ur elor -eds IIlroJ se paguuepr Suol ljos eqljo sluouele lu?lodrul ue p3,( ld pu? u"ru?^[^suu0d olejqalop pedeqs-iord eje snqwusopdlx ]]ualc.t r{8nojql u?uetseqc ^F?ep ruo+ atu?j trl{datrlells -elerlfurjo slueurele tn'outpouost7 ol pjluournjop? s?q leql ptutpoluoud a^tljull -x?l rrrjoj ur pau8rsse,4ferujoj sluetuole ûouo eleu -slp E 'snporuoudolpl Jo se^n?lueserder -uedrq.{q uonrsod JS etql pue :snltousopetlot prooar osle ' 8'S uoucos ^llpe ui (,{Iqeqord) pue snrydusopolx EreueA urroj eql pejeprsuoc eq ^lq?qord I[.!\ qcrq,n êqj 'eeprqleusorlceg pezr Jo [mrd,& stuauele etepedonrel,{q(s,peojxol{ {prceds gql ol [ejlsaoue selceds prurporuoud lou 'uourdo [lu ur) pelru se^\ uo4rsod qs Jo procar lelele{s eqt epnlcur lsourl? arlt ld ap.nqqrh ol,tlsnolêrd pojjejet sse3 sdnor8 eseql '^ mruouoxel uieqt Îulsuoc qtr^{ lpep -ord Joualsod elqncrluep e q1r/tr slueurels 0lEI3 Jo pepjocer sdnoj8 lualncej agl lno pallo^t,{q perdncco sp,r snlejedde snqtdu8 le^ s?q auo ou tnq 'oepruporuoud eql Jo -oprlx lujureljrllnu ^0uerEddE eql ur uonrsod ES aql soroedsnou?a luesajdal,{lq?qord leql slueur 'I 'S 8lC ur pepnlour sr s/lryiousopolx -ele ujojrurpod pue IxroJlrueJ pal?f [1u0p Jo uorlcrulsuojej aaueuiselui uv [eêl luej 'ebjeljo/qeu"a ur luoc slcol ueld -gru8rs ^?rusqels? l sdnors lueunoej eqljo ^leler3srp " -drssrssrl l upuelseqc-ajd urorj suoucelloj slueuoduroj reqlo r{lrnd dnoj8 lou op stuo(iielo 'l(frq eqt roj (eeprtlapreqqlh lou) erpj aseql teql 1csJ sql alldsep 'elu e?prurporuorjd pue JspJo eql roj eprurpoluoud ot IBcrSoI ^le^n?iej,{oueunuo suaas siqj pos?q ir\ou ar? suj"u oqt tursn,{q osec eql eq tq8ru sql l?ql szneds snqnusop0lx gcrq^\ uo sdnojb luounc peledrcdu? eêq I pu? 'esues luaueleqfur? ui -er oql ol suo4rppe lsuuelod se (1861) p?orxel{ uorlducsep [zr,l.e Durporuoud Jo serjeds Jeqlo 1286I) Ilrew pue r(qtuny{ urorj slueuole r{lgjo seqflels stueuele d pue 'qd 'I{ 'cs'qs,tq Uol ot po/$olloj 'lq8u uo sluaurolo ps (oeplurporuoud) z{ttg pue snqrdusotddy ol peu8rsse sorceds Jo lecrd,{t sosnlaedal pue sluouela '0 'S'3!d ff-m VJNOCONOJ AHJ

90 THE MAJOR CONODONT GROUPS immediate ancestry of Kladognathus, bnt species ofthe genus appear to have been members rate elements as occupants of the Pb position time regarded such "enantiognathiform" digy- of nearshore, shallow-water associations that in the skeletal apparatus of Ellisonia and, in also included species of Cavusgnathus. With those ofa succession ofspecies of multielement only a few exceptions, this ecologic preference Xaniognat hus and. Cypridodella. Hence, occurrence in the Pb position of ttle ldioprioniod.us is also characteristic of the Prioniodinida and may help confirm the assignment. apparatus of elements reminiscent of these Idioprioniodus (Fig. 5.31) was diagnosed in a later Paleozoic and Triassic specimens proyides strong support for the origin of Ellisonia multielement sense by Merrill and Merrill (1974), and their reconstruction has been confirmed in a number of subsequent studies. Ele- closely related genus. And, because I regard and. Xaniognathus in ldiopioniodus or a ments of the skeletal apparatus ofthe two species known are large, mostly hyaline, and nent of the famity Gondolellidae and E1lr'sozla Xaniognathus as the most generalized compo- include distinctive digyrate pectiniform elements in both the P positions; dolabrate M eletural similarity of Pb elements plays an impor- as the central radical ofthe Ellisoniidae, strucments (including the tlpe form species of Neaprioniodus); and a symmetry-transition series those lineages. tant role in my ideas concerning the origin of offour ramiform elements with large cusps and very short, sparsely denticulated processes. Especially Family significant in Bactrcgnathidae this array Lindstrdm, ofskelelal components is the diglrate element that I assign to In the Treatise Atstin and Rhodes assernbled 1970 the Pb position. Lateral processes of this element tend to be quite short (although they may gnathus, Doliognathus, Dollymae, Eotaphrus, the distinctive Mississippian genera Bactro- be longer than those of other elements of the Scaliognathus, and Staurognathus in a family Idioprioniodus apparatus), and they project Bactrognathidae. However, they were unable to downwardly and anteriorly so as to form a distinct V with the inflated, but undenticulated, related stock to any ofthe other groups ofcon- suggest the relationship ofthis obviously inter- base of the cusp. A closely similar type of digyrate element is common in collections of In 1985 Kad Chauff demonstrated (to my odonts described in the Treatise. Permian and Triassic conodonts and was refened by Clark and Ethington (1962) to rhe liognathus, and, Staurogna.thus, the central ele- satisfaction, at least) that Bactrognathus, Do- form genus Enantiognathus. I have for some ments ofthe Bactrognathidae, have skeletal ap- Fig Elements and apparatuses typical of species assigled to Kladogaathus and ldtopioniodus (pironiodinidae). Sa elements on right, followed ro left by Sb, Sc, M, and P (or pb and pa) eremenrs.

91 -lels gq 01 eurec sluauele uljojlurpeo peuroj -l?ld eseql'sejnpruls 4"l^3lp rujojrsuotxe ur u uo rreql elrdsep 't?ql snolmuoj,(lojrluo eq lou,{"ur 1I suonrsod d oqljo euo ui slueluele Jo uortecgdorr iq (ee S '?rc) snqtdu8stdqlug snounc eql r]i,{lq?qord pue 'snqlousondts 'mqpusouo1 ',snqlou3ottzd{ ui esor slueur -ele peurojl?ld eqt 'sdnore luopouoc roferu reqlo ui sv 'sluopouoo Jo dnoj8 Jof?ul srql SuDIelu uuojleld l" ldurar" tsju aql lua$rdej ^q '.4JlcalJoJ rueql petejfuolur eêq IJr 'asnec êql -eq EPrurPoruoud eqljo uorssncsrp? ur ecu?f,i -JruErs puoqrpp?jo arz eeprqleueorlceg eqa 'Icols E qcns luesejder leur (snpotuoudolpl Jo seneds euos lseel le pue) eepqleuso4c?g oqj 'slellqeq ojoqs.go purrou ejou pep?aul 'ÛJuq Jr '^llnjsseccns t?qt ${iols peu^reds oêq ol r[ees sedolorq esorll Jo suozluep '^ eclposl -dg 'slueuruorhue relea-^{olpqs,fte^ ul{[i?ci -qd"r8meorq peordsepl\l lsou pue -xel esr9^rp lsorrj uoeq e^?q ol Ixees ^[?crurouo sluopouoc eprurporuoud 'u"rcrôpjo f,lj?g eqt u! uoll -docur Jrern Jo eunl eql ruo{ auodcerlp SuoJî eq1 ur SuDIool uegq o^?q lou lq8ruj JneqJ Jr Jepuo^r I 'uorlelerfuelur elq?uos"er 3 eq,{bur slqr oih,^n 'pjooer u"rddrsslssltral u,{\ou)l eql ur potuesejdej lou sngl $ pu? ejoqs.go rbj peîj "F,41 strolotdtl) ot pel?lej sd"qred stuopo -uoojo dnort ui peluur8uo err,eq lq8rur snxeld oql " l?ql pepnlcuoc oq,t\ 'Jn?qJ,{q pegrluepr lou eje,1d. eeprql?u8o4ceg aql Jo slors:ej8xn srulpu oltojs-snqldusonoo 5ql sezrjolsa?q; lueurele qd eqt Jo uob"cupour 3l1eue3ol,4qd reinurs 'dsnj Jql Jo sopts louelsod PUE lou -alus eq1 qloq uo doleôp sassocord ellluuoj -teld 'p"orq '(snudtoq)uo'g pue sud^djxa 'g) dnor8 auo ur 'pue pjealno,(llsurlsrp arou spueq sarcods Jstunoil ui lueurelo qd aqljo ssec -ord l"jetel uoqs aqr 'Z 9 '8rd ur pel"crpul sv 'sessecord rouetsod pue rouelue aluop?lq q1i^\ lueluelo rrrrojrullced elsuluuec sb pequcsep " eq tqfiur ernlcru$ oql 'asv'{reqto:.{[31srp pre,4a -ur se^jnc sse3ojd EuoI eql pu pj?^\lno,(ltqaqs ^[qbiis spueq ssecojd lejetel yoqs eql (snldw -n4 'g) snqtousottcr8, Jo salf,eds u^rou)[-1s0plo eqt Jo snlej?dd? eqt ui'sesnptedde o apjdq -qth pue Dulpoluol.rd ur uonlsod elq?jeduoc e peuerssu slueurelg ol snosol?ue osp el? qcrq/i\ 'slueuele s1er,{ttp uuo;rsuolxo perdnf, -co eje snuet qcea ur sercedsjo sosnlej?dd? ^q 3ql ur suolrsod d rern pu? 'Dutpotuoud pue o ap -nqqth sprurporuoud eql Jo sebads Jo sosnl -?J?dd? eqt ur osoql 01 rel u$ si leql saues I J pu (S Jo) uodrsue4-tuleuu^s ^lasols eql ui sluourelo urojrrrr?j Jo,{eJ" u? eêq (Zt S 'Brg,) snqtousolloe pu? (z s Bl.c) snqpuso'tl -rr r qloqjo sartods lsql pe^{oqsjnbqj elmb suleas repro sql qlr^\ uo4?rcossp ^le)iii leql sejnlpal eprurpououd os qll.$ sesnlej"d ûelu 1S861)JnEqJ uorj u,rerpor ere s$qto :leurauo setn?rj sfilltdusstoqwg 'elge -qsrn8ur$rpur oje leqt sluourelo I I pue S e^?q sebads snqtou3ornds pve s l tou3olloe '.v^\oul..ljn sn lou3stoqtug Jo snleredde ololaluro] eeprqleuborc g eql Jo eroue8 ot peusrsse sercods Jo sosnlapdde pue slujuola 'Zf'S 'Eld s n4 ) a uo o t n e ) S. s nq teu 6040 O vl-noconoj lhl t8

92 THE MAJOR CONODONT GROUPS 85 liplanate and thus similar in their general organization to those developed at various times in unrelated prioniodontide and ozarkodinide stocks. tina(fie 5.33),ktown thus far only from a distinctive Pb element from the I-eonardian Hess Limestone of Texas. Later Permian collections, described in detail by Wardlaw and Collinson (1986) and Croft (1978), include the complete Family Ellisoniidae Clark, 1972 The first representatives ofthe Ellisoniidae, interpreted by von Bitter and Merrill (1983) as two species of Ellisonia, appeared in the Atokan array of elements, which indicates th^t Sweelin a had a seximembrate apparatus like that of Ellisoniabuthad, an element in the Pb position that is reminiscent oflhe triradiate extensiform digyrate element of Ordovician Erraticodon, (Pennsylvanian). The youngest species the earliest prioniodinide known. That element known are of Late Triassic (mid-carnian) age, and the type-species (-E lrlajsicd) is Early Triassic. In architecture of their skeletal apparatuses, species of Ellisonia (Fig. 5.33) are similar to species of ldioprioniodus, from which has one long and one rather short lateral process and a stubby posterior process that bears only one or two denticles. Species of Merrillina (Fig. 5.33), another Permian ellisoniid, developed skeletal apparatuses that were closely similar in their confor- they almost certainly developed. The apparatus is a sexi- or septimembrate complex, with morphologically conservative alate, digyrate, and bipennate ramiform elements in the S and M positions, an extensiform digyrate element mation to thqse of Sweetina speciesbut had extensiform digyrate Pb elements that lack a postenor process. In successiyely younger Permian populations, the short lateral process in the Pa position and, in the Pb position, of Pb components becomes even shorter, and another digyrate element, with processes reflected in the youngest Permian collections I have sharply downward and anteriorly. I have earlier commented on the significance of seen, the short process is largely vestigial. Species of both Sweetina ard, Merrillma were eyr these "enantiognathiform" digyrate elements dently restricted to the Permian and were apparently in establishing relationships within the best adapted to very shallow, agttated, Prioniodinida. Obviously only minor morphologic ditrerences separate the apparat.uses of Ellisonia species from those ofpartly contemporaneous species probably hypersaline water. Commonly, their large elements are the dominant (or only) components of collections in which they occur; however, those elements also tend to be frag- of Idioprionioda.r. Such features include mentary, so reconstruction ofapparatuses is dif- the tendency for processes of Ellisonia elements ficult and only a few species are known in to be longer and more profusely denficult ticulated than those of Idioprioniodus and. for detail. In the Early Triassic (Scythian) E/llsozia was the attachment surfaces of E/ftsonra elements joined (or replaced) in shallow-water environments by species of Furnishius, Hadrodontina, to be composed of small basal pits bordered by prominent zones of recessive basal margin. In and Pachycladina (all illustrated in Fig. 5.33), some IdioprionioduJ elements the attachment which formed seximembrate apparatuses surface exhibits features similar to those just whose component elements are distinguished described, but in none that I have seen are pits so small or recessive-margin zones so broad and conspicuous. It might also be noted that by wide zones of recessive basal margin and whose alate Sa elements lack a posterior process. Pa elements are extensiform digyrate the M element in apparatuses of ldiop rioniodus structures in apparatuses of species of both species is a distinctive dolabrate structure, Furnishius and Hadrodontina, blot extensiform whereas the one in Ellisonia apparatses is bipennate and readily confused (by me, among ticles on the anterior face. In Pb elements of Pb elements develop an additional row ofden- others) with elements common in Sb positions Hadrodontina the supplemental row joins the in the apparatuses ofother species. main denticle row at both ends. In comparable Early in the Permian a species of Ellisonia elements of Furrrishius the supplemental row was probably the ancestor ofa species of Swee- joins at only one end and additional denticles

93 a crsssuj Je^\o'I 3rI1 ruo{ ote sffe.{ ep?trl I suorlco oc ur peluosojdoj,{duepunqs û"iu s 'DJlss,ut g 'oruoslllg Jo sarceds-ed^l oql 'lueurele d reqlra ur sel3rluepjo s/{oj,fuelusrualddns s{c?l 7l lnq'duuuopotpdh pue snfi{srulntr Jo szrxeds porujoj seuo oqljo uorsjo^ euallxe ue aq ol ^q sj"edd? l"ql snlu?ddb ue petl DurpDlJr(tpDd Jo sarseds u^lou)l eqj ejc4uep ureur aql pue aor Îuo ^\oj l?ql uoe,raloq sceds aql ur doleêp,{?ur l qr orecrpur saor r"luozuoq oqr ur sdec sruauere ed pue '!qd'.n"ri:.t lltjl'fiili$it?t3;fi",uxtit;""j lueruelo es oql sesntbredde IJe ui oepnuosrlla oq1 Jo lejldiq elgse8 ot peutrsse serjods Jo sesuejeddv ' f'9 '3!d auulutan VJNOCONOJ:lHl 98

94 THE MAJOR CONODONT GROUPS I Fig Iareral and underside views of a Pa element of G ladigo ndo I el la (Ellisoniidae). Thaynes Formation of Utah, and one ofthose collections also contains a number of platformed pectiniform elements that are gradational in morphology with the unplatformed Pa elements of.e. triassica, and. are also identical in form with the elements on which Huckriede (1958) based Polygnathus tethydis, the typespecies of Gladigondolella Mnller (1962) (Fig. 5.34). Paull (1983) noted the same features in her large Triassic collections and described the Lower Triassic specimens as representatives of G. meeki. A distinctiye feature of gladigondolellid Pa elements is the fact thal narrow platform brims completely surround both anterior and posterior processes, hence the elements are formally anguliplanate. Comparable elements of the gondolellids, which also occur in Triassic rocks, are segminiplanate and thus are readily separated from those of Gladigondolella Family Gondolellidae Lin^ftam, 1970 The late Paleozoic and Triassic conodonts assembled by Treatise afihorc in the families Gondolellidae and Xaniognathidae form an obviously interrelated stock that is best considered as a single family. The name Gondolellidae, coined by Lindstriim in 1970, is the oldest one available for the combined family. Gondolellid conodonts formed a basically seximembrate skeletal apparatus distinguished primarily by angulate Pa elements, breviform digyrate Pb and M elements (the former "enantiognathiform"), and a slrnmetry-transition series that includes alate Sa elements with a long. profusely denticulated posrerior process; extensiform digyrate Sb elements; and bipennate Sc elements, commonly with long, delicate anterior and posterior processes. In the apparatuses of generalized gondolellids, the postenor process of Pa elements tends to be short and fragile. whereas the anterior process is stout and is commonly surrounded at midheight by a well-developed midlateral rib. In specialized gondolellids, however, the posterior process of Pa elements disappears and the segminate structures that result may also develop platform segments that are confined to the sides or joined around the posterior end ofthe cusp to form a continuous brim. For many years it has been my contention that when gondolellid conodonts developed segminate or segminiplanatelements in the Pa position they also ceased mineralization ofelements in other positions in the apparatus. According to this view, the Gondolellidae would include species with both unimembrate and seximembrate apparatuses. This interpretation ofgondolellid organization is based on my observation that collections made from rocks within the range of the Gondolellidae commonly conlain either the segminate Pa elements or an assortment of ramiform and pectiniform elements from which it is possible to assemble a complete seximembrate apparatus. Only rarely do collections include a balanced assortment of platformed and ramiform elements. For a number of gondolellid species, particularly Triassic ones referred to Neospathodus, Platyvillosus, Epigondolella, Mosherella, and Misikella (see Fig. 5.35), I believe my original idea holds. That is, those species formed unimembrate apparatuses-or at least only those elements in the Pa positions were mineralized. However, evidence from a couple ofnatural assemblages [one almost certainly coprolitic (Rieber, 1980)l indicates that other gondolellid species with segminate or segminiplanate Pa elements may have had complete seximembrate apparatuses. Fot example, Pseudofurnishias (Fig. 5.35) and at least some species of Gar?- dolella (Fig. 5.35) and, Neogondolella (Fig. 5.35) appear to have had apparatuses composed of segminiplanat elements in Pa positions and ramiform elements like those tvoical of Xan-

95 'suodrsoo s pu? w ur slueurel ezrl?jeuru ol ejnii4? Jo snl r?dd? erll Jo uolpnpar alelduroc lsorup ^q,{q raqlre perusdruocc? ueeq e^?q 01 suree slueru -el3?d eleueldruruses Jo eleurureos Jo luaiu -doleêp'sraqlo ui 'uoursod?d eql ur luauolo elqntu? e^q"^jesuoc ojorrr eql roj luelu -alo(oteu?ldrurur8es ro) el?ulrueos e Jo uoqnl -Dsqns,{Iuo pogrpour s"/a snteffdde oql serc -eds pez{ rceds ^q ejoru esoqljo auros ui eiub ol eurl rrro{ pedoleêp sluorrjelo?d ol?uqdrunx -8es Jo el?urursos q1l4r srruoj pezl"r3eds ejoru qcrq^l uro{ e prtlelopuoc eql Jo {cols-urels e^l]'e^jesuoc 'EurSuet-8uol erll dn epeut o apop -udt) pue snqpusotuox Jo saroeds l?qt puel -uoc I 'peelsul'old(ilrs os 1ou,{lJ?olt sr rellerrr eql'd1appuosoan ro D appuog Jo serceds JO SesnlBJ?dd eql JO SlueuOdrXOC rrjjojrruej i]:.relj{r ere Dlppopttd{J ro srulpusoludx tueuj -ola4lnru ol pouerss?.{lsnorêrd slueurelo [? leqt (Allumer euop eêq sjoqln? euos sp) lse8 -tns ol upolu lou op I ejuepl,{e srgl 8ur1rJ ui 'suorlrsoo s pu?win(sts e c) o apopttdo ro srull2u8o 'Dflapopudrb pue snlltdusorudx lo sosnleledde oql ur esoql uio{ olqeqsrnsudsrpu slueuolo uuojruej perdncco oro,r{ suoneod ed-uou qcrqr[ ui sesnle.iedcl ol JqureuqFrrr p"q oêq rueqljo sruos dol oql le elour8 ^q, eql rcj peleisnii ele sluouolo 9d slueruala ed pue 'qd 'I I 'cs <qs,{q uel ^gru oql pr ^lol po^rolloj rlqsp oql uo ere s1jtewel. es sfilltou3oluox pue onapopltdts ^luo Jo sesnlereddd oql ul eep{lelopuoc aql ol pou8rss reuo8jo le rd^l sarjodsjo sosnleddde pue sfueursla 'St'S'Eld VJNOCONOJ:IHJ

96 THE MAJOR CONODONT GROUPS Origin of the Gondolellidae is obscure. Apparatuses of Xaniognathus species, the most liest Triassic steta. dle Ordovician age; the youngest are from ear- generalized gondolellids, are very close in Except for a few genera transferred from the structure to those characteristic of Ellisonia Prioniodontida, my concept of the Ozarkodinida is essentially that of the superfamily Po- species, and it is likely that both stocks appeared at about the same time in Atokan lygnathacea ir the Treatise classification. In (Pennsylvanian) seas. I have already commented on the likelihood that Ellisonia devel- Ozarkodinida into 12 families. Treatise au- Fig (and in Appendix A) I divide the oped from the prioniodlnid ldiognathodus, and, thors recognized only 6. the gondolellids may have had a similar ancestry. This suggestion receiyes some support of Fig. 5.36, the Spathognathodontidae, in- The cenlral family in the taxonomic scheme from the fact that Pennsylvanian Xaniognathus cludes an assortment of ozarkodinide genera arld Gondolella characterize a relatiyely deepwater biofacies that overlaps one in which ldi- could be made much less so by including Eog- that is superficially quite heterogeneous. It oprioniodus is also very cornmon. Ellisonia nathodus with the Polygnarhidae; by erecting and its kin, of course, are especially common separate families for the compact but distinctive stocks now represenled, by Ancyrodella, by in rocks that represent very shallow-water environments. Amydrotaxis ar.d Ancyrodelloid.es, and by Polygnathoideq and, by further revision of Bispa- My views on relationships between major genera of the Gondolellidae are summarized thodus and, reassrgnment of the resulting parts. diagrammatically in Fig. 5.28, and apparatusesin effect, that lype of raxonomic trimming was characteristic of typical gondolellid species are begun in the Treatiseby crealing separate famllies for Kockelella and, Ancoradella and. for illustrated in Fig is my suspicion, however, that formation of segminate (or segminiplanate) elements in Pa positions (and I have resisted the temptation to erect the Pterospathodus and. its kirr. commonly concurtent apparatus reduction) several new genera and families just suggested happened repeatedly in the history ofthe Gondolellidae, perhaps as an expression ofiterative taken by someone far more familiar than I with on the grounds that such a task is best under- adaptation by successive members of the Xaniognathus-Cypridodella stock to similar envi- have not hesitated to refer Alternognathus and. all the species involved. On the other hand, I ronmental conditions. If that were the pattern, Siphonodel la to the famity Elictognathidae, because species ofboth are well set offfrom those the taxonomy summarized in Fig is vastly oversimplified, ofcourse, although it is difrcult retained in the Spathognathodontidae and authors who have contributed most to unraveling to imagine a defensible alternative. the evolutionary history of the two generic stocks agree that. despite resemblance in some morphologic particulars, this 5.9 The Ozarkodinida Dzik, 1976 stock originated in the Spathognathodontidae independently of The basic skeletal apparatus of ozarkodinide the Polygnathidae and at a much later time in conodonts is sexi- to septimembrate, with P positions occupied by carminate and angulate ever, be too happy about my choice of the Devonian. Those authors may not, how- pectiniform elements or their platformed analogues. In ozarkodinide conodonts with fully I have also divided the Idiognathodontidae Elictognathidae. developed appantuses, elements in S and M of lhe Treatise classification into Gnathodontidae and Idiognarhodontidae, because such a positions are commonly generalized in morphology and, from published descriptions at division recognizes a natural and highly significant interval in the mid-carboniferous history least, are much the same from one species to the next. Pa elements, on the other hand, r/ary of both groups. The Palmatolepidae is newly greatly and have provided the principal means established for a phyletic lineage previously of taxonomic differentiation. The oldest ozarkodinide conodonts are from rocks oflate Mid- plognathodus-sweetognathus linea$e is submerged in the Polygnathidae, and the Di- re-

97 erlj eprurpou?zo egl Jo {solsl,oor se snlels rreql slgeq s3 'dnoje aultuer-euol pus 'cns?ld 'olq"ue^ e aj? sluopouoc prluopoqteutoqted 'ssoh adpiuopoqldusoqrdds qtwdl I'6'9 'uerddrssrssrt{ eql ur eurrleluos sj^rleler slr ro snpoqpdstq vtojj peûep i(puepuedopul s" \ qcq,{r 'eeprql?u -8olee,ns ^lur?j eprurpo{rezo oql se Peleerl pue eepnuopoql?uslqcuv eql uro{ peôut 'snor,rqo ore suoqerôrqqb.roqlo :eeplqleu?onol I = XVCI,nl :stt{r"u3lqodopflasd = sd '.snpollluusol -ord = u8d :sn pu8lqdoxs = xs:ou! aultopuod = 'puod epurpolezo eqljo eloue8 pue sorllur J '9 S 't!tr t vo I I N ooo H I v N 90H.1 v ds fvot11tx30x I : 6 :lvotd:l101vw1vd o ;: I fvothjvn00j2tl:l o$d =ê 9< I F r=f a+!i F! : 5 5 a{ lvot.n U -G l-- rl 3 I! o : B F d 1\ ]VOIHIVN,OJ ] ]MS L. - tvotht vntsnav3 V B t t YJNOCONOS AHI 06

98 THE MAJOR CONODONT GROUPS 9l sexi- or septimembrate skeletal apparatus is basically simple, with bladelike carminate and species that have been included in Aphelogna- of early spathognathodontid is represented by angulate pectiniform elements in both P posi thus and. ln Plectodina. The type-species of tions; a dolabrate or bipennate M element; and Plectodina,however, has a pastinate and not an an undistinguished symmetry-transition series angulate or carminate pectiniform element in that includes alate, diglrate, and bipennate the Pa position and is thus a typical prioniodontide. The type-species of Aphelognathus, elements in the Sa, Sb, and Sc positions, respectively. and all other speces ofthe genus except Middle The alate Sa elements of most of the earliest spathognathodontids (e.9., "Plectodina," has a pair of typically spathognathodontid P Ordovician A. kimmswickensis and. A. gigas, Aphelognathus) lack a well-developed posterior elements. Thus, in this volume I will assign process, and breviform digyrate elements occupy the Sb position. A few, however, have Sa and P. bullhillensis to "Plectodina," for their P species such as Pleclodina tenuis, P. florida, elements with long, profusely denticulated posterior processes and at least one species had deform elements, not the pastinate and angulale elements are angulate and carminate pectiniveloped extensiform digyrate Sb elements by structures typical of Plectodina s. s. Similarly, early in Cincinnatian (I-ate Ordovician) time. Aphelognathus gigas and A. kimmswickensis The Spathognathodontidae are recorded first will have to be included for now in "Aphelognathus," in recognition of the prioniodontide near the base of the Nonh American upper Mohawkian (i.e., the Rocklandian) by conodonts with several distinctive types of appa- " Plectodina" (Fig. 5.37) evolved from P/ec- structure oftheir Pa elements. ratus. One, typified by the specimens Bergstriim and I (1966) referred to "Bryantodina" documented in great detail in sequential colleclodina, it the late Middle Ordovician, an event abrupta (bat probably referable now to Yaoxianognathus abruprrs), has a simple carminate Cincinnati Region. Aphelognathus (Fig. 5.31), tions from the L xington Limestone of the Pa element, an angulate Pb element, a dolabrate (or"cyrtoniodontiform") M element, and dovician, came to be even more widespread which was also common in the late Middle Or- in a symmetry-transition series with a bipennate Sc element, an extensiform digyrate Sb element, and an alate Sa element with a long, denticulated posterior process. Bergstriim and I ( 1966) referred the ramiform assembly to a species we named Plectodina? posterocoslatat I transferred it to "Bryantodina" abrupta in t979. A second type ofearly spathognathodontid is represented by the Lexington Limestone specimens from Kentucky and Ohio that Bergstrtim and I (1966) made the types of Bryantodina2 stauferi. '[he apparatus of B-? stauferi includes only slightly arched, angulate Pa elements, conspicuously arched Pb elements, and an alate Sa element that lacks a denticulated posterior process. Other components of the skeletal apparatus of B.? stauferi haye yel to be identified. 8.2 stauferi ranges into only the early part of the Late Ordovician (Cincinnatian), but a species with morphologically similar P elements, "Ctmognathus" pseudofissilis of Lindstrdm (1959), may have continued this line into even younger parts ofthe Ordovician. The third and by far the most common type marginal parts ofthe lowlatitude seas that covered North America in the Late Ordovician. The youngesl "Pleclodind" species are evidently the Earty Silurian "P." hassi and "P." oldhamensis, which have been referred in most studies to Ozarkndina but evidently represent "Plectodina," because their skeletal apparatuses seem to haye included breviform digyrate (or "zygognathiform") Sb elements, instead of the extensiform digyrate (or "plectospathodontiform") Sb elements typical of Ozarkodina. The three types of spathognathodontid conodonts described thus far from Ordovician rocks differ from one another in several particulars and probably represent diferent lines of development. That there were also other lines is indicated by discovery a few years ago ofdistinctive but as yet undescribed forms with extensiform digyrate Sb elements in early Late Ordovician rocks in both Kentucky and Oklahoma and by the sporadic occurrence in late Ordovician strata in Europe of more or less typical representatives of Ozarkodina (e.g., Ozarkodina n. sp. of Bergstriim), whose P, M, and Sc elements have been known for more

99 'ssocojd Joue6od Pedo -pêp-]ja^^ e seq oul auuopltdd Jo lerll sear.q^\ 'sserord louonod e sryel DutpolDzot Jo tuotuele "S 5ql l ql olon 'sluorrjele ed pud 'qd 'I^[ 'JS 'qs,{q Uel or perrolloj 'tq8u uo sluoruele S leepnuopoql uto[eds) Du! aul.topuoj pueoulpol.tozoswroluelsoprurpouezolu"uoduraqljol crdxlsolcedsjoses$erealddpu slugtuelx'8 'S'8ld -r,.rd ol uorlrsoo es oql ur slueurela e13l? snour Jo) olefeue 'slusurele?d (,,lujojrluopoqleue -?Ju1 qllr!\ saneds snorgjruoqje3 f,fea,ne3 e pu? ueruoêo JeJeJ sjoqln",(uetr l 'ssocojd -oqt?ds,, ro) eleullruej qlr,r'snt?jedde l le Jou 1a{s elsjqrueurxas 9^4e^Jesuos E eaeq elejls -olsod poleln rluop? $lcel sorcods Dulpouozo ueruoôc pue ueunls ralel ur sjosseccns rl9q1 Jo tualllele es et?i? eql '.{le^qcadser'suoq pu? sruroj eseql ueunfs eqljo es?q 0rl13ôq? -rsod cs pu" 'qs ts eqr ur slueulele (,,lujojrl -lapoepuq,, Jo) ol?uuedrq pu '(,,urjojrluopoql 'Brg,) outpoqtozg 10 se,{rlelueserdej ul?uej -edsopeld,, ro) el?jrgrp uuojrsuolxe 'elple Jo 'pequcsep seues uoursu?jl E pu 'sluat'uele I I olbuuodrq aq ol te,{ eêq stuourela qs pue?s osoq,{\ ro elerqelop'sluolliola qd (..uuoj[urpo{j3zo,, fiq(zl6l 'urorls8rag pu? lee/'\s) ap?cep? ueql 'sluaul0io ed pue 'qd 'hi 'cs'.qs,(q Uol ol po^rolloj 'lq8u uo stuotllolo S'seprurpo1Jezo uercrôpro orll Jo.4suetcEEqt pue peejdsophr Noru oql,.'oulpopah,, p.de snqtousoplldv lo s.oeds Jo I?Jral^l sesnlereddp pue stueuola '/f'9 't!tr VJNOCONOJ AHJ z6

100 dorinellinamiller and Miiller, 1957 (Fig. 5.38), which Uyeno (in Norris, Uyeno, and McCabe, 1982) has shown to be closely similar in apparatus construction to Mehlina Youngquist, THE MAJOR CONODONT GROUPS 91 (Fig , 5.39C, and 5.39D); in the Early Devonian of Ozarkodina seffi (Fig. 5.39G), the shortliyed species from which Lane and Ormiston (1979) derive both Eognathodus (Fig. 19as (Fig. s.a0). 5.39H) and Polygnathus (Fig. 5.39I) of the Unfortunately, the complete apparatuses of Polygnathidae; and in the late Middle Devonian, when Ozarkodina semialternans (Wirth) only a handful of spathognathodontid species have been worked out, so it is not always possible to decide if Ozarkodina or Mehlina or the Palmatolepidae. Evidently, as Branson and spawned " Polygnathus" latilossdtus Wirlh and. Pandorinellina is the appropriate generic assignment for many Devonian and early Car- basal cavity of spathognathodontid Pa le- Meht noted long ago, the notoriously unstable boniferous forms or which generic stock is ments expanded and migrated toward the posterior end for the last time in the early Missis- involved at various evolutionary junctures. Sandberg and Ziegler (1979) have somewhat sippian. Species produced in that episode and simplified the problem by restricting Pandoinellina Io those spathognathodontids whose Pa ilies Anchignathodontidae, Sweetognathidae, their successors are assembled here in the fam- elements are morphologically close to those of Cavusgnathidae, and Mestognathidae. P. inslla (Stautrer), the type-species. Carminate In a second type ofdevelopment, sides ofpa Pa elements ofthe latter have a high finlike anterior process that exhibits a slight rightlateral form lobulate lappets on one or bolh sides elements expanded at or near midlength to offset at itsjunction with the posterior process. above the central part of the basal cayity. Not which is built of much shorter denticles. uncommonly, the upper sides of these lateral Although there are certainly well-marked differences in other elements of the spathognath- came to support one to seyeral nodelike denti- extensions grew longer phylogenetically and odontid apparatus, dividing the family into cles, commonly arranged in single rows. Pa elements modified in this way characteriz early subordinate taxonomic groups and tracing developmental history has been accomplished stages of Pterospathodus (Fig. 5.39F) in the primarily through studies of Pa elements. This early Silurian; Amydrotaxis and. Ancyrodelstructure exhibits great plasticity, as I attempt Ioides (Fig. 5.39E, 5.39P, and 5.39Q) in the to show diagammatically in Fig early Devonian; and Ancyrodella (Fig. 5.39K, In typical representatives of Ozarkodinq and 5.39L) much later in the Devonian. Each (Fig '), the basal cavity of Pa elements is oflhese modifrcation episodes represents a geologically short excursion by spathognathodon- a groovelike indentation along the lower margin that expands laterally to form a cuplike tid ozarkodinides into the never-never land of structure at about midlength of the element and tapers toward the process extremities. From time to time in the long history of the platform building in the Pa position. Although Trealrse aulhors identified the platform-building excursion that I ed to Ptercspathodus and its Ozarkodina-Mehlina-Pandorinellina plexus, allies as a stock worthy of recognition at the however, and possibly also in the still-obscure family level, the others were not so identified Early Silurian history of "Plectodina" and species derived frorn Aphelognathrrs, the laterally expanded portion of the basal cavity came to occupy a longer and longer segment of the underside of the posterior process. Elements like this (e.g., Fig G and 5.39H) have a ladleor scooplike appearance, with the unmodified anterior process serving as handle and the posteriorly widened basal cavity as scoop. An exercise in basal-cavity modification like this apparently preceded development in the early and I will not tamper with this situation. In species of Silurian Polygnathoides and mid-devonian Torlodus, Pa elements were modified in yet a third way. That is, riblike thickenings of the sides of basically carminate spathognathodontid elements developed into smooth-surfaced brim- or shelflike platforms along a segment of the element, commonly the posterior process (e.g., Totlodus, Figs. 5.39J and 5.41), or around the entire element. The latter type ofdeyelopment characterizes the bizarre Silurian Palygnathoides (Ftg. 5.40), Silurian of Kockelella and the Kockelellidae which

101 Jo s,{roj lall?jedqns 'elqnopjo lueudolaêp I?n -grpou lueurale-ed 3o ed,$ qgnoj e '^lleurc -p ur rejrp tnq ( D6E 9'AIJ.) *as'o ro (v6 'S 'seqrlr?j A{ou Jo sed^l epplu Suroq 'eij) oidulput outpo4ldzo leqlre Jo osoql Jo peetsul aeprluopoqlzueoql?ds aql ur paul?l ol J?lrurs suollsjneguo3,{1lêc-l?s?q e/r?q -er ele qloq ecueq:aleqa,{u" o}.,3ull ul llr,, sarceds eserll Jo slueuele?d (It'g pue 'O6E S eql uo ueeq eêq ol sjeedde sapnqldu8tlod 'N6 g 'I 16g S 'sbr{) se^rl?auep snojolrrnu )ou snpouoj JJqlIeu 'sojnljnrs Jo sod^l J^ll sr pue snpolltddslar Jo sor3eds snolejluoq -cuuslp.qqtq splo uod?culpour luelllolo-ed -rpc pu ueruoê(i relel pus (It'S pu" H6E S 3o adfl srql qsnoqtlv snlh?dde plluopoqleuso 'serj) snpolltousog uetuoê(i,tfpg Jo serj -ql?ds 'e^nrulud paapur ',{l"uipjo,fie^ e^?q " -eds ur sosnl"jedde plal3{s sezuelcej"qt uoqec ot peurrrralep s?q ( 86I) uossddal ^llu$er 'sap o apor lbu V ld\' ( d)'.snp 4\todslg p.cte^pe (O\ :sn1.flou3ots.ttpoqy (N) :su.uoj e^qe^losuoj '.t po FDdslg \ln)'eae:utl D apojtjul (1'J'OIl sipoybji)'.nqiou&i1o41i1:snpoqbdbx (u):outpo4rdz)(d\:srlpotllodsoqtd (l)'.s!m@lp!(u1l' (3):spl olelco{ sn6r:e"1ftj113; '1g1: i"tpdinio 6^ne"lxuoJ 1yf siaeeuq ruengrp Jo lecrddt slueurolo ruroj ol pocnpord erer$ aeplruopoireit-ioqieis eq1 uisrueusiet43osjpriiqrqcrq,riursre,risioue,'r.eq1e1e4sn11o1ure- elc'6 's'8ttr VJNOCONOS IIHJ t6

102 denticles on the upper surface. One denticle row, the primary one, extends from one end of the element to the other. At the anterior end it forms a single-rowed "blade," which is bordered on either its right or left side by the shorter secondary row. Numerous modifications ofthis basic pattern lead to ozarkodinide groups identified here as the farnilies Gnathodontidae and Cavusgnathidae. History of the Spathognathodontidae was marked by several intervals of accelerated innovation that were expressed primarily in modifications of Pa elements along lines just discussed. In the late Llandovery (Silurian), for example, migration ofthe expanded part of the basal cavity toward the posterior end initiated morphology that came to be typical of Pa elements in the apparatuses of species of Kocke- Iella and, the Kockelellidae (Fig. 5.39B, 5.39C, and 5.39D). At about the same time, lateral expansion ofthe central portion ofthe basal cavity, eventually to form denticulated platform elements, established the pattern characteristic of Pa elements in apparatuses of species of THE MAJOR CONODONT GROUPS Pterospalhodus (Fig. 5.39F) and other members of the short-lived Pterospathodontidae. The Early Devonian included two closely spaced episodes of innovation in the spathognathodontid stock. In the first, shortly after the beginning of the Devonian, Pandorinellina (Fig. 5.38) separated from contemporary Ozarkodina populations (Fig. 5.38) by developing Sa elements with a denticulated posterior process and distinctively finned Pa elements. At about the same time, iniiation of Amydrotaxis (Fig. 5.40) and Ancyrodelloides (Fig. 5.40) was heralded by rapid, lobulate expansion of the central parts ofbasal cavities in Pa elements in segments of widespread populations of Oz4rkodina remscheidezsrj. In the second Early Devonian episode, posterior widening ofthe basal cavity in Pa elements ofsom what later populations ofthe same Ozarkodina stock led to O. selrt (Fie. 5.39G) then, promptly, to early representatives of Eognathodus, with doublerowed Pa elements (Figs. 5.39H and 5.41), and Polygnathus, with triple-rowed Pa elements (Fig. 5.39I). Although Klapper and Johnson Fig Elements and appamtuses of sp cies typical of genera of the Spathognathodontidae. The complete aff palatrrses of AmydrcIaxis, Polygnathoides, and Mehlina ate shown, but only the P elements of Ancyrodelloides ite illustrated. The M and S elements ofthe latter are no1 known. Rq 4 Ancy.ode oiclct

103 -uersse I3 urej Jo uousenb eql eq ueql plno^r ueruoê(i elrl luelodulr ornjo uo4?rllul spjo ereql 'qcusjq..snpogl?dslq,, eql Jo selteds JoJ -cal (qloq rn,(lsnoeuerodufetuoa ro) oltul Dull pspeou aq p[no,t\ eueu cuaues raqlouy '.tnp lauhopuod ro luudulauuds DulpolttDzo teqllz oqlodsrg ur pouelej eq pfoc ll{iuo 'sorcodsjo suonslndod ur uo$etgrpou lueuele-?d Jo -ed,{l eqt 'snq$ojrlnurds 8r sepnlcul qcuelq aposrdejeuq e u?iuoêci elppq I lselel eql ui.,sn1?elnce,, eql esn?cog 'seurlluej3,ulp 7e slllq 'eepqteueflod eqt',{iluej -"r.s 8r uro{ padole AeP eaeeu\ snpoql0dsry er41 luejeurp? Jo seqjuerq.,snloarjo '9,, Jo ruels.w se pue oulpotrdzo ujo+ pve.;npolllddslq lueurdolaêp luopuedjpur ue se snqtousilod '8r,, eql leql almpur,{lreolc(tr6l) unsny pu? 'EJoqpues're1fler2 iq pezueuruns serpnls 'sr ^\oqs '9 '9 trj ur'pu? a"plluopoql?usoqteds eqr ur (It's 'Eq) snpoqldusog uelal I 'uoseel leql,$e8ms puoqlpp" annbej plnot\.srtpoqt renel aql nl srulpu8ltlod Jo uoqelp"l Pele -rdsrg'eeprluopoqleu8oqleds e\l Jo Du UqaI,4{ -qur l"ql euo e\l 'adauand snllpusiiod Pue 01 peuerssesj ejz.i,.r. ',snpoqlodslg Jo srujoj uels 'uoq?lndod lellsecu?.{lpesoddts 2rI1 'snldps SurauH-Auol oql eq ol pejeplsuoc,!\ou ej? pub?jo esoql uoo/qeq ASoloqfuotrl ui puoqsu8jt (slueuele es et?i? snou?rul pue) sluaruele Pd sluouele {cel qclq l 'e)ls?lv ruo{ suollcel po^\oj-olsurs eêq qary ',ssuaqoln'g pue slllq "d 1oc Jreql ur spualelu poloddns lou si luoê -rl,s'gjr ue^g'[(t86i){crq3s1nc pue Sreqpues u? qons l?rtrl tno lurod ^q (616I) uorsruuo pu? :(tl6l) uusnv pue 'tueqpues 'reiezrz ''e'el euv-i 'snporltdusog Jo suowfdod,{llee u.io{ suodej a^rleluoron? ur snues eql ui pepnlsur mqwus/qod Jo uoll? uep persotilns (St6l) JJe slueurjlj Ed pe,rol-jlqnop pu? -JlE -urs qloq qlr^\ sorcsds asn"jeq 'Jeê,t\oq'0epl1 -uopoql"utoqteds eql ur (I?'S 'erl) snpo ldd -,r/8r snojejruoqrpj,{f?g-uauoêq ul?loj I 'V xlpuoddv ui Pu? 9 '9 '8IC ui ecrl -J?rd leql,{lolloj I pue 'oeprqleuasnûj eql Jo se^rleluesejdoj relel q1l& pedno$ :.r2 snqwusoptl) puz snqlduso$od ^luourlloj t iqell -tllrs 'o?prqlsusolcllg oql ol?jedes e Jo su?d s" (V xpueddv ui pu?) "{liu?j 9t'S 8IC ur u^\oqs.je D apouoqdls pue sn\wusoud V eauzh 'snorejruoqjb] lsoluej Jql ul ejueuodul crqdejerlejls l?e$ Jo sr tl)rqn.l.'d apouoqds 01 'u?ruoêcl lselq ero ur 'pel 1?q1 eeeoull eql pelewur snqldu Souatlv pluz'eeprl{}"u3oleer\s pu? eeprluopoqleu9 eql Jo Jolsecue eql '(It 9 'a1g) snpoqtddslg ot esu oabb (Of S atd) Dull -LpW snwousdptt) pue snqpusotldd Jo selo -eds snoue^ 'retel lrqe'pue(lts AIu) snqfiu -SlqdoJS Jo sorcads sezrutocet euo qcrq^\,tq suuoj paaoj-alqnop ^ll?e aqljo Jotlaa 8ursnJuoc e or pal (8 'S 'AIJ,) Dul auuopuod Jo tuolsq ueluoô(i el?'i eql ur seeen I?re.\os 1 suon"ln -dod ur stueruelo pdjo suort?cgpou ',(UeuIC 'oeprluopoqleu8oql?ds eql ur osl? 1r spnlcur I 'u?rus"jc eql Jo Pu3 eql l?eu enssr lnoqqrn pe4dxe eêq 01 sreaddp lpql at?a -ur[ cueuesouour 'altuls? ur popnjcur,(fpeor sr esore leql lcols eqt osneceq'pu" (0t S tic) sapolppo.thuv Jo tueurdoleêp ol pel leql euo usruoê( eq1 sifjer eposlda srql ',{llecrsolorldrol ^lleg l lcors (It'S 'Brl) o apor{ruv VjNO(IONOJ AH]

104 THE MAJOR CONODONT GROUPS me']tfor Bispathodus and the new genus. Since spathognathodontid species such as Ozarku the situation with Early Deyonian Eognathodus (Fig. 5.41) seems almost precisely parallel, toward the posterior and also to expand dina abrupta (Aldridge, 1972) began to widen it seems to me that the best solution is to assign conspicuously to the sides, giving rise to carminiscaphate elements with a relatively long, broadly conceived and unrevised Bispathodus [and its obvious later Carboniferous derivative, Rhachistognathus (FE 5.41)1, to the postenor process surmounted by small denti- even-crested anterior process and a rather short Spathognathodontidae. cles that decline in size toward the process tip. Finally, Bispathodus stabilis, with conservative, single-rowed Pa elements, was apparently modification resulted in Pa elements with an Near the end of the Llandovery, continued the stock from which species assigned to Pseadopolygnathus (Fig. 5.al) developed at leasr most posterior basal cavity whose basal margin even shorter posterior process and a large, al- twice, once in the late Devonian and a second has an almost circular profile in superior view time in the early Carboniferous. The complete (Fig ). Pa elements ofthis sort characterize the apparatus of Kockelella ranuliformis apparatus of Pseudopolygnathas has yet to be described, but Pa elements of primitive species (Walliser), which also includes angulate Pb and in both the Devonian and Carboniferous iterations of the genus combine open, Bispatho- elements and a symmetry-transition series bipennate (but nevertheless pick-shaped) M daslike basal cavities with at least rudiments composed of bipennate Sc, asymmetrically of three (not 2) denticle rows. Later species in alate Sb, and symmetrically alate Sa elements, both lineages are distinguished by carminiplanate Pa elements, with a large basal pit that is process. the latter lacking a denticulated posterior surrounded by a zone of recessive basal margin. In this respect, Pa elements of Pseudopol- lineage involved litlle apparent modification of Subsequent development of the Kockelella ygnalhus are homeomorphic with those ofpo- elements in the M or S positions but substantial change in those in the Pa position. That Iygnathus, znd, the two heterochronous lineages now included in the genus v/ill probably merit change is marked first by development ofshort sepamte generic and familial identity sometime processes on one or both sides ofthe cusp, with in the future. At present, it seems best to retain no conspicuous modification in profile of the Pseudopolynathus and, " Pseudopolygnathus" in basal margin. The basal cavity of Pa elements the Spathognathodontidae with the ancestral in samples from slightly younger populations is B is pat hodus stabi I is stock. laterally restricled beneal.h a poslerior process that is somewhar longer than in specimens from Family Kockelellidae Kkpper, 1981 older populations; and, in the Pa elements of the youngest species of Kockelella Toward the middle of the Llandoyery (early (Fig. 5.aD, lateral processes lengthen and also Silurian), the basal cavity of Pa elements in a bifurcate, and the basal cavity beneath them is Fig Elements and the apparatus typical ofa species of(ockele/1a, typical genus ofthe Kockelellidae.

105 'seuoceq slueuiale d ur,(luellruls cr8oloqfuour pue'(9l61 'reddeix pu? Icur"g :Z16I 'llocrn pue peorxad '3'e) ecueuncjo-oo uo?tep peqsl qnd,{q pouuguoj ^lfoo^rnbeun lou sl snpaw -Ddsotatd Jo sluourela S pue I I eq ol pesoddns suerurceds pu? slueluols qd puz ed crlsou -a?rp uee,{$eq uo4ercosse eql 'reêaoh 'selc -eds Dulpoqozo,fuHoduatuoc Jo sasnthedd? eql ur sejnfruls olqej?duroo ueql ejolu serrods snpou.toisre Jo sesnt?jeddeql ui asoql elqures -er(eb'g 'Arg,) snpolltddsodtd Jo seneds u^{ou{ eerql oql Jo o^\l Jo sesnl?j"dd" oql ui suortrs -od S pu" I I perdncco o^"q or (916I ) redd?dj pus {crueg,{q tq8noqf slueurole 'ejns 0q oi 'asrtdatj eql ur petejo^p? s? 'f,iurey eprluopor -uoud u?unlrs lou 'sluopouot opruipolj"zo " Jo lcols? s e?p4uopoqledsoreld eql pjeeej ',{uee -oluo ur e8els potue^p",{lqeqojd e 1? leql pue-slueujle Ed ur uoneuuoj uttjbut -l?seq Jo slojluoc eql ui Urqs roulut e eîoûr plnoar ssuat1aof DnapDnJuV Îuo Jo pcrdih esoql olul slllqdlro^ o apl)ox Jo cllsueper"qc slueruola 3d eql Jo uon -"rujojsuejl eslexeq'dllapljox IJro+ pe^loê D apdloruv teql [pelou oêq (9161) red -d?i)i pu? {olr?g sel slsa8ens AIuI?lec sluoul -JlJ Bd ur JsolJ 3t.1t lnq 'slsua4zdold 'U Jo snl"jedde ^luelrturs eql Jo Ir/t\oDl si elou tuqlon 'aleu"ld{lets or? slueruale?d eseqt 'uoqs ui ul3l"ru J?s?q o^rssecej Jo auoz peojq P pepunolns si qtlq,rr' '1rd dsn3qns? ol pejnp ^q -ej sr Ir^Dc les?q eql 'sj leql 'xeldruoc ejour sr aceyns lueurqcql? oql lnq 'JosITl?A\ s41g I '(2861) utel{ pue ^qtunl I,{q asues luetuelall -D!to^ ofiap\)ox Jo seuo eleqdecsqlals aql Jo lnru? ur paqursep (Ot'S 'AIC) sapn apo ) esoqt ol JElrurrs.{Jasol3 ej? Jesrlp,/!\ s, suqjaold -u f'jo serceds Jo osorll pue ns111e16 saptor11ou? DnapD.toiuv Jo sluauale ed 'eulnno ui -oqdtolud snpoqtodsotaq Jo slueurelo qd pue 'olbqdsjsltlels,(ubruoj ej" zd ueaûaq,{tu?l[urs eql Jo qfuers oql uo stuelllale qcns 'alstl8lp $ 1nq 3ôqe uo{j pea\er^ sz JBIncJIc ^llcuqslp reeuol ou q uiejeu ll6j zadooj avpuuopotllodsonid tltutdf 6'I ps"q aquo olgojd eql l?qt os 'pepulser requru 'oepnuopoqledsoreld eqt Jo ereuobjo sorjeds Jo lecrd,{l sasnteredde pue slueurolg 'f,t's '3!d YJNOCONO" IIHJ 86

106 THE MAJOR CONODONT CROUPS for me, a more compelling reason for reclassification ofthe family. The Pa position in the apparatus of Pterospathodus species vtas occupied by stelli- or pastiniscaphate pectiniform elements with simple or bifurcate lateral processes that may be adenticulate or may bear denticles on one or both sides. It seems obvious that such structures developed from Ozarkodina-Like carminate elements through gradual lateral expansion ofone or both sides at midlength (Fig. 5.39F), just as Pa elements of Amydrotaxis (FrE. 5.40) and Ancyrodelloides (Fi!.5.40) are thought to have developed in the Early Devonian. The Pb position in the apparatus of the type-species of Pterospalhodus was occupied by a distinctive angulate element, which bears at midheight a stout lateral rib or ridge that projects out and downwardly on the outer side to form a chevron-shaped lateral lappet. An element of Family Polygnathidae Bassler, 1925 earliest species known by carminiplanate Pa elements, angulate Pb elements, dolabrate (or bipennate) M elements, and an S series with bipennate Sc, extensiform digyrate Sb, and alate Sa elements, the latter with a denticulate posterior process. Pa elements formed by early species of the stem Eenus, Polygnathw (Fig. 5.a4) (e.9., P. pireneae, P. dehiscens, P. gronbergi), are carminiscaphate; however, in slightly younger species (e.g., P. lalicostatus, P. inversus) the underside of Pa elements is planate, a condition that was attained by development of a wide zone of recessive basal margin at progressively earlier ontogenetic stages and consequent restriction of the inilially broad basal cavity to a pit in forms representing later stages ofeither growth or phylogeny. The pit is commonly elongate, situated at element midlength, and enclosed within a keellike ridge that projects below the lower surface, is narrowly almost precisely the same conformation occupied the Pb position in the apparatuses of plete length of the element, and represents (as grooved on its under edge, extends the com- various species of Early Devoniat Ancyrodelloides. element prior to the stage at which the basal does the pit it encloses) the under edge of the The stelliscaphate Pa elements of Astropentagnathus (Fig. 5.a3), Aulacognathus, and Ap- In Pa elements of a few species (e.g., Poly- margin began to recede. sidognathus (Fig. 5.a3) are only slightly different in plan from those of Pterospathodus, and, the immediate vicinity of the pit, which is surgnathus spicatus) there is no discemible keel in all three genera were included vith Pterospathodus in the Treatise concepl of the Pterospa- that mimics a structure termed a pseudokeel. rounded instead by a flat area of varying width thodontidae. However, if elements such as the Such structures are common to the undersides ones Walliser (1964) refened to the form species Ambalodus galerus and Pygodus lyra werc may, in most cases, be used to distinguish those of Pa elements of Siphonodella species and also components of the Apsidognath lrs apparatus, as has been suggested by several authors, Iygnathw species. structures from comparable Pa elements ofpothen all bets are ofl at least for Apsidognathus. Soon after the character of Polygnathus became established in populations of Early De- Unfortunately, I have no other idea about relations or alternative classification of Apsidognathus and corrlinue to show it in Fig as selfi l-ane and, Ormiston ( I 979), three main linvonian conodonts d escended, from Ozarkodina a member of the Pterospathodontidae. Carniodus, as rcconstracted by Bischof(1986) and 5.45 as the linga{ormis, robusticostatus, and eages were founded. These are identified in Fig. others, is also assigned to the Fterospathodon-costatutidae and not to the prioniodontide family their many branches and the subsequent Early slocks. The nature ofthese stocks and Rhipidognathidae as was done in the Zreatise. The apparatus of the type species is illustrated in Fig and Middle Devonian history of their component species have been explored in some detail by Weddige (1977) and Weddige and Ziegler (1979), who drew Fig and made the interpretations that I summarize in the following paragraphs. The few polygnathid ozarkodinides that have The three rnain stocks recognized within Pobeen fully reconstructed have a seximembrate lygnathus by Weddige and, Ziegler are distinskeletal apparatus characterized in all but the guished in the fossil record by the outline and

107 JOUoISOO Aql Ol?uIl?C eql enu4uoc 01 eires qc l&\ 'sapou,(q qlplr,\pur te ua{orq erp slueu -el} ed uadooj d Jo..en8uol, Jouetsod eql uo squ esja^susrl 'Je,/l.a^roH'\Jols sna-toll8 -r{ aqljo sjqjuejq snous ur sjrjedsjo sluau -ei5 elq?j"duror olqurosej snql pub 'pua rouel -sod eql le..en8uol,, pepeljep,{lpj?ndu^ropu" f,lpret"l? a^"q 'culauul{s? eje 5lcols srql ur serceds l?rfecue eql Îlqftls eq 01 (6/6I) rels -orz pue e8rppeld ^q rqsnoqr 'reddel>i lndoor snqpu8qod Jo sluaulolo?d 'drl rouefod eql 01 eql? spuelxe qtrq,{ 'eulr"3 eqljo aprs reqlro ^?î uo pedoloêp s^\ f,[enbe lnoq" are 1?r]1 srrrrojleld a^?q (lt st'g pue 'LE sv'i '9E sv's -Iep orlj 'suollcefloc ur..luerjoq? J?odde ' ' 'GL6t) reltev pu" eftppei[ pelou s? ", 'pu" azrs leoj8 qceej l?ql ^q slueuelo Ed poluou?ujo,(lesj"oc Îuoururoc 1c?duro3 'lnols aêq '(LT, st's pue 'gz'sv s 'se'sn 9 'Ez'9n'9'BIJ) pu"q raqlo eql uo 'qct{erq smbutd pellej-os aqt Jo sorceds lujojteld eqtjo puo Jouolsod eql te,.en8uol,, paqqu suell 'pedoleêplle\ e pu??uuec pjluec ^lesje oqt;o eprs reqlre uo (sry3no.it louuojpo se u.r'ou)l) sq8nol deep qllt\ slueuala ^fl?cruqcel?d oletuole e^?q (tz S?'S pue OZ'S''S 'ErC) Iools slqt Jo qcu"rq 'D1ru,{t -ftq ro 'lertuaa eql dn e{eru leql asoqj ',fii -auur^s? lcuusrp Jrer{l pu? '..eneuot,, r.ujoj 'Et'sfs'r79n'9'8r'9r'9'9r'st's' 'gr's -tqd roua$od oql,{q peqsm8urnrp ^q er? 'Z'Sn'9'l'SV S trc) seqru?rq eerw slr pw lcols l]lxo"tstuttofiteul eqtjo lueudoloôp ^llpeer ur sa8els snldlsosrlsnqot eql ui sarcads Jo slueuele 3d Jelel SuuueseJd seroedsjo sluetuele ed 'soepu '(rt'9v'9 pue 6 9r'S 8rd) qruerq esla^subl oleldruocur I?JeAes ro euo sleeq snutpds etll Jo sorcods Jor o pue snuuotas d ao"ins Joddn osoq^\,.en8uol,,? u oj ol JO SIUOIuAIO Ed SaZ apejeqj /fulelulu,{se SUOllS -elsod pje/iru,$op pue pelceuep sl ^Fou leql s?ereqa 'seepu osjo^su?4 3 [luo sjeoq rurojtqd e doleêp pu? ^llerelel ^\ej Fculauflu,{s? leql,,en8uol,,,{ub e e^?q 'qauerq sryoaqd -nordsuoc ej? rlcrq^{ '( l Stg ErC) uosuqot ^lsno rqr augrp qrrq/a '(87'9n'9 we'zz'sys'61'9n's pue redd"d{ snstaûl 'd Jo slueuele ur '3rg) se,trle,ruep JoEunof slr pue sryoa^p "d lsrg r"edd? {co1s slurolnsu eqt Jo s elcereqt stutolr8ull snwousllod Jo stueurolo?d otec prluessg'slueurele Bd Jo sejnl?oj ocqjns-jeddn Ie pldeloreurled) sdapvuqbd pue (eeprqtetj8(lod) srywu8qod 01 peusrss? serjeds Jo lecrd^l sesnlepdale pu? sluoruolg 'tt'9 '3!d VJ,NOCONOJ AHJ 001

108 THE MAJOR CONODONT GROUPS r01 out beyond them for slight to considerabte distances posteriorly. Pa elements ofthe morphologically conservative robusticostatus brarrch (Fig ), on the other hand, are symmetrical, retain both platform segments, and differ from those of ances1ral P- cooperi only in lacking any trace ofa posterior "tongue." Symmetrical Pa elements of the trigonicus branch (Fig , , , and ) are end ofthe element. Thus the Pa elements ofp cooperi are transitional in rnorphology between those typical ofthe linguiformis and Ihe robuslicoslatus stocks. In the early Middle Devonian, Polygnathus cooperi apparently gave rise to forms with subsymmetrical Pa elements that lack a posterior "tongue" and are distinguished by a carina that extends to the posterior tip. In species of the zieg lerianus branch (Fig , , , blunt, robust, and have wide adcarinal troughs and ), platform segments ofpa elements that extend far to the posterior. become reduced in widlh and the carina iuts Pa elements typical of the Polygnathus cos- Fig Lower and Middle Devonian lineages it Polygnathus- Species represented by the el ments figured are identified in the text. Modified, with additions, from Weddige (1977) and Weddige and Ziegler (1979).

109 ueeq,{foururoj a^?q 1"ql srorllo FJe es qu^l regle8or '(tt'g 'Art) stdappupd pue '(LV S '8tg ur pe1a1sn11r Ue) skdpsaw 'DutJaddolx 'snllwusolptuqjs ol pautrss?,{nuaunc sarceds aau 'adpgalopwldd ttllu0f 9 6'9 'sluopouoj Jo stulpunoj -Jns ro djolsq eji ar ui sejnl"al luerjnjej,41[?crposrde 01 sluaurale q3ns Jo luaurdoloêp al"loj 01 elqrssod oq l(?uj lr pu? 'ejnl -celrqcj? J"lele{s ur ecuecgruars ^Bporuos rujel-euol elq? -rjplsuojjo sb.r uorupuoj eleurlsud snour?jul eql l"ql 'Jeê \oq 'slsetbns edeqs ur ecue8le,r. -uoj pel?lar ^lesolc,fuo^ lou flojns ore qcrq.r 'snqpu8dqdqd) pue snqpusojoldog sep\ -uoporuoud uercrôpjo elpprntr aql Jo stueu -elo eteu?ldruns?d erll Jo luecsurrroj osl? aje uoo"lueurciljo ecqjns Jo slceds? leqlo êql ui ragrp pu? Je11q eqt Jo?uue prourfis pue epou lejluec snonordsuoc oql lcq lnq srdalor4-42j4l snuo8qns eqt ol sjoqlne aruos,tq pauej -ar sldappulod Jo sermds (lr?a eqljo asoql 01 euqlno (ri reljtl]$ ere snqpusojtjuv lo stuesr -ele ed al"u?ldurtsed eql 'trd leseq pereuroc -aejqt,{llejeue8 'lleurs 1 le3u ec"ins Je^\ol eql uo qee{ :a3qrns Jo,i\ol " sl.r uo IeaI pedo jeêp1le^\ pu? ec?jlns reddn s1r uo sepou " Jo e^rlru4slp? sreeq leql eqol prelpl e pue ^{oj euo Jer\ol eql uo JaeI e pu? ooeyns Joddn eq1 uo?uuej? qlhr srx? JouolsodoJelu? pel\oq? Jo lsrsuoc teql sejnlrnjls eteueid ^lpratq -Iuns?d ej? sluer.r.relp zd frq'srulfdusojhuv ol pauersw A\ou seroods 6 er{ljo,(u" Jo snlej?dde '(196t) swlph r\orl ol op -otldolttod lo sernbrc 1oepql"u3,{tod) otuopotldoltlod pue sfiqldusortjuv lo ser.odsjo stueuole?d'9t's'e!d etuopotldolalod snqteu6ota?uv Ielelels eql 1noq3 atu 01 elqelr"ae uorlsrrrrojur ou f,luejjnc sr ajeq I'sn)upurutsD srxdrcsam su q3ns a"prdolol.eurled eqt Jo roqurou e uro+ sdeqrod ro (S?'S'8ld) r{laor snjolsu snqpustl -od erll ui rolsecue u^rodlun la,{ s? euos ruo{ ueruoajc Jlpprhl lselel Jql ur pedoleôp 'sarj -eds ueluoêq elrl e ururlsjp Jo uorssecjns e,{q pelueserdar '(9t'9 '8lC) snqpusotl)uv 'olbp 01 poqutsep sluopo -uoo rr?iuoê(i reddn Jo suoncelloc lsour,(q peluesejdej esor0 upql ejoqs ol rasolo slueu -uolrûe ul poîoûr e Eq KPJIJ f,jols snqpu -&qod ar]l. l?q \ olul lqersur u" peprôjd ueaq e^?q o,$ teql (586I 'euq puz reddelt) ](ltuec -er sr ll pu?'(1961 'sulleh) ll?lep ur tno ^luo pdlro^\ uoeq s"q (dnore srlolsojopou ûe snqt -Du8qod e\t) esoqt Jo euo,tluo Jo fueeol,(qd eql 'JeAeA{oH sluerxela Bd raqtjo peqsmtu[srp 'sdnoje lblueurdoleâ êoloqfuour preês luasajdal ^q serceds eseql'snojojruoqjejglao'i oql luo{.{luo u,rou)l ale S pub :(u?rlu?urq Jo) snojejruoqj?je^{o'i eql olur anunuoj pu? u?iuoê(i reddn eql ur J?edd? S :u?ruo^ -eo reddn eql ot pepl4ser ar" SL i(laleurxojd -de'asaqljo St'S 'ErC ui pelueserder,{u ubql Ja8uno{ s{joj rrro{ IEual?Iu uo pesbq ueoq a,1p'q snqpu8rqo4 10 sarcads S I I ueqt ejoi,^{ 'u?ruoêo ele I aqljo crl -suep?#qc Eraue8 palelej pl.lz snqwu8tlod Jo se8eeurt otur pedolaêp l3ols sntrl -soj eql Jo seroeds ^la^rsoldxa e^ne^rosuo3 Jo suonpfdod elqzue^,(harq'st's SrCJo dol 0rIl peluoser -der Ieâl eqt aôqe lsnl 'pepulsuoc ^q euoceq 01 pepuel suuopeld rreqljo suoqjod rouelup pue J3?t\o!?u OIIIDCOq ICOIS Snlo$n eqt ui SaICedS ueruo,l.o6l epprl I Jelel Jo slueruele?d 'rlleuol ojrlue Jrer0 roj paujnldn eu"ceq sur8j?ru rujojleid s? 'osly 'sa8pu ldtlsot i reproq l ql setpu agl pu" 'rarursoj e peurel sr perujoj snql ejnleoj o^rlculslp lnq xeldruoj aqj euu?c eql ol Ie er?d se8pu u oj ol esru ol pue puu"j eqt ple^\ol o^jnj ol slueutes ^lol?urrlf pjujnl -dn osoql uo se8pu esre^suejl eq1 JoJ pu? pj?.r -dn ujnl ot srllrojleld lueurale-?d Jo slueu8es Jouelu? aql Jo sur8jeru JoJ,{cuepuel E $"el l? si ejeql llcols srqljo seqcusjq II"Jo djolsrq eql ur Jsl? I..'pue rouelsod eql l"eu ejncsqo seluoc -eq Jo sjeedd"srp raqlre,, EuueJ eql '(616I) JeJAelZ pue a8rppja\ ot EurpJoJJ? 'lnq lejulaur -ru,{s,(?quesse ejb (St S '8rCJo oprs lqtu eq1 Euop 1 sarceds aôqe sauo eql lp) Icols sztrt VINOCONOJ IIHJ z0r

110 Fig.5.4?, Elements typical ofmajor species ofthe Palmatolepidae. Modified, with additions and omissions, from Helms and Ziegler, in Clark et al. (1981).(l) "Polygnathuf' lalilossalus Wirth, (2) "Polygnathus" limitaris, (3) " Polygnathus" cristat s,(4\ Schmidlognalhus wittekindti,(5) Klapperina disparilis;(6) K. dispatalvea,(7) Mesotatis asymmelncusi (E\ Palmalolepis trunsilans, (9') P. p nclata; (10) P. proversa, (ll) P. hassii (12\ P. nicornis, (13) P. subtecla; (14) P. gigas; (15) P. lmguifurmis; (16) P. t ahgulaisi (17) P. pe obata perlobata; (18) P. uepida; (19\ P. termini; (20, 23) P. pe obata schindewolj; (21) P. perlobata moximai (22) P. perlobata helmsi; (24) P. pe obata postera, (25) P. pe obata sigmoideai (26\ P. rugosa ampla; (27\ P. pe obata grossi; (28,29) P. minuta minuta; (30) P. minulo schleizia; (31) P. grac is gacilis;(32) P. gtucilis gohioclymehiae, (33\ P. grucilis ma ca; (34) P. quadruntinodosa nllexoidea; (35\ P. quadrantinodosa iaflexa; (36, 31\ P- marginifera; (38\ P. ntgosa tachyteru; (39) P. rugosa rugosa: (40) P. quadrantinodosalobata;(4l) P. subpe obata:(42) P. ten ipunctata;(43) P. gtabra prima,(44) P. klappen: (45\ P. glabra acutai (46\ P. glabra lepta; (4'7) P. glabra pectinalat and (48\ P. glabru distorta. 103

111 -srp Jo Jequnu? ezrusocer (1861'l? le lrelj 'selcrluep ur) reiaerz pu? suleh sldappu.qod urllr^,. lep?orq 'rebuol,(q sle^rolur r?lnter l? raqloue 'relderz euo uro{ pet?$des seprtuep e{qolpeeu 'uoqs pue surlsh,{q eurnlo^ asuoatj 186l etlt JO Sles Jo slsrsuoc qjrq,{ 'uo[elncrluep r,prol JoJ par?dojd ruejs?rp e^rsu9lxe ejolu qcnur E lepoepuq,, e^ q lp sluauele s Jo sessecojd ulo{ peldep? sr qrlq,n '/t S 8rC ur 'ourporuot]d pw 'snpojlo{'olnmjs ol /trnouo -4?urgqcs ÎeEr?l uaroqs ej sjossocepojd slr pue ^lpc s/d -xe1 u.uoj ur pjll{er ueeq J^Brl qjlq^r 'slueu -alopnldd Jo fuoaol,{qd eql ur sojnl?ej rofetral -ele cs aleuuedrq pue'qs ele BIp urojrsuelxa 'suorlecrlqnd snolotunu ur sjello^\-oc snor '?S elp1 epnlcur seues uorlrsuerl-frleurur(s aql -r?^ pue Ql6l '2961) reqerz slcor dn oleu teql stuerrjele Jo sed l JnoJ Jo eojqt ueruo?rec roddn Jo.{qd"JEneJlsorq ^qpaqucsep uo4nlosej eql 'ssecord JoueluE pepajrp (lpje^\u^\op -gaiq eqt roj srseq Fdrcuud eqt seprôjd pue pue petelmlluep,{lesnjojd'8uol p qlr.r esec,{le^rsuelul perpnls ueeq seq 'pllo^\ eqljo supd rell?t aql ur 'sojntcn.ils uuojrrrr?j el?uuadrq,{upur uro{ ur\odl sr leql sarjqorq? ui paluos aje' apo DuqDd pue DutpotuoLtd -ojdej,{lluepunq sl qclq^\ 'sldalopwloj ^le ^]laedser'd -rls Jo seroeds",{uouoxsl ruroj ur pegrtuopr 'turojl?ld pedoleêp oqtjo pue rouetup 'sldaloptalod pue srxdrcsall4{ Jo stueuale l J eqt J?eu pel?jol sr 'opprdeloleuled ^Heo,,a eqt Jo lol 'o avousoqlon snuee -secue aqt eq ol posoddnsr qrrq,/i{ '( l'rt's tic) rujoj eql Jo saroeds luerejrp 0Z euos ot pojroj r4u'tl\,,snpsso! o snqpu8t\1d,, Jo sluourele -ej ueeq ls?d aql ur e^ q sqt a{rl slueuale qd?d elpueldrurr.uj?c Jo lrd Fseq otr?l oqt 'pu?q 'seprs qloq Jo auo uo r.uuq JlrlruJoJt?ld Jsop raqlo eql uo luauelj orll Jo uoruod pjrxroj -ou,(?rcgjns D qlr,r\ ssejord Jouelsod? pue -leld eql Jo gleueprtli J?eu pat?nlrs sr leql 'dsnj snoncrdsuoo lld ps?q el\-duuadddlx 'Jutauur^s? 'efuel " 'ss$ojd Jouelu? a{qapzlq 'qtlq e qr4 'stueurele et?uuldrpeu? pe,r\oq e.êr4(l'lts 8rJ) snwousolptwly'rs Jo serr,(lo^rlrunsrp,{q perdncao s?,r uorlrsod qd -ods,{q tlnq slueurele Bd el?ueldruruu?c eql er41,'sdalopu4dd Jo '[? serceds lsour ur pvb (L'LV's l" lrd pseq snor^qo '8rl) srxopsaw Jo serceds ui ep"lq ea{ loqs e ou eêq,{iuouuoo qjrq^\ '(8?'/t S 01 g'/t's pu" secelns reddn esoftsnd Jo esopou 'erl) sdappuqdd Jo stuotuele?d r?lrurs -ojd q1r^\ 'stueulele aleueldrulruj?c e{iepcs ^lesnj -Eoloqdrouruo{ Jo 'leculaultu^s ^lprr oq 01 'pporq perdncao,{ipcrd,{t s?,{i uoursod ed spuel lrd IEs?q l?jluecqns asog,tr '(9 ^lj?eu 17'9 3rg) eql qcrq^\ ^q ur snl?j dde plslels el Jqurourrldes snp6lrj snqjdus/qad Jo 'oldru?xs JoJ 'esoqt ro -rxes e peq sprdelol?url?d u/irodl-tsoq aqj uror! DuuaddDIX Jo stueulole Ed qsrn8uesrp ol 'pjrnsse sr.uejs suees trd Fseq culetutu^s?,(lsnounc aqj 'eprs eqljo sjequreu lu"uodur ajour er0jo sernl?gj ^lltuej euo ol (lcuusrp fuo^ spuedxo l?ql lrd leseq IueuaE oql Jo oepol,i.rool rujg leqt lusurears" tourlsrp e sr leel u"rperu eqljo qfuelp$r leau esolc qjns ui e ej" eseql (616I ',{:qny pue 'eprs repun eqt uo uuojlqd eqt Jo puo JorJ pjeesoog uep ue^) ses,(l?ue relsnlc pue (286I -etsod erlt qc?er ol slrej s,(?^\p,{puer?dde pu??ôiqseiî pu? 'Jedd?fx 'ôlqrnd) se8?lq qfuolprru Jo Jouelsod puusrpur sl teql -tuess" I"rnleu '(896t 'sausf), suon?rjosse 3 pue sepelq 00{ "uu?j uoqs e,\eq,{eql 'eleu?idrulu] orlrlojdoc uo peseq ueoq o^?q -J?c pue 'esopou,{lpnurns 'peojq ere Dlotod sdapputld{ Jo ^llugpuedepur -s!p'x serceds lereês Jo sesnlsjedde pue '(9'LV'9'trl) Da^prodstp X 'G'LV'S oql Jo suorlorulsuoaar pue 'snst.rlauulsd slxol '8lc) sllt.tddstp Dultaddolx Jo sluourole Ed -osaw Jo snlefidde eql peqrjcsop pu? potjruls 'sluelllalo ed -uorer oêq (ZL6l 'll6l) drtrqd pue redd?i) JreqlJo sojnleej ruo{ peurrujelep eq snql lsnur 'Je e,$oh 'sjolsecu? Jraql ejea stdalototuldd pue sffdjosaw Jo serceds u.lrou)l leql slueurele?d pol?ld ^lqeunserd qlhr seroeds -rjlljq Jql ol pue Jeqto qjee 01 sedjds asjqt sn DuStlod eql Jo l"ql uo ^lpeorq Jo DuuaddDlx ro Jo dlqsuoq?loj oql slueurala e4 pelqd,{lpeorq snq tdusolprlutljs reqtre Jo seroedsjo snl"j?dde qtr{l sercads l?jl'serue,(iqeujnsejd eqt Jo osoql eêr{ Jou 'pequcsep Jo pelrnjlsuocgj ueeq pa eê\f DurcddDlx puz snqpusotptuttps Jo sededs Jo sesnlej?dd l?lale{s eql 'petou sv plelels eql Jo uoursodruoj uo uodeujojur ou eêq I e"prdotofrrrled eql s? pel?bej8es eleq eje '(sntd$r-tj d 'suotrutl d ' E'o) sercads.en?t -oustlod,,peleld-epr^{,, Jo dnojt B ur pepnltur V.LNOCONOJ lhj t0r

112 THE MAJOR CONODONT GROUPS 105 tinct branches, most Out not all) of which are rugosa. P. rugosa ampla (sketch 26) is thought shown schematically in Fig Initial Frasnian radiation is represented in Fig by Pa stock, which is where it is placed in Fig to be a derivative of the P. (Palmatolepis) elements ofthe group ofspecies numbered 8 to However, Sandberg and Ziegler (1973) postulate development of P. rugosa trachttera 15. This species group is identified by some authors as the subgenus Manlicolepis. Note that (sketch 38) and P. rugosa rzgosa (sketch 39) Pa elements of these early species of Palmatolepis have a prominent lobe on the outer side; related to the one u/ith Pa elements like those from a species in the Conditolepis stock that is a straight or only slightly sinuous carina; an undistinguished central node; a downwardly denetic arrangement of these three subspecies is shown in sketches 36 and 37. If the phylogeflected posterior tip; and no parapet along the as shown in Fig (and we may always have inner margin. to guess about that), some nomenclatural adjustments will obviously have to be made. The The several Famennian lineages recognized vtithin Palmatoleprs diverge from P. triangularis (Fig ), whose Pa elements are re- morphology ofsingle elements may not always more important lesson, however, is that gross lated in rnany morphologic particulars to those be the best guide to relationship. All of these of the Frasnian "manticolepids" but differ in "subspecies" are said to be connected through having a more distinctly sinuous carina: a more morphologically intermediate Pa elements conspicuous central node; and a platform that with other members of the lineages to which is flexed upward (instead of downward) they are assigned infie 5.4'1. posteriorly. Species in the Palmatolepis branch represented by sketches 28 to 33 in Fig are Sketches I 7 and 20 to 27 in Fig are Pa elements of a group of species (or subspecies) characterized by small, narrow Pa elements in that includes lhe type of Palmatolepis, P. per- which the smooth-surfaced platform withdraws Iobata. Pa elements ofspecies in this group are phylogenetically from the anterior end and becomes widest and best developed posterior of large and conspicuously sinuous; have narrow outer lateral lobes that generally bear a distinct the central node. Anterior of the central node, secondary carina; and develop a low, ridgelike the main axis ofthe element is developed as a parapet on the inner side anterior to the central conspicuous blade. A more important character of this stock, which was referred to the node. The Palmatolepis lineage that begins with subgews Deflectoleprs by Miiller (1956), may species 42 in Fig is distinguished by Pa be the discovery by van den Boogaard and elements with long, mostly smooth platforms Kuhry (1979) that Pb elements are not "nothognathellan" but are arched pastinate forms of that lack an outer lateral lobe but bear a serrate or ridgelike parapet on the inner side, anterior a type that has been referred in form taxonomy of the central node. Species in this lineage are to several species of Tripodellus Sannemann. It inluded by many authors in the subgenus is difficult to see how these structures can be Panderolepis. homologized with the "nothognathellan" Pb van den Boogaard and Kuhry (1979) refer elements of species in other Palmatolepis lineages, so it may tum out that this group will most of the Palmatolepis species in the stock thar begins with skerch 35 (Fig. 5.47) to the ultimately merit separate generic distinction. subgenus Conditolepis. Pa elements of most When (and i0 that day comes, the venerable species in this group lack an outer lateral lobe, name Tripodellus Sannemann, 1955 (not Deflectolepis M.ijller, 1956) will be available. have ovate to quadrate platforms with a carina that is weakly developed posterior of a large Conventional wisdom has it (e.8., Ziegler central node; and a sharp-edged parapet that and Lane, 1987) that Polygnathus latifossatus rims the inner margin to a point well posterior Wirth (Fig ), progenitor ofthe Palmatolepidae, developed from species of the Polyg- ofthe central node. Pa elements depicted.in sketches 26, 38, and nathus varcus stock (the far righthand branch 39 in Fig. 5.4'7 have been taken to represent in Fig. 5.45). Species in that stock built carmi three chronologic subspecies of Palmatolepis niplanate Pa elements with long, subquadrate

113 eôjd ol IJo^\ puonrpp? e{et 1I^r 11 'elqeqo:d aq ot, ollapouotldtg pue 'snpoute 'snqlnusol -rrlg 'snpuldtr tuorue fur,(uou,{s eql eâqeq I qanoqtv 'Dllapouoqdrs Jo seoods Jo snler?dde equo EJ?d eja/{ leqt stueluele roj snp ^lqeqojd -ui ue s? o?prdelol?lupd eql Jo uotru8oceu oul( pue sntlpusopqg saur"u JueueS-uJJoJ 'eeprdalot"urled aql EuErutoJer eqt (6 6I ) rodooj pue snpoqol eweu e\t pesn roj srseq pdrcuud sql sr ^lrurq.{tqrqrssod srqtgo sseu p?q (t 6I) elppnh 'elq,r\ubei I -D apouotld -e^rp?4.le eql l?ql ssejuoc I pue 'uodaelr qjns -rs elu?u elnlnsqns oqt posodord Iqat{ pu? uos Jeqlou" tueserder,teur eeprdeloteurled eql Jo -uejg 116l ur'ocuoh 'qsg? JoJ pesn lueu.idoleêd'seun?j luopouoo snorejruoq$j uaeq p?q tr esnecaq sluopouoj ^lsnorêrd roj posn eq lou,(ljeg pu? 'ueruoêc 'u?unlrs Jo uoqnloê plnoc orrr?u teql tnq'(? 6I) IqeW pu? uosu"rg II?Jo o aql ur sluaê lueuodurr s? slsjnq o^n I'q snqnusouotldrs perueu lsrg se,,l' D apo -aatr qcns pceer (t86i) sue'i pu? reiserz pue -uoqdts'sr l?ql tl Jo l"crd& lsoru eq ol ue)fl '(o apotltruv uelrc^ A!.y-Ipue 'saptolppott) snuee eql '(gv's 3rg.) Dryapouorydrs Jo teql $ s? -ru usruoêo LIrEg 'snpoqpdsonld ueunls 'pal?nl"â pu" peprulsuocej ueeq aaeq uousenb ur sero -eds eqt Jo sesnlh?dd ptrala{s eql lnun pe,{"i -ep eq IIe,!\ lq8lu lueujuelsseej leu]roc lueru -qcueurou Jourur eruos ejrnboj (pel"lu?lsqns JD IIy'r U lnq 'dnor8 eqt Jo ^rotsq leurelul eql Jo Sulpue$repun rno etueqc lou IIrA{ eeprluopo -ql"utoqpds or{l IIIo+ luaurdoleêp luepuedop 'pet?crldluoo sr,(iiluej srqt Jo ojnlepuauron ui 'E e) olull ur pelejedes,(iopl,n suollelndod 'lrd eql Jo Jouetu? euo eql u?ql pupsrp JprurpolJEzo ur slujuralj Bd ssol ^lqejeprsuor sr Jo sadfl J?lr leqt lea)l p"orq ',{ol e,(q -ulrs luaudoleêp e^rlzjelr,{lsnohqo Jo 'qfuel slrjo II" ro!?d suros roj a oojb urqt Jo s33u?lsur ^lesolcjo lereôs paqujsap r(peerp eêg I e a^sq.i( u.i tlxrl 'palopnasd e porrrjol?elp leql uorljjuuoj srql ul pelou Jq osle 1l teu p?ojq? perdncco sr trd eqt 01 JoFelsod 'pu"q le esolc oje se^4?ujelp elq"uoseel ÊuJ uollrsod str lnq ^q 'lrd ps?q egl ot Jouelue sjnc Jr.{q uo peu^\o{ -co'eôort uprpsu e qtlr 'leei pedolaôp{a^1,tluoururo3 ^ljelncrupd----slsrjrlaueso[^qd ejp spuejl uual-buol ur slesreêj ssel ro eroru y 'lrd 1?s?q eql ol rouelsod ecejjns aîoûr leql soueuejs lnq 'asrnoc lueuqc?lle aql uo lao{ pougopjle^l Jo 'elqrssod {5el lnq -tul lou sr uorlujûr:r qjns'sjrjjds uuluo^jc 'snqpusqod " Jo esoql e{ll 'eleueldrurr.ujec ere epprw pu?,tlj?g retq II" Jo slueurala?d eql IIruJ J srql ol peu8rsse ser3eds Jo sluerrje[e?d Jo I"rrd& srujojtu Id Jep?oJq pue strd relpuls eql,(q peo ldar uoos are^\ faql lnq 'e?prqtee{l l86l'sapouv puo ar$nv aoplrltdasor1q7 tltu.tdl] g 6 g -od eqtjo tuolsrq,{lr?o oql ur peulroj stueruele d ur 'osjnocjo'^nueulruojd pojneg sjslj?j?qc asoqj serlrluc leseq efuq fue,r qllt sluaruele ud peuuojl"ld luoûrer ot sntossolu -r1 d sejrnbej {ools ^l,noueu mzn^ 'd eql ar snpssollol d Jo urauo leql 1no lurod 01 olq?uos?ajun lou sr lr 'eeprdelot"urpd eql pue sntdssof -u8rsse pruro;ur elecrpu 01.,snqJou3!qod,,-!pl ^lejns snqpu8tlod Jo ur3uo aqt uo uo4elnceds ouqnl eqt pesn eêq lnq'/t S ro 9g'9 strg ur JeqUnJ as?q 01 qcii/'(\ uo suoltrsslloj [?3lluc Jo 'ejeq selnoj f.rejodu.iel esoql Jo JoqIa pe,{\ol aq1 rou esruedxe eql Jeqlreu e^?q I qenoqtlv 1oJ lou aêq I JpEJJp e ueql ejou JoJ (snj.. poolsjepun lou sr.rn,trs -upwtultso l{) requnu reqt Jo euo pepnjcur -soludl d Jo urglro aql,, l?qt Îr?elJ tno lurod seq qcq^\ 'smpsal,\[ ar seoeds pel?id. eql lnq ',qrtrqrssod JrleueSol,tqd? s" ^llnjar?c ojuenb e\t pue snqpusotplurljs ul popnlcul ^p?ojq eq -es e qcns pre8ar osle (9161) uosuqof pue'jod 1,r73rut sryossottlol A'esJnorJo'arnsperu fu?lod -dei>l 're1aarz 'epqq eqt Euol" oreq,{l,tue lueur -rrrol e sv 'snnssoftldl AJo stu puecsap eq ol -doleêp ujojt?ld lc?l snql pue eteuruu?j sr? pesoddns er" leql $uelllele?d pet?ld sluourele asoq^l q1l{r seroeds reqlo eql ptre '(f.' LV' 'Arl) '(t4ur1,,1) suoutaqotuas (DuIt ^p?ojq snpl "d -s!r 'd '(Z'Lf S '8rJ) -qawl=) DurpoltDzo I.lJorJ pe^loô sttd rui sn Du8tlod ugrs snpssofipl d 1"q1 sededs eql ^llcelp poqsrjq?lse eq -seej ol tuesseoau eq osp plno^r li ortel,{qd,tlod ueqî polso38ns 're e^\oq '(/96I) qul^\ 'urroj snue8 elq"rouol teql e{?ru pfo^\ os op ol JoJ -lqd pue ep?tqjo uorpunf aql Jeeu Jo le pet?n 'snqpusqod ur tde{ eq re8uol ou plnoc sr1trs -lrs seurêj IEs?q a8r l,tlqessed pue 'srujojl?ld -sotrtq snqpustlod 'sr teqi lueuusnfp [?rnl paprslall"red 'aojjeu 'uoqs,{laûqej :sepelq VINOCONOJ 3HJ 90r

114 THE MAJOR CONODONT CROUPS 107 $ql bj& Fig Elements typical of m\ltielement Siphonodella (Elictognathidae). it. When (and if) that happens, Falcodus will and that they might not yet haye appeared in clearly be the oldest valid name for the typical populations of S. praesulcatd, the earliest and genus of the family Elictognathtdae, and EIictognathw, Dinodus, ard Siphonodella will be even in early populations of S. sulcata. Those least Siphonodellalike species of the genus, or junior synonyms. The family name Elictognathidae will stand. however. because it is the ments with the essential characters of Siphon- early representatives may have evolved Pa ele- oldest one proposed for any ofthe genera (synonyms or not) now included in it. eralized Pb, M, and S-series elements of their odella, bnt they might have retained the gen- Although a great deal of attention has been ancestors. In short, evolution of Siphonodella paid to the morphology ofelictognathid Pa elements, there is no published reconstruction of skeletal apparalus equally or at the same time, may not have affected all components of the the complete skeletal apparatus for any of the and there is no reason to assume a priori that 20 species now included in the family. No one, non-pa elements were morphologically the 10 my knowledge, has ventured even a guess as same in the apparatuses ofevery species. to composition ofthe apparatus of any species With the exception of Siphonodella praesulcata Sandberg, all known Late Devonian rep- of Alternognathus (Fig to ), but Sandberg et al. (1978) speculated that the Pb resentalives of the Elictognathidae belong in position was occupied in the apparatus of at Alternognathus, which was created by Ziegler least some species of Siphonodella by anguliplanate elements ofthe sort commonly referred fened with question to Polygnathus or in- and Sandberg (1984) for species previously re- 1o Eliclognathusthat the M position included cluded in Scaphignathus, whose species have elements that have been described in form taxonomy as Falcodus angulus; and that various phology but were probably derived from Pan- Pa elements that are closely similar in mor- form species of Dinodus occnpred positions in dorinellina, not from Mehlina. the S series. As Sandberg and his colleagues The oldest known species of Alternognathus, noted, however, no specimens of Dinodus, A. pseudostrigosus (Dreesen and Dusar) (Fig. Elictognathus, or Falcodus angulus have been ), formed carrniniplanate Pa elements reported from rocks with elements of ^trplronodella praesulcata (Fig a) or from collecform that bears only a few nodes marginal to with a narrow, asymmetrically developed plattions with early representatives of,srphonodellathe sigmoidally curved carina, and with a narrow, flat undersurface that has an elongate sulcata (Fig ). These observations were taken to mean either that S. praesulcata and, basal pit but no very distinct keel. Younger species of Altemognathus (Fig and ) the earliest representatives of,s. sulcala would have to be removed from Siphonodella on are characterized by Pa elements with more grounds of apparatus incompatibility, or that elaborately deyeloped platforms, which have a the occurrence of Dinodus, Eliclognathus, and. median carina that is separated by a slight Falcodus angulus with the Pa elements typical depression from the anterior blade and rnarginal rows ofnodes or short transverse ridges. of al I other species of S iphonodella is a rcs,rlr of "similarity of niches." I suggesthat there is Although there is currently a substantial also the possibility that the really distinctive stratigraphic gap between the youngest known features of Siphonodella developed gradually specimens of Ahernognathus and the oldest

115 'snso8ttisopnasd snqpusoudtlv uro{ pe^loô DtDTnsantd S: l?qt lseb8ns (t86t) Sreqpues pue J.leerz 'sq8norl leuu?cpe spur fq so8pu Ieu JEur esopou riio{ pelej?des ^lesje^su?jl sr leql?uum I?Jluec e s?q slueluale ed,l,, lnsaotd 'S lo rujojleid eql 'lld l"ssq elb8uols eqt ot rouelsod lee{opnesd l"u 'pesrer? trqrq -xe qjrq,lr 'seuo Jelel ur al?u?ldrurrujec oruooeq lnq se8?ls l?tuaurdolaêp ^li"a ur a].?qd?rsr -u[ruej ej" leql slujujlj zd lejulauui,{s '/'\oj -JEu padoloôp 'sicoj u?ruoêc ui poluosejder auo,(iuo eql pu? snue8 eqljo serceds undou)l lsa -plo eqt 'tueqpues otnpsa d D apouotldts 'sesnlelzdde DIPP -ouoqdrs pu snqpusoujavv eql Jo sluauod -tuo3 Jaqlo 01 se alq?ll?ê ap?ur sr uo4?ujjojur oleldruoo ejour ueq,{r pe$o8ilns eq i(eru lueur -doloêp Jo senuo^? Jorllo qtnoqlp 'spunoje crsoloqdjoru uo pcrsol,{llueullua surees s\il 'sn$dusoutarlu ur pepnlcu /(ou l3ols ern Jo ued ouos uro{ peqoê 'Dllapouoqd -ts tseplo eqt '(t'6t s etd) Diorlnsaofi 'S lrtll, ruopsra leuouuaûoc eql Jo ued e uagq sr?e^ aruos roj s?q 1r 'rllrparorydrs'jo se^4plueserder ',qtasos Jc S'(6I) pue'.p4j4cos1's (81):ualosqo-oqr.ltsos! S (Lt)'.oppsqo'S (91\:Zl 'uadoots GI) :pidzlldtupdnb S'(tt):ssEH nsues rroxrdnp's (fi)'. 'urlnuarts (Zl)'.ppqol S ( l)'.fin'uadoots (0I):Zt{ 'DtDrudnp S (6\ :Dt'l lutrox S (8):lSraqpuDs S (L)'.otolldnp S (g):btnfls S (9):Dtorlnsaotd o apouor dls (t) :s1dln3at'v (E):s6uapnq 'V (Z):snsoButsopfiasd sn tdusourarty 0) (8t61) Ilug pu 'zrueln"-i 'relsorz'tueqpues urol Dlapouotldls Jo sorcods roj u^\oqs ureled pu? 6I ol t sejnsrd oeprqteusoplg eqljo,{uo8ol^qd.6t.s.3rd aepryreu60tctlj I \{ ue!uoaeo uetddtgstsstw 6 o1 lt VJNOCONOJ :IHJ 80r

116 the simplest and presumably most generalized that appeared early in the Mississippian (Fig. member ofthat genus, and not from one ofthe ), anterior ends of cup segments are directly opposed on opposite sides of the blade. probably more specialized, younger species. As indicated in Fig. 5.49, Siphonodella praesulcata was succeeded early in the Carbonifersissippian species (Fig and ), how- In Pa elements of two somewhat younger Misous by,t sulcata (Fi ), which was evidently the progenitor of highly variable,s. of the blade at slightly different points. This ever, anterior ends of cup segments join sides duplicata (FiE ,5.49.9, and ). Following an interval of substantial yariation, the elements of all species of Gnathodus, but it is condition heralds one that is common to the Pa duplicata zones, features characteristic of Pa combined in Pa elements of Protognathodus elements in various segments of the S. duplicala populations stabilized, and younger pop- (Fig ) with features of surface ornamen- praedelicatus (Fig ) and P. cordiformis ulations with those characters are recognized as tation that are more like the Pa patterns of independent species, most of which ranged to older species of Protognathodus than those of the end of the Kinderhookian Epoch. somewhat younger species of Gnathodus. Shortly after Protognathodus praedelicatus (Fig ) appeared in Early Mississippian Famib Gnathodontidae, new Conodonts assembled here (Fig. 5.36) developed late in the Devonian frorn Bispalhodus rrdbil,1 (Spathognathodontidae). They are characterized by a basically seximembrate skeletal apparatus in which Pa elements are carminiscaphate, and Sc elements are alate, with a denticulated posterior process. The sides of gnathodontid Pa elements flare laterally posterior to midlength, and their upper surfaces rnay be smooth or ornamented by a few scattered nodes or by longitudinal or radial rows of nodes. Little attention has been paid to the complete skeletal apparatus, so taxonomy of gnathodontid conodonts is based almost entirely on features of Pa elements. The oldest gnathodontids, from rocks of latest Famennian (Devonian) age, are referred to Protognathodus (Fig to ), whose species formed carmlniscaphate Pa elements with attachment surfaces in broadly expanded basal cavities (or "cups") that occupied the posterior halfofthe under surface. Pa elements of the three late Devonian species of Prolognathodus difer primarily in the manner in which the upper surface ofthe posterior cup is ornamented; one species (Fig ) formed Pa elements with smooth-surfaced cups; Pa elements of another (Fig ) bear short rows of nodes on either side of a subcentral carina; and homologous elements of a third species (Fig ) have a node or two on either side of the carina. In Pa elements of these Late Devonian soecies- and in those of a fourth one THE MAJOR CONODONT GROUPS 109 seas, it was joined by geographically widespread populations of conodonts with similar but substantially more elaborate Pa elements. These conodonts, which represent the first species of Gnathodus, differ from P. praedelicatus, their presumed ancestor, in a number of ways. First, Pa elements are conspicuously asymmetric. The anterior end ofthe cup on the concave (or "inner") side of the element invariably joins the btade at a point well anterior of the point at which the anterior end of the cup on the conyex (or "outer") side meets the blade. Furthermore, nodes on the upper surface ofthe inner cup segment commonly join to form a distinctive ridge- or comblike parapet, vthich may be short and weakly defined or long and prominent. In Pa elements of most species of Gnalhodus, the outer cup is more broadly expanded than the inner one; it may be essentially smooth, may bear inegularly distributed nodes, or may have longitudinally, radially, or concentrically arranged rows of nodes or low ridges. In the highly variable populations of Gnalrodus that spread with the initial explosive burst, Lane, Sandberg, and Ziegler (1980) recognized three rnajor groups. The group that centers on G. delicatus (Fig ), and also includes G. cuneiformis (Fig l), is characterized by Pa elements with a long, well-defined parapet. The groups 4pified by G. lypicus (Fig ) and G. punctatus (Fig ) have Pa elenents with short parapets. The latter groups are distinguished by the fact that

117 pouephl pue ladend podole^ -ep1la^\ 'Euol ^llueuluojd? 'sr t"ql :sdnoje uerddrssrssrtr l i(llea oû eqt Jo sernleej peurquoc t?ql sluour -elo?d peurroj serceds uerddrssrssrl l lelel potel -aj pue (t I'09 9 'elc) suoauliq expoqtdug l ttrt pezrusocej '0S S '3ld ur pozueuuns uod?lejd -.ra1ur crleuaeol,(qd eql JoJ elqrsuodsel,{loelei ej? oq,{ '(0861) relselz pue 'tueqpues'oue.i 'ZI 0S'9 pu" 6'09 S '8ld pelhnnllr sr,rr -d& 'g Jo saldrues pesotuedns ^q,t[?crqd?jedhls oû eql uro{ slueural edjo sojnl?ej ur luepha,tlr?elc osl? sr tnq '9I'0S'9 pue '1.I'0S S ' I.0S.g '0I'09 S eld ur u^\oqs dn.ore snppund 't oql Jo srequreu lereâs aql petej1snllr Ile \ l(lpljedse sr l?ql urell?d e-jelduns ^q eq ol puel trnq 'pezrueocej eq osl" aex sedtl snpl êql -Jund pue 'sn)rd& 'snp)tpp eqt Jo stuerrlelo?d'slcoj uerddrssrssrl^l Jelpl l?q/r\euo;ll$ snjrdtt 'g eql Jo slueurele ed ur pepu?dxeun pue eldurs ueruar lrrq'dnote snppund 'D etll ui sercads Jo stueurele?d ur e)lfla8pu,(lasie^ -suejl eruoceq pu? i(flerelsl p?ejds ol puol?uu?c eqljo pue Jouelsod eql pff.{\ol selcrluep 'Dqoqluasopltasd O (LI) p:ue:snudxat C (gltfiorfb-c G:D,svoaulq.D (t l) taqoqvds '9 t (ZD :clwtolraunr 'g /l.t):sa'pa d (ti):zbt,wdq t (Otl tsdtdlt C 16) :stltdruap flpot1tou, 1f1:stutotrpto.d (L)'.swo) -ltapaord'd (9\ luqanq d G) :!plro.d (t) '.luosulllor.a (E) ltauq)eaw siporldu8ototd (z) :i!i!qo$ snporltod g (t) (086I) rolsorz pue,tuoqpues,oue-i,{q peuturr}.p suor1e1e1 eepsuoloqieug eqllo fusiolfq a11 6 I N y, A/ V]1 ',t,( SN rlj d YINOCONOJ AHJ 0l I

118 THE MAJOR CONODONT GROUPS lll denticles in the posterior segment ofthe carina. Lane and his colleagues did not speculate on relations between G. bilineatus and earlier species of Gnathodus. However, since simplification in the morphology ofpa elements appears to have been the hallmark of evolutionary development in the three major groups of early,infs presumed progenitor, be abandoned in favor of a sirnpler arrangement. I opt at this stage for a scenario that requires fewer reversals in trend-that is, for a relationship to tjie delicatus grotp (and, perhaps, G. bilineatus), which has a long parapet and posteriorly simple denticles. Mississippian species, it seems unlikely that G. bilineatus, with its highly complex Pa elements, is very closely related to either the lypicus ot punctatus grcups, even though posteriorly widened denticles are characteristic of the latter. Thus, if there is a relationship belvteen G. bilineatus and any group of early Mississippian gnathodontids, one might be postulated with the delicatus Eroup, which specialized in building Pa elements with long parapets and might also have taken up denticle widening in mid- Mississippian times. Belka (1985) deives Gnathodus bilineatus from his species, G. praebilineatus, which is Lochrieq and Vogelgnathus Two additional Mississippian lineages, referred tentatively to the Spathognathodontidae in Fig. 5.36, merit discussion here, separate from the Gnathodontidae. One lineage is formed by the several species of Lochriea (also known as Paragnathodw) (Fig. 5.51), the other by the two known species of Vogelgnathus Notby and Rexroad (Fig. 5.51). Species of both Lochriea and Vogelgnathus are represented by bedding-plane assemblages, hence there are few mysteries about skeletal anatomy. There are said to be "... a perfect horneomorph of substantial questions, however, about their relationships Gnathodus delicatus." Although this would seem to vindicate my "guess" that the G. bilineatus slock had its origrns in the delicatus group, I should also note that Belka chooses G. semiglaber (Fig ), a member of the punctatus group, as the likely ancestor, and not a species ofthe /elicatus grcup. This would require reversal of morphologic trends in the G. punclatus group rccognized by Lane, Sandberg, and Zie{er (1980) by requiring that posterior denticles ofthe carina revert to simplicity in G. praebilineatus (only to become complex again in G. bilineatus itself), and that the parapet become longer, despite a tendency in the puncta-,rj group for the parapet to begin short and become shorter! Gnathodus girtyi (Fig ), which appeared at about the same time as G. bilineatus, might be a somewhat simplified member of the same group. However, Belka (1985) has recently described a new species, G. awtini, which is said to have Pa elements transitional in morphology betweet lhose of G. texanus, an end member of the punctatus Erorrp, and G. gir- /yi. Derivation of G. girtyi from G. austini, however, would require that a short parapet, with a high anterior node, become longer and more uniform in heiglt; and that the posteriorly widened denticles of G. texanus, G. aus- to other conodonts. Lochriea commutatrs (Branson and Mehl) has a seximembrate skelelal apparatus in which the Pa posilion was occupied by carminiscaphate elements that are closely similar to those of Protognathodus meischneri (Fig ) in that the cup is smooth on its upper surface. Indeed, it would be easy to confuse Pa elements ofthe two species which, however, differ in relative height of carina and basal cavity and in the fact that denticles of the carina tend to widen laterally and develop a distinctive cancellate pattern rn L. commulatus. L. cracoviensis Belka, the oldest known species of Lochriea, is distinguished by Pa elements with cups of more elliptical outline and laterally expanded, surficially cancellate denticles on both anterior blade and posterior carina.other species of Lochriea, like other species of Protognathodus, developed Pa elements whose cups are variously ornamented by nodes and ridges. Lochriea uacovienjri appears stratigraphically in the biozonejust above the one in which Protognathodus cordifurmis is last recorded andjust below the one in which Z. commutatus and Gnathodus bilineatus (Fig ) make their debut. It is easy to postulate a relationship between Z. cracoviensis all:d L. commutatus, but difficult to relate either sdecies lo Para-

119 Fffi ffif,* leeprtuopoqleusoqleds\ snqrou8psoa p\re oauqjo1 Io s.!ced$ Jo lej.d l sesnlereddd pue slueuola 'I9'S't!d '^lr?ejc lueruele tuo^ lno operu eq touuec soruebol,{qd l ql sdet "S elsle ue sapnlcu leql snlej?dd? Fta -lols el?jqrueuues oêq sadeds u^\ou)[-lsoq,(ueru os,{q petentcund sr sdnor8 gloqjo,tor oa{l eqj 'snl"ls cueues " elsjedes lu3ur lou,{euj -srq eq1luasard ly snxeld puuopoqleuaorlleds Pue DauqxoT ot rellljrs sr '(v xdusddv errns sql ui slooj 3^?q osl?,teql esnecaq pu?) 9 S '3rg w e?p4uopoqtsusoqt?ds Îasolc eql 'pojeprsuoc ueeq osp e^?q (edprql?usoloe,'as) Êru qlrii\ papnlcur osp '(ls'g ev) snqpuslasoa "Jeue8 peleler pu? snpoqpusoldtl Jo sdrqsuo4 'o?puuop -?ler eqt ldun 'raô^\oq'ouop eq lou sql l?ql -oql?usoqleds eql Jo ellerqun pop,t\or3 pueruuocoj I ureql JoJ? eur?u pue tsq,{reluos oql Japun ur l! pezeenbs eêq Pu? oleojc ol elq"rsep eq ^lrru4 ^\eu ^lq?qojd III^{ LI 'o?pnuop 9 '9 'ErC ur eep4uoporpeu9 eql utorjdauqjot -oq13u9 pue eep[uopoql?usoqleds eql uro+ poôrrjej eêq I 'serpn$ qcns turpuad eler"dos oaeouq e luessrder snqpublasoa pue 'serpnls erntnj uro{ uoddns paeu llrna 1r lnq Dauq)o1 7ew ele4suouop solpnls amlnj JI 'e^rtcerlt" uo4elnceds l"qt puu 'AlrJrqrssoo _ I 9 S 'EIC ur u.doqs qcols pnuopoqleub u"rddrssrssrl^l e^rppll? Ue ls?e[ le SIl]eeSrqlDaUqzOTJO uors,{ljee eql Jo uro{ Jo peetsul sllqdls snp -sncsrp SurpeceJd eqljo /r\er^ ur 'Joê,r\oH poje -otltddslg urorj ûe KlluepuedePur pedole Lep srswr -prsuoj ueeq e Eq ol uees lou seop 'splluop -^ndrr oauqrot treril solblnceds (sg6l) ag -oqleu8 Jeqlo ro snpoqput Jo 'sebpu ") Pu? sapou I?l3U 's!llqo$ snpoqpds!8, rrjo{ uort?ûa(i'ûoloou ^lluepuedapur -Jns Jo ujol.pd xaldruoc? sl"eq l"ql dnc Jolno q8nojql paêrqje srsoqdlouropeed Jo elduexe lueuruord 3 pu? ledh?d pezuefuolla^\ '3uol ue eq lqfiru sql leql lsa8tns leql'snqpu8p8 E a^"q osl",{eql lnq 'seljuuep popu?dxs,4lp -ol Jo sluoruole?d ejnl?u 0ro Jo lu$sruruer -relq qlk\ esuu?c a^?q mtdauutq snpoqldud are 1eq1 se8els plueudoleâp,(ljb3 q8nojql JO SlUJUrala Ed 'SOJEJ]nS Jreql JO Ued UO Urel ssed, snpoqrcug Jo seroeds û"ru Jo stueulale -ted puos^lod snounc E qlr.r solcnuep pepued 3d aql leqt epu'snqlousptoa roj slsout"ip -xe sopnlcul l"ttrl Euu?c e pue pue ouleu qtoq peprôrd oqx"(s86j) p?orxeu rouedns Îlerelel ^\3I^ ur olsô,(lp?ojq er? leql sdnc pelueur pue,{qron ulsuajun ar? sdrqsuoq?loj crleu -"ruoun eaeq snlrlnuluoj 7 pue ssuallo)d,tj -e8ol^qd lreql lnq 's?un J luopouoc usrddrs 'ZJo sluarllele -srssq l el?l Jo sjoqiileiii pu ojdseplr\ zral'd snql "d s"ejeq^r 's/rloj ur poeuerre ro p oll?cs ej? l?ql sepou,{q peluaur -ou8p8oa Jo serceds sejelns Joddn rroql uo -eruo flsnoncrdsuoc Î[opu?r pu? eôqe uro{j pe^\or^ qloous eje sdn3 pelsnlrs r{foualsod 'pepu"dxe se pedeqs u?eq eff l?r sdnc culeuu,{s" esoq^{ sluouelo ed oleqdecsrurur-rbc,(irqeis e^?q (r'0s S tlg) stuttoltptord Jo pu? Îl?ratq ssecord rouetsod pel?lmnuop '6uol e qll.r sluorrjolo ed 'sr 'tzrlj-'snpollloug rc snpoqtous VJNOCONOJ AHI zli

120 THE MAJOR CONODONT CROUPS ll3 A Fig Upper views ofpa elements typical ofvarious genera ofthe ldiognathodontidae. (A) Declnognathodus; (B) Idiognathoides; (C) Neognathodusi (D) Idiognathodusi and (D Strcptognathodus Family ldiognathodontidae Harris qnd Hollingsworth, 1933 Idiognalhodontid conodonts are distinguished by carminiscaphate Pa elements whose upper surfaces tlt,icatly bear three longitudinal rows of nodes or denticles. One of these rows, the carina, is a posterior continuation of the free blade, which is assigned an anterior position and may account for more than half the total length of the element. Conceptually, at least, the other denticle rows are maryinal to the carina; in fact, the carina curves laterally at varying distances posterior to the end of the blade to join one ofthe marginal rows or is replaced across much of the platform by a median groove or trough, so that many idiognathodontid Pa elements appear to have only two denticle rows. The complete skeletal apparatus is known for only a few of the species now included in the Idiognathodontidae. In those species, the apparatus is seximembrate, includes an alate Sa element with a denticulated posterior process, and is in other respects closely similar in composition to that of the presumably ancestral Gnathodontidae. Declinognathodus noduliferus (Fig \), the oldest knowr idiognathodontid, is drstinguished by carminiscaphate Pa elements in which the carina curves laterally to join the outer marginal denticle row a short distance posterior of the end of the blade. In Pa elements ofspecies of Idiognathoides (Fig ), which appea6 shortly afler Declinognathodus, the posterior end of the blade curves abruplly to one side andjoins the outer maryinal denticle rorv wihout forming even a short carina. Furthermore, Pa elem nts of some species of Idiognathoides exhibit Class III symmetry; that is, sinistral and dextral specimens differ in morphologic detail, but not in overall pattern. Early species of Neognathodw (Fig. 5.52C) built subsymmetrical Pa elements in which a well-developed carina extends nearly to the

121 Jo dnort lu?lodru srqljo,fuolsq pluoudola^ ere g9'9 'E1g ur ssqcle{s aqj- snr*u8dw -ep eql ul pe^\olloj sp^r u"rsojd,4j?uounloâ 'I pue snpjnap J 'snpoqtousotpl Jo sercads ub qcns JI snpoqtdusotpj Io seteeuq snous^ oû ur sluerxe1e Ed Jo lueudolelep crleueeol polceje srsoqtuoruopeed se uuu? [.,(suued -uo eql pelueruncop,(ituecor s"q (5861'ssalg sql qsnorgl,( ecrposrde Jo 's?unq luopouoc pu? preeeoog uop ue^ ur) pj?eeoog uap up^ u?iulod pu" uerue l^suuad Jelq ur esje^ 'sse$ojd ur ej? sorpnls -rp ejolu ^ljee pu? eroln elljocoq ol ureos snql plno^l Sum8Flur 'Jolsecu? l"qrur er4l 'snpoqpusofiaus 'se8?ls I?JoAos pu" palsod ueeq a^?q suers uo4cojrp q8noqlp 'snxeld snpoqtdu ^lluecor lfp? ol(n sjelcej"qc snpoqpusofialls ellue^ -3otp1-snpoqlnuSoldrJts' eql JoJ eceld ur,tl'uouo -nfgo sgrqs crualoeu pe,tlo,rur e,req,{erx snxeld -x?l InJ uru"eu ou ta^ se sr ereql '^lelsunuoj snpoqpusoryi-mpoqpuaofia4s oql Jo,tuolsq -ufl 'sluopouoc opurpo{jezo Jo dnor8 srqt Jo uerulled pu? uaue^lfsuued Jelq lseeitns S S sas,{pu" pcrluc uo puedep lii/'\ $looj u"rujed '3r{ ur,( ecrleureqjs pazueruurns?l?p cngu Jo.rol pu snorejruoqrej Jeddn Jo soqdeje -eeoluo se 'ûetoluo,{lj?o Jraql ul atets snpo -rt?jlsorq poll?lep ocurs 1rclap teej8 ur tno -tltousodals e peul?tej serceds.rnpoqpusotpl psljo^\ ueeq eêq pfo,t\ serceds esagl tuoue Jr pu? 'el"cpur ol slueas ocueprê crqdeja suouplej l"ql pedxe lq8rur euo 'seun?j -gejls se 'snpoqrdusotpj peu,..eds snpoqpus -le^rp-a\ol Jo sluouodruoc ejsl,.^ sflpotlldusotp ^trs J -otdarts'(u?^\ouow) uef?^l^suued.{lj?e JI pue snpoqpusoial /S'Jo serceds esnecog '$lcoj ',{urouox? luopouoc ur rualqord pa,r.losun u"rrujed re^{ol pu? ueru" l^suued luo{ sald JofeuJ? sluesardal pue snxeld srq13o turpuzls -Jepun palecrlduroc,{lejns s"q srql 'usru"a 1^suuod egl \el.ory snpollidusorpl,{q pot?u -ruop esoql qlp at?ujsll? snpoqlousofiatlg [q pst"uru]op sl?^jelul crqdzj8n?j$ 'sr t"ql,,'u"ru"^l^suued eql Suunp saurl l?jot\esnpo -qpusorpl ot ross$cns pue JolsocuE qloq ueeq oêq ot sreedd snpoqt,usofiaus ",, t?ql '^llmud,tuc teq \euros petou (L6I 'relsqola pu?'e)i"rls 'llurel I 'eur1 ur) 1p:e u1 'poseq ej? sert -eds snpoqpusorpj Jo sldecuo, qorq^{ uo seuo eql er? slueuele?d Jo sej$?ej eseqj 'soqol ejnl"iu eql elquesej se8?ls Jrleuoaoluo '(OZS'S eh) snpoqnusorp Jo serceds polelor ^[J?o,{lesop Jo slusruele ed ui'dno erd Jo srepfoqs.roujlue eql uo epelq aql ol lujjefp? dole^ -op fluoruruoc selcuuep Jo sepou,fuepuocos Jo set?sej8it? xelduroc pu" 'aôor8 ro q8nojt uew -eur dn uelel sr rujojleld eql Jo rapur?u " -ar oql ^q Jeô uoqrsod su 'rujojletd eql Jo pua JoueluB eql oluo ajuslsrp uoqs E Aluo JoJ spuel s.uljojleld eqt uo dolaôp sspou perdncco -xe lnq uonrsod ui u?rperu sr?uu?r eql (!IZS S seej? eleqol pue 'drl Jouelsod s1r ssojce ^q Jeedde 'tuj) snpoqtouso@alis Jo slueulole?d oqt ui se8pu osje^suejl 'suepeorq uuogleld eql 'suaurr 'snpoqpusouwa O Jo slueure[a -Jeds Jefuq ui,{urouoxel rujoj ur ed er{l Jo lpql ol r"lrurs almb snql sr,{3o snua8 l ql ol ^Te^rs$ccns peuarsseq plnon\ pu" szp -loqtuoui lpjeô egl pu? 'euu?c oql uro{ al?r -oqtdusomaus Jo sjetoereqo ^lerns l?rluesse eql ol?q -?des $ ndoj l?u6reru gql Jo elcrluep $orrrjou 'esjno3 Jo 'sueurroeds gcns sa8pu I?urEJ?ru -etu" eql,{luo 'u.rorr)l saneds snpoqtdusoan Ielp&dqns uee,{rleq luelllelo oql Jo pue JorJ tse8uno,t eqt Jo stueurala?d ur:dnc eqtjo pue -elsod aql ol spuelxo l?ql eurj?c uerporu e pu" roujlue Jql ol JJsolJ pus JesolJ slurod le dnc al?tuole ue eaeq se8ets q rols tsereee oql pursreur ^\oj relno eql surof Buuec eql 'Je ea{oq luasgjdej leql sueurcads,(url l"ql elon 'pjocej 'serceds Jel"l Jo sluerxele?d ui s,{or I?urSJEur crrldhsotoqd pelrelop ejour sq uro{ peldep? SuuepJoq uaa^rlaq dnj eql Jo pue Jouetsod IEurAJeru esopou pu? fllejel?loretu" peropjoq ^lsnoncrdsuoc,(q,{iprelq oje leql soepu esje^ -suer1,{q peleen::oj esrareqlo sr qcrq^\ 'uuoj -leid oq1 Jo u d lsou-rorjolue eql,{[uo sjotue uuec eql '(586I) ssolg pue preeeoog uep ue^,tq pet"rlsn[ snlrjrpp snpollldusolpl Jo sluau -ele ed lsefuq eql ui 'sroplnoqs I?JetploJotu" -ur?s ur uoruruoc ej? pogluop! el? qorqa slueurole ed erp pu?'snojournu êql oje pro ^q -uo8 o,r1 rellel eql Jo seroeds perrr?n 'uelrrjod eql olur u?ru? l,{suued orll qenorql e8uzr snp -or.ljdusotpl pue snpoqwusofiatls: tnq'ueru?^ -I,{suued re^lo-i eq1 ol peuguoc an snpoqwu8 -oan pue'saptoqtousotpl'snpotflousouq)ao 'se8pu Jo squ asje^su"ll Jo serjes? Aq peelsur pessojr sr qrrq \ 'ujoj -lpld eql uro{ seedd"srp q8nol uplpeui oql sa34s Jolel ul snpoqlousojdat ls Jo sluauele VJNOCONOJ AHJ tu

122 THE MAJOR CONODONT GROUPS ll5 Fig. 5,53. Ontogenetic sequence in Pa elements of Idrognathodus- Smallest specimens have morphologic fea]]'jfes of Slrcptoghalhodus. D.'aw,n froni photographs in van den Boogaard and Bless (19E5). conodonts, I suspect it involved several lineages, u/hich may have been affected to different degrees and at diferent times. Sorting this out will require careful biometric studies ofcollections from rock sequences that represent long-continued stability of depositional conditions. I doubt that it rvill be worked out in the cyclic deposits by which the Carboniferous and Lower Permian are represented in much ofthe world, despite the fact that collections from such rocks are commonly rich in specimens that represent the Strepognathodus-IdiognathodzJ plexus l0 Family Anchignathodontidae Clark, 1972 Ozarkodinide conodonts included in this family have a basically seximembrate skeletal apparatus that includes carminiscaphate Pa elements, angulate Pb elements with relatively short processes, and alate Sa elements that lack any trace of a posterior process. At present one anchignathodontid species is assigned to letiota-,cis, which is peculiar in that its apparatus appears to have lacked elements in the P positions, and all the others are included in Ilindeodus, wbich is probably interpreted far too broadly. The oldest anchignathodontids known are of Early Mississippian (Kinderhookian) agei the youngesl are ofearliest Triassic age. The rootstock ofthe Anchignathodontidae is formed by a succession of Carboniferous, Permian, and earliest Triassic species herein assigned collectively (and probably quite loosely) to Hindeodas. Only a few ofthese species have been diagnosed and described in fully modern, multielement terms, so future work may well establish that several different lineages are involved. In line with the practice in many other families, each of those lineages would merit recognition as a genus, and there are names already available for most of them! The oldest anchignathodontid known to me, Hindeodus crassidmtalus (Branson and Mehl) (Fig. 5.5a), represents a group of Early Mississippian (Kinderhookian) species in which carminiscaphate Pa elements have a cup-shaped basal cavity beneath their posterior half and a finlike anterior blade that consists of three or four denticles that decline in length and decrease in width posteriorly. These elements were originally diagnosed in form taxonomy as various species of Spathodus or Spathognathodus, and it is not possible at present to determine if they represent one or dozens of species in a multielement sense. In any event, Pa elements of this type are regularly associated in collections from Kinderhookian strata with bowed angulate pectiniform elements that have relatively short subequal anterior and posterior processes and have been identified previously as species ofszbdryanrolrff Branson and Mehl, Such elements qualifu morphologically and fraternally as Pb components of species in the H. crassidentatus gjrou'p. Maybe, after this group has been revised and its taxonomy brought up to date, Subbryantodus will t.urn out to be the oldest available generic name for rt. Cudotaxis piceslingl Chauff, based on material from somewhat younger, middle Mississippian rocks, also seems to be a member ofthe crassidentatus group, and I see no way to distinguish it generically from other species in this plexus. Hindeodus scitulus (Hinde) (Fig. 5.54) represents a second component of the Mississippian species-group here referred loosely to Hindeodus. H. scitulus has a distinctive car-

123 uerddrssrsqtr I alpprrr Jo $[toj ui lsju J?od eql sluosordor 'sarceds-ed,q oqr '(ts S 'AlC) -de dnort sryn$!.tj snpoaputh etl^t Jo seloods (re rr\ pu" tsrnbeunol) sryntsuj snpoapulh 'pue plsrp slr le selcllu0p a{ll 'seloeds snpoapulh raqlo Jo sluelu -elpeeu'euoijo relsnlc elelp?r sîljullsrp e sdo -JlJ nt qllrr essj agl lou sr qjrq,,a '(ujojlurpol -laêp Jaqlo aql s?eraqa 'dsnc eql -uoudu,$ ro) aleuuadrq sr tuoluale t l eql pu? r[o+ a3u?lsrp ^Forlruos uoqs e,tljouolsod pue pj"adn 'sssjojd Jouelsod E $IJEI lueurolo?s el?i? eql,{laleqs tuoq eq ot spuet tueurele leqljo ss$ord 'srulpu8olddv Jo sercads uuoj se sluopouoc I?Jel?l euo SeUeS Uoqrsu?4-ful9rurrjfs Oql Ur uuddrssrssrtral Jo sluepnls,(q pegrluepl uoprsod qs oq1 serdncro 13ql lueuiela al?j,{8rp -IIIoc suuoj o^rlsuusrp eql ejp slueuela ^luour seuos rrrjojrsualxo snounc aql si 'nder^ ul 'serjeds -S pue h[ pue 'sessetord uoqs pue dsnc ebj?[ snpoapurh Jo snt"redd" eql Jo ^ru ejnlsej crlsou E seq -Eerp tsoru egt lng 'ssecord lueuala qd elq-snpoludtuqglrs 'peaoq Jouatu? ellepslq [1p.rs1ey eq1 'eurnno IeJept Elneu?ulqns eql Jo uoq?rrrjojuoa ur snlnlt)s 'H Jo esoql Jo olcnuep peojq'llel elsuls BJo,(IlEtrIIJd slsrs elrt pue lrun eqljo pue Jouelsod eql 01 uorqs J -uoc ssecojd JousluE pesserdujoc,(ljelel?l oql Dlrldn3 ur spuetxa l?qt ps?q E Sur,req ur pue eprsrepun eqljo uorlodplur eql ol papfls d,,'1.or8 sntdtuapqsdtj aqljo Ûêc esoqt e{i oje slueur -ej sr,{lr^bc l"s"q ped?qs-dm lpllls,{laîl -elp 2d snpoapmg Jo sorcads Jo dnoje pjrql -eljj eql qclq,ar ur lueulelj Ed elegdejslultu 'u,ôul.lou stxolo DY Jo stuourele d slueuole ed pu 'qd 'I,Î'cS 'qs Uel ot pe,{\olloj '1qAu uo quetuel. es loepquopoqteu8lqcuv) slr,pqpvptje'spoapulq'$nporudtuqqnsl)snpoaputqlosna.dsjolecid^lsosnl JeddepuBsluetuolg'ts'g'8lf, ^q s nt.tueplasu e I s npotue Aqqn s F t s npo.pu! H snlnl,js snpodputh snpo.puth VINOOONOJ IIHJ 9I I

124 THE MAJOR CONODONT GROUPS 1r7 (Meramecian) age, and the lineage clearly extends through the remainder of the Carboniferous, the Permian, and into the lowermost Triassic. Initially, in 1970, I interpreted Pa elements of the youngest species krown, H. typicdlrj (Sweet), as components of the unimembrate apparatus of Anchignathodus typicalis, whereas occupants of the Pb, M, and S positrons were regarded as components ofthe multimembrate apparatus of Ellisonia teicherti Sweet. Later (Sweet, 1973) it became obvious that Anchignathodus typicalis and, Ellisonia leicherti werc names for different parts of the apparatus ofthe same species, which ultimately (Sweet, 1976; Sweet, in Ziegler, ed,., 1977) was shown to be closely similar in skeletal architecture to other species of Hindeodus as interpreted in a multielement sense. Before all of this had been sorted out, however, Cl ark (19'12\ had based a family-group name onlnchignathodas (superfamily Anchignathodontacea), and this must prevail for the family under consideration despite the fact that Anchignathodus has been considered a junior subjective synonyrn of Hindeodus since at least 1977! The skeletal apparatus of Hindeodus cristu- /ff (Youngquist and Miller), the Mississippian includes ancestors of Homoiranognathus, the less well-known Permian Rabeignathus and, Iranognalhus, and the Early Tiassjc Isarcicella- In the Treatise, Clark and I included all these genera (except Homoiranognathus) with Hindeodus and, Aethotaxts in the Anchignathodon- 1idae. However, information published since the Treatise manuscript was prepared makes me uncomfortable with lhat assignment. Thus, I now treat Diplognathodus and its kin as an independent group with familial status. The family Sweetognathidae was established (as Sweetognathinae) for this group by Ritter (1986) who, however, included it within the family Anchignathodontidae. In terms of the morphology of their pa elements, species of Diplognathodus (Fig. 5.55) are in many respects homeomorphic replays of the simpler species of Late Devonian-Early Mississippian Prolognathodus and. mid- to late Mississippian Lochriea. The pa elements in question (Fig. 5.55) are carminiscaphate structures with a cup that expands widely to the sides and extends to the posterior tip. Upper surfaces of the cup are characteristically smooth, but rare specimens in a large sample may have a node or denticle or two. Esoeciallv type-species, is now well known, as are those of distinctive of lhe Pa elements of Diplignathodzs, however, is division of the med.ian denti- Late Permian H. julfensis (Sweet) and Late Permian-Earliest Triassic 1L lypicalis (SweeI). cle row into a high anteior free blade and, posterior of it and above the cup, a lower carina For the most part, howeyer, Pennsylvanian and Permian species have been neglected, and that may consist ofa few denticles but is more their skeletal apparatuses are largely unknown. typically fused to a smooth idge ot spatula, In fact, a majority ofauthors.who deal with late which has a subquadrate lateral profile and Paleozoic and early Triassic conodont faunas drops off steeply to the posterior end of the recognize only one species in this long interval, cup.diplognalhodus was said to have a multimembrate apparatus at the time it was estab- H. minutus (Ellison) which, despite substantial differences in morphology of its various skeletal elements, is even regarded as the senior syn- but no illustrations were provided. It is signifilished by Kozur and Merrill (in Kozur, 1975), onym of FL typicalis, whose types are from the cant to note, howeyer, that a hibbardelliform Lower Triassic. The timited material available (i.e., alate) element with a long posterior process was listed as a component. to me suggests, however, that critical analysis of larger collections that span greater stratigraphic intervals will result in recognition of (1975) established Diplognathodus, perlmutter In the same year that Kozur and Merrill many species. But that is a job for the future. rnterpreted an aggregation of elements that form a recurrent group in several samples from Family Sweetognathidqe the Ritter, 1986 Lower Permian of Kansas as the skeletal apparatus of D. expansus. Perlmutter's reconstruction, which includes an alate Sa element The group of Carboniferous and Permian species refened to Diplognathodus, Sweetognathus, and. Neostreplognathodus nakes up a dis- mentroned vaguely by Kozur and Merrill in with a long posterior process, follows the plan tinctive and probably related stock that also their generic diagnosis. However, perlmutter's

125 BpeueC urels"a ur $lroj uerddrssrssu l Jedd0 srql pazutocej osl? I tr6i ui ssorojd Joue$od IrIo+ sluourolo sd pe^resejd palp4 u qcel sorrods snpoaputh Jo lueuolo DS eql -sn[r oêq (2861) Ireqac-lurld pue ^Food rellrg uo^ eju$ 'snpoqpusoldrqr ol peu8rsse sebeds B Jo leql Suuou ^q 'ra^g^\oq 'pofliululur sr uorleur sqej"dd? eqt ul sseoord rouenod Buo[ E rol\r -rojul srql Jo pbdrul eql erllp ueru?^1,{suuadtueuele elqe ue Jo sreof uoruui Jo uo$npu s,jeunurljod Jo Sl lsrg er{l lnoq" tuesardoj lscrlrjt lsour eq 01 uress Ilure] l pu? relllg uo^ ol pelorfualu IB Jolur u?-sougs u?îouo]al '[llzlgrceds'mtuddxa 'O roj pesodord rennu ejnue oql 01 luep^rnbe p^jetui ue Aq sntdt -nuwoj '7 -Ilad euo oql ueql reuel eqr Jo 13q10III eroru Jo esuerrnsco lsq aql uro{ polej? snlaedde ue e,{eq plnoqs axueq pldb snpoap -das s 'snudqdto'(j 'snpoqlousoldte Jo sorceds - r.l? Jo e^n"[ar esoll e sr snpoqtdusoldle tr.tll perusu lssplo oql Jo erueljncro lsjg eql l"ql uortcrûoc Jreql.{q si uo[seeensq1 qlhl tuelqojd ledrcuud oql ^lusd ts?el 1? pocuonuur ueeq oêq ol rrjees llure] l pu? Jgllrg uo^ 'uor 'snpoaputh 07 ue\l sntotnu,twoj oaulpo1 o1 -urdo/fu?jtuoc srql turqceor uy 'slueuele EdJo pelelej otout sr snpoqpusoldle lelq0'sr fluo pasoduroc snlejedd? olejqurorurun e pbr{ tzrlt-ll'l ^lasolo ur pe$e8llns I e eroldxe 'snuoe oql Jo serceds reqlo 'uojsuelxe,{q 'pug ol olqgluojd seruoceql'snpoqpusoldte ^trtrqrssod Jo selo snsuodxa 'c, l?ql apnlcuo3 llrrran pu? renrg -ods Jeqlo Jo snleredd? eqljo o^rleluasojdej se uo^ 'uoqs ui 'snuee leql Jo I?crd,(l sluoruole ueryr si '(S/6I) rotfujlred petcn4suocar s? Ed aql pelcel 'snsuddxa snpoqiousoldte Jo ^q s$ejp.'ddeqt li ^puer?dde t?ql (esprqlpuesn^ -"J snqpu8sn^dj lo seneds urolueqd 'tsesilns lqeru? Jo ^llru?j) snlh"dd? eql Jo sluouoduoj se snsuod sluaruelo Bd Jreql ur ssrlublturr srtolor{djor[ -xa'ojo snla"dde eql ur suorlsod S pue I l eql se pet?lej se lou ele/,r,. snpoaputh pue Jo sluedncco s" palardjalur Je nurfed slueur snpoqtdusoldt1 ÎosolJ l?ql etecrpur lq8ru sesnl?red -ele uriojiirer aql pr?eoj oq^{ '(986I) IIlrraW -de lelalels Jreqt Jo luauolduror uuojru?j eql pu Jenrg uo^ peuorlsenb ueeq ur sacueje.up l?ql pe$e63ns tnq 'uslqojd e se s"q JeqloEol sluauale ^q aseql dnols ol uorsbep ^lluecej 'snpoqtdusotdal$oan lo esoql e)iil qjnu xtqeqord ore lnq pequcsep uoeq tou eêq flquusopa^s pue snpoqtousoldle Jo slueuole qs Uel 01 sluou.rele?d pue.qd.w,cs,qs ^q pa,rolloj 'lq8u uo slueuole es oeprqleusofe^{s eqt Jo aeues ol pou8rsse solceds Jo sesnleledds pue stuetllala.gg g.3![ tnpoqr.utotatlo taqtau'oraaas VJNOOONOC AHJ 8ll

126 THE MAJOR CONODONT GROUPS I l9 that appear to represent Diplogndthodus and are from a stratigraphic interval that is well within the range of Lochriea and. Vogelgnathus. Close sirnilarity in morphology between Pa elements of Drplognathodus expansus Perlmutter (1975) Sweetognathus merrilli Kozur (1975) suggests ^nd. that the Sweetognathuslock developed from diplognathodontan ancestors in the Early Permian. Species of Sweetognathus (Fig. 5.55), like those of Diplognathodus,had, a quinqui- to seximembrate skeletal apparatus in which alate elements in the Sa position have a long, denticulated posterior process and structures in the Pa position are carminiscaphate elements with a relatively short anterior blade that continues posteriorly across the broadly expanded basal cup as a carina that is basically an adenticulate ridge, but may be replaced by a single row oflow broad nodes or supplemented laterally by a pair of subparallel rows of such nodes. A characteristic feature of the Pa elements formed by species of Sweetognathus is development of a pustulose pattern on the upper surface of posterior nodes. Such a pattern was also developed on Pa elements by species of Lochriea, which may suggest a relationship. Evolutionary development of the Sweetognathus lineage has recently been traced by Ritter (1986). Ritter (1986) has demonstrated that species ol Rabeignathus Kozur (1978)(Fig. 5.56) have tognathoduspecie seem not to have the distinctively pustulose surface that is characteris- a quinqui- to seximembrate skeletal apparatus, similar to that of Sweetognathus. The Iwo tic of comparable nodes in the Pa elements known species ofrabeignathus are recognized, formed by species of Sweetognathus, Homoiranognathus, Rabeignathus, and Lochriea- T re however, by their distinctive Pa elements, which are like the double-rowed carminiscaphate elements of some Sweetognathzs species sess with information presently avaitable. It is significance of these features is diftcult to as- but differ in having one or two additional subparallel rows of somewhat rnore irregularly represents a stock developed de novo fron Di- possible, of course, that Neostreptognathodus pustulose nodes latenlly. Rabeignathus, which plognat hodus, whose stratigaphically discontinuous record extends almost to the end ofthe almost certainly developed frcm Sweetognathus, has a r/ery short range in the Early Permian. Homoiranognathus was established by Ritter (1986) for a single Early Permian species (1L huecoensis) known only from carminiscaphate Pa elements on whose upper surface an adenticulate, pustulose median ridge is flanked laterally by two to four subparallel rows of pustulose nodes. Elements of H. huecoensis are surely distinctive in appearance, but I am not Babeignethus Fig Pa elements typical of species assigned to Rabe ighat hus and I s arc icel la (Sw eetognathidae). yet completely convinced that this pattern (or that of Pa elernents of Rabeignathus) merrts recognition at the generic level. Sweetognathus wlritei (Rhodes, 1963) was also the apparent ancestor, in the Early Permtan, of Neostreptoqnathodus Clark (1972)(Fig- 5.55), a stock of stratigraphically important sweetognathid species with Pa elements characlerized by subparallel rows of nodes separated by a well-marked median groove or channel. It is also of interest to note that nodes in the posterior rows of Pa elements of Neostrep- Permian. The Late Permian Pa elements for which Kozur, Mostler, and Rahimi-Yazd (1976) established Iranognathus arc, in many respects, homeomorphic replays of those on which Ritter (1986) based Homoiranognathus. Evolutionary patterns in Permian stocks are currentty diftcult to reconstruct because collections from criticat intervals and facies have yet to be made or described in detail. However, it

127 JO SluellIele "d eql qsmsu[srp PFo^\ l3q1 sejnl -"ej Jo uorleurquroc luecgrusrs ro ar$eal olsurs,(u? ol lurod 01 llnslgrp ^lj?lncru?d 1r pug I 'uerrrjed eql Jo uud Je^{ol oql olur u?ue^ -I,(suued eql qsnorql setuer pua uerddrssrssrl l lselel eql ur Po Ioê qjrq 'vrypu8oppy Jo pu? 'ubrddrss$srw eqljo do1 eql ot pr?^{dn sen -urtuoa ptre srultdusottlddj Jo eeuer t\ Jo ued alq eql q sjeodd? qcrq.{ 'snqlou3snan3 qyil. osec oqt osle sr sql ujojl?ld Jouolsod pe^\oj -olqnop aql go urtreur fqtu eqt srrrjoj tpql AroJ eql Jo puo JoualuB erll qlr^\ snonuuuoc sr epqq oql Jo pue Jouelsod oql qcrq,yr ur slueur -olo ed tlrnq l?q1 serceds pqleuesn-{?c sepnl3 -ur 'euoz EtEInua0 Joddn-Erlorlsosl uerddrs -srssrl I Js,'ao.I eql olur pje,$dn soeua oslb pud snqtousolt9d ueql ralel tlq [Iuo ueruoêo oql rrr " lnqep slr epeu qcrq^\ 'snqpu8dpqj 'Io OI JUoU -Ec Jo sesnl?jeddv 's1aor esorll Jo Joqto eql ûeur Jo euo qll^l snonurluoc oq l(eur 1I Jo 's,ltroj ulrojleld rouolsod o/$ eqljo spuo rouelu? aql uea^{leq elsrpeurjelur lurod? le urjojleld aql urof i(eur epelq eql 'pue rouelsod sll tv urjoj -t"ld roualsod pa^{oj-elqnop ',{rolj?u,{?lo -ue8 s pue ep?lq aar.y roueluz 3uo1 flaû?lej? qll.r stueulele el?qdecsurtl$c Pe \oq [q peld -ntco sr uorlrsod eql pue ssecojd Jouelsod pel?fcrtuep '3uol "d s"q tuelrjele?s alqe egt qcrqa ur sesnl?rcdde " IEleIa{s elsjqlueu.itxes paurroj araq pepnpur sluopouos epiuipoij zo I96I 'sapoqv puo uusnv aoplr1ldu8snv) tllutdl ZI'6 5 'eprurpoljszo aql Jo'osle 'pue ero pelffiu seull qloq Jo uo4curlxo snoeu -?rodueluoj i(ijee uaq^l 'rrssbuj lsorljee egl -et eql uo ecu?rgru8rs Jreqt Jo I?cqdoIS ru? I olul uerujod pue snojqruoqjej egl q8nojql tnq'snuee elx"s eqljo sercads pelelej,{lesoljjo, lpoteeder,,8uqt srl pp,, qcq^\ Jo qr?a 'se8ee sluoruolo?d eql qsmeuqsrp 01 luerouns,(fr?t -v\ snpoqwusoldle pue snpoaputq-durpol -JJC ejb sajnleej asjqf'luenuuoj J3 -nzo er+ 'eprurpolrezo oql Jo se8?eurl Joferu l?ql sapou Jo sîoj I?urtJ"ur Iellendqns ^ll?rolel oîl,(q lujla.urp or(1jo srjqtuatu pue Jql lujs ejdal D)t) pejeidoj eq ielrr srultouslwnlldrj Jo sluoru -nsr Dna)rz.tDsl pue srloztdlt snpoaputh leql -olo ur selcnuepjo s^{oj pursffu] oqljo euo sr uoq?lajfuolur ](lo{ll ejour V snouecr^ eje,{\ s?ejeq^{ "d 'epqq ee{ eql Jo u rcur reddn agt Jo pjeuo8 o^\l erll Jo serceds Jo slueurala rruojl eruord oql u [luo snqpusotl?d Jo esoql u]o{ -ru"j l"ql (sreqlo Suour? 'oiii (q) peunsse ueeq n$w snqpusnqsol) Jo sercedsjo sluouele?d seq li o?prluopoqt"vtr\.uv aw Jo snpoaputh 'ejeue8 rnoj eql Jo uoqpndes elqertoj e loo.de (n potrs ueeq.{f?uolsnc seq D aninsl Jo ol llnsgrp,fio^ 3q pfo^{ lr uoqnqulsrp srgd?r8 dllsecue ecuer{ :Jrss?ul -rle4s punfsrp lsellleo eql Jo u?rurrad sql JoJ lou eje.tr lrji JoqEq euo lsalel fto^ egl roqlra luo{ paqursep ueeq s?q lxeu eqt olur etuel ro euoz teql ot peuu snpoqtousoldlo on?uuec eql Jo seprs qloq -uoc Dqlre eje ^luo pu? 'u?rddrssrssq l eql ur JeqEq Jo euo uo dsn3 eql Jo $[ueu IBJolel uo pedole^ seuoz o/ru euros 'euoz snuexel aql ur Jeed -ep eq Feu elonuap pcruo3 elsurs? pu? 'qlbuel -d? dnoj8 srqt Jo Ejeuag reqto eql '.eaoz ewq llnj slr roj pol?lnjrluep sr?uuej uerp3tu eldturs -uejc reddfl- rljrlsosl uerddrsslssrl l Je^\o'I aql et$ "fiq'snpoqwusoldro Jo osoql ol t3ads? [Ere olur setu"j pu" u?ruoêq 4".I eql ur pejeod -1e[ ur J?lrr[rs ere serceds lu?uodur -de snqtousottod s,r\oj alcduop purtreru on1 -rlells slql Jo slueurale ed JleqdEJsrurr.ureJ ^lecrqder8 slr uee?$leq 4erpeuuelu lurod le rujojl?[d 'rrss?lrj tsorlreo or{1jo (99'9'3r{) (epeplcnh) eql " Jo puo rouaue eql surof opelq eql qjrq^\ DJtz.tost o ajrjtosj ol pedsgj qlr^\ pal?clld ui sluouolo?d peurroj (/S'S 'EIC ui pstertsnl -rrp ere sru.lpu&our.qjo sdrqsuo4eler pue ur8r -[ 1ne) sn{du8oqdn1 pue 'snqwuslutort.tddj -ro aql SurleJtuaul qlp\ pet?rjosse suelqord 'snqpu8nqsolj'snqpusoltdd Jo sorceds 'uerrured lsq.el eql ar snpoqtdusold 'sojnleoj craoloqdjorrr Joqlo ur Jo uorl -!O ruo{ tueudoleêp crqfuouoeruoq paîi -elnolluep Jo el,qs pu? ezls ur JeJrp Jr?d -uorls E sluaserdaj snqeusountl t?ql (rseel lp e Jo srequreur UeJ pu lqtu ro '/rroj ^prll rujojleld 'eur ol) aur?s er0jo pua Jouelu? aql surof s^?^\l? epelq ^lo{rt ojouj sr U 'uerdul TloA\ elel eql ar Dtrq$ snqpusoiaa,lrs',{q pou^\edse^\ qcq,r eqt q8noql uoô suorpejrp olrsoddo ur peaoq ')4.aolsnqpuSouottoutoH etll eq êru JI?d Jo sjequeur gel pue Jo suownuduoc lqeu 'sr l?ql cqauasotfqd luesejdel snqpusoud.tl uewjred :,{Jleluul,{s III ssejj lrqqxe serceds prqleutsn^ e1?-i Jo sorcods o,,,(rl oql leqt,{[e{rtun sruoos VJNOOONOJ:IHJ

128 THE MAJOR CONODONT CROUPS t2l ClogheEnathus Adetogntthus Clydagnathus Fig. 5,57. Elements and apparatuses typical ofspecies ofthe Cal.usgnathidae. Clydagnathus, Cavusgtathus, and AdaognalruJ. Apparatuses of Cavusgnathuspecies ap- fact that specialists on Carboniferous conperience with these genera were it not for the parently exhibit Class IIIa symmetry in that odonts appear to have problems lhat arc ai right and left Pa elements are distinguished least as great as mine! In any event, elements of solely by being bowed in different directions. cavusgnathid conodonts are common in rocks Right and left Pa elemelrts of Adetognathus, on that record marginal marine environments that the other hand, are morphologically somewhat were characterized by shallow water ofvariable different and thus exhibit Class IIIb symmetry. salinity, and they are useful as guides to such In addition, Pa elements formed by species of environments. Adetognathus hal/e essentially no fixed blade, Ancestors of cayusgnathid conodonts have whereas in comparable Pa elements of Cavusgnathus srycies as rnuch as half the length of in Late Devonian populations of spathognath- been identified by Sandberg and Ziegler (1979) the blade may be incorporated into the marginal platform row with which the blade is lina insita (Stauffer). In those populations, Pa odontid ozarkodinides referred to Pandorinel- confluent. elements (Fig. 5.38) are dominantly singlerowed, carminate pectiniform structures with a I would ascribe my consistent inability to separate specimens representing species of Cavusgnathus and Adetognathus to rny lack of ex- right at its posterior end. However. minor prominent finlike blade that is deflected to the seg-

129 f]jlj-le!) srypusoptl) ruo{ pe^loê snqnusol -san ll.tll (9961) pr?qcro pue Eroqpu?S 'raulg uo^ ot slse88ns ',{lpcuauesol.{qd lueurdole ep s1r ur pecunouo:d erorll sauroceq oslp JelJ r?qt re.el aql leql lcej eql gll^{r raqta8ol 'srql ui8 -J?ru IESsq e^rss3coj Jo seuoz ou pu" secbjjns repun eleqd?cs Surêq ul snqpussno) tlnpe Jo sluelllele?d ot,{jl?c oloqdjour rzlrrrlrs ej? setoad snlpusotsaw Jo eqt ur seaels,(lj?a tuosojdoj leqt slueuelo ûesoluo?d 'lrd [es?q eqt ol Jouelsod pue IeeI,ftBurud eql 01 Ipura -Jsur ur8jeru pseq e^rssocej Jo seuoz Jepeo.lq pue JapeoJq Jo luaurdoleôp pnp"l8 pu? :laa{ loepqleusotsel l) szil lduso$an Jo luew fu"puooes eql Jo uoqlugep Surs?erour :qjlou -ole ed Jo rouelu? orlljo lueurdoleêp ur gs?ejcur s,{er repun pue 'op$ 'Ioddn '8S'9 '8Id pnp?ra "? :ur8j?u rurojl?ld Ual orll Jo tueul8es teder?d eqtjo Atoloqtuouj ur a8ueqc pnp?jt peîoûr -trg uo^,(q,{pnls srqda ouoru luocoj dje?jo snqpusoisal4t lo tueudoleêp crloueeolr(qd sfefqns oql ej" '.{lruej srrlljo slequreu u^\odi lueruees lede -red pu" euum aqljo pue rouelue eql qteouoq Îuo eqt elnlusuor qclq^\ '(89 S 'tlj) (rs6l) pedoleêp sr 'oôoj8 u?ipolu eql Jo qcuejq e JJo\asrg snqrdusotsrjrf Jo serceds a^g eql apnlour [?ru qcrq r 'leel fu"puoras V '(pjeqrjo I86I 'sapoqy puv u4snv anplrltdasotsai4j (ttrutdl pue SJoqpu?S'Jellrg uo^ uorsjaê,, EI'69 us pelujol) urejeuj I3s3q ^q,.dr!s e^rssecoj Jo seuoz /rloleu ^q lld eqljo Jouelsod pejepjoq $ pue ' pluipolj?zo qlauopru Jo rouatu? lrd ps"q ["Ius? sesolc eql Jo see?eull tueje.grp snorr? ui peldop" -ue qcqî leel u"rpeur peôojt,(q palr"ru sr,{lepl, a lueludoleêp Jo uje Bd eql stuerl.ialo?d sr?{/ru8o$aw " Jo eprsjepun oql s?/i\ 1r terll p"j eql loj ld$xe Euruonueur ^lreelc '3tu?uootul quo.4 aq lou plno,,a,{trjrqrssod srqj sjotseju? clruouoxn rarurard utrss" (986f) pftqcjo pue puruouuopued petuouncopun ro poullueprun 'SreqpuEs'ro rg uo^ qclq \ ol loda?d pelel te, s? rriolj {1e,r4ere1r pedoleôp (mqlnu8n -njrluep,{le^dcurlsrp? otur pedoloêp sr ule -Ll8ol) pte'snlqou8tutdrtdd)'srulldusoiapv -reu elrsoddo aquo pue rouelue aql 'uuojteld -mqnussn^d) 'snqpusoqddj ''a 0 spqleua eqt Jo urfu"u rq u p3bpu oql qlv( snonu4 -snêc Je13l eql 13q1 lno pe[u oq lou uec 1r os -uoc sr'qltuel pnbe,(leteurrxojdd?jo slueuees 'Jeê^\or{ 'sljols prql?u8sn^?j4"l eqljo sa^4 paxs pue ej{ olur PePr^rp sr r{jrq.n 'Jpelq aql -Elueserdar $rg eqt uro{ snqpu8dptlj pue 'uuojt ld equo drl rouolsod aql ol spuelxo l"ql snqtduso.tlod alejedos,(lluojjnc sdec qcuejq puu"o lerpeuqns leulpnlrtuol e ruo.g sqtnorl snqpusopq) et+ Jo std.olrcnu\ttd.o} ere'sntlpus I uumpe [q poterzdes e:e 1eq1 sursreru peaplj -otapv 'ratel 'pu9. snl ou8sn oj leql pue '^lr,{issje^su?jt'paulnldn,(dq8rls qtr^{ uuojl?id -ure orp Jo qtu?jq snqpusolpd eqt vrorj etjrrl ped?qs-a rouelsod z pue ep?lq roualue qerq usrddrssrssrl l-pllu ur pedole op snqpustu E qll/'( sojnpruls rujojrurlced aleueldrurlujsc -tnuddj pue'srulpu8nq8ol)'snq JouSoqdoJ ere serceds snqpuso$ai,4{ Jo sluarxele ed l"ql ssone 1q3[u ouo urroyeld eql Jo eprs 'urjql PaurJoJ leql sluopouoj Jql fq pezr lqeu eql uo ssopou eql glr^\ snonunuoc l?jeulur ele^r serxeds snlpusolsal[ Jo sluaur sr epsjq eql ^\oj sluaujale Ed Jsoq^r ur 'sr?{, -ele d eql i(iuo osn?caq Jo sasnlel?dd elejd -DuBDpqJ ol Jo 's,r\oj purs:eur o,lrr1 slr uee/(l -uoj tuqcn4suocoj Jo qof egl 01 el?nbepeur -oq [ujojl"ld eqt surof teqt opqq? qt[^{ '.snryl JJe,r suorljellojiqplre e JsnEJJq Jeqlla 'sjrj -DuSottDd ot Jaqtre esu ue^6 o^"q ot tq8noql -eds snqpusotsal I Jo slueurela?d eqljo uounq eje eseql Jo slueu?a 'epelq eql 01 Jouel -ul.slp pu? '.tuetotuo ',Goloqtuour uo sesncoj -sod selcuuop e{rlapoujo s^1or elqnop podola^,{pnts terij (986I) preqcro pu? 'EroqpuEs'rol -ap suoq?fdod au?s eqt Jo stuour ^llusjedd? VJNOCONOJ AHI zzl

130 THE MAJOR CONODONT GROUPS t23 Cavusgnathidae), whose scaphate Pa elements have a double-rowed platforrn and a blade that joins the right maryinal row. Pa elements of Mestognathus are homeomorphic with those of Scaphignathus (Fig. 5.41), which is thought to have evolved in the Late Devonian from Pandorinellina insita (Fig. 5.38;- as did Clydagnathus, the proximale ar\cestor of Mestognallrus. Short of a thorough restudy and revision of Pandorinellina, the Cavusgnathidae (including Clydagnathus), and, Fig. 5,59, Elements typical of sp cies included in the Meslognathus,however, I see no way ofaccommodating these remarkable homeornorphs Coleodontidae. (and their common ancestors) in the same supragenenc category. Thus, somewhat anomalously, I suppose, rctain Scaphignathus it the is difficult, if not impossible, to diagnose properly because the type-species of Coleodus, its Spathognathodontidae, whereas its younger homeomorph, Mestognathus, is accommodated in a separate family, the Mestognathidae. that make comprehensiye morphologic inter- type genus. is based on fragmentary specimens Possibly the best way to insure taxonomic symmetry would be to establish a separate family cies in this taxonomically isolated group pretation impossible. In general, howeyer, spe- also for Scaphignathus, which would raise the formed relatively large elements that have hyaline, fibrous crowns, which (in the case of,s/er- possibilility, of course, of a separate family for each conodont genus! eoconus and MixoconuJ) consist ofrobust coniform elements or chains of such elements Mestognathus is interpreted as a denizen of harsh, nearshore marine environments characterized by high saliniry and probably land- connected (in Coleodus and. Neocoleodus) with weakly (in the case of Archeognathus) or stoutly ward of the shallow, inshore environment inhabited by its progenitor, Clydagnathus- von crowns are flat, broadly convex, or longitudi- their neighbors at the base. Undersides of Bitter, Sandberg, and Orchard (1986) speculate nally grooved, and in numerous specimens of that restriction to such an extreme envronment may help explain the rarity of Mesto- a prominent basal structure that consists ofan Archeognathus and, Coleodzs crowns surmount gnathus and. the fact that it may have mineralized only the Pa element$ of its skeletal ward projection and apparently lacks a cavity elongate bar that exhibits a conspicuous down- apparatus. or excavation. No basal structures have been observed with elements of.s/ereoconus, Mixoconus or Neocoleodus. 5,10 Order Unknown Barskov, Moskalenko, and Starostina (1982) illustrate numerous bonelike features in the Family Coleodontidae Branson and basal structure of Siberian specimens referred Mehl, 1944 to Coleodus,bntK)apper and Bergstrdm (1984) This family is retained for Coleodus Branson were unable to identifi, comparable features in and Mehl, 1933, Archeognathus Cullison, 1938, the basal structure of Archeognathus. Altho]j;gh and Neocoleodus Branson and Mehl and the crowns of elements assignable to species of possibly related forms such as Stereoconus the Coleodontidae clearly exhibit the intemal Branson and Mehl, 1933, a.nd Mixoconus structure of conodonts, the basal structures Sweet, Elements of species assigned to have no counterparts elsewhere in the Conodonla. No relationship to olher groups is these genera are shown in Fig In connection with their thorough recent apparent. The Coleodontidae, if a natural study of Archeognathus, Klapper and Bergstritm (1984) point out that the Coleodontidae unit, might represent a separate class of the Conodonta.

131 -ouoj 11861) C V 'sirj"h pue ''J 'f tetlll,.{ urnua ev eql uo{ seun"j tuopouoc eluos r'ni 'ugrlspurj "l'{\ 'ralserz 'f ) 'Jelt!-l l '(986t)'lt 'f trl'sselg pu?'uap ue^ 'J H 'C I I'pr""?oog 'sepoqu"'i 'U 'u4snv ''C'rsdd?f)I 'Ltt, ''l I S 'urojls8jeg 'C.r!\ 'tee,ng'"i '(I 5lJplC -l '68 SJaquqJaas $utsburulzstol Duno).'I I 'sele^\ qlnos ujensa\prur ruo+ sluopo -ZOl'(Z)6 salpnts 1oa9 qun Suno^ utdtlsug -uoc ueunlrs epprj ^\0N l pue,{lrea- (9861) - '"cusulv quon ruel$,r\ w sluopouoc uerrujad ',9-l Jo,teNns 'Q96D '.1 U 'uor8uqtg pu? '.I '6l rljstoluapog satwds -apuo'i ssah qqv azuard-uoqre)/uoêo rep 'O '{r IJ 89I-rtI 'tg:s uoaolod 'pa) 'Awo pun ejnts-eueumplco^\ Jep Sun8nqc${cueg -uox?l luopouoc JrssEuJ-oruJad uo 8uu?eq tlru suoqjdlreluo ueqcsru,{zjoq-ouoqj sep etqd slr pu" srsuc ueruued,{f?a (Z/61) 'I O 'lreic -?J34?rts-ueluopouoC elo (t961) D goqcslg '6OE-662'Q)65 soa o4 y 'sn\musotndls p'de 'rnb-r o8plrquleg :op8roloj Jo euolspues AurpreH eql ruo+ sluopouoc :[ 'ou setpnls luopo -uoj ( 6t) C 'hl 'Nohl pu? ''g A 'uosu?lg '9SS-619 'lz 'tuoaldd 'f f)ljnlqo) uo{ sluopouoc ueunlrs re^rot (tt6l) C'J'uosuErg pue g a'uosuprg '802-l '(OEI salpus unosstw '^ un 'ltred 'unossrj IJo u?rddrssrssrj l re^{o'i eql Jo,t3otol -uoepd pu? fqd?j8rl?jls (8 6I) 'S g 'uosu"rg '89t I -Lelt 'G)eV 'ruoal2d 'I 'sexoj 'qtseg uoql - TEI '(uerchopro elppq l) uo4?ruroc?ged uoj eql tuo+ stuopouoc (6961) g 'I ',\{Eqsperg '/S-l '6t EcrSoloeo?tdrrts 'loôl rgrceds pue 'Juoue8qns 'cuoue8 eql te (spuoqdoluopouoc u?ruoêc elsl) snlejsd -de sdaloputl'j eqt Jo uo4crutsuoaej l"cllsrl -4S'(6/6t)'g 'tunq) pue'uop ue^ I,^{ 'pj?psoog 'tsi- t '(Z)88 S tas 'd0qrsual -a/u polv asputtuapan x,ord 'PuEq euusru Lz '(6zd0s srultdusoqo1'srulwusott)vg BJoueA luopouoc 'tuoaldd wv Ing eugrprrl pug orqo ur quel? tusulele4lnul oqljo fuesol,{qd (S861) ) UnEr{J -Arnbe plelel str pus',olcnlua)jo (u?iciaopjo '961-ZLL'lS luoaldd f EpeveJ urslse/$quou elpprn) euotseulrl uolturxal eql ulo{ sluopo ruorj sluopouoc pue setrqolul u uo{qto'i -uoc (996t) C A\'teo^\S pu" ''W 'S 'ru,ojls8reg '(LL6t)' -'O 'tured pu? 'E ( g 'uouou?qc '8S-St '8r7,-99t 'ZEt 'qqv 'SI 10d puo sltssol sluopouoc ulojleld uachopro ',r"iis 'pa) 'qt 'N (uelueds-an) uelf) ueqcsusql Jo ecuecsrusrs crqda8rlejlsorq pu" 'sdqsuoll ueqcrlts9 Jep suoê(i-dlun sep ueluopouoj pun arqdsrtrlats 1696I) f'lpu?o pup'd'slr J -eler tu?uonnloê ',{qdei?oosorg( 861) - 'L0t-s6z'69 blsspu loa, )lston sepr '98- I r -uopel?j u?raoûon 'uor8o){ ruroqpuorl eqtjo '9 MoaDlDd p?oa, (sluopouoc) se8elquesse Juolseurl EpuoloH aql [uo{ sluopouoj (uelj snportrj leruoêq elpplhl (Z16l) d 5lsu,tllng -rôpjo) u?p{corslrqa (6/61) W 'S 'urqrtstuog 'v9t-6tt '9t oldtls '09- t'(z-i)9 PUO SllSSOtr 'Snpolnl JO uo4nloâ eql pu" eeprt DzlUOlOd loa9 DlzV tnsefj erselrs-er^?johl -uopoucl,{illuq luopouoc eql ur srsoqtuouop eql -eed( 86I)'U lqruojcl Jo u"d ujel$equou eqt ur fqda IleJlsorq I pue ' /t J 'peaqpeojg luopouoc snorejruoqrpj ro^\o.i {986I) Z 'qlas lro^ '^slrd[{{corqs d 'U '\ZZ-BtZ'ge' nb pu JaruIIs l^ ld'pe) ^\sn onnuy quon lo stlssoi 'wy los 'pad 'sluopouoc aql Jo osn crqders xapul urglz-s Z 'dd'sluopouoc GV6l) - -rlerls pue uorlecgrss?lj (5Z6l) S U 'relsseg '99t-99r '[06-28'(l)9r 'Zl tuoaldd ]. uo4nqulsrp JrgdDr8n?Jls slr '2861 'lpu.moi ldlsolotuoaloj ur qslfug puc. snpoujl stj.ue? tuopouoc eqj (8 61) - 01 pel"tsuerjl '(f)286i ldutnqz 'luoal '692-lLl '(08 sa'lpws unosslw '^lun -rj ulfuqcouo^zod { puojoluopouo{ Ilsou 'unossqîjo eleris {esjc,tssejc eqt uro{ sluop -qoc : 'ou sarpnts tuopouoj 'Ot6i -qzolp uud e^1s.la1?zdlop odôn (ZSet) a f - 'esrlsojsls pue' V J'oluelE)[sol/{ "S'I'ô{sJEg 'zl-g'c)8 sar '86-65 '0I 'tuoadlod ta pa9'p ap -pnts unosstw,u?n 'unossri I Jo (usrcrôpjo -ZroXJo pue '?luoq"plo 'sure1unol,,{ Je \o'i),ttrj uosjejef :unossrl,^{ Jo (u?un[s) eplcnqjv ^rc8ol^qd 'uon?uroc slueij aql Jo sluopouoc (uedlcolue^.\-rrsueôpuel'i el?d ueunlls lueur -elorrlnw (9161) C'redd txpue 'g I.)ltueg '061-O9L'(dLV ',uoal -Dd 'I epeue)'ceqenb 'uortbrujoc cqs,tw eql rrro{ sluopouoc uercrôpro elppu l pu Jeao'I ( /6I) 'S 'I JÎ 'r-{srr?tdod PUE 'U 'C 'sauffg '91-l 'ZEl Ing /b6tns 'pad outoqdltlo '?ruoqpplo ruetseo ur (uerchopjo raddn pu? elpprw) dnorc elor^ pu? uoiletrijoc epluorg roddn ( 861) C A\ 'lae,,{s pue 'ta J 'uepstuv.9zz_lzt,(dzz,pa).rs!h.tdn 'sfit[ qsltyg ng 'puzljepjog qslel\ eq1 tuo{ stuopouoc,ftoôpu"ll '(ZL6I\ 'f U 'eapfplv 'OB-92'BS DaoWa'J DuDl8laquDlruas (puel -qcslnec 'uje,(?g:uoô(-le11lw pun -Jotun) uolqnc4uoj pun uetuopouo] lrw sepls,{{ -uetueu sep ujlqjrqjs-ujlrlnjhuef rep AunJ -epsqc eqcsqde$ltejlsorg (r/61) C '!^\eulv sejuarajau YJNOCONOJ IIHI tzl

132 dolta- In Treatise on inyertebrate paleontology Pt. W, Suppl. 2 (ed. R. A. Robison). ceol. Soc. America and Univ. Kansas, 202 pp. Cooper, B. J. (1975). Multietement conodonts from the Brassfield Limestone (Silurian) of southern Ohio. "/. Paleont. 49, (19'77\. Toward a familial classif,cation of Silurian conodonts. l. Paleont. 5f, 105? Cooper, C. L. (1939). Conodonts from a Bushberg-Hannibal horizon in Oklahoma. "l Pa- Ieont. 13, Croft, J. S. (1978). Upper Permian conodonts and other microfossils from the Pinery and Lamar Limestone members of the Bel[ Canyon Formation and from the Rustler Formation, west Texas. Unpubl. M. Sc. Thesis, The Ohio State University, Columbus, 176 pp. Drygant, D. M. (1974). Prostye Konodonty Silura i nizoy Devona Volyno-Podolya (Simple conodonts ofthe Silurian and lowermost Devonian of the Volyn-Podolian arca). Paleont. Sb. Lvov Univ. GlO, Dzrk, J - (1976\. Remarks on the evolution of Ordovician conodonts. Acta Palaeont. Polonica 2r, (1983). Relationships between Ordoyician Baltic and North American Midcontinent conodont faunas. f'offils and Strata 15, Dzik, J., and Drygant, D. M. (1986). The apparatus ofpanderodontid conodonts. Ielrara 19, r Ethington, R. L., and Brand, U. (1981). Oneotodus simptex (Fumish) and the genus Oneotodus (Conodonta). "/. Pqleont. 55, '1. Ethington, R. L., and Clark, D. L. (1982). Lower and Middle Ordovician conodonts from the Ibex area, western Millard County, Utah. Brigha.m Young Univ. Geol. Studies 28(2\, t Fahraeus, L. E. (1984). A critical look at the Treatise family-group classification of Conodonta: An exercise in eclecticism. Lethaia Fahraeus, L. E., and Nowlan, G. S. (1978). Franconian (Late Cambrian) to early Champlainian (Middle Ordovician) conodonts ftom the Cow Head Group, westen Newfoundland.. J. Paleont.72, L Fortey, R. A., I-anding, E., and Skevington, D. (1982). Cambrian-Ordovician boundary sections in the Cow Head Group, western Newfoundland. Pp in The Cambrian- Ordovician boundary: Sections, fossil distributions, and correlatioflj (ed. M. G. Bassett and W. T. Dean). Nat. Mus. Wales, Geol. Ser. 3, 27 pp. Furnish, W. M. (1938). Conodonts ftom the Prairie du Chien (I-ower Ordovician) beds of the Upper Mississippi yalley. J. Paleont. 12, THE MAJOR CONODONT GROUPS Gagiev, M. H. (1979). [Conodonts from the Devonian/Carboniferous boundary deposits of the Omolon Massifl. Guidebook, Tour 9, Biostratigraphy and fauna of Devonian-Carboniferous boundary deposits. l4th Pacifrc Science Congress, Khabarovsk, USSR, August 1979, Suppl. 2, 104 pp. (In Russian, \ryith English diagnoses ofnew genera and species.) Harris, R. W. (1964). Subgenera of the conodont ge\!s Multioistodus in Simpson-Burgen (Ordovician Arbuckle) conodonts f.om Oklahoma. Okla. Geol. Notes lI8- Harris, R. W., and Harris, B. (1965). Some Wesr Spring Creek (Ordovician Arbuckle) conodonts from Oklahoma. Okla. Geol. Notes 25, 34-4'1- Harris, R. W., and Hollingsworth, R. V. (1933). New Pennsylvanian conodonts from Oklahoma. Am. "L Scl., ser. 5,25(t47), t93-2o4. Hass, W. H. (1959). Conodonts from the Chappel Limestone of Texas. U. S. Geol. Sury. Proll Paper 2941,365-40Q. Helrns, J. (1961). Die " nodocostata-gruppe" der Gattung Polygnathus. Geologie t0, 6'14-'71t. Huckriede, R. (1958). Die Conodonten der Mediterranen Trias und ihr stratigraphischer Wert. PalAofi L4l-175. Huddle, J. W. (1934). Conodonts from the New Albany shale of Indiana. Bull. Am. Paleont. 2r(72), 136 pp. Jeppsson, L. (1974) ll9'151. Aspects of Lare Silurian conodonts, Frssils and Strata 6,19 pp. - (1983). Silurian conodont faunas from Gotland,. Fossils and Stratq 15, l2i-144. Kennedy, D. J. (1980). A restudy ofconodonts described by BRANSON & MEHL, 1933, from the Jemerson Cily Formation, t-ower Ordovician, Missouri. Geol. et Palaeont. 14, Klapper, G., and Barrick, J. E. (1983). Middle Devonian (Eifelian) conodonts from the Spillville Formation in northern Iowa and southern Mi[- rrcsota. J. Pq.leont. 57(6), Klapper, G., and Bergstrom, S. M. (1984). The enigmatic Middle Ordovician fossil Archaeognathus arrd its relations to conodonts and vertebrates. I Paleont. 58,949-9'16. Klapper, G., and Johnson, D. B. (1975). Sequence in conodont ge rs Polygnathus in Lower Devonian at Lone Mountain. Nevada. Geol. et Palaeont.9, Klapper, G., and I-ane, H. R. (1985). Upper Devonian (Frasnian) conodonts of the Polygna- /ltis biofacies, N.W.T., Canada. J. Paleont. s9(4), Klapper, G., and Murphy, M. A. (1975). Silurian- I-ower Devonian conodont sequence in the Roberts Mountains Formation of central Nevad,a. Univ. Calif. Publ. ceol. Sci. ttl, t-62. Klapper, G., and Philip, c. M. (197D. Devonian conodont apparatuses and their vicarious skeletal elements. Ietra ia 4,

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134 THE MAJOR CONODONT GROUPS Toko Range, Glenormiston, pp. l2-15. In Hill, D., Playford, G. and Woods, I.'1., eds., Ordovician and Silurian Fossils of Queensland. Queensland Palaeont. Soc. (Brisbane). Norby, R. D., and Rexroad, C. B. (1985). Vogelgnalhus, a r'ew Mississippian conodont genus. Indiana Geol. Sur,. Occasional Paper 50,l-14. Norris, A. W., Uyeno, T. T., and Mccabe, H. R. (1982). Devonian rocks of the Lake WinniDegosis-Lake Maniroba oulcrop beh, Maniroba. Geol. Surv. Canada Mem.392, 280 pp. (Also issued as Manitoba Mineral Resources Div., Dept. Energy and Mines, Publ.77l.l Orchard. M. J. (1980). Upper Ordovician conodonts from England and Wales. Geol. et Pa- Iaeont Pander, C. H. (1856). Monographie der fossilen Fische des silurischen Systems der russisch-baltischen Gouvernemetts. Akad. Wiss. St. Petersburg,9L pp. Paull, R. K. (1983). Dennirion and strarigraphic significance of the Lower Triassic (Smithian) conodonr Gladigondolella meeki n. sp. in the rvestern United States. J. Paleont.59(l), 188- t92. Perlmutter, B. (19?5). Conodonts from the uppermost Wabaunsee Group (Pennsylvanian) and the Admire and Council Grove groups (Permian) in Kansas. Geol. et Palaeont.9, 95-l15. Puchkov, V. N., Klapper, G., and Mashkova, T. V. (1981). Natural assemblages of Palmatolepis from the Upper Devonian of the northern Urals. Actq PalaeonL Polonica 26(3-4\, Repetski, J. E. (1982). Conodonts from El Paso Group (Lower Ordovician) of westemmost Texas arrd southern New Mexico. New Mexico Bur. Mines Min. Res Mem. 40, l2l pp. Repetski, J. E., and Ethington, R. L. (1983) Rossodus manitouensis (Conodonta), a new Early Ordovician index fossll. J. Paleont. 57(2), Rexroad, C. B. ( l98l). Conodonts from the Vienna Limestone Member of the Branchyille Formation (Chesterian) in southern Indiana. Indiana Geol. Surv. Occasional Paper 34, l-16. Rexroad, C. B., and Nicoll, R. S. (1972). Conodonts from the Estill Shale (Silurian, Kentucky and Ohio) and their bearing on multielement taxonomy. GeoL et PqlaeonL SBl, Rhodes, F. H. T. (1953). Some British Lorver Palaeozoic conodont faunas, Philos. Trans. Roy. Soc. London Ser. B. 237, (1963). Conodonts from the topmost Tensleep Sandstone ofthe eastern Big Hom Mountains, Wyoming. "/. Paleont. 37, Rieber, H. (1980). Ein Conodonten-cluster aus der Grenzbitumenzone (Mittlere Trias) des Monte San Gioryio (Kt. Tessin/Schweiz). lzr. Naturhist. Mus. Wien 83, Ritter, S. M. (1986). Taxonomic revision and phylogeny of post-early Permian crisis br'sseftwhitei Zone corodonts with comments on Late Paleozoic diversity. Geol. et Palaeont.20, Sandberg, C. A., and Dreesen, R. (1984). I-ate Devonian icriodontid biofacies models and alternate shallow-water conodont zonation. Geol Soc. Am. Spec. Paper 196, Sandberg, C. A., and Gutschick, R. C. (1984). Distribution, microfauna, and source-rock potential of Mississippian Delle Phosphatic Member of Woodman Formation and equivalents, Utah and adjacent states. Pp In Hydrocarbon source rocks ofthe greater Rocky Mountain region (ed,. J. Woodward, F. F. Meissner, andj. L. Clalton), Rocky Mountain Assoc. Geologists, Denver. Sandberg, C. A., and Ziegler, W. (1973). Refrnement of standard Upper Devonian conodont zonation based on sections in Nevada and West Germany. Geol. et Palaeont. 7,9' (1979). Taxonomy and biofacies ofimportant conodonts of Late Devonian styri4ctr- Zone. Unired Shtes and Germany. Geo!. et Palaeont. 13, Sandberg, C. A., Zle9l,e\ W., IJuteritz, K., and Brill, S. M. (1978). Phylogeny, speciarion and zonaii,on of Siphonodella (Conodontz, I)pper Devonian and I-ower Carboniferous). Newsl. Stratigr. T, Sannemann, D. (1955). Oberdevonische Conodonten (toii"). Senckenbergiana Lethaea 36, Satterfield, I. R. (1971). Conodonts and stratigraphy of the Girardeau Limestone (Ordovician) ofsoutheast Missouri and southwest Illinois. "/. Paleont. 45, Savage, N. M., and Bassett, M. G. (1985). Caradoc-Ashgill conodont faunas from Wales and the Welsh Borderland. Palaeont. 28Gl t3. Serpagli, E. (1974). Lower Ordovician conodonts from Precordilleran Argentina (Prowince of San han)- Boll. Soc. Paleont. Ital. 6, t (1983). The conodont apparatus of Icriodus woschmidti z,ie9ler Fossils q,nd Strata 15, Sparling, D. R. (1981). Middle Devonian conodont apparatuses with seven types ofelements. J- Paleont. 55, Stouge, S. S. (1984). Conodonts ofthe Middle Ordovician Table Head Formation, western Newfoundland. Fossils and Strata 16, 145 pp. Sweet, W. C. (1970). Uppermost Permian and I-ower Triassic conodonts ofthe Salt Range and Trans-Indus ranges, West Pakistan, pp In Stratigraphic Boundary problems: Permian and Triassic of West Pakistan (ed,- B- Kummel and C. Teichert), [Jniv. Kansas Dept. Geol. Spec. Publ (1976). Skeletal anatomy of the Late pa-

135 '2fi-16 'B tuoadldj p loac stojejwoqrsj Je,ro'I pue u"ruo,{ec Jeddn aqt ur (eluopouoj) dlora snpoqlddsrg Jo uolslêu (tl6i) ''l 'l{ 'urlsnv pue V C 'Sreqpu S' 'n6t-6ll '961 laddd rads ^/J''ralA.rZ wv 'JOS load uo4euoz tuopouoc u"ruo,\e(i elrl pepusts Jo u?d mddn Jo uorsrêj pes q-,srdalo,l -owldd '(nb6d V C 'tueqpues pu? r'a\ 'relserz 'dd 0g 'letseqcqc 'poo^r -roh sllla '(eapirpiv f U 'pe) stuopouoj lo /BopryoaDlDd ui 9I-8tI dd snorejruoqrec -pltu 01 u?ruoê(i uro{ uodnlo^3 luopouoc ur selc,{j (/86I) U H'eu?.l pu"'a\ ileferz 'zel-6ol 'ol 'luoadlo{ Ja loac 'ecl-jewv quon pup adojna ur (ueru -oêq roddni-eppr,\l'sluopouoc) euoz-sn, -1"^ eqljo uorsr^rpqns pue uo4rugepeu (9/6I) 'D f 'uosuqof pue ''C 'radd?r)i '17'n1tar7 'n Ls -I' SurypuDqqrnqs8DlnA aqjs,uoqazzftps? sluopouoc Jo ensolplec '(4161) pe -.LZT 'MaJq pruau/v ros ToaO ('urqrls8rog I^l Spup 'tes/i\s 'C l pe) tl dttt8rtotjsotg juopouo) uo wn$odu,tts ul nsz- LZZ dd, u ruoêq ueedoj -na oql Jo luopouoc (l/61) - ^qd"r8rl?jls '99I-I '8 'qcuoluapog satwosapuo.j SsaH?q/ Suntnepeg eqcsqde$ -I1?4s ejqr pun ueluopouoj Jeqcsruoêprcqo elueal,(qd pun eruouorxej '(2961) 'M'raFerz ' L9t-9,8 '61 'luoaloj 't '8,!\oI Jo (r) eleqs acuspuedepul eql uorj sluop -ouoc ueruo,r.oc reddn (St6l) ia 1srnb8unol 'nnz-6lr 'LZt qqv tuoplqd loag qi N ueluopouoc uo^ ojfh trru (ue?uar,(dtsea\) tpeu olurnb sep lelqec ulr (rnru?n-10^rc) sun{rozoepd uojeqoq sep Sunreperlo JrtZ 'C96i 'I I 'qui,!\ 'b9t-lst'er 'tuoaopd ta 1oa9'snpou1l p'de snq$)u8tlod eje -qos luopouoc ueruoôo olpprj l ur sujo ed fu -uo4nlo^g(6/6f).rr\'re6erz pue ') 'e8rpper\\ '6lb-t Lz '89 DaDqp'J DuDrSnquapuas uatarqe8see -pc ueu?qqceueq ur pun lerqo8sndfj rrjr ojnls lejr:i Jep ueluopouoj el(i (tt6l) ) 'e8[ppe^\ 'zrt-l0l 'k)nz IoaD 4uo3 Sutruotrl4 'uoqeurroj ^rrr? "uoqdsoqd aqt Jo uonrsodep pue fsololuoel -?d {986I) A I 'uosulloj pu" U g '^\etpre^\ '901 -l 'lt l.psrcfuapog satudsapudt 'ssah qqy 'srnlls sap uatuopouoc (i961) H O 'resrltela VINOqONOJ lhj 'dd St t 'glf rtuoc lrs arti snw oltdtuo 'tby snqntuso$aw snua8 luopouoc (u?rddls -srssqî) snojajruoqr"c,tlr?g eqljo,goloceoo?l -sd pu? 'uorledods'ûesolfqd (9861) f W 'pleqcro pu" 'V J 'Sreqpues'H d 'ro rg uo^ 'tzz -E6I '61'!JS qttvg t l,r"j '?p?u?c'puejpunoj -^\an uefo^\qlnos'(snojojruoqrpj Je^rq-I) dnojc,{ojpo3 eqljo,{qdej 4EJlsorq tuopouoc (286I) V H'lroqeC-tulld pup'h'd'redlg uo^ '96-18'6I tuozdlod p 7oa9 'sluopouoc uer -ruled ur s$uc flrluepr ue-palrsrêr Dtuosulg pue snporyousoldlq 'snpoaputu (986I) - '9S-I'9tr 'ttuoj!?s ah srry l ottotuo fou.'ocu?cglrlfts IsJ olojeoo?pd pu?,{ruodnlo^g-(epuoqd -otuopouoo) Dtuoslllg Jo seoeds crozoesl d al?.l ( 86I)'X C'[IreW pue H d'rellrg uo^ '97l-l'01 UnB uoapdo.oltlj ryjattn 'uap.^s ruels?eronos 'puelo ujolse,rquou Jo uercrôp -ro re ro'i puz ueriqrue3 Jeddn eql Jo fqder -Srlutsorq tuopouoj G L6l) 'v ia lelu?in u?^,86 -IB'JIOB DdDd DpDuoJ load oeepdrqr -JV crlcrv u"rp?u?j 'pu?[sl ^rns ejeusefig ujelsa^\ -q1nos'sseje luecsfpb pue ed,{l eqt le (ueluo^ -eq eppu I-Ja,t\ol) suort?urroj pjorc pjrg pup prorc enlg eqt Jo [qd?]3qa1sorq luopouoc Jo tusuruns 10861) C 'radder) pue 'J I 'oua^n.zlt_65e,($5,?t.^!un pto^.tdh.looz 'dtuo) snn ng ue\ ujelse^{quou 'rqseg V-e-qn)'et?Jls c$s?uj-uer1uled ( /61) 'c,/t,\'teea,r5 pu? ''g 'leuirun) ''l 'ueqjrel '65-ll '6'tuoaDl2d ta pa9 'te6t '1I{aIN? NOSI{VUS snpolno sr].u.b eql Jo sluopo -uoj (S/6t)'d'H'qnquqqcs puu'j l '1aa/hs 'zn-62 'lss 'tuoa?l2d p 7oa, 'sluop -ouoc uelcr opjo pue,{uouoxel luerualaq -Inhl (Z16l) I^t S 'ruons8reg pue 'C r,\[ lee rs 'S6Z'oN 'otso '^run 'rluoj luoeled (uotnrg "I 'O P3) raatsts upqrôp.to aw lo sdadsy ul '9 - Z dd 'v S'n'ecur ord luourluocprhl uecl -Joruv quon 's{coj uercrôpjo Jeddn pue alp -prl{ reddnjo uorlbleuoc aqd"rc (t861) - '6r0t-620t '99 uoalod 7 s rh {c"tg ule -quou eql Jo (uenrôpro elpprhl) uorlsrrrjoj Ssdruur^\ eq1 uorj sluopouoc (286I) - 'nl-sn'(f)92 satpns pad Mun Suno^ wdqslrg $vôrd tueuquocprw ujalso,{\ eqt Jo pu",tqde$dejlsorq stuopouoc uercrôpro?4e1'(6161)- ' IS-ZI9 '8 Sotd 'sqy'utv 'ros pa' 'r96t 'HsINUn{ r8 (Ivouxgu s74po2p -rrlf snuea luopouoc crsseuj i(f?a pu crozoel

136 6. EVOLUTIONARY PATTERNS 6.1 Introduction As noted in Chapters I and 2, conodonts occur abundantly in most types of marine sedimentary rock; they are widely drstributed geographically; and, as a group, they have a long stratigraphic range. Consequently, conodonts are exceptionally useful as providers of biostrati graphic information to geologists interested in a broad spectrum ofproblems, and those ofus who study conodonts have expended most of our efort in supplying biostratigraphic service to the geologic community. We have had little time left over in which to address the more esoteric aspects ofwhat might be considered truly paleobiologic topics. On the plus side, however, our service orientation has resulted in the assembly ofan objective, if widely dispersed, data base, which is several orders of magnitude larger than that available for any other group of Paleozoic or Triassic "macrofossils" and is also one that may be viewed within a biostratigraphic frame- data bases that are the enq' of their peers who study larger fossils. This is due partly, I believe, to the caution automatically provided by very large population samples from stratigraphically well-controlled sequenc$. In some parts ofthe geologic column, dense spacing of large samples provides an almost continuous record of the development of populations that can be seen to have had and to have rnaintained very great internal complexity for appreciable intervals of time. Not uncornmonly, it is difficult or irnpossible to express what we know about such populations within a generally accepted systematic framework that yr'as designed to handle a rigidly typological taxonomy. And this, of course, has resulted in hiding a good deal of very useful information in categories named and treated as species or genera in accord with principles established and rigorously maintained by Ihe International Rules ofzoological Nomenclature. But students of conodonts have had additional excuses for caution. That is, the subjects work currently capable of resolving the 300-my oftheir study represent a group of animals that history ofthe Conodonta into 152 divisions. In evidently does not occur in the living biosphere. This means, of course, that there is lit- addition, of course, we now have a fairly clear idea that recurrent groups of morphologically tle unequivocal anatomic information available for conodonts and that biologicalty different element types are more suitable than individual elements as the basis for specieslevel taxonomy; and, as I have tried to show in must be generated quite indirectly meaningful systematic and ecologic concepts Chapter 5, species may now be assembled into Now, however, there are in place at least the supraspecificategories that provide considerable insight into the patterns ofconodont el/o- is probably time to take up the biologically broad outlines ofa defensible taxonomy, and it lution. At present, our organized collections (and philosophically) challenging task of evolutionary interpretation. To this end, I assem- provide little information as to the modes or processes by which evolutionary development ble in this chapter some observations on the was effected, but pattems may ultimately suggest processes that may also be tested against my history ofthe conodonts, and comments on evolutionary patterns I recognize in the 300- the objectiye evidence. a few examples that seem to suggest process as Micropaleontologists, as Lipps (1981) has well. Perhaps rny observations and comments emphasized, are not noted for generating, testing, or evaluating fundamental paleobiologic more penetrating studies ofevolutionary mode will proye sufficiently outrageous to stimulate hypotheses, despite their access to finely tuned and process. I hope so.

137 o : e ic obz o9 *ln-*-n -*-n -'t - l -* -re.{rp Buneredes uorcuuxe rusjs,oars Jo seo,n ",*,0,,',r.r.r.t*.r*'fy:ffil.Tfiii"1t#*y'ltriH$i fii seulll olsjrpur 3ol orlbr uoncuqxo-uoqeufuojo sluorusos pelddns.seuoz ueruo,{c(l lsoruee q8no{l ueuqu J ele-i 0t roj (eurt p.qsep re^\od sou J uoucuqxe-uorl u uojo tol pue (eurt pllos $ddn) 3ol,{lrsra^rpsorJeds.I'9.3!d Jepro'lsrg t Jo uopru8mor lnuad ssol oseql 'uoqryoâ lo xapur ue s? pasn (z16l ) {relc qclq,{r 'orl?j uortcunxe-uoq"ur8uo ^le^dceje oql ur suoqenlrnu s^{oqs l?qt tol? epnl3ur osle '8 9 pue 'Z'9 'I'9 'selg q peprdop 'stol eseqj '?luopouoc eqtjo serr?j crss?ui q8nojql u"uq -III"C el"l ojrlue eql JoJ srs"q euoz-^q-euoz? uo,{lrsra^rp IeêfserJads ur suonenlcnu rrorls l"ql stol eejqt lueserd I 'eluopouoc eqtr Jo fuolsq dj?uobnloô oql ur slueê rof"iu eql Jo eruos Jeld?qc srql ur SururruBxo JoJ srsbq aql sv 'srs?q suoz-fq -ouoz p uo sarceds luopouo3 u?unljs pue u?rc -I opjo Jo,ttrsJe^rp eql,'aoqs of (98611eo^{S) -oo eq1 ul peautocer.{eql souo orto,b sql ol J?lrurs surel"d l"ql elou plp,(oql tnq 'ueunlrs el?l uslll replo Jo uerddrssrssrl l u?ql retuno^ sluopouorjo,fto$rq fueuorlnlo,\a eql ui slueâ reprsuoc tou pip (186I) ou"-i pu? relsorz 'e?p4uopoucl eppuoporuoud eqt Jo,fuolsq eql ur slueê Îru?J ui lg 01 osl" eperrr sear ldurell" ue '$Iools Jprurpo{r"zo snoue^ Jo luorudoloêp oû -?Jelr eql ui sote$ ol,{le8ei selc^j eseql pet?l -er eue'i pue JelSarZ qtnoqllv 'uorlourlxa Jo aposrde ue pal?jurul,(lol?iurlln pu? uoq?^ -ouul Jo lsrnq ^q Uoqs e,{q pernpolur $ qrrq^r '&lsreîp Jeq8rq Jo euo pe,{rolloj sr,{lrsje^,{puecej pelrduoo I l?ql Eol e seop se 'selc -l(c,{lrsje,\rp Jo uorssoccns pellojluoc -rp,{ioljo Ie relur ue 'paqucsop.{aql ^q salc,{o xrs Jql Jo rlcej ul sluopouos snorejruoqr"j /tlrea,{.oqs osl"?rouse uuoj ^lepruc " luopouoc Jo uorlelnqel pu? upruoôo Jo luourdolaêp,fu?uodnloô seues-,(q-seues e uro{ (Z16I) Ir"IJ,(q paprufs eql ui lrrall"d 'cqc,{c Jo 'e p[edej u peuqlno -um seo'j'eluopouoc erll Jo,4Jolsr{ uerddrss$ (186I) oup-i pu? relserz '^pnts tusjer tue^? ui -sq41-1sod pue ueruo,req-ud eql pezuolcpeqc e^?q osl? lqelu u?rddrssrssrw pue ueruo^ suradbd,{usra^!c Z'9 VJNOOONOJ:IHJ 0gI

138 EVOLUTIONARY PATTERNS l3l vt-*_v _+ _*_ x _r_ x[ _*_ xfi- r-' \v,'.-.,, ',// i7-1,.\- \,,"."' "- rdm...n I v - - oevoxratl Mlssrsst?flar{ PEI{I{SYL Fig Species-diversity log (upper solid line) and log of origination-extinction ratios (lower dashed line) for 64 Devonian and Carboniferous zones. Stippled segments oforigination-extinction log indicarc limes when more species evolved than became extinct; asterisks ildicate times of sigdificant extinction ieparating diversity cycles idintifred by Roman numerals VI to XIII. cycles in conodont diversity and also delineate (of 246 genera) that I regard as reasonably distinct in a multielement context, even though about 20 second-order cycles that support the concept advanced by Ziegler and Lane (1987). complete apparatuses have been established for The logs, ofcourse, extend that concepto both only a few of them. Clearly, as additional data earlier and later intervals of time than Ziegler become available, certain peaks in the diversity and Lane considered. logs may be emphasized and certain depressions filled in. But I suspecthat the general In the tabulations depicted in Figs. 6.1, 6.2, and 6.3 I have included only the 1446 species pattern will remain much the same. Fig Speciesdiversity log (uppcr solid line) and log oforigination-extinction ratios (Iower dashed line) for 48 Permian and Triassic zones. Stippled segments of origination- xtinction logs indicate times when more species evolved than became extinct; asterisks indicate times ofsignificant extinction separatilg diversily cycles identifred with Roman numemls XIV to XX. x l -* - xtv - * - xv -*- xvt_*-xv _*_xv t *xtx*_ I xx I PERMIAN

139 rofeu proter,(lerns r{cq^{'(896 I) ssols Jo solc 'o.{\1 -,(c cruolerc eql uee,,llleq ocuopuodsesoc esolc Jo euoz 3 roj I,t\oleq uo4nlo^s Jo xepur eqt ur oql lejfuatur ol si(b,,ir Jo Jeqrunu oje ejeqj 8es e sesej tsour ui pel?drctue $ teqt 'Jrss?ul " pue uerur5d -rp ur ^q dojp ldruq? ssel ro erour? Aq pel?urujel ^llsjo^ or0 ui eu{cep 'lnjlg l?q^\auros Jr 'pe8uolojd pue i(lrsje^rp reqeq Jo ouo,{q po^\oiioj,{lrsra^? pue u"rue^l^suuad ar{l ui IJeAocaJ Jofeur -Ip,{oI? /(oqs qcq^{ ',qrsje rp sededs luopouoc ^lo^rl?ioj Jo Ie^relur ue sopnlcul qclqa JO qc"a 'UOBsrnp reuoqs rlsnrrr Jo seuo rourur u"rddrssrssrj l-lsod Jo s6ol,(q pelmpur,{lj?elc 0Z l$el l pue selc.{c uuol-auol tjo sprooal eql oje eljô e)lor?sqv cufurur,{se sjp erlt Jo sauqlno leqt '9 pu" Z 9 's8rd 'lsojelur Jel?er8 Jo pu? 'Je e ^llejodual ur elon -^{oq'uje Ed I"JeueA ^lqsjeprsuoc srql pesoduuedns '?)lor?sqv peui?u ( 961) ssots leql alr^c o^rs 'poueq _ -sejeej-e^rsser8suejl snounc e procar f1e,rr1ce1er0 Jo puo eql le uorlsu4xs 01 rcrsssuj erll -loc qrq^{ '"le4s crss?uj pue ueurod peejds -epl/( ssel pu? u?ru? l^suued pzejdseph{ aj? Jo ropul?ursr ew genorqt aullcep InJlg E,{q pa^\olloj se^{ lnds eluplouur srp lnq?cuourv quonjo roualu cruolerc eqtjo qcnur 'crss?ul flwe eql ul ourl lsq sgl JoJ 0Z eôq? ur gjuenbes?dlse){scx oql Jo $loor eôqv dn i(lrsro^rp sorcods tlnq uoqercods esuel 'Jrr.rrl ueruoêq lsalsl u! sarjeds ggjo -ur Jo eposrde Jeuq V [aêl 33ueualurcrll eql urnurxau {lrsje.arp E pue u?rddrssrssrl^l Nel"l pu" u?ruoêq oql ugoûoq..drunq,, I"cu -leurur^s lsourp ^lleg u,tq peljeru,{lj?elc sr le^lal -ul teql Z'9 8rdJo 3ol eql ui'aouenb -es?diseiss) e^rssojaoj-o^rssejesu?4 ^lrsre^lp eql Jo uou?uuoj,{q po{j?lu s"/rr u?rddrssrssrw lsal"l eql q8nojqt u?ruoêq.(fee aq1 (Ilo{ JE^Jolur ue '?cueuy quonjo Jouolur cruolbrc 3ql ui '( 96I'ssots) ecuetllv quon cluolerc ur peuroj se^{ ecuenb eôqe se.r..xepur fu?uoqnloê,, oqt pue 0l ^lejer punoj? Îuo pejoôq flrsje^rp qcrq^\ Suunp I?^ralu Euol E,(q( '9 '3rg) u"flured eqt ur pen -u4uoc se^r leql eurlcep lerouoe e ueeeq ueql tnq 'eulu ueue^lfsuued-prur ^q leêl elq"tceds -er e ol dn lllnq 'fuepunoq u ru -?^lfsuued-u?rddrssrssq^l ^trsra^p eql Jeeu lueê uorl -cunxe rof?u? 6ul,tr.ollo{ '(2 9 '8rC) snorejruoq -J?J pue u?ruoâ(i eql ur ro8r^ e^rld p? pe^\ouej ^lj?e Jo l"^r3lur ue pu" u?unlrs pue u"rc -as ooueceddrj e^rssejegj-o^rssoj8suejl eql -Iôpro Jetq eql qanojql dlrsje^rp ur eurtcep qcrq r Suunp eurq eql ol 'esjnoc Jo 'uortejnp peldnletrur f ecrjc,b? peaolloj se^r srql ur spuodsouoc eposrde u?ruoêq lsorlfte 01 (l'9 'AIg){lrsro^rp uerchopjo elpprl l lo["u s {I 'u?ruoâo [eôl-serceds ^q ur {Ead ourrl $ei -Ip ue ol esrj prd?j,tjo^? qlr,r\ 'u?rcrôpjo -l?e eql olur ueunlrs aql q8norql oou"punq" ur,{l5^ sql ui uorterper e^rldzpe Jo uje ed euqcep Ipreuo8?,(q (djepunoq ueunlrs-uerjr^ ^lj?a pc$selc e se petejdjelur eq lq8nu teq,{r,$or{s -opjo oqt l? uondmetur repro-puoces rof?i'u t'9 pue 'Z'9 'l'9 'stl{ ui pozu?lllqms BIB(I? qll,{\) pe^rolloj s",,a qcrq^l 'qftq u"rcrôpjo 01e-I e ot pos?ojcur uonod DnÔ ui?ee sarcods luopo I 7'9 -uoc Jo,{lrsre ^lprdej rp eql (u"dj^{?qow) u?rjrôp -ro elppu I elel eqt ur leqr I'9 '3lC ul eron 'paluaurnjop Jî Jlrnb '( 961 sj? seeus pu? socuojjncco Lsou qcq^\ ur 'es?q 'ssols) ecuelllv quon Jo rouelur cruotejc elep rafuq oql eql ur pelrsodep s3^\ ocuonbes ImS aqljo Jo txetuoc eq1 ur ejuejejrp ell U?d -lll 0l3rrr plno^{ spjocer qcnsjo uorsnlcur 'u?d psajdsephr lsoru eqt qcrq/{ ur euo eql ol poued lsour eqt rod 'l?rrol?ur pefjlsn r ui spuodseuoc eposrde sql qcode uzdi,,a"q-ur Jo pe^rosojd,{lrood uo peseq eje ^lluejojrp l"qt spjo -ow,{lj?e eqt ul sejceds 0Z ueql re^\ej Jo,iAol -cer pelllluo,tlpcrl?jcolne e Eq I 'sesej Jo Jeq 3 ol,qrsje^rp ur i([snolrdrcerd paurlcep surl -unu e ui 'pelquass? ar" t 9 pue 'Z'9'I'9 's8rd usdlcojeuqla elq ur lnq 'sqcodo u?dl3orolrq^\ qtq^\ pu u"ueql oql s? I'9 '3rC uo euarl3s crqdejartejlsorq eql uqlr/rr ur peguuepr sle^ sercedsnoue^jo sesuh eql eururelap ol sesec -relu oql ui 'u?rjraopjo eql Jo u?d aql,{u?ur ur lueruapnf u,to,{ur pesn oslz e,{eq I ur lsel?eje Jreql paq3?ar sluopouo] ^lj?e lnq 'slsq?rcedsnoup^,(q sj?a^ luocar ur peqsrl ^lrsje,a.rp -qnd suoqnqulslp sercods Jo suodelnq?l ouoz saptr wat8uot ez9 -^q-euoz eql enp^ ec-bj tz peldocc? eêq I YTNOCONOS 3Ht zti

140 eustatic episodes, and first-order segments of the species-diversity logs in Figs. 6.1, 6.2, and 6.3. The simplest, I believe, is to postulate a direct relationship between diversity of conodont species and the expansion (and subsequent reduction) of suitable habitats recorded by rocks of the transgressive-regressive sequences. 6.3 Second-OrderCycles Superimposed on the first-order cycles recorded in the logs of Figs. 6.1, 6.2, and 6.3 is the record of 20 second-order cycles, each with the general characters ofthe ones recognized by Ziegler all.d, Lane (1987) in the Devonian and Early Carboniferous. By and large, each of these cycles begins with an interval oflow species diversity in which the ratio of species originations to species extinctions (the"evolution- EVOLUTIONARY PATTERNS ary index") is below 1.0, followed by an interval of higher diversity-that is immediately preceded by an innoyative episode signaled by a spurt in the evolutionary index. Cycles are terminaled by more or less abrupt drops in species diversity which, for the most part, seem to be the expectable consequences ofa decline in the evolutionary index in immediately preceding zones. As is clear from the logs in Figs. 6.1,6.2, and, 6.3, whose horizontal scale is approximately proportional to the length of time represented by the intervals shou,n, second-order cycles were of greatly different durations and hence seem unlikely to have been the results of any regularly cyclic mechanism. As the following remarks will show, these cycles are complex intemally, and it may be difficult to find a general explanation for them Cycles I and II In the latest Cambrian, Ordovician, and Silurian history ofthe Conodonta, I recognize five second-order evolutionary cycles. These are identified by Roman nurnerals I to V in Fig Cycle I, which began in the Late Cambrian with the appearance of the first conodonts in the shallow low-latitude seas of North America, Australia, and China, is largely a record of the rapid diversification of the Teridontus lineage, which founded the Paraconodontidand, in the very early Ordovician, launched the Prioniodontida. Early diversification of the Cavidonti was also accomplished early in Cycle I. The Proconodontida surely reached the acme of their evolutionary development then, and only Polonodus and, Pygodus are known from rocks deposited during later Ordovician cycles. The Belodellida, which I interpret as descendants ofthe Proconodontus stock, appeared at the climax ofdiversity in Cycle I but were not conspicuous components of Ordovician conodont faunas until the interval of Cycle II. The 40 conodont genera and 227 species that are largely confined in their known range to the interval ofcycle I representwo groups. One is made up of mostly shortjived experimental stocks such as the Clavohamulidae and Cordylodontidae, which appeared briefly during the initial radiation of cavidont and conodont lineages but were apparently not ancestral to anything else; whereas the other, typified, for exarnple, by Rossodus, Tripodus, and, Prionlodzs, includes genera that founded or are intermediate parts of evolutionary lineages that, in modified form, assume greater importance in later cycles. These lalter lineages were evidently subjected to more or less continual pruning during the prolonged regressive phase that characterized the waning stages in North America of the Sauk cratonic cycle, so there is no evidence of their catastrophic or mass extinction at the end of Cycle I. Note that by early in the Ordovrcran conodonts were common not only in the tropical to subtropical waters of North America, Australia, Siberia, and probably parts ofchina, but also in seas at much higher latitudes, such as those that overspread Europe, western Australia, and western South America. Although there were remarkable parallels in the evolutionary development of low- and highlatitude Ordovician faunas, already evident in the interval of Cycle I, there was limited exchange between their chamcteristic faunas. Very possibly the existence through the Ordovician of well-developed conodonl faunas from the equator almost to the pole contributed to the exceptionally high diversity ofthose faunas. Cycle II is related, at least in North America where it is best known, to a short-lived trans-

141 'etxrl ueunlis ts3l?l ur uolpurlxe 01 lsorup peulpep sluopouoc pu" 'lq8rts",{r -re^rp ur fta,{ocell spguopouolstp oql Iuo{ ^l[s snqwusosstto) pue lrotrs ppuopoqlsusoql?ds er{l uo{j sapnqpusllod 5lcols pl[apoucl eql rrjo+ asoje sttdpad qjlq,t Suunp uott -elouur Jo aposlde ue,{q pe,to11o; se { qjiii { 'ro8r^ fubuoqnloê pecnpet Jo P lelui u?,(q pecnpolur sr U pazuettej?qo JorDer sr A elt(] repjo-puoses pu? 'u^rou)l ^ppola pu? eseds eje $unej luopouoc ueunls ele'i ^ljood '$l3o1s peuopoluolslp sqljo sjos -rtlapoujl serlrur?j apnuoporuoud eql Jo uou -ejgrsra^rp qll{\ palelcoss? si AI elc^c 'qcoda {colue^\ ^loajel eql ui l?ad E peqc?or pu" Bol xepur-,!?uorlnloê eql ur 9) ds lu?cglu8ls e i(q pacnportul se, a 1"ql sposrde ftrsjo^rp-q8lq 3,{q peaolloj 'fueôpuel'i eql ur,(llsje^rp aoljo IE^ -Jetu po8uolord sepnlcur AI el3,{j 'A pue AI 'selc,{c JapJo-puoces " oû olul popiaip si?luop -ouoc aqt Jo,tuolsrq u?unlrs eql I'9 'tld ui saplb uouryts t' 9 'u?unlrs aql olur penu4uoc s?un?j ueror opjo (Jel?,t -replm ro) epnldefroqttq Jo Imldr(l se3"e -urt aql Jo suon 'sepn14"l el"ipoulalul pu? Arol ur s"un"j euueur-uedo Jo crlsuopejeq3 lle ere r qrols eseql 'uer3rôpro eql ui pe^r^ -rns 4,(po'seuneJ uercrôpjo $alq ui salc -eds peluesarder stuopouoc Jo 3Jeu33 S [ 3ql JO uouerc?lt ^q eu,r..puoc uo luenbasuoc u"eco pfo,r eql Jo SuITooc pu u,$op^\erp cllelsna Jo spoge paurqurot eql 01 pelnqf[e,(poururoc sr pue uorlcurlxe sserll e se papjeaej -ue8 sr ^llejo III elcl(c pel?ulrulal teql lueê eql 'seun-gjiozooi?d Jelgl set"ururop pu" ueunpg eql ur f,peer8 pegrsre.r -lp qrlq.,r '"plulpolr"zo rapro orlljo srepunoj eql eq ol serjeds eseql reprsuoc I 'S raldeqj rn peleclpur sv 'snwdusop\ldy Jo sercods snol -re^pue slnual..7,, s" qcns suxojjo el?os 3Jo xeldutoi DpalnJD oulpopah nle^-tr\o\eqs erp ruo{ lueurdolaêp s"a ecu"ogruers :alzere 39 'sluauruojrûj apnlllsf^\ol auu?ur-ujdo ejoul ur sjalea{ redoep Jo euill u?rci opjo Jalel ur IEJrd,(l Jq ol eurej q Jrlt 'snppun 'd pue snd : -r? 'd peu {eds xeldt[rcx snsonxalj[ snpouso.tlld rale^r-,roll3qs eql'aldruexo Jo{'slueluuoJt/rue euu?ur I"r[Jou ejolu'jele^{-jodeop l?q^\eu]os flq?qojd 'oroqsjo ejolu ol peldep" selcods ol esu e^?t sluouruojlûo IEuISJEru '^\o eqs ur p3ûql l"ql sorssds 'penuduoc uolssojssu Jl -secans ruo+.{lqrssod pu"'ppuopoqteu8ord?ds eouursddrl s'd snqtdusosapoqv pue o ap 'pqlapoucr eqt uro{ lueurdoleôp,{la^[ -o?jrf sepduoporuoud pozrtelteds eql Jo sero -ejetr psjnpord pu" AI elc{f, Jo crlsuolc?jeq3 ^q -eds lslu eqr fq 'sbun J epnlt"l-leqqq ul 'pue slsrnq,fu?uortnloô oql Jo s^"ldoj Aq pezrjatce :II op(]jo aposrde,{lrsroîp-q8lq aql ui poread -JEq33JE qsrq/rr 'Se[t]b u"ruolec pu" u?unls Jelq ui onu4uoc ol s?^{ ejoq peqsqqene ujel -d" qolq { 'owpopald -eds KqlsnllwuSoltn) pue snpousotqd Jo selo pue snpou'tstjg Jo Kllzlo -t?d eqj espuloploo) pue 'aepnuopoqteds -edse'e"prqleusojlqc,(l!urej eprulpououd -oljald'eeprtuopoqleusoqr?d saqtulej eplu eql Jo serceds e^nltuud sluellluojrûa l?ura -rpoljezo oql pu? e?prluopouolslo pub e?p ^q -Jeu'/rrolJ?qs ur pjzuad?leqj s?,{''q Joda uepl -^\eqow oquojl?rl,(lje3 oql ur 'sposlde.(isle^ -Ip-/irol eqj 'ol3^c allslsne eoupcsddrl ( 96I) s.ssolsjo eseqd o^rssar suejl 3ql qll,t\ ecuelilv quon ul pel?itosse sr III elc^3 fuepuoce5 IIJ aptc u0lrlaopto a1d7 pud alryhl e 9 'luelxe ur PalJulsoJ fle^ eq 01 eluec ssas Jleqs qcrq^\ ui u?i3il ^ro "qs -opro eql Jo Ie^rolul u3 qll,!\ pel?noss? 'JeAo -,r.\oq'oj" luo^g uoncurlxe-sselrr e luesej -dal suoncuqxs âql eseql leql acuapl e ou sr aql 'ui"bv 'sees ep$q"f,rol ur elc^c slrn Jo eposr -de,{lrsreaifqbiq eql pezuep"$qc qjrq,ll 'spq -uopotsroqlnrx eqt Jo ^luof?ur e pip se 'lcull -xe ellieceq sluopouoc epnl4?fqelq Jo sesseurl peqsqq4solla,n 0l II elc^j Jo ued rslel eql ul '1r ol pelcflsej,{llua&dd? ere 'snpolluozonld '{cols tuered aql lnq ureql Jo IIe pue 'scrralliv quon ui alctu slql Jo cllsuelcej?qc ^ll?r3ed -se eff eeplluopolsloflnl I sql '(snpoutsoqd pte'durpopald'snpoflot.tdotod'snqvu8 aqdnuy 'snpo$louddatq ''A e) sasnlupdd" pet?nuere:glp,qlnj qtl,ld selteds ep$uop -oruoud pue op4uoporapu?dolojd p$u?^pe qlua I eic,{j tuunp pepunoj seeeeul eîlrluud Jo spue Eel eql Jo ejnlxur? ej? oic^j slql Jo JnsFetr?J"qc s?un"j luopouoj ( 96I 'ssols) elcô oruolerc {nes eql pelelduoc l?gl es"qd elrssej8ej Jof"u gql Jo uolldrujjelul e^$sal3 VINOCONOJ AHI,tl

142 6.3.4 Devonian and Carboruferow cycles As noted in Section 6.2, Ziegler and I-ane (1987) have recently recognized six secondorder cycles in the evolutionary development of Devonian and Early Carboniferous conodonts. These are identified in Fig. 6.2 as Cycles VI to XI. Cycle VI began with a short interval in the late Silurian and earliest Devonian during which the diversity of conodont species dropped to a low of 6. This critical interval in the history ofthe Conodonta was terminated in mid-lochkovian time by an innovative burst, effected by vigorous speciation within Ozarkodina and iterctive deyelopment from the spathognathodontid, icriodellid, and/or distomodontid stocks ofa flood ofspecies assigned to Amydrotaxis, Ancyrodella, Pedavis, Pelel<y* gnathus, and luiodus (in a very broad sense). That burst introduced a short interval of high diversity in the late I-ochkovian during which the number of conodont species built back up to about 26. Although temporarily vigorous, Ihe Amydrotaxis and Ancyrodelloides stocks were fairly shortjived dead ends, and their dis- EVOLUTIONARY PATTERNS 135 the one that terminated Ordovician Cycle III, appearance, along with that ofseveral similarly is commonly included in the short list of major shortliyed species of Icriodus s. 1., produced Paleozoic rnass extinctions. They note that "at the "extinction event" that brought Cycle VI to this position almost all previous species ofpalmatolepids, ancyrodellids, ancyrognathids, and a close. Cycle VII, like its immediate predecessor, polygnathids became extinct." The tabulation I represents yet another episode in iterative development of the Ozarkodinida, reinforced by species diversity in late phases of Cycle VIII, present in Fig. 6.2 also shows a rapid decline in bursts of vigorous speciation in shallow-water but not one that is as abrupt as suggested by environments by the ltiodus, Pedavis, and Pe- Ziegler and Lane's comments. Although this Iekysgnathus stocks. Particularly significant developments frorn Ozarkodina (Spathognath- assembled ranges on a biostratigraphic scale disparity may resuli from the fact that I have odontidae) were the Eognathodus lineage, that is cruder than the one used by Ziegler and which is confined primarily to Cycle V and, a Lane, it may also suggesthat the species to bit Iale\ the Polygnalhus stock, which rose rapidly to importance in the offshore envrron- the late Frasnian than has been assumed. Ifthis which they refer disappeared more gradually in menls that became more widespread with the were the case, conodonts might provide some advance of Kaskaskia transgression. In the high-diversity interval of Cycle V, which peaked in the Emsian and Eifelian, at least 36 conodont species prowled Devonian seas-a sixfold increase from the low-diversity interval of Cycle VI. The high-diversity interval of Cycle VII was terminated in early Givetian time by the disappearance ofall but two ofthe lineages ofpolygnathus established in earlier phases of the cycle, and diversity dropped to 2l in the mid- Givetian low-diversity interval that initiated Cycle VIII. A bit later in the Givetian (late Middle Devonian), iterative development of "Polygnathus" latifossatus from the spathognathodontid stock led rapidly to establishment of Mesotaxis, Schmidtognathus, Klapperina alnd, ultimately, Palmatolepis,which I have set aside in Chapter 5 as the new family Patmatolepidae. Species of these genera, which were apparently adapted to the increasingly widespread open marine enyironments of the late Middle Devonian, together with new forms developed from surviving members of Ihe Polygnathus stock and short-liyed species of Ancyrodella that also evolved iteratively from spathognathodontid ancestors, accounted collectively for a Frasnian high-diversity episode that numbered at its peak some 53 conodont species. Ziegler and Lane ( 1987) recognize an abrupt decline in species diversity at tlte end of Cycle VIII and attribute it to a sharp extinction event just before the end of the Frasnian which, like support for the idea expressed by Johnson, Klapper, and Sandberg ( 1985) that at least part of the end-frasnian mass extinction ofbenthic animals might have been the cumulative result of three earlier Frasnian deepening events and not the result of a single sudden shallowing event. That is, the drowning ofreefs and reduction in extent of marginal. shallow-water environments that followed such deepening events

143 -dod 'IIX olc^j pel?nru leql,{'ol Jo -rqlbueopllg ew!o) o apouoqdts Jo uouelp I?^lelur (ueru?^l^suued) ue^\ojjoi ^lrsjo^rp eql -?J prd?l ol elq?tnquie sr teql luoô Suunp 'reê^roh 'ss?e.!\ snllpu?psol ^lreo pue e^wôuur ^lu?uud Jo[Eur? qll,il u?rsr?ujnol,{ljee 'DauqJoI'snpowoug eql Jo u?rddrssrssu l al?i a(o ur pofurur ueeq oêq ol Z'9 '8rd ul sjeed 3ql ur uolcurtxe pue snqlousolapy tq snqtdu8 -de lnq 'eluq ueruoêq lselq ur,{lrsrs^rp pell -sr?dd Jo lueru$eldej luo{,,(l-upurud pslfsel -rurt Jo le^lelur uoqs e qlrl{ ueeeq X ep,b IX emcjo uorlburrrrjel aql $Ir?ur t"ql ftrsje^ 'selrqofl -rp leêfsorcods ui eurtoop snoncrdsuoj eql ureljoc pu" 'sprouorullle euos 'sprouaur 'u?rueî,(suued-prur eql otur IIX elc,{j -,{lc aqt tulpnlcur 'sdnojt elejqeueûr Jeqlo q8no-rq1 pe,rr,r:ns eez euq mq\ousotsu toqg eq1 snorarrnu Jo uorlou4xo pefou s?q (t86i ' 861) lnq 'elr,{c sql ol peuguoc an sqcols snqnug resrtl?a\ 1?q1 erun eru?s eql lnoqe le pojjnc psoa pue DautpoT erlj- 'IX alr^j Jo es?qd -co XI elc(l Jo pue eql $lj?ru teqt serceds e^rl?ôuur er4 u mpoqlodslgr ur sjolsocu? luopouoj Jo ui uorpnpar eql 'snore uro{ pe lo.â oee snqpusofslq)dtlv puf. -Jruoqr"C,qr?g ^lrsrelrp aql olur penuquoc $lcols.e?4, 'snqtdubiasoa'dauqro.i 'IX elc,{j Jo Ie rsl -Du8(qodopnasd pue'snqpusojldd'snpoqldds -ur &rsra^lp-q?q eql $lj?ru tu rd flrsje^rp IoêI -t8r eql pue 'D apouol.ldts Jo erj.o 'snpo -senods w /fueôcor lq8rls eql ot petnquluoc -qldusolold Jo ssl}eds eentrl'srunuwoz snqpu i(qaroql pu? pol?jejllold grrqa\ 'sprupor -8qod Aluo l?ql etou (186I) eu?'i pue n1fle17 -uoud pu?'sprqleutolsour'sprqleuesn,rec " sq1 pue '6 ol peqsrururp peq,{lrsje^rp ueruoêq ot,ttrunuoddo u" psjejo,{jqeqojd el"rlsqns eqljo pua eqt r"au orrr4 ur lurod pu,{llu{es elq?ue^ elolll pu" Jel"rr\ JoA\olpqs peurelueru se^{ qcrq^{ ",{g',(uegq ',qrsje^rp sercods qonru pozuolc?t?qo sguo purejelu Jo eaj? ur ^luo ur SgJo l"ed ueruueru?{-prur E ur peljnsej srql os?ejf,ur ^q pue slueujuojrûe esoql Jo e8")[uur{s IIv 's"un?j usrurad pu? snojojruoqr"jjo Jrlsr 'Je e,,{\oh '?ej? ur peqsrufixlp e(xoq l? lsotu -JelJ?JeqJ sluopouoj Jo $ljols eql Jo eje,'.',{eql qclq,!\. ul slueuuojrûe eloqs,uo? ocet e^\ qcq.{{ ol '(a"pnuopoql?u3oqf?ds) ^luof?ru eql s? $lcols prqteusotceqpae'snqlaus/qodop eeeeu\ mpoqpdslg orlr Jo uon"rp r I"rlrur -nas4'snpoqnusolotd elu Jo atuu uersrcujnol pu? :spqfu8sn^?c lsjg tt4t Jo ouqlauuop elel ur uoneurrrrjol cnel^qd Jo uoqcuuxe aql ^q -zrg prluopoqleusoqleds aqt uro{ lueudole^ o1,tlueulud 4nqunB I qcq,'tl '^lrsro^rp serceds ur eurloop snoldrcerd e,(q pe{lerll sz^\ X slc^j Jo pue eqj 'elc^c rrlelsne ( 961) s.ssols "rxsp)[ss) Jo oseqd e^rsset ar oql 01 uouejnp -op,{q :xelduoc sr?tlidu8slbppd-snpoltjjete}.i. -^{o?qs eql ur uolercods Jo lsrnq IEug E :sluoruuojrûe ojoqsjo ur setoed snqpustlod ^q Io dnoj8 snptsuopo, eqljo tuue/r\ol] pu?,sldal ur spuodsouoc 'erun snojejruoqjsj Jo slueu -olduldd Jo set?ourj Alou JnoJ Jo uorlerp?j eql -eas (u?rddrssrssq l elel Jo) ueumrnn pdij"ru os?qd oûeôuur ssuolur ub,(q aurq pu? ueesr^ aql perdncro qcq r 'IX ep^c ÎJee ^q ueruusiiiec re1e1,tpq8qs ur petuslddns 'Z'9'Erg Jo Eol xepur-,fue d?j sena l?^relu feqi 'XI etc,tj ^lpr -uobnloê aq1 ur e4ds uersr?ulnol-elq snon u?ruuau"d ralq eql ^lrsje^rp-,rol Jo soseqd ptrul olul I?^ -trdsuoc eql JoJ elqrsuodsal sr lueê Ja el aql -rjlurjauq e JoJ pjnunuoj UtA JIJ,(JJo os?qd '(snqpusonols puz' adu/qpe'snqpusoqoe usruuelllec lserlj?e-uerus"rd lselq eql Pe{Jzrrr 'snqpusottidg\ruqdolog''e'r) splqleuso4c?q l"ql {lrsre^rp serceds ui uoqonper edâs eql pa^rt-lorls lnq olrlcuusrp eq1 go (srolsecue '?luopouoc orjt epurporuoud uaordlun t.l.jog) pue snpoqpug Jo tuolsq u"rusejc elel eql ur peuedd?q lsoa Jo seroads (snpoqtdusolotd wo{) tueru -Ens suorlepqel fru leq,{r lsnf sr qorq,{r ',{trsre^ -dole^sp.{q ^lj?ejo uzrsr?rrjnol tsetel eql olur IoôT -Ip sercad sonpej snql pu? 'ursrupl{odoursoo q8g e 1e peuelureur se^\ 'serceds es?ajcul tsruropuo Je^\o[ ol.,(lpnpej8 pel? 0S ueql arorrr,(q pezuaperegc ^lrsja^ro plrolur ftrslel -redo eêq IIe/,r 1qftur slcaiua qtog 'uortej?i('u -rp-q8rq u?$r?ujno L-prur E ot pel\xo$ snqpu ol sjerueq sno erd EurôruoJ,(q 'sd"qrcd 'pue -3ilod ew ur uorlebods pendeuej qull poldnoc peld"p? eje,{r oluos qcrr.t ol slueuuorl\ue 'sluoê,fieuorlnloê eseqj (a"prluopo I?urArEuI eql EurcnpeJ Jo Euq?uru{Ia -qt?usoqleds ew Jo) snllrdu&qodopnasd pue i(q seqrunruruoc euu?ru ^lleeja Jo sluerrjele cqlueq '(eepquopoql?u9 e\t Io) npoqpusojold '@ep -odleu pu" c?led papej" a Eq osl? tq8ru YJNOCONO] AHJ 9EI

144 EVOLUTIONARY PATTERNS 137 ulations of idiognathodontid conodonts de- also provide in Fig. 6.3 a zone-by-zone log of scended from highly variable Gnathodus girtyi the ratio of origination to extinction of conogradually segregated into discrete and some- dont species. That log may be used (with the what less variable stocks identified as Decllno- customary caveats) as a crude index to temgnathodus, Idiognathoides, Neognathodus, poral oscillationsin eyolutionaryvigor. Idiognathodus, and' streptognarhodus. Radia- Although at least lg5 conodont sfecies origtion ofthese stocks kept the evolutionary index inated in the permian-triassic interval, speciis above the maintenance level of 1.0 through diversity hovered around l0 at any one time, most ofthe Morrowan and promoted a slow re- dropping to a low of 5 in the earliest Triassic covery in species-level diversity, which peaked but rebounding rapidly in the same interval to in the succeeding Atokan epoch with addition a post-mississippia nhigh of 22. of the first representatives of Diplognathodus Fig. 6.3 also ouflines four second-order cyand the Gondolellidae and gradual phyletic cles in the permian and another four in the evolutionofthe/ry'eognathodusltneage. Triassic. Extinction of Neognathodus and probably The earliest of the Permian cycles, Cycle also of Rhac histognathus in tl 'e late Desmoinesian (Pennsylvanian) marked the end of Cycle late Pennsylvanian and Asselian when the evo- XIV in Fig. 6.3, followed a long interval in the XII, which is also shown in Fig. 6.2 to be terminated by a rapid decline in species-level di- was provoked by the appearance in the Saklutionary index was consistently below 1.0 and versity. Continued gradual phyletic speciation marian of an early species of Neogondolella (N. in the I d i o g n at h o d us - S t r e p t o g n a t ho du s lineage, bisselli), the first species of Sweetognathus (5. together with the appeaftnce of Aethotaxis, EI- merrilli), and a distinctive species of Drplognathodus (D- sakmariensis). N. bisselli is Iisonia, and new species of Gondolella, Diplognathodus, and Hindeodus, signaled a brief interval of innovation in the eady part of the which precedes it stratigraphically. However, thought to have evolved ftom N. praebisselli, mid-pennsylvanian Missourian Epoch and the these two species are separated by much ofthe somewhat later peak in species-level diversity that marked culmination of Cycle XIII. Note in Figs. 6.2 and 6.3 that in the latter half of Cycle XIII the evolutionary index was continuously below 1.0 and that specieslevel diversity declined gradually to 15 in the Virgilian and to l0 in the succeeding Assel.ian Stage ofthe Early Permian. Although species of Hindeodus, Diplognathodus, Streptognathodus, Idiognathodus, Adetognat hus, Gondolella, and. E llisonia survived through much or all ofthis long interval ofsorely restricted evolutionary vigor, only the Hindeodus, Diplognathodus, gondolellid, and Ellisonia lineages survived Clark's (1972) Early Permian crisis to provide the basis for secondary cycles in later Permian and Triassic seas. Pennsylvanian from N. clarki, the earliest species with elements morphologically assignable to Neogondolella. For this reason, I suspect that the N. praebisselli-n. bisselli lineage is an independent Permian development from the long-ranging Xaniogna.thus-Cypridodella stock which, as I speculated in Section 5.8.5, was probably the progenitor of several Gondolella lineages in the Pennsylvanian and earliest Permian and the ancestor, as well. ofnumerous additional lineages of Neogo ndolella, Neospathodus, and, Epigondolella later on in the Triassic. Secondary Cycle XV follows the early Artinskian extinction of the typically Carboniferous genera Streptognat hodus, I diognathodus, and Adetognathus. Following a brief interval of slightly lowered diversity, a short innovative burst resulted in the appearance of the earliest Permian and Triassi cycles species of.ly'eostrep tognathodus, Sweetina, and Fig. 6.3 is a zone-by-zone summary of conodont species diversity through the Permian represents a modification of the Diplogndtho- Merrillina. Neostreptognathodus apparently and Triassic periods, which together represent dus-sweetognalhustock, whereas I have interpreted, Sweetina and. Merrillina jn Chapter 5 as 78 million years of geologic time. As in summary logs for earlier parts of the Paleozoic, I successive stages in a prioniodinide lineage that

145 {reij 'reê^loh 'uluopouoj oql Jo fuotsttl dj?uoqnloô ejrlua aql pel?npund suoqcurl -xe cu.ell(qd pue Furuuel qloq 'polou $nf sv uollrullxg t'9 -ln'pue snnlslutnl'ou!tuopotpdh'dutpdptrtlj -rd Jo sorcods Jo \aols Dluosttlg e IlE lesuoo 'crss?uj eqljo pue,fuo^ aql ol e^r^jns 01 'pe ll-3uol eqt ruo{ lueudolo^sp lueunc {cols,(fo oql pue snpoqpdsoan xrsseul -uoc equasse pegldrud s",{ tsjnq (u"ql Jo f?ldej e 'o ÎrEa ltslw pup. oljtlls nsuas D al -^cs Jo) ^ crss?ul ^q srrlj u?ruusd awudnal -opuo3ldg Jo (D appuosoan uro+ ilqeqord) -opuosoan Jo seeeeuq ^lffe o,n1 ls?el le 'Î3Îlaetr uerurs) lsalq aql ur lugrudoleêp eîl?re 'osl? pu" u ruuad lsorlj?o pu? uerue,,r.1,fuuue4-11,(q popuers se^\ 'u?uon lserljeo eql ui 'opos er/0 Jo so appuod..peurojteld,, pu?..poleu,, -rde stl'stuopouoc prllslopuoe Jo dnor8 ^lrsje^rp-qftq DlpuuDJ et\t plde tvlpdllsow eql pejnpojd ter0 auo eru?s oql pue a?pl[01 'snulsru -opuoc eqljo Icolsuols aql'xeldvrol D apop -tqopn2sd Jo uoqcuqxe 3ul{rolloJ slrrq u?ru -ttdt9-snqpusorudx Sur8uer-Euo1 eql uorl -J3){ ur ueseq 'sluopouosjo.fiolsq oqt ui ouo -"rceds ls?l eql pu? el3^r rlsseul Ieuu 3ql Jo lsjnq Jerltou? 1a[ sluesarde: ^q qcrqn 'xx olc^c 'snpolltddsoan lo crsseuj,(lj"g eqt ur uou?il 'e8eeu\d adqson -rur qll^\ polersosse,{te,{qrsod si pu? ueiirjjad -snlllslunlopnasd srll Jo DllapoprrdtJ utorj Nelel eql ur xepul fueuortnloê pessejdop lueudole ap luerjnruoc,(ile4uesse pecjoj Jo 1e elur pe8uolord e pa^\olloj II X elsi(j -urar se,!\ xix 3lc^c Jo eposrdo ^q 'lqblls oql pepecejd leql lsrnq e,\il?ôuur ^lrsre,\ip-qftq eql se^{ ueglnqzo turpaa3rns eqt ur,{llsje^lp ôj -npng [.rdi ot" sj"e,( ouios 1I JoJ posodojd ur fueôcej pue 'souo ueruued JeIIJee,{q pepu se^r'qarq 'o ^q au DJ eu?u eqljepun PelsJedes-fis lsmq e^rlerc1r Jo uos errj s eql luosojdej rolleq sdeqred [lq'dllappuo8dg ur pepnlcur ol J?edd? lou op,{eql 'se8eeu\ Dutllutah[ PIde,(Fouruoc e8eeul? Jo )Iaots Dllapopt.tdt) snqpusopaks er4ljo serjeds lsq 0q1Jo uorfun -srullousoludx.tlt rc o appuosoan srojj tueur -xe,tq Ual pro^? po g serceds,{leu eseql elqla -doleêp ol pel"lar si l"ql eposlda.lue8unuo3 Suruorur eq] lno punoj (rryjst! -reîp-q8q e sepnlcur ^ljeelc xix elc^c u?rurpe-i ^trs -ôqsôw e) snpoqpusotdle Jo ouo pu (sqrr? 'se elopuosoeusisiuy -dlt 'H) snpoaputh Jo seroeds V osprtlslopuoc pue usrrlt fus ueeûeq uon"persj4ul clsoloqd 3q1 Jo {cols uels eql uro{ oôu ap $ llpsslq -Jorrr selejlsuouop legl saldluss Jo uorssejsns W Jo suo4?lndod u?dl"uiuv ur reqlte peleu e aurlquasse ur InJsseccns uaeq te.{ s?q euo ou esnecaq,{ rqrssod rellel eql Jo^?J \aors D ^lusrrrrjd apopltdt)-sru$du3olu0x aro ruojj,(le^rl Jolr padoleêp Jo se slopuoaoeu u?rql -,bs luo{ peîoê sepeds esor{l JI elqeuollsenb sr u lnqep Jreql spstll osle- (srsua8nqruoru N 'ediq eql Supnlcur) o appuosoan Io seloeds I?reês reurq eur s srll lv lcols o apoprtdr{j -snl?dusoluox pozrpjeua8'tu u"l-8uol eql (]o u?d ro) uro{j peûep,{iq"qord pue stueur -ela fue^ i(q petuesejdor IIE 'sirrjoj paleler pue ûu olapotry) ol pauejej selcedsjo dnoj8?jo ejeql\esle slueuruojrlua papulser fgegurls u1 sdeqjad pus urseg Jru?urJaC eql ul lujtudolo^ -ap uersruv 01,{lueuud pelqer sr IIIAX elt^j tu?puoces Jo eposrdo.{trsjs^rp-q8q eqj ipeletalelur ^lsnou tnq e^rtourlsrp AIqAq si leql Eun"J luopouoc u"rqlbs ecnpord ol peurquroc?plurpoluoud oql " Jo seqcuejq Eullr^rns or't aql Jo fuotsq eql ur stueê ese\l'dlplopuosryolt 'ilfl vtrr - uo pu? erurl u?ruuod elb'i,{lj"e ui u?8eq 1?q1 eseeurl u"rujed puosas? enurluoc pue D appuosoan ol elq?u8rsse oj esaqtjo eerql 'oû lsnfjo uo4curlxe pu? selcods ^reu eau Jo uprrrued 1selq eqt ur mueleedd? ot elqelnqul -le sr lsrnq eûeôuur fuopnporlur sll 'sa8ee -utl DutllttDw-Du rraaus pre snqjousoaat4s eql Jo uoqcurtxa reub i(lpejlp pa.holloj 9 '8rC ur,{["cn?uror{os u,yroqs I]\X el3,tj (u?g Jnqzo ro) u"ruued elei uoqs fje^ eqj ^ll"e 'seazeu\l snp oq idu 3 o 1 d a t 7 s o a 11 pue oulll! aw-ouuaaqs 21tr1 Jo uolsl^rpqns (cuel,(qd''e 0 cgrcedsouorq3 luenbosqns luesej -der ol uoes 1eq1 sorceds,4q,{leejei patel -ndod ^psoru I"^lalul,{lrsre^rp-qAq sepnlcur X elc{] Jo tueueos u?ruled elel Euol Jeql?J eql 'Dluosltlg ruo{,{lo^rfrotr peûep eq o1 s8ulql -secur lsourp pu?,(lpcrloue8 pelful qjns Jo sjuas? Jo lslg ew ujaq Jêq ^lsnol^qo ^?ul VJNOOONOJ IIHI 8tr

146 EVOLUTIONARY PATTERNS r39 )r I = z tu, 10 z o x I \ \x { \ x\ \ Fig Survivorship curves (left figure) for cohorts ofconodont genera (e.g., all genera originaling in Ordovician) and curve oflongevity ofconodont genera ofall ages (on right). Redrawn from Clark (1983). (1983, 1987) has recently focused particular attention on events in the late Paleozoic and present, however, like those for conodonts the Phanerozoic marine record." The data they eady Mesozoic history ofthe phylum that preceded its extinction at the end of the Triassic. high extinction intensities throughout the Late shown graphically in Fig. 6.5, show generally In his 1983 study Clark presented a series of Triassic, with a maximum in the latest Norian survivorship curves (Fig. 6.4) for Cambrian (or Rhaetic). This suggests to me, as it apparently did to Clark (1983), that the end-triassic through Triassic cohorts of conodont genera and a summary curve for all conodont genera extinction ofconodonts may have been the cumulative result of several factors. not of a sin- listed in the Treatise (Clark el al., t98l). Clark noted that these curves indicate that the ayerage survival of systemic cohorts was 109 my lum "well before its time." gle catastrophic event that terminated the phy- and that mean survival ofconodont genera was Farly in the Permian, at the end ofsecondary about 30 my. Thus, as Clark pointed out, an Cycle XIII, a majority ofthe typically Carboniferous stocks disappeared, following a long observer in the late Paleozoic with access to the same records would not have foreseen the end- late Pennsylvanian and early Permian interval Triassic extinction of the phylum but would during which species-level diversity plummeted and the evolutionary index was consis- probably have predicted surviyal into at least the Jurassic and possibly into the Early tenfly below the maintenance level. Permian Cretaceous. recoyery was surely not spectacular. It primarily involved a couple ofbursts of speciation by The record indicates that the Conodonta did not survive into the Jurassic or Cretaceous, the gondolellid stem group, one each by lhe EIhowever, but that the phylum became extinct Iisonia and. the Diplognathodus stocks, but very in the latest Triassic. Conodonts were not the only group to become extinct or to suffer major declines in diyersity at this time. Indeed, Sepkoski and Raup (1986), summarizing the opinions ofothers, note that "the I-ate Triassic contains one ofthe five largest mass extinctions of little action on the part of Hindeodus, which merely "showed the flag" through most of the Permian. Note in Fig. 6.5, however, that, despite these fitful attempts to restock Permian environments with new and vigorously successful conodont stocks, extinction intensity

147 Jofeur snou?a Jo lueurdoleêp e^rlaelr ol selc,{c,$lsre^rp rapro-puoces Jo uoqpadar aql perl seurd I?Je es aêq I 'sujeu?d,fu"uoqnloê patelar-,{lrsje^rp Jo uo$sncsrp Eulpocard oql ui sundad,t.ruuollnlo^g a^pbrall S'9 ',{lrc?d?rur Jrleuet crseq Jo luoprore crursoc Jo usqt (eruq lq8u 0q1 te eceld EuoJ/I\ eql ur Sureq) Ionl p?qjo tlnsel eqt ejor! ueeq eêq snql,{?ru?luopouoj aql Jo esruap eleurlln 'ueru? l,{suued eql ur uoqdeour slr ecurs slueru -uojrûe crteled ejour 'Je1e,r(,-Jedeop ur euoq le ejour uoaq p?q sepruporuoud Jo lcols sql pue-peureurej spqlalopuo8 aqt,(po pue ouoe JJa^\ SprruosrllJ lalem-^\olleqs Jql 'u^lop s1u3d o^rt?d?p" slr qlr,r\ lq8n?c ueoq oêrl f?iu rnnl -,{qd eql'uoqs ui leâl?as ur dorp ephrpljo^l E crsseuj erll Jo pua eql le p$npord -eqojd ^q suonpuoc,(ejoue-joq8rq'jo^{o eqs ^lq eql 01 ld?p" 01 olqe se^\ leql euou serceds crsseul lsel?l JnoJ Jo eenll slr tuoure pepnlcur '3rss?ul pue uenrrred ar{l q8norql sauaôjej lsepour pue turun:d orposrde,(llbjrleu ^lsurseercur -ea paua{ee^r 'etuopouoc eql l?ql ^q pel Inoeds (t86i) {relc '(r/6i) uosduroql pu" 'runqr -IIIAI 'll?a pazuztuuns c]ep cdelsne uro{ pu" uoberrrrojur ^q crsojolad u1r{o srq uorc 'uerron eqljo pue ifie^ oql l? uorlcudxo lelol ui polburuqnc srql pu? 'es"ajcur l?np"lt ue8eq ureee uorlcuqxe " Jo /qrsuelur eql (uersruv) orss"ul alpplr\l eql ul ^lj?e ruo{ lnq 'lueuruojr ue euueul olq?lrns Jo seare 6uruepr,rr' 01 sesuodsej luesojdsj ol uroes $Ico$ eprurporuoud SuruEureJ o,tr1 oql,(q uod -eôuur e^rlejelr Jo slsjnq Jouq 'uerurs) eql ur lsalel sql 'crsseul eql Jo sle^relur rnoj tur -Jno 'poqsrururp requnj s?.r\ sluopouoj 0q1 Jo etuoue8 eql 'eprulpouezo oql Jo dss8 ls"l eqt 'snpoapurg Io arss?ul eql ur ssol qlr^\ ^lr?e 'serceds t Jo,'dol oru4ll? ue ol peddojp eluopouoj eqljo ^tlsje^rp U?Je o ueq.{r'pouad oqljo pue eql reau (sq8q ro) q8rq? ol uerrrrred eql q3nojql peseojcur,( enp?rt 'el p A{Er ellres eql e loûr ssoj IIV sujrl roj pelsnfp sl pue uorlcurlxo elldec Jod slold 3ol re^\o.i crsseuj lselq eql ur ujnl,{qd oql Jo uoncunxa 01 ulebe paseedur ueql pue,crsselll f,fsj eqt q8norql poses:csp 'uerru:e4 eqt q8norql peseorcu uoqcuuxe teql slse8ilns,{leleru eurl peqsep pue 'ouoz qceo ur sooods Jo dorc Surpusls Jo o8eluecjed e se suorljurlxo ^l$uelur slold 3ol JeIuoC euoz qjeo roj suollcullxe Jo roqurnu oldurs slold 3ol do.l stuopouoa crsseuj pue ue[ulod roj sculeu uo[cunxo snou AJo s8o-i.8 9.6ltr ctssvtul NVrt uld lessv lo to '= q5 L oaa I Ot lur os ; oor > 0to VTNOCONOJ AHJ 0nl

148 EVOLUTIONARY PATTERNS The recent suggestion by Sandberg and Dreesen (1984) that a group of Late Devonian spet4i groups of conodonts, particularly the Ozarkodinida and Prioniodinida. A similar pattern is is also an attractive explanation. Plectodina gin iterative deyelopment from basic lineages apparent, however, in at least segments of the and. Phragmodus, for example, appear de novo Panderodontida and Prioniodontida, and it in the early Middle Ordovician, and their species forrned skeletal apparatuses that are, in a may be general in the Conodonta as a whole. As shown diagrammatically in Fig. 5.36, nurnber of ways, closely similar to those built which summarizes my views on the phylogeny by several species in the Multioistodontidae of the Ozarkodinida, elaboration of the sides (e.g., Paraprioniodus costotus\. Because the latter precede Phragmodus and, Pleclodina slrati- and surfaces ofpa-element crowns was carried out repetitively in spathognathodontid populations at several widely spaced intervals in the among olhers) as attractiye candidates for graphically, they have been considered (by me, Silurian and Deyonian. As a consequence, apparatuses ofthe species that developed in each ments are mostly hyaline, and there is little to ancestors. However, multioistodontid ele- ofthese iterative bursts are closely similar. For recommend them in other morphologic particulars as hallmarks of the ancestors of either example, Ancyrodelloides of the early Devonian has Pa and Pb elements that are very similar to those of early Silurian Pterospathodus those two lineages developed independently, Phragmodus or Plectodina. I now suspect that and also essentially identical in morphology to and at slightly diferent times, from generalized those of later Devonian Ancyrodella. The species of early Siltian Kockelella experimented dontidae). Although one may distinguish read- prioniodontide ancestors in Tripodus (Oixo- with elaboration of Pa elements in much the ily between rnany of the elements in apparatuses of Phragmodus and, Plectodina, others same manner as did early Devonian Eognathodus, pitnitive representatives of somewhat (including certain Pa elements) are closely similar. Thus homeomorphy may not be as great younger Polygnathus, and, a number of later Devonian and early Carboniferou species assigned to Scaphignathus (Spathognathodonti-but it is nevenhelessubstantial. as between Ancyrodelloides and, Ancyrodella, dae) and the Cavusgnathidae. And iterative development of the Protognathodus-Gnalhodus, lurian development ofthe prioniodontide fam- I suspecthat iteration also characterized Si- Diplognathodus, Lochriea, and, Rhachistogna- ily Distomodontidae, but this may be very difficult to establish objectively, and there are /lius lineages from B is pathodus (Spathognathodontidae) produced such a welter of species surely other possibilities, as indicated in Section Ifthe basic apparatus pattern ofthe with morphologically similar Pa elements that supraspecific phylogenies are notoriously difficult to reconstruct or defend. elements in the P positions, then iterative de- distomodonts included unplatformed pastinate In Section 5.6I have also noted my suspicion velopment may have been responsible for in! that Parabelodina denticulata, a panderodontide species with well-developed rastrate ele- Icriodina, Hadrognathus and, ultimately, even tiation of stocks such as those represented by ments in its skeletal apparatus (and thus similar to species of Belodina and, Pseudobelodina), Peny (1977) seem also to have suggested that some or all of the icriodonts. Chatterton and evolved directly from a conlemporary species iteration might have been the active pattern in of Panderodus (P.bergstroem), not from some icriodont evolution when they wrote that earlier species of Belodina or Pseudobelodina. Other evidence, mostly unpublished, suggests species that could be or have been assigned to the genus that Panderodus itselfincludes a number oflineages, each probably deserving of independent generic (or even familial) designation and representing chronologically distinct iterations of stocks characterized by skeletal elements of closely similar morphology. Within the Prioniodontida rhere are quite a number of"cryptogenic" stocks for whose ori- Pelekysgnathus, as it is broadly conceived, may have been derived from other genera during four diferent evolutionary events (origin of"p." inder in the Late Silurian, origin of I hadnagyi in the Lochkovian, origin of lsteptotaxis'l Iumishi group in the Eady Devonian and. oigin of "P." comn r/rrs in the late Devonian.

149 'uo uercrôplo elppq l aql IIro.lJ ser3 Jo qppopttdt) ruo{ luerudolsêp ur p3^lo^ -eds tuopouoc nd.ej e tnq Ip pezrropej?rlc pue -ur ueeq eêq IJe,{l uoqejolr Jot?.I.snl u"rrhopjo eql rn [q $lcols lejoâs ui lue -er?dde elelquraru4lnru ^Bul e pe\ D alopuosoan -sejd ore,tr sed^l luouele ^ljea luejejrp leqt elllojdoc c$s?uj? rrlo{ ecueprê elrdsep -ror[ ueês ro xrs qlr/r\ sosnleedd? ^fl"c olorid pelhoq?lo.(d apopudtj Jo) snqpusotuox ui,{flecrurou,qlnd.{toloqdjour luojojrp,tp?ej8'jetq lrq? -ox?l ueppq eq,(ouaunc,(eur sesnlh?dd? 'ueql ',{Il'qftls $rg t?jo stuauele peg4uepr plela{s rreqt alaldu]oc leql stueurele ulrojrurej eq 01 aur?c snl?redd? eql ur suo4rsod ^q luelejrp er{l 5lcols-ujels snqpusotudx? rrro{ 'reêaoq 'sess?lc qtoq Jo tuolsq fu?uounloê -prelr pedole ep se.:/eds snpotltddsoan ^le^rl pue eq1 ur uoos AeA (9'9 '3rC) pcrruepr ro relrur6 D1alopuoSoaN Jr,sl l"ql.ruelqord stql Jo lled,{llmrtolor{tuou ojea\ suort?jol lle le sluaur eqos:p- Aeuro apopudtj pue snrlpuqotuox Jo -ele gcn{^\ ur sesnlbjedds el"lqrrje{lun llfq sercads snoue^ 01 pousrsss a^ q I sdnojs luej (fle^lcodsoj 'snruopual pue sntuopouo)ojd) -rncej eql,(q pelueserdor souo elbjqrueruulnur 4uopouoc pu" Ruopr^?c eql Jo sjepunoc Jo sesnl?j"dd? el"jqr[eurun p'.j] snpollldds uottorcqop snwldddv I'g'g -o:-y--p:e sprllslopuoe crss?uj ' ' - - :lrlowosoan -orrujd aql Jo serjjds JJqleq^r ol sz aleqacl spuertrr(reuopnlo^g 9'9 'snqldutsotudx uro.g seurq laaês pedolelep eêrl Rern o al -opuo) tp.rplsoaens osl" sercods Jo sdnojg o^rl 'rxnl^qd aql eql Jo sesnlaedd" ui pcuuepr Jo lelrxrs el? sluarusle rujojrrrj?j 1?rll lc?j eql pu" 'sluolliela txrojrtlalopuoe JeAuno^ leq,{.euos ol ej? Jo uollcunxe Teug ol petnqeluoc 0^?r{ Ile,{r.{tllqlsuodsar Jo 8uu"qs srgl 'l.r-?j ui eplurpor ^puj -uoud agl Jo fuotsrq eql ur seposrde e^q?jelr pup slueê cu?lsne ueeûeq drqsuoq"lej JeIr -ulrs elecrpur,{?ru seuo e^rssojsoj Euunp spu " -uosrtla Jo pue ses?qd turuedeep Suunp spllel -opuo8 Jo tueudoleêp crposrde 'crsseuj pu? crozosled ele.i 0q1 q 'sl.xols Dulllau!fipuDd pue snpou)i-snqtousstulapd eql uorlulo -q?le roj serlrunuoddo pejejo e^?q ^q seljô esoqt Jo ses?qd o,trssersar eql gll^\ ^?ui pel?rcoss? 8uh\olpqs s"ereqa 1lcols pnuopoqleusoql?ds eqt Jo ebeaurt outpoltdzo eqt.{q uorletoqele o^rlerelr JoJ sedrunloddo pelejo e^"q,{eut selc^c Euruedooo 'slueê cnqsna aql Jo l?ql peprôrd ueoq eaeq,{plu slsjnq e^rl?ôu -ur ^q JofEuJo 8u[url aql leql lse8sns slueê (e^rssejeej-e^rssej8suejl Jo) Jq?lsno êtu pu" slsjnq sarl?jei uoe^lleq lsrxe 01 suees 13ql dqs -uoqelej asolc eql ',{le^rlrtedoj peqcuejq soeee -url popuo-p?ep mnouasol,{qd <pe^rl-jauoqs qciii,yr trro{,{8oloqfuotu ^ pezrpreuat'e,rr1err -resuoc Jo snl?jedd" ue,tq pozuolcej?r{c {Jo1s 8ur,r1o,te. 1,rrro1s JerJl J se^\ slaplo luopouot oql Jo qjpe ol lelluec leql tsessns ol eur slad -Iuot pezueururns lsnf uos eql Jo ajuepr^g 'sln?qjeô orseq ojrnbal III^\ e"prtlelopuoo aql Jo fuesol,tqd pu? fuouoxul qloq '^pnls roql -rnj,(q poloddns oq suorcrdsns esew pfoqs 'sebeelj\ DlplopuoSldg plue D auuoj erft ueql Jncro serurlaulos,{eql êql qclq^r ^llecrqdas[ejls qu^r sluerrlep el\-snqnusotudx lper..eu eql ol pel?ioj ejor!,{foruuroc eje Dlplopuo, lo I?rrd& ^lesolc stuoruole etzu?ldruru8es eq1 1?q1 uoee esqo oqj '0r6t ur snqpusor -udx sr].ue8 txjoj oql peseq I qcrq/a uo sluelu -els ed eql Jo sqfuouoeuoq cdoloqdjorx el? l"qt sassecojd JoualuB ssafrjolpld pue Jouetsod Uoqs glyr\ slueuele Ed ^ll"duesse..peleu!! psu.uoj serceds esoq { Jo eljj,os 'o appuog ur Surpq eq fnuounc Aew'l's snqtousotudx Jo sorceds,{ljee 'elduruxe Jod.serJeds croz -oelbd elbi snoue^ Jo uorlecgrss?lc elelpd -sip pem3sqo aq,(bru lueurdo -Ie ep ^q e^n"j3lr JoJ ecuaprê ^FueJJnr oqljo elllos ecueq 'sdnor8 asoql qtoq ur turop speeu clluouoxbl ^lp?q {ro?t\ cneruels^s Jo l?ep poot y e^rl?je -1r s?/a esprruosrtlg pu? eeprllolopuoc serltr[4 epurporuoud oql Jo uonnloê crozoeled al?l f"q1 9 '9 uorpes ui ui?ee pu? urc3? pessord -xe uorlcrûoc eqt lpedej plnoqs,,{lpurc I icrtol^qd,{lod eq snql,(?ur esprluopoucl eq1 l3q1 pue uo4nloê ÎpF^{ luopoucr ur ujelled e^q?ledo Jof?u aql ueeq eêq,{ 1u uonejelr leql uorcrdsns suelq3 q slueulele ed eirl-snpou)i qlyn serceds ^ru Jo snqpusst4al -rd uro{ luerudoleêp a^dpjolr eql lueseldel peelsur [euj snpou4 ol peu8rss sotj ÔueJnc VINOCONOJ:IHI zbi

150 EVOLUTIONARY PATTERNS Apparatus reduction by the fact that there is a stratigraphic reduction in the ratio between ramiform and pectiniform elements in several major groups (Fig. In species of a few Ordovician genera (e.8, Eoplacognathus, Polyplacognathus, Scyphiodus) and in many post-ordovician ones, Merill and Powell (1980) suggesthat ele- 6.1). there appears to have been a concened, if only ments in the S and M positions may have been superficial, effort to undo the hard work of mineralized early in the ontogeny of certain rnorphologic diferentiation carried out by their species, that P elements may not have been mineralized until later, and that the early-formed predecessors. That is, species in these stocks apparently formed apparatuses that were reduced just to P elements, or apparatuses in wholly resorbed by maturity. This intriguing S and M elements may have been partly or which elements in the P positions were the only hypothesis is supported by evidence from the ones mineralized. This conclusion is suggested Drum Limestone of Kansas, in which succes- Fig Frly diversification of the two basic corodont lineages, the Proconodontida on the right, the protopand rodontida on the left. Numbers in circles indicate number ofelement$ in appamtus. Note tha,earliest members of both lineages had only a single element type, but that dive.sification produced appantuses with two to four element lypes by early in the Ordovician. Redrawn from Sweet 0985). z = ; o o = (.,

151 pepnjcur s{cols epruipo{ezo lsoru '3lozoolDd eql u! J4e[ pue usruoêc eql ui 'eep -rtlepourl pue'5"prluopourolsr(i'e?pouopo 'se8?lqruesse FJnlEu,(q peluosarder seljeds Jatuno^ pue 'saroeds ueunls pue u?rcrôpro lsow pgzqereuru lou eje,{a suonrsod W pu? S eqf ui stueuelo ^ldrurs ',qlrqell"a? elsqdsoqd perlujll Jo suourpuoj Jepun 'snqj 'suoulsod snlpndd" reqlo ur slueurele Jo uodcunj aql ol -qleusoqleds eql ur stooj glv{r serceds,tq suoq -rsod d ur pedoleaep eje,r Euourele peuuojl?id ^lpel?eder 'ueunirs oql ui 'suoursod esoql ur perrrjoj sluorrjele porujojfld ora,$ (e?pql?ue (ocusuodur oujo Jo) ecuelodur resseljo sdeq -oceld,(lod 'eepqleusoleg ''6 e) sst"eurl.e\ej e -Jed lnq slueureje d Jo uobcuru eql ol acu?uod fpo ur lslueurala ru-rojrunf,ed peu ojpldun -IuI IssIluC Jo s?,{r UoB?zll?leullu leql S01?Fl perdncco ejo^r sesqej?dd? polbnuerejrp ^q -sod oqucsqns I qcr-q,'a ol auo eql 'suolluu?idxo ueê ur suoursod d 'sruroj u?rcrôpjojo,quot ^llnj elqrssod reqlo aj? ejoqt lng 'se8"ls tlleu -eur s ui suoursod d aql ur slueluglo urjojrurl -e8oluo relel ur poqjosal AII?nlc" ela,{{ suorl -ced Jo uorluoqsja prb,rol s",$,tcuepuel Jof?ur -rsod esoql ui slueurale q3rqna ur Jo-/qrJnlsuj? sot"euq snorj?a ur snlej?dd? eql Jo luoul erojeq p0s?0r slueruala,^l pu? s Jo uod?zrlb -doleêp pu? uodsrtuaje:urp,{j?uoqnloô ui -JOUTIu qcrqa UI SOrtOdS JO SelruA^nf luesejdoj caontsod d ut stuataap lo uoudnqdlg t 9 9 Êru 'suonrsod I" ul slueluele pozrlejeuru qlp\ 'satelqruess? I?rnl?u arn l"ql pelso8itns ueoq seq 1I 'slueurele elojtslp Jo suolltelloc pel?l -nqel ruo{ peurrrjjefp esoql pue 'sasnl?jedde IqeJe{s elelduroj lueserdej AlqeumseJd qorq,{ 'sebelqruass? IeJnleu ulo{ pelelnclsj sorl -?J uuojrurlred-urojrrusj eql ui &ubdslp pp '/(uasoluo JerlJ?g ui slueurele esoql ur parots aleqdsoqd eql se8gls tlnp" ur Surqrosal,(q ro suon$od I I pue S ur sluelxole Jo uoqezrlujeurur dn tur^6 sluauruojr uo Jood-eteqdsoqd ol peldsp? e^?q ^q,{eur slueur -u4sqns e sr areqt leql JlBcJPur I l.'9 'ElJ ui -ele d '^larrlua ro '^lsaj J petuasojdoj esoqj 'serc00s. 'punor? ^q oe ol qenouo oleqdsoqd szr\ ojoql eleurs Jo (uesoluo oql ur set?ls e^rssgccns qcfi r ur slueuruojrlue pelqequr o^?q furu Jo spjocer ejnd /(F?eu urslej 01 ruees speq e^rs 'suondpueue qll^r '(986I ) leoas uro{ u,r\erped 03? Jslrurs Jo (sprs) s.selquresse Ielnl u tuo.rj poûep osoql uro{ lue$jrp (seurj peqsep oo) seeuonberj lueuelo-efjcsrp Jo slodej tuo{ peûop solej 'oslv sdno or(uouoxel ^luoruruoc IIE ur olun olrlbs eql l ecqd e)igl lou plp sollej ur uoqcnpar oql pue suorlcolloc ueunl -ls-lsod {ueur ur sluouelo rulojnuer Jeqrunulno slueuole urojrunjoal r(q^r.igolc lou sr U sluopouoj crs -s?ul q8norql uerjrôplo Jo sosnlerealde ul stueurele uuojruuced pue rurojlruer uoe,{rlgq orler ur spuorj 'r'9 'Eld \. r, I nura I I i t ';.. ttlt ^3o I ep'utpotrs.o./ rrs,;.. i i SU\lSOllNlICld z I \\ ' '. :stnuollt,lvu eepuptopuot ''./ i.^ epluopotuotrd '/.\ 8r-. "l "', I i ouo e z I \EZ T s z i.. ""''"'0,,o'"o'1" '-;.r;'i"?; ""r,u,",r.,,ri/ i- ;? VINOCONOJ AHJ nnl lz

152 species with platformed pectiniform elements in the Pa position. The Prioniodinida delayed development of platformed P elements until the Mississippian, when the curious, shortlived Bactrognathidae invented thern. Later, however, in the Pennsylvanian (and increasingly in the Permian and Triassic), prioniodinide stocks came to be characterized by platformed pectiniform elements in the Pa position. EVOLUTIONARY PATTERNS 145 biologists are thus encouraged to seek informatiod on developmental pattems and potential ecologic controls in the materials they study. The large, stmtigraphically well-controlled collections ayailable to students of conodonts should also be well suited to studies of developmental, or evolutionary, strategy. Because well-made collections commonly include elements that represent various stages in the ontogenetic history ofthe species that contributed to those collections, it should be possible to relate ontogenetic timing ofthe morphologic fea- In the absence of firm information as to the function ofelements in any position in the conodont apparatus it is diftcult to relate evolu- the lineages that formed them. And, if collectures recorded to developmenlal strategies in tionary elaboration ofp elements to specific environmental or behavioral factors. However, other biologic properties of the rocks from tions are carefully related to the petrologic and from the fact that such elaboration characterized some or all of the lineages in nearly every possible, in time, to determine the nature and which they vvere obtained, it should also be major stock at one time or another in their history, it may be concluded that platform elabomental strategy and environmental pa- extent of any relationship between deyelopration was surely of positive adaptive significance. Although information on the ontogenetic rameters. de- Nicoll (1987), who suggests tllat the skeletal velopment of various skeletal elements has elements ofconodonts may have been internal been provided by various authors, I am not supports for ciliated tissue in the food-gathering system of generally microphagous animals, in the ontogeny of a conodont species frorn aware that anyone has yet documented stages concludes that P elements were opposed and studies that involve all elements of the skelelal operated in such a fashion as to roll, bruise, and apparatus. Consequently, in the following sections I summarize pertinent information from crush particulate matter caught between them. Phylogenetic elaboration of P elements might a few recent studies ofpa elements that sugg st thus have been related to changes with time in that developmental strategies may have differed greatly from one group of conodonts to size, shape, and bruise- or cmshability of food particles. If P elements functioned as teeth, as the next. We can only guess at the extent to Jeppsson (1979, 1980) and others conclude, a which additional strategies may be suggested similar relationship might also be postulated. by future studies of complete apparatuses. 6.7 DevelopmentalStsategies Gould (1977) has provided signal service to the biologic community by emphasizing not only that "parallels between ontogeny and phylogeny are produced by heterochrony" but also that there may be a continuum ofrelationships between ecologic factors and the life-history patterns that may result from alterations in the timing by which various somatic and beharrioral features develop. In short, Gould expanded on Van Valen's (1973) somewhat earlier observation that eyolution might well be the control of development by ecology. Paleo Recapitulqtion Heterochrony involves "changes in the relative time ofappearance and rate ofdeyelopment for characters already present in ancestors" (Gould, 1977) and may be effected eirher by acceleration or retardation. Ifa character that appears in the adult stage ofan ancestor appears at a younger stage in development ofa descendant, acceleration is the process involved and classical recapitulation the result. Ii on the other hand, a character that appears in the young stage ofan ancestor appears in, or is retained into, the adult stages ofa descendant, retardation is the process and paedomorphosis the result.

153 Jo 'a^q?jelr q8nolql seqruniloddo pelejo,(lpe Jo uounloê eqt rljjq.r ur oueuecs -leedej Jo se8ualleq orll Jol(su? ol $lcols-urels " peul0no osp eêq (t86i) quroccl l pu? peoqp?org ol4elrasuoc snou?^jo eqt ol pue (srs"q 'ûetoluo euo-roj-euo e uo s,te^{le ^lqrq" lou qsnoqlp) slueê Jo se8?ls Jelel pu? ralq olur sjepsjerlc 3q"lsne rapro-pumes ol pol?lar uees elrue^nf Jo uouuelej eql-ûoloau Jo etdrx? -Je^rp Jeâl-seroeds puu JoErA dj?uorlnloê ^1$ ur -xe 'ssor8,{ljr?j IIIIS JI 'petueulncop Uo^l,(Jq suou"nlcnu TeJrTc/b 0Z 'sdnojs eseqljo fuolsq -euoseej 3 eq 01 sueos sql seprulpo{jezo Jo luenbssqns eql ui 'sdnort crurouox?l Jofuru dnort xelduoc srqtjo.ftolsq oql ui elel 'selurl Jo lueuqsrlqelse,(lr"e pu? snlej?dde lblelels Iereôs sd?qrod 'sttpoqtdusorpj ruo{ pe^loâ eql Jo uoqeroqele (pld"r AITIBJ pue) elqelou e^"q ot sj?edde szpoqtdusofiaus rcrll plue snp s3 \ eraql qcqnd tuunp 'uonerp?j e^rtd"pe I"c -oqtou&ofia4s llr.p? Jo slueulele 3d eql Jo A3o -rsselc e Jo ler0 ol ujell?d ur suuojuoc Eluopo 1oqfuou ur luecsrurrrej sr l?ql f,ljee -uoc eql Jo p"erds pue luourdoleôp purul (rr et"ls qtnor0 ssed snpotllousolpl ûesoluo Jo sluelu " fr8ururns -0I0 ed eql1"q1 pelou s"^\ li 6'6 s uoqces ui 8'9 'sejnt?ej c oloqtuou allue^nf lrqlq -xe lnq '^lunl"u l?nxes l? ozrs puuou Jo,{lleJe 'crsseul ete.l eql -uoe oje llnsgj se'slenpiaipur crualoon Alu " ur srolseju? p elopuo8 pezrlaeua8 ejour Jo -nl"ur IpnxesJo SuuIID eql ro azls ur uoqerell" esortrt to o appuosoan Jo suoqelndod ur Jeqlre tnoqll^\ 'pepreler Jo 'peêlep eq i(eru sejqeej D Dltstw Jo urtuo sql ui pu" snqstuntop r oloqfuour Jo luaudojeêp eql qclt{,{r ui ssec -nasd rjjorj o anqsow Jo lueurdoleêp eqt ur -ojd crqdjoruopeed? sr'pueq reqlo oql ao'tual pe^loûr uegq aêq osl?,(uoloeu l?ql olou -aad pnxes Jo luoueâlqcs Aur,,Aol I 'ure^ peteiaj ur 'puv ^?ru 'seloeds D appuo?dt loj,(llber8 ^lunleru dolaêp lou op l?ql sc4suelc?#qc o/al. " tseal le roj uortefldjatur s.jeqsotral pol? e[ue^nf,{q poqsmtulsrp ar? slcedsej roqlo ui -lluslsqns seq ( 861) pr"qcro 'suorloelloc e^rs lnq'eml"rrl Alpnxes oq,(eu] sfnpl{ipur?rrls -uelxe ajoru lsq,reulos uo poseq ',tpnls luecej 's$auasojd pedole ep eêq ol pl s '$lco1s ejoru e ui 'ûeloau qenojrll uoqrpuoc crqfuotu orqfuouopeed ^q auos ui 'seaets llnpe olur -ope?d sql peêrqc? e^?q,{"ur pue set?ls suoruodojd Jo'^lrortdurs',48oloqfuotuJo sejnl c4auaboluo Jelel pus lalel olur sjeloejuqc-eej elrue^nf ureloj leql sluslu?fuo Jo sujalsd elua^nf urcter (aep11e1opuop) o appuo? plueudoloêp sezuef?jeqc srsoqdjot[opeed -rd!, Jo sarcads c$seul elrl ur?uec Jo sl.uaru stsoqdtot'uoqazd?'l'9 -ele eqt t?ql pezru8mer (0161) reqso^ 'peîoûr "d ueeq eêq lou,(uoloau'pejeprs -uoc eje seurjrqrssod osoql ^"III JI st&pad ot pet l '/t 9 pu? st 9 sarj -oj,{iuo ej" teql se8eeurt uro+ 'sr l?ql ur pezu?uruns eje ',{luo slueuele ed Jo 'sruqnp ^lluelslp DurpoJopunpY vrorj oôu ap ro 'snql po^loûr qc[l^\ 'saruetol^qd osoql (186T ^pnts 'le -ou8sblalad tuo+ ssruq lareês pe^loô e^"q te {ftlj ur) relsorz pue surl}ij KqsrdaloloulDd AevJ snpou)i egt lse8sns suo4?jeprsuoc reqlo roj patculsuocej euo eql ui pu? (6161) rala '9 t's uoqcos w pelecrpur sv'suonrsod snl?j"d -erz pue e8rppe^\ pue (tr6l) asrppe^\ peurl -d raqlo ur slueurala qsmeuqslp leql socuejej-lfro snqpustlod Jo,(uo8ol,{r{d eql ur ecuoprô ^q Jrp IsrlueFqns eql p cefeu pup- snpoujl pue ur aj? soldrudxo l uoqlppv 'Jeuel eql s^dpad Jo slljeljj.elo?d eqljo sjefbjeqc ol uoq JO ^lureld SeuO pe^\oj-aejql eql 01 lelrurrs esrûeqlo -uei? fueulud eêt qruojjl l pue peeqp?ojg slueuele d peurrojl?ld ot el3uuep qlnoj 'ejuaprê e^rlrefqo pouoddns pue îor I?c6oI e Jo reuuoj eql uortppe po^loûurrr.r ar" et?lnlsod,{eql ocuonbes ^q dl?uo4nloô eql ur 'd \norj snuuasud ^q snpo8td Jo uorlnlo/re l"ql sdels elrq^ slueurele d uo Jnds pjelel JoualuE u.{rou)l IIea sr lr 'aldur xe roc suorl?fdod 0I Jo ',{uoloou qanojqt 'ssol crqdjourop snorêjd,tll"jrqd?rtuprts ^{ou Jo Imrd,q stuelliele -e?d,{q pet?crpu eq (aeplllepolrrl 'epll..oluo Pepp?,, ueeq eêq 01 uoes t"ql sernleej -uoporuoud) s?,lrprd ruo{ ^"III (oep4uopoucl'eprl crsojoqtuour posncoj e^"q sjolleur tueuobnl -uoporuoud) snpoujj Jo salp?tuesejdej i(f"a -oô Jeprsuoc 1"q1 sluopouorjo serpnls lsol/li V.LNOCONOJ!IHJ 9br

154 EVOLUTIONARY PATTERNS t47 repetitive, development of generally shortlived lineages that were strongly homeomorphic with their predecessors in features of their skeletal apparatuses. From the l-ate Pennsylvanian on, however, speciesjevel diversity was low, and populations appear to have been at or below the maintenance level for long periods of time. With only a brief interruption in the Early Triassic, extinction intensity increased from the Early Permian to the end of the Triassic, when the phylum was reduced to a few species, probably represented by populations of small size and provincial distribution. Although studies of generic-level survivorship would not have led Permian observers to predict the extinction of conodonts before some time in the Jurassic, the phylum did not survive the Triassic. Reasons for extinction are not at all clear but may have included not only those built into the long post-iate Pennsylvanian decline, but also a dollop of bad luck in the Late Triassic when surviving basinal populations may have been unable to adapt to conditions produced by a worldwide drop in sea leyel. References Bergstritm, S. M. (1983). Biogeography, evolutionary relationships, and biostratigraphic significance of Ordovician platform conodonts. Fossils and Strata 15, Broadhead, T. W. and McComb, R. (1983). Paedomorphosis in the conodont family lcriodontidae and the evolutiolj of lcriodus. Fossils and Strq.ta 15, Chattenon, B. D. 8., and Perry, D. G. (1977). Lochkovian trilobites and conodonts from northwestern Canada. I Paleont. 51, 7' Clark, D. L. (1983). Extinction of conodonts. "/. Paleont.: 57, (1987). Conodonts: The final fifty million years. Pp Palaeobiology of Conodonts (ed. R. J. Aldridge). Ellis Horwood, Chichester, 180 pp. Clark, D. L., Sweet, W. C., Bergstriim, S. M., Klapper, G., Austin, R. L., Rhodes, F. H. T., Miiller, K. 1., Zieg)er, W., Lirdstrijm, M., Miller, J. F., and Harris, A. G. (19E1). Conodonta. In Treotise on Invertebrate Paleontolof? (ed. R. A. Robison). Pt. W, Suppl. 2. Geol. Soc. America and Univ. Kansas, 202 pp. Gould, S. J. (1977). Ontogeny and Phylogeny-The BelkDap Press of Harvard Univ. Press, Cambridge and tondon, 501 pp. Jeppsson, L. (19'19). Conodont element function. Lethqia 12, 153-l'll. - (1980). Function of the conodont elernents. Lahaia 13, 228. Johnson, J. G., Klapper, G., and Sandberg, C. A. (1985). Devonian eustalic fluctuations in Eurameica. Bull. Geol. Soc. Am.96, Lipps. J. ( l98l ). What. if anlthing. is micropaleo\toloqy? Paleobiol. 7(2\, Merrill, G. K., and Powell, R. J. (1980). Paleobiology of juvenile (nepionic?) conodonts from the Drum Limestone (Pennsylvanian, Missourian-Kansas City area) and its bearing on apparatus ontogeny. J. Pqleont. 54, L0'74. Mosher, L. C. (1970). New conodont species as Triassic guide fossils. J. Paleont. 44,' Nicoll, R. S. (1987). Form and function ofthe Pa element in the conodont animal. Po in Palaeobiology of Conodont s (ed. R. J-. Aldridge). Ellis Horwood, Chichester, 180 pp. Orchard, M. J. (1983). Epigondolella popllations and their phylogeny and zonation in the Upper Triassic. Fossl/s and Strata 15, l' Sandberg, C. A., and Dreesen, R. (1984). Late Devonian icriodontid biofacies models and alternate shallow-water conodont zonation. Geol Soc. Am. Spec. Paper 196, Sepkoski, J. J., Jr., and Raup, D. M. (1986). Periodicity in marine extinction events. Pp in Dynamics of Extinction (ed. D. K. Ellion). Wiley, New York, 294 pp. Sloss, L. L. (1963). Sequences in the uatonic interior of Nonh Ameica. Bull. Geol. Soc. Am. 74(2),93-t14. Sweet, W. C. (1970). Uppermost Permian and Lower Triassic conodonts ofth Salt Ranse and Trans-lndus ranges. west Pakjstan. Ppi h Stratigrephic boundary problems, Permian and Triassic of llest Pakislqn (ed. B. K.ummel and C. Teichert). Univ. Kansas, Dept. Geol., Spec. Publ (1985). Conodonts: Those fascinating little whatzits. "L Paleont. 59(3), Vail, P. R., Mitchum, R. M., Jr., and Thompson, S. III (1977). Seismic stratigraphy and global changes of sea level, pt. 4: Global cycles of relative changes ofsea level. Pp in,sedmic Stratigraphy-Applications to Hydrccarbon Exploration (ed.. C. E. Payton). Am. Assoc. Petrol. Geol.. Mem. 26. Van Valen, L. (1973). Festschrift. Science 180, 488. Walliser, O. H. (1983). Geologic processes and g.lobal events. Terra Cognita 4,l'l (1984). Pleading for a natural D/C-Boundary. Pp it The Devonian-Carbonifer-

155 'dd 0gl '$lseqrrqj 'poo^1roh srija (sbpupiv I : I'pe) suopouoj lo t3o1orqoao1o4 ur 91-l?l dd 'snorejruoqj?c -pllll ol ueruo,1.e( uro{ uoqnlo^e luopouoc ui selcb (/861) U H 'eue.i pue 'l!\ 'relserz.v9i-lii,ei ',uoaolod P load 'snpoujj pue snqjvu8qod ere -ue8 tuopouoc u?ruo^oo elpptur ur suje ed fue -uo4nlo^ll (6/6I)'A\'JelSerZ pu?')'o8rppeia '6tn-tLz'\s / 99 'DaDqp'I pud8taquarljuas uetarqe8see -"C uoueqqc?ueq ur pun lerqe8snd,{i ur ajnls -IeJIg rop ueluopouoc 0ICI (f/6i) X 'e8lpperra 'L9 'SDquDpuaS $ulssunqjstol DunoJ'(leeJls 'W pub l{lord"d A 'pe) ttdpunoq sno VJNOCONOC:IHJ Irl

156 7. PALEOECOLOGYAND PALEOBIOGEOGRAPHY 7.1 Introduction For many years after their discovery it was generally held that conodonts were cosmopolilan in their occurrence within the marine realm and that most species would turn out to be worldwide in their distribution. However. as more and nore information was assembled, it gadually became clear that conodont species behaved like the species of most other animals. That is, there were lateral limits to their geographic distribution and decided, ifbroad, ecologic factors that determined where they lived within Paleozoic and Triassic seas. Furthermore, in 1958 Huckriede suggested that the development of Triassic conodonts followed different courses in various biogeographic provinces, and in 1959 Sweet, Turco, Wamer, and Wilkie concluded that the distribution of conodonts in rocks oflate Ordovician age outlined two distinct faunal provinces. Neither the ecology nor the biogeography of conodonts could be studied in a very meaningful way, of course, until a biologically sound taxonomy had been developed and fleshed out systematically. Nevertheless, the repeated discovery between 1926 and 1966 that conodonts are exceptionally useful biostratigaphically stimulated the assembly of comprehensive, geographically widespread collections through the known range of the group. Thus, with the development of the multielement taxonomy I have outlined in Chapter 5, much of the information needed for both paleoecologic and paleobiogeogaphic interpretation of conodont faunas has fallen into place. Because conodonts are extinct and have no very close analogs in the living biosphere, features of their biologic associations and lithic occurrences must be used to reconstructheir habits, habitats and ecologic preferences. Information derived in such indirect ways is always subject to debate, revision, and periodic reinterpretation, of course, and this must be firmly understood as a preamble to the following discussion. Obviously, until we have satisfied our curiosity and reached some agreement as to these matters, conodonts will be less useful in reconstructing conditions in past depositional environments than are features of the rocks formed in those environments in interpreting the conodonts. Thus I approach a discussion of conodont ecology cautiously, urith initial emphasis on features on which there is general agreement.?.2 Mode of Life. or Habil of Conodonts It is common knowledge that elements representing the same or closely similar conodont species may be collected from sedimentary rocks that represent a wide variety of deposi tional environments. In addition, many conodont species have been shown to have had a very broad geographic distribution, and a few may have been cosmopolitan. Those facts, together with the elongate, wormlike body and distinctively finned tail of the few complete specimens known, support the generally held conclusion that the animals were probably nektic in habit and that the distribution of most species may have been largely independent of conditions on the bottom. Such an interpretation seems to be supported most strongly by the common occurrence of conodonts in certain types of black shales that yield fossils only ofpelagic organisms because they accumulated under anoxic bottom conditions that inhibited development ofa benthic fauna. Conodonts occur in rocks with corals, brachiopods, echinoderms, and cephalopods, whose living representatives are all marine, but they have not been reported as autochthonous components of rocks known to have accumulated in nonrnarine environments. Thus, as at least a first approximation, conodonts may be interpreted as pelagic, probably nektic, marine ani- 149

157 -nqulsrd lejolel Jreql ui seumuuuocsrp ruo{ sql 10u sr srql lng'sstqquress? IErnl"u u 10u)1 sluopouoc Jo ejfl Jo epour lo lrq?q aql uleld ul Jncco faql se suodlodojd eiiies oql lnoqe -xa ol sldluell?'pueq rorllo oql uo '(516I) sne?r ur sluoruelo punfsrp Jo suoucellor ui tncro -q""c pu? setlj"g Jo lepolu uo4?tojaoslelelq pfoqs snpowdusofia4s Jo snl?j"dd" aql Jo oql 'uonnqulsrp l?jel?l Jraql ur sefrnu4uocsrp slueuoduoc 1?q1 padxe ol elqeuos?ar oq pfo^\ Surlzznd roj uort"u?ldxe u" eprôrd ol peldruet lr uoqt,(z56i) ssporlu ^q srouiii Jo u?ru?^l[s -le pu" c6?lad era,r sluopouor l?ql uo4duns -uued oql uro{ pequcsep se8elqulesse prnl?u -se oql qll^l ueeoq 1ee,{rs pu? uoppes ^q It6I eqr ur pe^lesajd seuo aql a)[i snl?redd? pla ur peulllno 'lepolu uorl?cgrla$-qldep eql 1e4s e wq snpoqldltsoldajts' pduopoqlsusorpr '$ICOJ euueril CrSS?UJ prr? Crozooled Ur SIUOpO u?ru3î,{suued eqljo serseds fueêjo slenphrp -uoc Jo uo4nqutsp eql ueldxe ol peshop -ui IIeJr.sr leql.sarseds orrres eql Jo snler?ddp ueeq eêq 'sosoqlod,{q Jo 'slepoul I"JeueA o,'al lslelo{s eqtjo sli"d lueserdor ol palerdjelur sje slapolt rlsotojg leql slujuj3lsjo uonnqulslp ljunfstp lo f'/ PJsDlq flsnounj oql tiio{ sluopouoj Jrsspul pu? srozoel?d el"l ueuas roj gjii Jo epour e qcns 'sluopouoc eql pler^ leql?l?jls eql perrejur eêq sroqlne reqlo pue (916l) rnzo) Jo lueuretuerre pu? ojnl"u eql luo{ pocnpep seî lfp? cqlueqol{eu lo cqluaq fu"lua s? urs?q puo4rsodep eqljo sejnlsej l?npr^rpur -pes Jeqlre dn e)i?l ol u/.rop elues ueql pu? srrlsr 01 sluopouoc Jo sed^l snoue^ Jo drqsuo4?lal -uetjo cr8?lod s? tuolsq I?^J?l Jreql w uo4ejnp aql 01 uouuell? InJe$c qenojql uo,la eq u?c lerll 8ul/{l"^ Jo sle^jelur pueds sl?utrue euuerll ule otrl?8 e sr lr lng 'peepur 'euie8 Sulauefl"qc? -pouj,tu"iu l?ql pulru ui deo{ osl? plnoqs ouo seurossq serceds luopouoc pnpnrpmjo sllq"q.osjnorjo,sllqeq ojiijo uo4ejeprsuoc [ue ui ojii oql SuueqdrJep uoql 'osuos ojor{sjo-ejorls.uorlpldep? Jo Uos srql qlrl( sjotepejd auu -Jeeu u ur'uorl?eojees I?lel"l eq osle eloql -Etu Eurrurur,ns go salduexa oj.seos ujepour uurnlo3 Jol?^\ eql ur euoz qldep ue I3 êur e urqlra\ ur sloêl snolre^ le pelnql4srp [lepl^\ oj? pu" 'teql uouelresqo eql sql ol spp? ouo JI 'f.rol sluopouoc qlrr'a uotutuoc ur sajnl"ej crrrjol?ue -srq ejrt Jreql ur se8qs luejejlp te ejrtjo seporu,{ueur a^?q qcq^r.sqleusole?qr eql.sl"urrue tuereiurp p?q oêq tqelu qcrq^{ pue etrs T?uoq JeqloJo oe^rl aql Jo,eEtl" tun ou.uodlu?idol -rcodep eqt eôq? sleâl orbelod laeôs oql -^qd uo peej eleq^r.uunloo Jsle.r\ oql ur ui aruoq l" erour ueeq e,..zq lq8nu qcq^{ 'slelq sle el luaregrp êql le ejrl ol petdeps ej?,seuo lieliis -qru cqluoqodlou ojelr eldur?s J"Jncru d e ur,{lj"lncnj?d 'sjol?pejd turulura\s Jeqlo peluasojdej serceds luoâs agl Jo rlcrq/d ourul.êjd crqtuoq -r0l0p 01 ^pnls InJer?c fle el?t III^\ Jreql Jo l?ql ol Jzlrutrs,{lesolc uo[nqutsrp ll'ejiijo apour Aurrurura{s? uo suorleuea ^lsnor^qo esoql? o^?q plnoqs sur?ulej raql l?ql ut susrue8 Jo II ro euos 01 peldep" ore^\ stuopouor JI -ro crqlueq Jo sdnod laqlo Jo leql eirt qcnru 'ssuo Jelel ur oporu cqtueq Jo crqlueqot{eu,fue^ Iool pfoqs slrq?q qcns qtlt\ slbrrnue ot se3?ts " crlouoeoluo,{lj?e ur ojii Jo eporu eurullnl^lsjo uounqulsrp lrssoj eql.t?lrqeq ur crs"led uro{ eeu?qj el"orpur,{erll sacue 3rqluoqoDleu ej"snqlpu" ejaql uoru?cjo suoe " " -ra.glp qtns leql pu? Jernoue ol oaels orloue? -elnurncc? uo Jo Joou?es eql uo sluqd Jo slelu -otuo euo rno{ uorlrsoduroc ul pojejip eaeq -rue SurArT uo elqqru eiiios.suonrpuor luajej,(eru serceds luopouor eulos ls?el 1?Jo sesnl -Jrp,{u?ur Jepun pu? ees eql ur se3eldjo -EJ?ddp plale{s aql lero el"crpu '$ljoj IEaJE? ur a ri u"3 sjolepejd turutunns ^leu?a 1ng crozoel?d elel tno{ suoqce[oc ouros Êtu ur..uortsl.,{lprd l oot?apr srgl6u4docce ur uorlnec lsoe -uosojdej-leô u.lrojleld,, Jo uoueuougqd uour -8ns,{eur snlej?dd? cl?qdec eql dn ep"u l?ql -uoc eqt ol sp?el qcrq,{\ 'uoqnqutsrp'peserq ro stuaruala e: l,rref pue -qloot eql pet?fdru?ur lcunfsrp sqt t?ql pelsetens uaoq s"q li snl?dd a,req lqerru,teql ^ror{ Jo uoqsenb eutoslllo,{\ -de I?leIaIs eqt ursuoqrsodjeglo luoserdoj leqt eql 'Jeâ.rloH.oqol cqeqdec oql ur slueuele stuorlrele eql el"uurop snpoqpusoflals Jo e)l{,r{bf pub -qlool Jo snlejedd? pozrl?jourur sluelllele Ed porrrjojl?ld eql'pljo,r eql ur sej?id ejo uorssessod lleql qll{\ luelsrsuoc luejeiurp uro{ pue uerue^l^suued aql u! sloêl ^lxetduoc sl t"ql uolsnljuoo?.slolepald ala/$ sl"ur snou?^ rxo{ uorlcouoc JaU? uorlcoljoc ui 'eseo -ue eql leql tsastlns osl?,(?i'u lrqeg? qjns sfur YJ-NOCONOJ IIHJ 0sr

158 PALEOECOLOGY AND PALEOBIOGEOGRAPHY a Oa rd a rd ar- --af 'a 'a r.) Fig.7.1. Schematic explanation ofthe depth-stratification model ofseddon and Sweet (1971). Diagram shows two species; one indicated by crosses is uniformly distributed in a surficial water stratum; the other, indicated by filled ellipses, is uniformly distributed in a deepe!-wa1er stratum. Elements ofboth sp cies would accumulate logether on the seafloor, butbetween A andb those ofthe "cross" species would dominate, whereas between B and C the reverse would be tlue. Redr-awn, with omissions, from Seddon and Sweet (1971). tion in sedimentary rocks. To Bames and Fahraeus, the existence of laterally segregated biofacies was taken to indicate that most conodonts were benthic or nektobenthic organisms, whereas Seddon and Sweet found that laterally segregated biofacies (which are real) required a special explanation if conodonts were pelagic. Although the two models seem very different-and they certainly began with very diferent premises-neither has been generally accepted or rejected. They both bear summary discussion before we go on to more concrete matters The depth-strattfication model Seddon and Sweet (1971) pointed out that the Ordovician and Devonian conodonts they were studying in eastem North America and Australia, respectively, characterized distinct, laterally segregated biofacies instead of being more or less uniform in their lateral distribution, as one might expect the remains of truly pelagic organisms to be. To explain lateral segregation of conodonts in the benthic record, Seddon and Sv,/eet proposed that, in their lifetimes, different conodonts inhabited diferent levels in the sea, in the manner of living chaetognaths. A schematic illustration ofthe depthstratification model is given in Fig. 7. l. Figure 7.1 considers just two pelagic conodont species, one represented by crosses, the other by filled ellipses. The cross species is assumed to have been widely and uniformly distributed in a stratum nearer to the surface than the ellipse species, which was also uniformly distributed, but was confined in its lifetime to a deeper-u,ater layer. As individuals of each of these species died, their heavy, phosphatic skeletal remains would haye settled to the bottom. We would expect to find fossil representatives of the cross species everywhere on the bottom. However, skeletal elements of the ellipse species would accumulate only seaward of the level at which the top of its depth zone "dragged bottom." Consequently, there might have been a tract of the bottom to the left of point A in Fig. 7.1 on which no specimens of the ellipse species came to rest and in which the fossil record was exclusively of the cross species. On the other hand, the ellipse species, a relatively rare component of colleclions made from tlre rocks that accumulated beneath point A, would pradually increase in abundance relative to the cross sp cies in samples taken fron rocks that were formed at greater and geater depth. At point B in Fig. 7.1, for example, the two species might be represented by approximately equal numbers of specimensl farther to the right, at point C, specim ns of the

159 eql (Z', 'ErC) euerpuj pu" 'oqo ',(Irnluo) ur -olleu Jo crqlueq are^\ sputru osagl Jo lsou uolsell q"uurcurj eqljo souolssru{ pue sepqs 'souqejll reql Euunp t?ql ubeur ol sluopo u"rcrôpro reddn pue elppu l snojejllrssoj-uoc Jo uorlnqulslp pel?8e$es flleletel aql srll ur luepunqe elb sluopouoj pelertuolu eêq (516l) snasrq?c pu? seureg ^fl?uonderxe uoday ttduuout)lo l8opjaoalad udnaop.to I f l ppour uorjos Saslonrol aqj Z f l '61.61 lnun 'sdrqsuoq"lej poqsrtqnd lou to seueql lnq /61 ul u011u^{ se,{ lero sluopouoj ubrsr^ uouuros fue 1se33ns uoql ur poqceej suorsnls -opro uor8eu u"uudurc uo uodoj? ur pe/(ol -um oql J! eurujelep ol serpnls luecal lelaôs 1oJ I leporu uorlecgrle4s-q1dep oql Jo uors ezueuruns I luopouoc lnoqe suoll -Jo B ur pel"rofuocur sua ejnlbaj?lriii$? pu" -ezrpreuot el?ur "(EoloJe ot 8u4drlIau? orojaq 'snql 'suonefdod psgrlz:1s-q1dapreês Jo qcea 'seldrcuud qcns ll\e+ ol elqrssod oq fllenl ur ejoqsgo pes?ejcep e^"q lqtur sonrsuop l?ql -ueê 1r qorq^{ ruo{ serpnts tue8elejo Jeq pooqioiii eql pazru8ocor ( 16I) ecnlq 'sued -urnu ^?ul sopnlcur ejuelalll oql. 'Joê,{oH 'dnol8 ejoqsiuo erou slr ur Jeqlou? E se Sluopouos " 'uoruod aloqsj?su ol poldde eq,{lejes êul l?ql slr ur ouo 'JeÊJ rol",{r orues eql perdntco eêq suorlezrlsjouet c oloca la^ s" elb ojoqj ^rej lqtru sebeds lueje:urp leql elqrssod sr li 'uoq,tsolorg luopouoj Jo salpnts papales -IpP? q 'ulunloc rel?ar pag4erls sql ur sle el t't lue3"fpe peldncco {eql qenoqt ueê,uo oq eq1 uo :aqletol polefurncce eêr{ tou lqtur 'slc?j l?uoqnqulsp sesdltle pu? sessojc 'lueruuorûo 'pur8jeur eql qll4i sprojje l$q lpqr uonelajdjelur ejrt ro 'eroqsjeeu? ol palculsoj s?^\ seroeds ler{l JI -lo-eporx aql uolqord qree Jo uoqnlos oql ur ro 'ojoqsjo reqpej ueql e:oqs aq1 reau releers esn ot pue crqtueqodlau Jo 'rqlueq'crt?led s?,r{ I', erea\ stuopouoc l"ql uobou cdslldlurs,(lqeqord " '8rC ur sercadssoj3 eql Jo,Orsuep uorl -Blndod eql Jr 'eldluexa roc 'sedolorq tuecefp? aql uopu qe ot sr szuruelrp aseql ol uounlos AulleduJoc uv'ajrl lpulrue orrllueq ^lesolo uoê ur pelqnrunccs t?q1 serc-?jorq aql ueerqgq pes"ajcur eq lq8ru slsejluoo 'pouguoc ol ejr$oq ueeq ^FurseeJcur a^?q plno^{ l?ql suorlrpuos ejea qcr-q,'ir 01 JoAEI rale,'(' eqt lnoqenor{l uolloq clxou? repun peldlnluncc? petnqulsrp êql qcrqr\ 'sepqs lc?lq cb?qdsoqd ur sreqlo ^lq"urn$jd ÎuoJrun lou ejea tnq ecuelshe pogq?jls-qldap pel sluopouoojr JO eououncco uolxruos ord pue sercgds û"rri " 'reô,,tloh leporrj uorl Jo uo4.nqulsp u"lqodorusor flpuuesse ûeru aql -ecurle4s-qtdap eqt Jo srolcdjlep ueldxe ol llnclglp Ilrls sr lr 'leê,tloh'soqlueq E se pegnuepr u00q seq suuoj lete.r-jodeep ^q ^\?U JEteJ luejte^ eql Jo slueuoduoo ojg^r Jo crqlueq,(q peleururop seldu?s ur 'ej?l,go ej? Jo -odlou eje/t\ slerurue oql 3r pegldrurs ;(1tse,r 'peluesejdoj lou AllErcuat oje sluopouoc Jel?.r JJe UOUnqulslp luopouoc Jo suouelejfujlul -^\oll?qs tpqt tc J eql pu? 'esec eqt tou.{[ple 'ajrl Jo epou -ue8 sr slql lsrll s,roqs ecueuedxg,na3 e,{po ur cqluoqolleu Jo rrqluaq e Jo JooJd se uel4 aq pepedxe eq pfoî sleôl lsedoep oql 01 pelculs i(.r ou ur ueo stuopouoc Jo pjocej pol?seltos -er eje^\ 1?q1 asoql s?3joq,'(\ 'eldures fueê eretel aql'u^\oqs e,\eq (8t61) rlcl"eg pue ui peluesejdal eq plnoqs acejlns aql lsajeau ^ JeddEI)I s? 'q8noqtl? padd" 1"ert seq tr 'qcns JeêI erll pellqequl leql stuopouo3 'sr leql sv slrsodep fuetueurpos ur sluopouocjo uoun 'sells pj?.r\?es ejour,(ie^rssejtojd uo{ ue)pl -qrrlsrp eqtjo uolaejdjelul u? ot aldrcuud seldujes ozuel'j?leqo plnoqs,{lrsje rp ur es?ejc -crldrurs eqljo uoqecrldd? u?,{ieraru sr 'pauuol ^lr -ur pnpzrs e'1 4 Erg ul paqdul sr se urlojrun ueeq seg srseqlodi(q srql se lepour uorleter8es s" f?u6uo se^{ urunloc Jel",r eql ur sio ei -lpjjl?l eql 'slueurjlj rulojruoj Jo posodtuoj snoue^ le sluopouoj Jo uorlnqrrrslp eqt JI sesnl"$dde I?lolols pue 'ecuepuedepur sarc 'tu?jb?ip -?Joqll pquesse 'uounqulsp cu{dejsoeb opr^\ eql,tq pelueserdar EaJe eql lnoqanolql pelnqul fie^ e,{q pezued?reqc II" 'crtpled s? peleld -uoc ejea{ sueujrcods ssolc -relur ejea{ sarjeds ^loj? fluo Jo sjequnu pnba 'tlq?q ur cqtueq qanoqt ueê 'lusulluop aq tqtur sorcods osdl[o VJNOCONO] EHJ a9i

160 PALEOECOLOCY AND PALEOBIOGEOCRAPHY 153 J-f -:- 7--! : =- r- f---t---t--,1_ i - \ Ldno -;'"'t?-- -';:,--:-*=!! ::;:.-_-i-_---i_ - 10cs r{ ocs::: t:::::::: Fig. 7,2, Situation ofthe Cincinnati Region in the Middle and I-ate Ordovician. The Cincinnati RegioD is th tristate tract in the center ofthe map. In general, it was part ofa broad carbonate shelfto which terngenous material was introduced from the southeast and that was bordered on the norlhwest by the distal extremity of a narow, deep sag (white) that permitted connection wilh cold, phosphate-rich waters to the south. Approximale positions of l0'and 20'S paleolatitudes indicated by heavy lines; Iight arrows suggest prevailing-wind direction; hea\rier arrows in sag suggest wind-driven circulation pattem permitting upwelling of phosphate-rich water in Cincinnati Region. Adapted from Crcssman (1973). species represented are quite well known taxonomically, and their stratigraphic and geo- many as 20 degrees south of the Ordovician tonic platform that was situated a few to as graphic distribution has been worked out in equator. Lithofacies are various mixtures of considerable detail. Somewhat less detailed information is available on the petrology of Or- east and highly fossiliferous carbonate rocks shale derived from orogenic sources far to the dovician rocks in the Cincinnati Region, and generated on the spot, primarily from skeletal there are some unanswered questions about the matter furnished by echinoderms, brachiopods, and bryozoans and reworked and frag- environments in which they accumulated. Nevertheless, enough is known to support generalizations about at least some of the factors storm-generated currents. Fossils in most ofthe mented in some environments by wave- or that may have controlled distribution of the carbonate rocks haye been transported, but conodonts in the warm, low-latitude seas that probably not too far frorn their living sites. covered this area in the Middle and Late The conceptually straightforward deposi Ordovician. tional framework ofthe Cincinnati Region was The Middle and Upper Ordovician rocks of the Cincinnati Region accumulated on a cra- complicated by differential uplift and subsidence of segments of the platform along pre-

161 sluopouos aql Jo srujel ut J?lrutrs 3J? qcrq,yrueql aroiai q8q sr pu"'sluopouocjo 'sercq Jo sdnoj8 JofEul o1a1 eje uorl?uroc slol sugluoo EuESol ^lrsra^rp oql 'qldop uoq?suedruoc se{?r(i prl? reqruer^l eql,{q.trd, ur aql 'tueuuolrûe clqorc?s,(p pelreru seluojlxe cuflu,{qlpq "u?eo-j eqt uaeûeg 'FInb ^roleq,{iiejeuea ^lqeqojd ur pelrsodop sb^r salel 's3ldru?s pol?losr ur -nrsod( /6I) uerrssarj " gcrq,,tl'opqs elrssu qsr 0Jeq1 pu" ojeq dn ulnl,(er[ uoleou nsuurcurj -u^\ojq PUE ellllrsrjlej snojejllolljd'qslu^rolq eql Jo u"rcrôpro reddn eql uro{j rr.rou)l sel, 'pappeqjelu sr eu?eo.j eql 'uou?uuoc soiejc -eds,(ue $orxl? Jo suerurcads efurs qtnoqtle (u?ipuouqcru) u?rcrôpjo ole-i oql sr puo,'aol 'seiejo eql ur,t\ol tue^ Alrst'^re snpofio 1?qs eql lv 'euolserr.irl uoltulxs-i uerorôpjo pue snqpusopqdv Jo serceds luesejdej JI?q eippriî,{usoiii eql Jo requjel I Eup8o-I eqt sr Jeqlo eqt seereq1ld 'snir.ttauu{s snqwusopl 'l'erc ur tossu?jl eqljo pue deap oqtr JeoN -d?ryu ol elqeutrss?,(lueruolsnc ej" suaturceds ' 'l 'ErC ur eruord,fuurrnns aql roj egl JI?q ls?ol 1? lnq 'sluopouor Jo a^4cnpojd s$eq eql $ '(6161) Elafod,(q pozu?rrruns elep olrnb eje sei?jq eql ui souolseurj crlrurolo(i pu" ( 16I ) uerusseo,(q lro,, 1 uo,{[êeq s,aderp (896I 'plegleh) l(truqss pet?aele l?q/reuros Jo rel"r'{\ ur perujoj selfiuolop q3rq^1 ufllr \.sleu qcq \ 'tueuroeu?jj? leql ]cosuell IE rlaql -od^q Auop rlleqt esueu? ol sarcejoqlj uo6 sel?rq aql uo ejaql pue ojeq suooeq pesolt -ed rl?uulcurc " paluosejdej sourreoj,{fuoue -ua o^?q sl"roc Jo spueg 'st?u po8jeut pu? qldep eql Jo ^q ssleluqse 8u{I" ejd pu" -qns Êur 'peojq uo pal"fruncc",{lq"qold s.joiltlea\ pasn e^?q ^1?l I'srs,{leue cl8oloce pje l?ql ^l^{o[?qs lrsodap rel"n^-tamb,{p:euud e sr se{ero -ue8 Jo sosofund JoJ 'os 'eu]il cgrcads i(ue -ro.y eql sleroc pruojoc ur qcu 0J? leql speq leloôs Jo oql Jo lueutos aplî dje^ JoJ prte^ 'U"d raddn eqt ur 'pu? slc"lc pnul '$lrpr.u eld eq "ej? pfo.r\ l"ql uoreod rt?uur3urj ûe egl ur Jooll du qlr,{ 'alrurolop peurcr8-eug pu? auolspnur -ees uerciôpjo eqtjo elgord? 1(Erp ol tfcgrp rnruocnels,{lesrzd sr ', EIC ul Lcosu"4 oql snql sr Jo puo ^{ou?r{s eql 1I slaêl olqdharl?4s IeJeAes ld sercejo le 'uonsuuod se{sjq aql -qlq ur suoll"ue^ IeJalq crlejle pue 'pezlmtojej prdh reqlej JoJ snql pu" eroql pu? ^l8uruees ejoq Jarler sarceds uozop Jeqlo eql Jo qceo ol elq? -uersse aj? nd.ej ",{lluo',reêôrl'swdpun snpout Is4uslsqns Jo ajueujlureu oql JoJ elqrsuodser a^l -3Dn1d lueserdar sueunceds eqt Jo tuactod 96 ^lluopha slueursôur eseqj '(g16i 'eujoq -so pue eos) sourl lejntrnjls u?lcl opjo "JIaJog _ aloloq paueu serc J eql ur sut tuerreqljo uonnqulsrp lerolel pue ocuepunq e^lelel eqr uro{ perejur 'sluopouoc cnsuolcbpqcjo suo[nqulsrp pelejtuolur eje eôqv.$lcor uerjr,roprg riuan puri epplfrso slijruuoir,r -ue leuorlrcodop Jo suorlqejtuelur tuo{ p.pnrlsuocej.uor8ea rleuurcur3 eqrf lcesu;4 pcilj{joarg.g.1.l!g VJNOCONOJ 3HJ b9l

162 they contain but are mapped as differently named formations or members because they are composed of carbonates and shales in different proportions or because they develop particularly conspicuous internal structures. In the late Middle Ordovician, before the arrival in the Cincinnati Region of much terrigenous detritus from the southeast, phosphatic limestones assigned to the Grier Member ofthe kxington Limestone were the chief deposit in oxygenated, well-lit water somewhat, to considerably, shallower than that in which the Logana Member was deposited. Cressman (1973) esti mates thal the Grier accumulated in water less than l5 m deep, but the range may have been much greater than this for at the base the Grier grades both laterally and vertically into the deeper-, quieter-water l-ogana and, at the top into the Brannon or Tanglewood members, which formed in very shallow, more highly agitated water. Furthermore, the lower Grier shows a dominance by Phragmodus undatus nearly equal to that of the I-ogana, whereas Plectodina dominates in the upper Grier. The high phosphatic content of the Grier, a matter of special interest to Bourbon whiskey dirtillers, suggests that water above Grier depositional sites was supplied by upwelling with more phosphate than could be abstracted by plants. This adds to the suspicion thal at least some of the carbonate rocks now included in the Grier were deposited below 15 m depth, perhaps not too far aboye the compensation depth. Late in the Middle Ordovician considerable quantities of silt and clay spread into the Cincinnati Region from the southeast. Much of this bypassed or was washed through bathymetric highs to settle in thick beds in topographically lower portions of the seafloor (the PALEOECOLOGY AND PALEOBIOGEOGRAPHY 155 idognathus may be as important in samples from the Ashlock as in samples from the very elongate, southwestward-opening sag shown in shallow-water Drakes, but the proportion of Fig. 7.2). Thus the broad region characterized Plectodina is comrnonly greater. Otherwise, the in the Middle Ordovician by carbonates ofthe two formations resemble one another litholog- Grier Member was partitioned in later Ordovician times into deeper-water areas in which the very shaly Kope and less shaly Point Pleasant formations accumulated, and somewhat shallower areas in which the much less shaly Clays Ferry and (later on) Faiwiew formations were deposited. The Kope and Point Pleasant facies are both dominated. by Phragmodus undatu4 have only minor nurnbers of elements assignable to Oulodus or Aphelognathus, and, never yield specimens of Rhipidognathus- ln Clays Ferry and Fairview strata, on the other hand., Phragmodus, Plectodina, Oulodus, and, Aphelognathus are almost equally represenled, specimens are characteristically larger, and total collections are smaller. Furthermore, Rhipidognathus is represenled by an occasional specimen in samples from the Clays Ferry (but not from the Fairview). The Calloway Creek facies, entirely of Late Ordovician age, accumulated in probably somewhat deeper-water settings than the mudflat environments in which the Drakes Formation was deposited, and in quieter-water environments than those in which the conspicuously cross-bedded Tanglewood Member of the Lexington Limestone was deposited. In both the Calloway Creek and Tanglewood, Oulodus and. Aphelognathus are the dominant conodonts; Plectodina is common, and Phragmodus is reduced to about 25 percent of the fauna. Specimens of Rhipidognathus may constitute as much as 5 percent of the collection from some units. The Grant Lake and Ashtock formations were deposited, in Late Ordovician time, at various sites slightly seaward of the Drakes flats; the Grant Lake represents waveagitated shell-heap shoals, between and among which various facies of the Ashlock (or rnembers ofthe Grant Lake) were deposited in sheltered lagoons. Grant Lake conodonts are mostly referable to Plectodina, Oulodus, and. Aphelognathus, but specimens of Rhipidognathus arc also common and, locally, may make up as much as 10 percent ofa collection. Rl,rp- ically and faunally. It should also be noted that the Logana and Grier members of the Lexington Limestone, and the Late Ordovician Kope Formation, grade laterally into dark, fissile shales commonly logged by drillers as the "Utica," but is nowhere exposed at the surface in the Cincinnati Region. We have retrieved only a few con-

163 ur elbjls ur uoruruoa sr snqpusopldryv 'sluopo -o'j eql leqt tudnlcuoc ur lqau sr (tl6i) ueui -uor eprluoporepueduou pdrcuud oql oje snpo -ssojc Jr'raô^\oH sluotuuojrûe Jel"^{-lelr\ol lno pue snqpusolarydu pue '?lells usrcrôpro -lerls olul slaqunu lalleurs ur selbrcosse slr raddll cnrurolop,{dueururop ar0 ur tublod PIdE snqqusoqdtolu t/ Jo serceds lg8nojq e^?q -rlr ojour Îo 4?leJ avroaeq snpoapudd Jo sera osl" tqfiur pu?..t"s,, eql ol IpurEJ?ru sorc J -ods'uolteu q?uurcurj sqljo (uacrôplo eqt Jel?Ar-/ oljeqs aql Jo snou?^ ur pel"4uocuoc ui quou) lse r er0 oj 'stuopoum tur^lljo uoll -nqulsrp pe o4uoc e^?q êui leql pue ^\ou ol?qdsoqd oql pecnpojd aêq o^{ lq8rur rets^\ ruo oq ploc l?rll Jo qldep lale,r(r ueqt reqlo sjolcq ol ^tlauo tu{le&dn.(qlnos se suorsnjo eql ol lse{r eql ol selrs Jel?a\-Jedoep -uoc punojojd $eaens uorseu 4"uurcurc rrro{ ^lou) luejjns rrrouoq se uofeu q?uurcurj eql ^ral Jo $ljor uercrôpjo loj pazu"ununs lsnr eql olur rj.{rerp 'lale&\ " JaploJ Jo,(poq 3 Jo leql uos equo el?p l?uollnqulsrp pue {cuanbojc peugep ueeq e Eq,{?Iu uolnqul 'lle le srr{l JoJ $ujprâ turl ^q {edruoo ou sr ereqt lnq' '/ 'arg -slp ÎrJeurFd Jreql l?ql slsetens laqunj (ojeq^laslo pue) ur JrtEed s? lr uor8eu q?uurcurj eql ui selrs lal"r'(-jedeep Aroqs I uol8eu 4Buurcurc ajqljo slusrrruojrûe eql 1? pelejnruncc? eêq 01 pelojfuolur $I3oJ leu-fpii ui luopouoc tubururop oql -Jec se^\ 'pelou reruze se 'snqftusoptdtqv ^Fr?l.uo.t1 ui sorceds eseql Jo sueurjeds Jo ecu"punqe rel?oj8 aqj tuosordoj serceds aql JoJ ejii -cexp ojoqsuo ue ur Dutpopald Sldloelder,(le^rs Jo eporu cr8elad? slsatilns ôr{l sopqs Ioelq -sor8otd, snpoflo pue snqnusolalldy rnrlr''nq -uou pue {c?iq ur selenoss? ^leuojls slr pue s't wdusoqd 'rel" r Jo ecqins-eou ou?s oql Jo sluel -.toutv Jo suourl3eds Jo ecuerncco uoruuroc -rqequr s? ^poq '(Janq eqt Jo uoru"duoc luetsuoc eql ' ', '3lg ur uaoqs sr uo4nqutsrp osoq^\ tsorjqlr ue) snpoflo pue'snvdusolaqdy 'ouryot sluopouoc eql II? JoJ ecuopl\e eql,(q pellnb -rald rôqs I 'l tld ur's(r\l srultousolaqdy -0J lou sr uo4elejfuolur crs"led? qanoqllv peteler,(lesolc Jo sueulrceds Jo eru"punqe e B.crEBIed s? t t.eic ul -?lej ur eseejcur ue qlr^r uecuoj ur selrs ejoqs uaql PeleJdJelu o^?q I.slueuruonûe pcrdojl -reeu le pelrsodap slcoj ruo+ seldrubs -qns ro lucrdojl ur p?ordseph\,tlecrqder8oat ur ecueuodurr ^\olteqs e^rlelej ur qsrurl'ulp êql lnq ojem uorte1 rleuurcurj eql Jo s{joj u"ror^ 'serc4oqll uol8eu q?uurcurc lsoul uro{ suoll -opjo ele'i pu? epp{ I ur poluesejdel,(lludp -cefioc Jo sluauodruoc eje (,,Dutpopald,, epru -unq? serjods eqt?.{llerur^ esnmeg. 'l.8rc -rpolr?zo aql pue) Durpopald Jo suourrsads ur pelejrpur osp uounqulsrp Suhrl uo suors ' mq Pu8 opt duly puz'snpo -nlcuoo oql aûep ol uoqeu "rur Jo lunoue 1nO 'snqqusolaqdy Jo sededs,{q u?rcrôpjo upuec? poppe a^?q I sqd?re?jed SuroEa-ro1 al?.l pub elpprl l eqr lnoqtnorrll psl"unuop ui,{ueuq pozu?urruns sluopouoc rer0 pue serc seoje l?u{?prl Jo '^treuo-qeq 'Jsl?a{1?oqs -."JOqllI u"rrhopjo uo uorlsrrjjojur oql oj olu eql Jo t.ejoqsgo,, pue ss?ul Jel?,ll-urol -loq raplor eql aôq? Je13^\ tllle^\ (paleuee 'rlo,\ xo nden Jo uercrôplo Joddn eql ur sercej rbir Jo luelrq?qur pdrcuud eql se snldpun d ao\s -rxrs Jo $lcoj ur paluosetdal sr,snppun snpoul I 'e, 8lJ ur 'snqj 'sarcbj uoreou U?uurcurC -8D.qd iq uounqutuoc lerlu4sqns E Eurpnlc -ur 'saroods luopouoc Jo uousrcoss? esje^rp erou e l?qt pouodet (996I).sepnlnpJ Jdoqos ureqlnos qftq 1? palrsodep $lcoj u?rjrôpro lqenoqt'uoleulxsl eqtjo roqruol l?u?eo.j eql ^q Jo crlsfalcej?qc s 'uopouad Pue,sru 'uor8eu q?uurcurc eql ur selrs Jale^\-Jedoep-DuSosapoqv 'D apouil sopnlcur qorq^\,luea eql sp pelejtuelul oje l?rli$ lp peurloj $lcoj -urluoj srql 'sercq ta13/d-ja,rlolpqs ui u^\ou)l ui urnurxpur $ snldpun snpou,tsdlqd ttdli.u:es -un,(lefuej sr lnq uolsurxe-i er{l Jo laquew -ejdej suauncods Jo eju"punqe eû?lej eql JeuC eqt Jo serc J role^l-radoopu?,edo) eqt Jleslr urolloq oql uo lou 'oôqe lsnf 'eu?8ot eql ui poluesejdej,(ltuepunq? fljrej Je13^1 IOOC et0 Ur pe^rt seleljosse si pue snry sr leql ssrceds orloxe Jo lue8uduoj -DuSoqdJoLuV l3ql,{lelrt sr tl 'qtdep ulniiiiuilu "Jo lueuod -uror uoruuroc e 'snqpusoqdnruy 01 elqelejer -ue8 xo eql suroboq uo psrrrjoj? el" essql 'uol8eu D?uuriurJ ujelse^{qilou (euolseurr.i ^\oleq,{lleteuab uofurxe-i oril Jo) Jequew?u?3 eql Jo ecejrnsqns 0q1 ur mqn oql ujo{ sluopo lle Jo sadpun d Jo ecu?punq? eîlelej lseqerq aql sllqqxe 'qldep unururur-ue8^xo eql,{roleq pelqnurncce a^?g 01 ( /61) u"ussajj YJNOCONOJ AHT 9SI

164 PALEOECOLOGY AND PALEOBIOGEOGRAPHY t57., ;y.4s /-s','tl'; Fig, 7.4. Location ofthe Deseret Basin and adjacent features ofthe Mississippian of the westem United States. Redrawn and simplified from Sandberg and Gutschick (1984). northern Wyoming thought to have accumulated at sites marginal to those in which evaporites formed in the Williston Basin (Sweet, t979). These features in the distribution of those conodonts square with the ones deduced from the record in the Cincinnati Region but ofer little more as to the actual ecologic controls Mississippian paleoecology, western United States Sandberg and Gutschick (1979, 1984) provide accounts ofthe distribution ofconodonts in the Mississippian rocks of westem Utah and adjacent Neyada that are rich in detail and of exceptional value in building up a general picture of conodont paleoecology. The rocks in question were deposited on and along the west edge of the broad carbonate platform of the continental interior, and in the Deseret Starved Basin, which was separated from the Antler Flysch Trough on the west by a narrow submarine rise, or sill. The general arrangement in the Deseret Basin and adjacent platform areas of Mississippian rocks of the Anchoralis-Iatus Zone is shown in Fig From the distribution of conodonts in the several lithofacies shown in Fig. 7.5, Sandberg and Gutschick (1984) have also inferred the habitat of conodont species that represent the genera indicated in that figure. Dark brown to black mudstones, phosphorites, and phosphatic shales are the deepestwater deposits recognized in the Mississippian transect summarized diagrammatically in Fig Sandberg and Gutschick (1984) conclude that these dark-colored rocks formed in cold, oxygendeficient marine water at teast 300 m deep along the axis of the Deseret Starved Basin.

165 85t! o o,{ il o (t if!; IE ai iii -{!9 ii!- g6 93 gf il :g zi.' iz ;g ''!:,! ri z; io lll a o -! o D a 2.od \! :9 JJ a E _o g, a tal c 8 So 1i :$ o D I I ^o 9a it Tt I I 5 E AAI g= R? s it s ri it :a tt LAI{D FqF?'J.o 0i d? 26 ae^ H. 6{ ^E 1)lJ

166 PALEOECOLOGY AND PALEOBIOGEOGRAPHY t59 The deep-water deposits intertongue eastward with thicker accumulations of dolomisumably dysaerobic, deep-water toe. The ab- the reconstructed foreslope, including its pretized biosparite that include encrinites whose sence of BaclrognarrrJs specimens in axial deposits of the Deseret Basin, coupled with its textures proclaim their formation as debris flows. These rocks, thought to have accumulated on the foreslope of the broad cratonic well-oxygenated slope environments, suggested occurrence in samples from both poorly and platform just east ofthe Deseret Basin, probably were deposited in the murky but well-aertrognathus was a swimmer, but that it confined to Sandberg and Gutschick (1984) r} lat Bacated water of the aphotic zonel the encrinites, its swimming to the aerated water just basinward of the slope floor. In other words, Bac- of course, are built of material that moved down the slope from the shelf edge or from trognathus, like its close relatives, Scaliognathus and. Doliognalhus, was mesopelagic, but sites higher on the slope itself. East of the platform margin, rocks of the Anchoralis-Latus Zone arc thick-bedded, light- the oxygen-minimum zone. its habitat may have hugged the bottom aboye colored, bioclastic limestones that are replaced Gnathodus and Pseudopolygnathus are also farther eastward by more thinly bedded limestones. These, in turn, gmde laterally into dodle slope deposits, but by very few from rocks represented by specimens from upper and midlomites. Sandberg and Gutschick infer that the that represent slope environments interpreted latter rocks should merge even farther to the to have been below the oxygen-minimurn level. east with sandy dolomites, perhaps with anhydrite or other evaporites. Those facies have not individuals of either genus ever strayed much Because of the latter fact, it seems unlikely that yet been sampled, however. In general, all these above the bottom or out into water above the facies represent deposition in the relatively deepest parts of the basin. In short, species of shallow-water environments of the carbonate platform. All those environments were certainly within the euphotic zone. Representatives of Bispathodus utahmsis Sandberg and Gutschick, 1984, and Polygna- Ihus communis Branson and Mebl, 1934, have been recovered from all but the most nearshore facies. This near-ubiquity of occurrence suggests that both species were pelagic and inhabited the euryhaline environments of the euphotic zone. Scaliognat hus and Doliognathus, curiously specialized and biostratigraphically very useful prioniodinides of the family Bactrognathidae, are represented in the deepest-water deposits of the Deseret Basin as well as in the much shallower-water strata of the foreslope (Fig. 7.5). Such a distribution logically suggests that indi viduals of these genera were also pelagic, but liyed at greater depths than did Bispathodus utahmsis and Polygnathus communis. In shor1 species of these two genera were probably mesopelagic. Their depth zone may well have been defined by the well-oxygenated but still rnurky conditions of the dys- and aphotic zones. Bactrognathus, a distinctive prioniodinide, is represented in sarnples taken from all parts of Gnathodus and. Pseudopolygnathus may well have been nektobenthic, with habitats that "bottomed out" basinward againsthe oxygenminimum layer. Eotaphrus is confined to rocks that formed high on the slope and in adjacent parts ofthe shelf edge; Hindeodus is commonly represented in strata deposited on the outer shelf; Pandorinellina appears to have characterized the inner shelf, in environments aboye wave basef and. Mestognathus, a close relative ofboth Pandorinellina and the cavusgnathids, may well have been adapted to hlt,ersaline lagoonal environments along the innermost margin of the platform. There is little in the reported distribution of conodonts assignable to any of these genera that proyides a definitive answer to their mode oflife. Their absence in slope or deep-basin deposit suggests they may not have been petagic, in the manner of Bispathodus and Polygnathus. Possibly they were also nektobenthic. It is always risky to generalize fiom observations made in limited areas, no matter how sophisticated the studies or convincing the concfusions. However, it may be noled, that Pandorinellina is the acknowledged ancestor of the Cavusgnathidae and. that Cavusgnathus (and,

167 srqj Jol?nbe eqljo quou lsnfeel? el?euola u" ur pel"nlrs ers^\ leql (9, 'ErC) surseq puelojoj JO ur?qc 3 ur PelalnrrrnJce?cuourv quon l"lujurluojp x Jo $ljor uerub^lfsuujd 'slu?puecsopue sjolsecrre Jreql Jo osp,(lqeqord pu? stuopouoc ueue,r1,{suuo4 Jo sletrqeq pue slrq?q eql otur lq8rsw elq?np seprôrd slodor Jo sles oû aql IIlo{ uorl -?rujojur Jo uon?urquroc E pue 'Joê,{roq'lse8-8ns pfo^l tuaruntff eqt Jo euol eql ui -uls l"uorsecco se leeje se ejb socueje.grp ^cuep osoql -Je^ pue IIUJaW sjod?d lueuodrur ul peu?u ueeq eaeq pue ^q 'pezuelcsj?qj'pogquopr ej? qorqla'sel'?jorq o^rlcuqsrpjo raqunu D sougop uo4nqqslp Jroql pu? 'u^\ou)i lla,r\ Arou sr,truouoxel Ie afcueuee Jroql :slcoj ^lqeuosbej uelu -e.1lj,(suued ur slrssoj uoruuoc ej? sluopouoj siuopouol udtudqtsuuad Io tsopraoapd E'r'l 's0l?1s polrun rue -$e { eqt Jo u?rddrssrssrl^l eqt ur (t86i) J[" lon sjeueru ur"uec uo uourdo Jo socuojoj {crgcs -1nC pue treqpu"s pagquapr selrejolq uuoj Jrp crs?q,{ll?elc er? eraql ejurs 'sluopouoc u?ru -l"ld agljo IeJoôs JoJ ^q sorcqorq uerue^l,tsuued -BÎ,{suued Jo,{tolooa eql tuu3edsej sjeu?rx pue u"rddrssrssrj l Jeqlo ur slell?j?d ej? ejeql qe uo luerueeree le:ouee sr ojeql leql lsa8ens sn\i 'snqtdu8sn^n) pajoêj s"ol? ejoqs o1 Eurpeelsrur eq plno^{ li (986I) op?^{s pu" -ur oql u?ql 'Jolc?J?qc ^q ouu?ru-puxou ejour '(516l) uueures*g pu? Ie{coH '(0861'l.t6I) Jo flqeqord pu? 'eroqs,uo Jequq erena t?ql ldlcoh suodej pelueurncoplla,y\ 'o^rs slueuruojrûs ozrjalaejeqc ol,suioes snpoaput H -uerlojdruoc ^q ui elluerejur Jo,(llceJrp reqlre 'E'?'t uoqcas ur pelou eq Lr sp'${coj u"ru Peuqlno el? s?es ^ u?rue^l,tsuued ur serc"jorq -?^[,(suued ui'slueuuojrûe ejoqsjeou'j91",{r eserll Jo uoqaluojojrp Ien?ds pu" uoqerrrjoj -^{oll"qs aql peure oe leql sroto?d (t861 'renrg uo^ ^le luasardej l?ql $looj ur sluopouoc lu?ururop sql ojeq^{oslo eje (sn DuB pu? IuleW ui pezueruuns) sroqlneoc snor -oppv 'e/-]ftlar u?rupî^suued {llueurruop slr '(0861I$p0H u.ro4 u^lerpor pue pogrpoi I luourl -uotpry{ 'S n eql ui sl$odep fuelueulpos ueee,{l^suuad crlc,b Jo uogrsodep Jo slueuuorrûo polejuj.9.1 ttd 0.\;--_-_-*.01 :l v -l> a I 09r

168 PALEOECOLOGY AND PAIEOBIOGEOGRAPHY l6l area was bordered on the north and northeast middle limestone is followed by a meter or so by the relatively stable cratonic interior and on of abundantly fossiliferous gray-brown shale, what were then the south and northwest sides which is typically (but not invariably) introduced by (or includes) a distinctive component by active ranges offolded or fault-block mountains. The southern margin and the southeastem end of the foreland-basin chain received shale" interval, conodont diversity may drop offissile black, phosphatic shale. In this "core- great quantities of terigenous detritus from off, but frequency of occurrence commonly streams draining the Appalachian and Ouachita-Marathon foldbelts. This spread out to erally optimum. Representatives of Gondolella reaches a rnaximum and preservation is gen- form a complex of laterally shifting alluvial are almost completely restricted in their occurrence in Kansas and Iowa to the core-shale in- plains and coalescing deltaic systems, which were only occasionally (and then briefly) transgressed by offshore marine environments. Far- oprioniodus are more numerous in this facies terval, and specimens of the prionidinide 1d,- ther west and north, the basin chain was more than in any of the others in the Kansas-Iowa persistently occupied by the sea, sediments are cyclothem. offiner grain, and the record ofconodonts and In the basat part of the "upper limestone," other groups of fossils is more nearly continuous. cyclothem, maximum conodont diversity is re- which succeeds the core shale ofa Kansas-Iowa In parts ofthe foreland-basin chain that were established and specirnens of the Idiognathodus-Streplognathodus plexus continue to dom- most persistently occupied by the sea, the Pennsylvanian rock record is made up of a inate in frequency. Adetog nathus, represented succession of cyclothems. These are repeated by few, if any, specimens in the lower part of sets of distinctive rock types, which record a upperjimestone intervals, tlpically becomes number of transgressive-regressive cycles that more abundantly represented upward in those are comrnonly regarded as the results of eustatic rise and fall of sea level. Heckel and Bae- uppermost part that carries over into the lower, intervals and may regain a dominance in the semann (1975) and Swade (1985) have related marine part of the superjacent outside-shale the distribution and frequency ofconodonts to unit. the lithic components ofa number ofthe Pennsylvanian cyclothems in Iowa and Kansas, with Iowa Pennsylvanian cyclothem is viewed by As indicated in Fig. 7.7, the typical Kansasthe general results summarized in Fig most geologists as the record ofa transgressiveregressiv event. Thus, from the relationship Note in Fig. 7.7 that sandy "outside shales" at the base ofa typical Kansas-Iowa cyclothem between conodonts and the lithofacies that represenl vanous stages in thal transgressive-re- initially record deposition in nonmarine environments but, in their upper parts, pick up a gressive history, it should be possible to reconstruct a general ecologic model. Such a model few fossils that indicate shallow, nearshore marine environments. The first conodonts to appear in these rocks represent Adetognathus arld, (1975) and Swade (1985) and is shown dia- has been developed by Heckel and Baesemann Ellisonia, but others referable to Hindeodus, gammatically in Fig Aethotaxis, and. the ldiognat hodus-streptognalhodus plexus follow shortly. In the "mid- black shale component of the core-shale inter- Heckel (1977) concludes that the phosphatic dle limestone," just above the "outside shale" val accumulated in anoxic bottom water beneath a thermocline and thus represents the in a typical cyclothem, the inyertebrate fauna becomes more diverse and is much better reprcsented.. Adetognathus may continue to be a the lithofacies in a cyclothem of Kansas-Iowa deepest-water environment recorded by any of prominent member ofthe conodont fauna, but type. From this conclusion it follows that conodonts commonly represented in core black diversity commonly is greater than in shaty rocks below and dominance begins to be shared shales were not only pelagic but were also segregated in depth zones in life. That is, Goz- with conodonts of lhe ldiopathodus-streptognathodus plexus. dolella, Idioprioniodus, Neognathodus, and In the typical Kansas-Iowa cyclothem, the various members of the ldiognathodus-strep-

169 'plm erdjo uonnqulsp equcsop t3q1 sr4eui?r -ed IEreâs eql Jo elq"reqdrcep ÎpeoJ lsolu eql,(lq?qojd s"^\ 1r lnq tuounqulsrp s,n appuoc PelloJluoJ l?ql loljbj P ue3q eêq lou,s.rad qldac 'aulrolllreqt er0jo rote,'(\ crqoj*s^p ^?u.r 'ploc eql pauuep uaeq e^"q A?rrJ euoz qldep s,dlplopuo) ^q lbql s,'aoiioj lr 'le^relur el"qs -ojoc eql Jo slueuodruoc epqs:êje pu" -Ic?lq eql 01 pauguos sr D alopuo9 Jo uo4nquflp paj" 3ql Jr pu :eurlsouueql? Jo ecusuelursrrr i2uz luerudole,rsp paleerj ere.{\ uropoq eql uo suourpuoc Jrxouz ^q 'g'1 '6rg ur palsesllns sr s? 3I 'sreqlo eql u?ql uurnloc JolB^r eql Jo ued Jadeop e ol ejrl ur pauuuoo uaeq e^?g lsnul 'le^jolur el?qs-ojoc eql ol sejueuncco uesr -JerlY quon slrjo [ueur ui palculser sl qcq,{ 'D appuog lnq :uolloq eql oôqe sass?u] Jal?a pe1er03 5ql ur ajaq \euos po^q 0^3tl lsnru 'BunEJ elsqs-icqq oroc oqt Jo slueuod -rijo3 uoruruof, eje qrrq.{r 'snxeld snpoqnusol 1//6I) IeIJoH r!o{ u^\erpor pue peglpol^l sluopouocjo ssd^l pdrcuudjo uoqnqulsrp leleue8 pue sroqeerujo uonrsodepjo sluoruuonûa pslejur qlr$ 'od^l e,rol-sesuf) Jo uroqlop,{c lenpr^dur uv ll'tld outjeulou :auolspues'leoc :oleq Ipues umorq ol AeJb ourjeur:aleqs Apues >ah m alrlniclec lelalals lrep 'asuap 'aleqs lcelq olrssrl sleqs u,v\orq-aer b el!lnllclec lelalals Aleqs Aer6 r ll I tl \_ \ 0lruareclec lelolols alrloo :olrlnlrcleq aaospjrq auolstlrs'ateqs Apues par'usar6'ier6 A6otoqlr't a=. ol ] sluopouos oroqs o -rean luauiuorauf leuorlrsodao uraqlolc^c alses YINOCONOJ AHJ z9l

170 dense, oxygen-poor water of the thermocline, to which Gondolella was best adapted and in which ldioprioniodus also thrived. As Heckel (1977) noted, that water may also haye been rich in settling organic matter, phosphate, and heavy metals, and these may also have played a part in defining Gondolella's depth-zone habitat. Adetognathus and. Ellisonia were certairlly at the other end ofthe ecologic spectrum in Pennsylvanian seas. The common occurrence of specimens of Adetognathus, for example, in rocks that represent obviously nearshore or marginal marine environments (like the outside shale of FiE 7.'l), in dolomitic strata that intertongue with evaporite sequences, and also (in greatly diminished abundance) as components of higher-diversity conodont faunas that include forms associated more commonly with normal marine conditions suggests that ldetognathus $tas earyhaline and adapted to life in well-oxygenated nearshore waters that were susceptible to wide variations in salinity. Mer- PALEOECOLOGY AND PALEOBIOGEOGRAPHY 163 rill recognized ihe Adetognathus biofacies in 1962 and, in subsequent reports (Merill, 1968; von Bitter, 1972), it has been suggested that ratios between specimens of Adetognathus and, Idiognathodus or Streptognathodas, which dominate environments more offshore, might provide a quantitative sense of distance from shore and a measure of relative salinity. Environments intermediate between the shallow, well-oxygenated nearshore waters with highly variable salinity and the much deeper, colder, more dysaerobic waters of the thermocline seem to have supported the most diverse conodont biotas in the Pennsylvanian. Throughoul the Pennsylvanian, dominant conodonts in these intermediate environments were members of the ldiognathodus-streptognathodus plexus, and rocks that accumulated in them have been assigned to a ubiquitoi]s I di o gn at h o d u s - St r e pt o g n at h o dus biofacies (Merrill and von Bitter, 1984). But these intermediate environments were also the ones in which the closely related anchignathodontids Fig Hypothetical c.oss sections ofpennsylvanian sea at maximum extent in the U.S. Midcontinent. Upper diagram relates sedimentary facies to inferred quasi-estr.rarine circulation pattem; lower diagram shows inferred living distribution of conodonts as reconstructed from tieir occurrences and frequencies in various sedimentarv facies. Redrawn and slightly modified from Swade (1985). prevartrng wrnd :l-;;.; El *_: :--===-'-2 - -t'racx snale Green-grey shale / )\ J,a;lsh,ffi; {:49+ skeletal ca lc ilu t it e - c a lc a re n rte (below/above wave base) Diplognathodus a Oeltarc claslrcs -4-F,+-:

171 esoql Jo sjolc4 l?qa\ pjocoj eql uro{ J?alc lou pfoqs suo4rpuoc qcns procer t"ql sepqs {c?lq $ li lnq '/grurt?s ur suoqenlcnu apk\ pue sojnl lsql s1se33ns pu? seqsj?rrr 1u31ou ur uorlrsodep -?Jadrual pele ele pszuolca?qr flqeqord Jo1"A\-A1OII?qS JO pjocej eql S3 SrIeql ajea\ leql slueuruojrûe ^q euueur eloqsjeeu '^{oj -olc,tc EA\ol-sesu?) eql Jo sapqs {3"1q Jrt?qd -leqsjo sluelrq?qur InJsserJns'sffe^Jo suoqlut -soqd oql tejdjelu ol llnclulp 1I spug oh eju?c roj 'eje^\ spqleuesnêa eql prjp- snqtduso$al/tl lpqt 'aldlu?xe JoJ 'r?alc sr ti 'pejjejur -gluers I?luauruoJrûs eues eql oêq lou pegu suounqul $lcor qsns IIe t8ql pue surs"q u?ru?^[.{suued -srp eql pallojluoc Î"nlc? 1?q1 slo133j lzcl8ol ur suo4lpuoc luere.urp repun pel?frrrncc? -orq ro 'pcruraqj 'l?crs,{qd eql,gquepr ol elqrs o^?q,teul oleqs {c?lq lsql tno pelurod s?q 'leê -sod.(lej?j sr lr l?ql uees eêq ea 'pueq rorllo -,rioq'(tf6l) IaIreH erualllv quon Jo rouol 3ql uo olqlueqodleu ol o "led,(ln4 tuo{ -ui oruolejc eql ur surseq pu?lejojjo ruals^s eqt poue^ o^?q sluopouoo Jo ojrt Jo epour Jo s!?d petrurll,&e,r,(po o1 ueruz,rl(suuad eql eql legl uorsnlrum ^"IIl eql qtl^\ Jor{loEol 'sleporu ui 9[q?c{dd? oj? Jo 8uofir Jeqlra qloq Jo sjrnle+ Jo uorleurquoj z errnba.r uorl ej" slapou ap?,{ls pu? uu?urese?glslceh ^llesra,\run -nqulsp tur rt Jo suoneleltuolm Fc6ol t?ql aql Iuo+ u,{rbrp suorsnlcuoc ueql 'efun lueel oslb e^1 'raêaoh,{le^rtredsej'(5/6i ) -J?dd" sjoqln?oc snoue^ pu? fiuratr l se 'sepqs ^llue snoerqq pu? seuj?g pue 016l) tee/'\s pu? {ceiq u?ru?^l^suued II? epnlcur ol pepuel uoppos,(q pesodord s" 'slapouj uorlees:ees-x0 sr uorl4ejfuelur qsj?ru-tuelou eql JI {eretel pu? uortb3grtp4s-qtdep eql qtoq ur 'IeIceH i(q pezrpnsh euo Jrxo parldur se^l 'esrnocjo'slql 'mjco,{eql qcrq,n -ue 'Jelaa-deep aql ueql Jelc?J"qo ur lugjojrp ur $lcor.fu4uerurpes eqt pu? slssoj aql ueo^!,{:e,l lueuruorr,ruo u? Jo snql pue 'qslerrl luel -eq dtgsuo4?lej eqt Jo sorpnls InJeDc uto+ -ou 'erogsjeou? Jo procar e^rssertsuejl oql se ep"ur eq u?c sluopouoc Jo uoqnqulsrp tur^rt pelejfuelu s".{r srouqll lse^rrluou ur Jeqrlgl,\l 0q1 ol s? secuojejur elq"uoseal l?gl uleel ea,' L elps e'j er{l Jo tuouoduroj el"qs lc"lq uoncas ur pazusrxruns sorpnls e0jq1 eql tllojc " qcrq^r suollezllbrauacjlaoiojg S', ur lepour " petdope (916I) u4re4 pue III.I -Jel I oee ep?cap " 'eldru?xe JoC 'suorleletdtel -ur Joqlo er? ejeql 'Jeê^{oH slc-?jjo ^leue^ 1se -pi^{ eql peuoddns aq or pug I qcrqi('(/t6i) 'srrrj4 ellles aql IeIJeH Jo ^q uouetartuelur oql polrlolloj e^?q ur poterdjetur oq sopqs {relq u?ru?^j^suuod IIe I 'sgd"j8effd turpecojd eqt q sureqlolc^c IEJ l?qt Sunsrsur ueql eur ol rollaq suroes ueqt loj -rd^l Jo aleqs ejoc eqt Jo uopefrtuolur se^lo^ uorl?u?ldxe elq?uoseej sr ojor[ teql pue lsrxe -ui stuopouoc u?ru? l,{suued Jo,{Eoloco oql suoqenlrs qons leql Sul3pel^\ou)lcv 'poc e pejeprsuoc eêq oqa\ sjelu^{ uo r(lperrp epqs {celq orl?qdsoqal "Jo uo4rsod Jo sdno$ o.{l aql ueendleq uoquoluoc Jo lurod l?drcuud aqj -Jedns pepjocer aq pfo^\ sql pue 'lno pen 'snpoapulh -tes relle(ii ^q crue8jo qcu-ol?qdsoqd pue Jen"ru JoJ rollq 2\1 'slxdloqpv roj lueuuojr^ paurejs-eug,(1uo qcrqa,r ur lueruuojrûe clxo -ue runllllldo eql EulprôJd JouuoJ eqt 's eje -ue 'ejoqsgo oql peqs{q"lse sreq lqtrur Eurue J4end-prqJnl pu? -Jeelc olur lueruuojr.llue 01EJ1s -deep luenbesqns 'uorl$odop Jeqljq lnoqll/tl -qns-eleuoqjec 'pel?uet xo- e^r 'el"rpeuuol pelepunoj eêq pfoc dure^{s AurruJoJlEoc -ur eql EurprArp ur InJesn oq lqalt[;t snpoaput H eql leql os 'uodcnpord el?uoqjej ol elq"roêj pue srxdloqpv Jo uo4nqulsrp eqt 'snqj 'sepqs -un luauruojrûe orqolees,{p Jo Hd-.!\ol? pejnp qlllr pappoqjolur souolseurq urql ur srnj -ord e^?q lq8ru luoruuopu"q" fj?tnqulsrp -ro osle pue srxdloqpv u"ql ssrj?joglll pjelt\ xnuur snoueeujol uro{jo lnc selrs dure \s-poc ^q -urseq ojor'tj ur peluesajdej g snpoapurh let]l Jo uorssejesuejt pld"j t"qt 'eldui?xe JoJ 'sol.ou selou 'JeAaA{oq'(986I) ope {S 'serjsjolq flj.rl Ie{JeH'slrsodep qsrerrr-luelou'je1ea-^\olleqs-oqpv aql lueulnojr ue srql ui padolaôp l?ql s" potejdretul aq lou peeu,{eql'spoc sqre,r.o seioujoiq 0q1 peqqnp a^"q (t86i 'Jellrg uo^ sepqs lcelq cn?qdsoqd Jr ue^g stuauruojr^ pu" IIrJJetr^{q pezu?urujns) sjoqln?oc snor -ue pur8jer[ Jo ejoqsreou Jeqlo Jo e^qecrpur -re^ pu? fiurer I 'rellq eqljo touoq ui ',{cuenb set reurolsuoc pue spu?s olul epe$ -e.lj lsel?e$ Jroql pe eqse pue uoqnqulsp.{fouuroc pup eleqdsoqd,fueluelurpas ^llejelel {cbi tsepra rraql pe{ofue sxdloqtav pue snpoapurh YINOCONOJ :IHT v9l

172 harsh environments controlled the distributions obseryed Depth as a factor Many of us who have written about conodont paleoecology have discussed the distribution of various species in terms ofwater depth, not because depth pel Je is a significant ecologic factor, but because a sense of at least relative depth may be derived from the textures, structures, and other fossils in the sedimentary rocks from which our conodont collections have been made. Although depth itself may not have exerted a primary influence on conodont distribution, factors such as temperature, light PALEOECOLOGY AND PALEOBIOGEOGRAPHY 165 Idioprioniodus and, Gond.olella in Pennsylvanian cyclothems in Kansas and Iowa suggests that species of those genera were confined in life to a relatively deep part of the water column and also that their depth zone may haye been defined by the cold, dense dysaerobic water ofthe thermocline thought to be responsible for anoxic conditions on the bottom. Unfortunately, from study ofthe skeletal elements of cold-water Ordovician and Pennsylvanian species, I have been unable to isolate morphologic features by which other cold-water forms might be identified Nearshore and ofshore faunas penetration, lieht intensity, turbidity, energy, All three of the models summarized in section salinity, and water density fluctuate directly or '1.4 relate the distribution of conodonts to onshore-offshore transects reconstructed from the inversely with depth, and one or a combination ofthese may have exerted the direct control on distribution and nature of the sedimentaryrock record. In all three models there is reason- distribution. I suspect, for example, that temperature, not depth, was the important factor ably clear distinction between an offshore governing distribution of species of Amorphu group of species that may be related to stable gnathus and, related balognathids. That is, temperatures, "normal" marine salinities, and those species are represented in highlatitude limited turbidity; and another group that apparently thrived in nearshor environmenls Ordovician rocks that formed in cool, relatively shallow water, whereas at lowlatitude characterized presumably by harsher, more sites their remains are largely restricted to the varied environmental conditions such as great deposits of deeper waters in which temperatures may have been comparable to those bidity. It is ofinterest that conodonts typical of fluctuations in temperature, salinity, and tur- nearer the surface at high latitudes. the offshore and nearshorends ofthe environmental spectrum in all three models have a number Temperature of features in as a common. factor In all three ofthe situations described in Section 7.4, species characteristic of nearshor en- Diferences in temperature were probably responsible for development, in the Ordovician, vironments built apparatuses of relatively large ofdistinctive conodont faunas in the high- and elements, with a reduced nurnber of discrete low-latitude marine realms. This conclusion is denticles of circular cross section and little, if suggested by the fact that rare invasions into any. white matter. I also have the impression higher latitudes of species characteristic of low thal elemenls of nearshore species are more latitudes were accompanied by accumulation variable in morphologic detail than those of of vaughnitic carbonate rocks that indicate offshore species, and their apparatuses are concurrent invasions of warmer than usual more variable in composition. Furthermore, water. Also, as noted in Section 7.5.1, the few note that Ordovician and Triassic rocks representing nearshore environments have pro- typically highlatitude species that migrated from time to time in the Ordovician into the duced all of the "fibrous" elements on which low-latitude realm became established there in Branson and Mehl (1944) based their concept deeper-water environments that were probably of the suborder Neurodontiformes. Finally, it similar thermally to the high-latitude ones in is clear that at any time species diversity was which the species were most widely distributed. considerably lower in nearshore than in ofshore environments and, because it is my As noted in Section 7.4.3, the distribution of ex-

173 -eq seijjrs I?srtoloet ur lserelur 13eJ3 Jo psrljoj 'seunej ejoqsj?eu Jo sjeqtlleuj -rno sr,{qd?jeoeaorqool?d Jo lcefqns eqj ^lluer era,r êql 'J}ê/:l.otl'snpou?DJ{d Jo selceds 'uonnqulsrp cqdejtoa8 rrsql ur ^FBep ur'aodi lsaplo eql 'uorlrsodep Jo urseq eqt Jo u?tllodou.rsoc,{jqdireuer ere,r stuopouot 'fuol su?d rodoop o1 uortell rt?uuburj eql Jo ${ooj -srq Jreql ur serurl Jeqlo l" leql u.roqs ueeq osp uercr,roprg reddn pue elppq^l ur s?tporu8o.trld s?q 1r qenoglp 'ejol luopouo3 Jo sued paqsrt Jo uortnqutsrp eql patelej I 'I t't uolpas ui -qelse-ile^\ auoreq,{lluenbesqns oaet{ 'rusrtn 'ese3 aql lou sr srql qcrg \ ur seldue -dels elqaeprsuof, qlr.tr {1p4u11eru eroî qrrq.r -xe I?reôs olrc pfoqs I'a5u?cgru8$ cl8oloca 'suo4se8sns eseql 'prcurôjd ueeq erues eql seq snue8 luopouor droô Jo saloeds eêq stuopouocjo uounqrjtsrp Îpu[slp orqdasoee lf Jo uo4nqflslp aql teql uorssejdurr ogl eql fuolsrq ^"ur Jraql ul sp^lelur ureuer lseol l? 8ur -uoc sql lse.l 'pojoprsuoj ojea\?jeuae,tluo â^ t'l -Jnp t"ql opnlsuos 0l sjol"bnsa ul lueje.glpel uoqces ur Pezu?urutns seldulsxe ealql Jql ui peq 'Îe^4cedser 'sluopouoc uslcli:ej9_!:: aotlnet$tp tortsoto?a ut sasudqr ruartr.lj JrssBuI,.9.1 Jo sjrpnls 6s6T pue 8s6l s3 Au?e se l?ql patou I Dld?qf, sqt 01 uoujnpojlur eql ui 'eroqs,uo,{qdbr8oasolqoalsd'9'! Tle^\,(lq?qoJd ojea\ lero slueuruojr,{ug Jol?A\ -doop l(le^q.elej se pelejfuelu uaaq aêq l?q^{ 'fle^qcedser 'eepr v D appuog Jo JlErJossE uu sbr'{. snpouottdo -ruosrtlg pu? eep$olopuoc aql ur paqsqqel -1 fir41 t't'l uorlses ui uaes e^?q e,{ lnq -ss fluug eje^\ JepJo ejqereua^ srql Jo soqcu"jq 'luouruojrûe Jel" {-nd.olleqs 'eroqsjeeu p lsea ejor{srceu pue eroqsgo 'uo eunl uerue -8ns,tlelns plno^r sernl?ajjo uo4?urqum siqj 1,,(suus4-prru ruo+ pue'(odprgleutojtoeg oql) 'uollces ssojc JslncJrsJo saljuuep elejcsrp sjejoldxe ejoqs,uo Jo dnoj8 pedoleêp p?q ^\0J? lsnt Jeeq t?q1 sessecojd Uoqs,(q pezuelc?lerlc eprurporuoud aq1 'eul4 u"rddrssrssu^l l?ql puru ur dool lsnur ouo 'uodezr[ Jeue8 Jo ^q lo,\el srql lp ueê 'JeênaoH slueluuojrûa Jolea -,rol1eqs 'ejoqsrceu roj eru4 q8nojql -Js [?Jaua8 peq o^"q 01 ureas-?prurporuolll ^lrug eql ueô Jo-e?prluopoucl " oql s? r{3ns s{cots 'erns eq oj 'le el serjeds eqt uo per(?ld eq tsnu,(soloceoeled tuopouoc Jo eui38 eql ',{tejes roj 'leql peuorlueru lsnf l?ql se qcns uoneujojur rr.ro{ uorsnljuoj JJqEuoseal E sr lr 'Uoqs ui 'uoqnqulsrp uer3rôpro olel Jroql peleclpul slueuuojr^ -uo oql ot sepm8 elq"ueûr ^q s" uercrôpjo eql ur ejaq,rjslj DutpoDdld Jo snpolusdjqd Jeqie esn 01 snojeeuep oq flojns pfo^{ tr 'snqj 'sluouruojrûe ejoqsjo ejori] Jo suozluap ejond AlJeela,,'Dulpopald,, ol perrejal sepurpolj?zo e.{rlluud sql turpnlcur 'sarjeds rele'i sarnl -eej ajoqsjeou,(ueur oêg peuuoj struou.i -elo er0 pue 'suob?rcoss? ejoqsjeeu êql ui polues -ejdej eje sarceds u"rcrôpro elpp{ l 'tuo$rq r"lrurs e soîoû oulpopald Jo ^lleg lueu] -doloêc sejnteej eroqs.uo,{q pezuolc?jeqc sesnlpj?dde llnq pu?.,eas ot lue^r,,,(pueled -d" 'usrorôpro alpprl I Jolq eqtr ur 'stu"pu$s -ep JroqJ 'JeD?rrr elq^\jo slunou" pel[urt pu? soltnuep pepunoj qlvr\ slueulele lelolo{s lnols pu? 'eulle^q,{lefuq 'lnols ere snpotuoltdorpj epmrporuoud eql Jo saroeds,tq tllnq stuaru -ala l"ql flecej,(lejeu I 'eldru?xe u? sv 'sluour -uojrûe qjns ol serrpur olqeueûl se srelce -JBqc aseql Jo teei 01,{pJeqlooJ eq plno,{r lr 'crss?uj pu? ûe orozoel"d eqt q8nojql ',{"^\ pjeue8 p ur lseel le 'polsrsjed e Eq ol tllees sluouruojr ue ejoqsjo Pue 9JoqsJ 3uJo Jusuel -cej"rlc sluopouoj Jo senrl?nb eql qanoqlv 're8ffl ere,$ suorlelndod 1"ql pu? slueu -uorrûa JJoqsJeJu ur rj"ql aloqsjo ur JJqArq s",r flrsje^rp serceds leql ocuouedxe,(ur osle sl lj 'slueuluojrûa ejoqsreeu ul ubql rele E qcnu ueoq eêq ol sursas slueurele urjojr -urloed peuuojt?ldjo oql pue 'selorluap luenuuoc,tllpjelel 'pessejdruoc ^teue^.,(u?ur glr^\ tos sessejord el?jrtap eaeq ol pual sluelllele rrrjojr -llled 'Jallelll ollq^l elq"jeplsuoj t0l,yr sluelljele ll?rus porujoj sluouruojrûe oroqs -Jo ol ^lo^b"loj petdppe f,puepr,re ere,{ l"ql sluopouoj 't, uorfes ur paqucsep suon?nlrs u?ru?î,(s -uuad pu" uerddrssrssq,{ 'uerchopro eql ui 'sluauruojrûe erogsffeu ur IJ"r.us -elej ueeq e Eq osie suon?fdod luopo ^lj^n -uoo lbql oepnf I '{ooj Êur ojogsjo Jo lqbre,n alq?j -eduroo e ur ueql IcoJ sroqsreeu go ruertoll e ul slueujele r:i$ej rej aje erjql leri JJuJuJd VJNOOONOJ :IHI 991

174 PALEOECOIOGY AND PALEOBIOGEOGRAPHY t67 cause ofthe light it may shed on the position of ley Province in the late Ordovician of the major crustal plates in the past. For this reason, wann-water realm. tateral differences in contemporaneous conodont faunas also permitted a number of defailed studies of conodont paleobiogeography have been published in the recognition of British, Baltoscandic, and Mediterranean provinces in the cold-water marine last few years. Most ofthese haye been brought up to date fairly recently (.9., Clark, ed., 1984), realm, in which conodonts may have lived in so I provide only a brief summary here. subpolar seas well above 60 degree south of the equator. I-ate in the Ordovician, as noted in Section Late Cambrian and Ordoyicqn paleobiogeography 6.3.2, conodont species diversity declined dramatically, and this seems to have led, by the Miller (1984) notes that both classes of conodonts appear to have originated in the Late fauna characteristic of the cold-water realm. end ofthat period, to virtual elimination ofthe Cambrian in warm, low- to midlatitude seas. Stocks that survived into the Silurian (i.e.. the By earliest Ordovician time, however, representatives of both groups had spread into dontidae, and Panderodontidae) are either Icriodellidae, Prioniodinidae, Spathognatho- higherjatitude seas, and Cordylodus (a cavidont) had become essentially cosmopolitan. A latitude seas ofthe Ordovician or are surviving ones that were well established in low- to mid- relatives (e.g., Distomodontidae) of ones that were. pair of major eustatic events in this Late Cambrian-earliest Ordovician interval are thought to hal/e been influential in directing the development of the Conodonta so that, by late in the Tremadocian, very different faunas had evolved in low- and higherlatitude seas. The faunal differentiation outlined by Miller continued through the Ordovician, when the manne realm was clearly divided into two major biogeogaphic units (Sweet and Bergstrijm, 1974, 1984). I now prefer to regard these major units as warn- and cold-water realrns, although they were originally described as the North Atlantic and North American Midcontinent provinces. Descendants of the pioneer lineage of the Conodonti, the Teridontus stock, figured prominently in faunas of both the warm- and cold-water realms and, as Bergstrdm and I pointed out in 1974, there was a not-surprising parallelism in development. Only a few cosmopolitan species existed, mostly representatives of Drepanoistodus and, Panderodus, but also including the cavidonts Dapsilodus, Walliserodus, ar:.d Ansella. By the Late Ordovician, and possibly before, distribution ofconodonts had come to defrne a number of biogeographic provinces in the warm- and cold-water realms. For example, a combination ofr- and Q-mode cluster analysis of data from 26 sites in North Arnerica (Sweet and Bergstrdm, 1984) permitted discrimination of an equator-straddling Red River Province and a soinewhat higherjaiirde Ohio Val Later Paleozoic and Triassic paleobiogeography Reported Silurian conodont faunas are surprisingly cosmopolitan. However.46 new species are described from the Lower and Middle Silurian of New South Wales in a recent report by Bischof(1986), which may suggest that Silurian cosmopolitanism may be partly a result of faulty knowledge of Silurian conodont faunas. It is also ofinterest to note that Silurian conodonts have been collected largely from rocks thought to have been deposited equatorward ofthe 40th parallels (Charpentier, 1984). Klapper and Johnson (1980), whose comprehensive review is authoritative, confirm that conodonts appear to have been restricted in the Early and Middle Devonian to more or less tropical areas. Early in the Devonian, endemism was relatiyely high, but later in the period, with increased rnarine transgression of cratonic areas, endernism decreased and the nurnber of cosmopolitan species increased. Although Klapper and Johnson noted that most conodont genera were uniformly distributed, they logged a number of differences, at the species leyel, between the conodont faunas ofvarious epeiric seas of the Early and Middle Devonian. It was their choice not to formalize the endemic units as proyinces because such a pro-

175 (u"rteuurjurj) uoq?ujoc Epnles er{l Jo,{8oloc -eoapd pu" (896t).S.J,pleglpH &lllqrssod eql ezrusocer 01 lsrg eqt s?^{ sluopo -uoc crsseul uo lodoj. 69-t 'g9l ^qd"$rlerts DdDd.to]d ta^rns 896I s,epelqcnh loac S n 'DlJnlue) 'Jeâ,Ytoq J?rluec Jo (u?rcrôpro) ouolsour.i 'pezuolc?jeqc Jo peqsrjq?lse uoeq uolsurxq eql Jo slueuruojrlue e,\eq saourôjd J"uorlrsodep IBruroJ on Ee"tu?d Jo slseoc pue,{qde$rtbrlsoq -I'GL6l) U g'us{usserc 1SO/( pue lsee eql uo s"unej ugo^rloq socuojojrp '0bt l?rcurôjd s1so63ns 'sl?p,{ej uo pes?q q8noql -l'961 tlowaw wv Jos loag ursq?durôtd pue sorcejorq luopouoc (tg6l) pe!'.i I 'srs{pue(y961) s.requedreqc 'u"ru]jod pu? C 5U"lJ 'ze-li \961ltowaw 'utv 2os load 'utsrlelo snorojruoqnj ate.i eql ur uob?rcei8 e^rsuol -urôjd luopouoc ui serpnls :eceds pue otu! -xe posnec e8u?rl crtbrurl3 ot srql petnqun" q?norql sluopouoj (tg6l) 'l{ U 'Jortuatu?qC eh ^q?rle4snv Jo ublrjrod 0q1 ruo{ lues '{ro^ ^\an ',{elr^l ()tcojqs U'U -q" ejea{ sluopouo3 'crss?ul pu? snojejruoq pu? reqjrrls l\ H pe) nualay quon lo slrssotr -J?C eql ur ejuepunqs Jreql alrdsep 'leq1 peuod xapuj VI,VZ-SEZ dd sluopouoc Gn6t) - '6Vt-s9Z -ej(9161) IIocrN 'lercurôjd seî uonnqulslp 'g salpus unossry4[ A.run 't 'ou setpnts luopo Jleql Jr e8pnf ol sluopouoc uerrrued Jo ocuoj -uoj '(t 6I) C W lqelî pup ''g'g'uosu?jg -rncco eqr uo uo4?rruo.]ur elrrt, oor 'f1sl-69s1'(0t)68 ll.".ijj,to, Ing 'Luv'JoS pa) 'esssouuej lejluec 01rblcnl -ue) IeJtuec 'ocurôjd -tû3 ejoqsur q v 4?uqrcurc aql Jo PeFr4ser lsou pu" lso Jo tuonrq u"rchopjo al.j flj"e pue epprl -qsj"q eql ot peldep",tlluej?dde se,t\ ll leql pq l ele-l {8t6I) 'H U 'euloqso pue ' a 'd (EIIerog eql elrdsep 'snqpuso$ala[ srruee u?rddrss$su I 'Ltrr'68 oql JoJ uonnqulslp uzlllodorusoc,(fursutuns? fuaqualjuas $uts7unq)snl Duno)'salell. elou (986I) preqcro pu? 'treqpu?s'retlrg uo^ qlnos {\en ujene?r{tpllu liio{ Sluopouoc Ueu '^Fu4soJetul'pedsns suorsnlcuoc fue eleur -ng5 e1ppq41 pue,{1r?a (986I) O J D Joqcstg 01 s? AreJ os ejo^\?lep 6t?I-ttl 'g vrdud-l leql pelou eq 'reêl.roh 'spuoqootuopouoc 'ee"3u"d uercrôpro Jo lrqsq rrqlueq Jo seprs alrsoddo uo podolaôp e^?q -odleu pesodojd eql pue 'senrunururoc'sejur -ôrd (946I) g.i'sne?rq"c pu"'.){ J'seqrsq ^slu seunej luaro.up tudeco crequ aqljo ejns -olc snorejruoqj?c el?.i qlv( 'leql uorsnlsuoc sejuarajau lej oj aql peqceej serjeds rujoj u?ru?,r1,{suue4 'ellq^rquo/r{ eq lll^\ suodnq -ulsp crqd"$oe8olq lnoq? slueuntre requnj l?ql lqnop I 'stuopouos crss?uj Jo eql uo [?pol slsxo ueql lueureetsp Îllouoxel laleeja sr ejeql Flun'rxsru?lqodoursoc turspsjcurjo euo Jo rus{ercurôjd Jo ldojuoc? Jeqlre Euruod -dns ur eloj elqeleprsuoc e peêld eêq,(?ru (suod"cg4uep$nu Jo) suorlzcguuepr p?ojq 1eôl serjeds eql te Alu?ulud pssou3erp ueeq aêq crsseul eql Jo s?unq pnurôjd esnec -eg'seunej luopouoo u?lllodorxsoc i(18ursee:c -ul{q perdncco ejea\ sees crss?rjj al?-i pup Jo auo pue uo4nqulsrp Jreql ur ^lqercurlojdjo pu" u"rddrssrssq^l Jo uo4nql4slp eql Jo srs -,ipu? (t86i) s,renuotu?qc',4fiecqdersoesorq 4snleâ 01 lfclurp aje ernleral{ eql ur pelset -8ns suo4curlsrp leql sorceds snojojruoqjej lsoru Jo lueurilerlfru eql ol uelr8 ueeq s"q ûrouox?l uorluedp ellul os pue 'Je e[ cueu -eb eql l? ursrl?rcurôrd ou,( equosso slaoqs sluopouoc snorejruoqj"3 Jo uo4nqulsp aql 'ueruoôo ole-i ero ur urs{aculôjd Jo Ic"l? urguoc ol urees,{eql lnq 'serceds ujoj Jo pesodruoc aseq?1zp e uo acueqar,{q pou?u] ele ses^l?ue (t86i) s.reduedr?qj 'ursrlerc -uhord pqreullo^{jo ecuesqerlt pue sebeds u?ruoôq sls-1 Jo uoqnqulsp crqdertoae eph\ eql 01 slsen" sluaujuojrûe ouueur pusou 'ojoqsjo ur polrsodep $pol ueruoêo leddfl ul (296I) re@eg fq peshep aueqos l?uoz elpprhl tpql pu? rrsseuj oql ur peqsrurul -rp rxsruopue leql slse8:lns ^lj?g 'Jeâl1.\oq'srs,(pu? (t86i) s,jerluedreqc eeetued Jo aprs lse^r eql uo ecurôjd uecuau.iv quon 3 pue 'edojng -orq eql Jo,tlr[q?crTdd? IesJo^run lsourp eql pjluec ur ecuhold ({ldlleqcsntr^{ lo) rluelu 'slollered qlot eql,{q qlnos pu? quou pepunoq -JeC e '"e?8upd Jo eprs lsee aql uo aourôjd lleq epnlq?l-,!{ol 3 ol ueruoâ(i el".l aql ue,{q1e1 z pozrueojej eêq sjoqlne luenbes q8norql peuvuoc aq ot penunuoc sluopouo] -qns e3?,(uejo stuopouoc Jo uorlnqutsrp sql..'?0s ui ejnleoj? se rusrprcur,lord lsa8ilns o1 lsrg eq1 curede ueruoôo olaedes qres Sutru"u ueql ejoiii Ou ' ' ',, Ol pelunorrrs e,\eq plnor\ ampas VJNOOONOJ IIHJ 89r

176 in Indiana, Ohio, and Kentucky. Geol. Soc. America Spec. Paper 95, l-34. Heckel, P. H. (19'1'7). Origin of phosphatic black shale facies in Pennsylvanian cyclothems of mid-continent North America. Am. Assoc. petrol. Geol. Bull. 6l(7), (1980). Paleogeography of eustatic model for deposition of mid-continent Upper pennsylvanian cyclothem s. Pp.l in Paleozoic paleogeography of the west-central united States (ed. T. D. Fouch and E. R. Magathan). Rocky Mountain Sec.. Soc. Econ. Paleont. Mineral. Heckel, P. H., and Baesemann, J. F. (1975). Environmental interpretation of conodont distribution in Upper Pennsylyanian (Missourian) megacyclothems in eastern Karlsas. Am. Assoc. Petrol. Geol. Bull. 59, Huckriede, R. (1958). Die Conodonten der Medirerranen Trias und ihr stratigraphischer Wert. PaLiont. Z. 32, l4l-175. Klapper, G., and Johnson, J. G. (1980). Endemism and dispersal ofdevonian conodonts. I Paleont. 54, Kozur, H. (1976). Paleoecology of Triassic conodonts and its b aring on multielement taxonomy. Geol. Assoc. Canada Spec. Paper 15, Merrill, G. K. (1968). Allegheny (Pennsylvanian) conodonts. Unpubl. Ph.D. thesis, Louisiana State Univ., Baton Rouge, 184 pp. Merrill, G. K., and Martin, M. D. (1976). Envi ronmental control of conodont distribution in the Bond and Matoon formations (Pennsylvanian, Missourian), northern lllinois. Geol Assoc. Canada Spec. Paper 15, L Merrill, G. K., and von Bitter, P. H. (1984). Facies and frequencies among Pennsylvanian conodonts; Apparatuses and abundances. Geo,/. Soc. Am. Spec. Paper 196, Miller, J. F. (1984). Cambrian and earliest Ordovrcran conodont evolution, biofacies, and provincialism. Geol. Soc. Am. Spec. Paper 196, Nicoll, R. S. (1976). The effect of Late Carboniferous-Early Permian glaciation on the distribution of conodonts in Australia. Geol. Assoc. Canada Spec. Paper 15, Pojeta, J., Ir. (1979). The Ordovician paleontology of Kentucky and nearby states-introduction. U. ^S. Geol. Surv. Prof. Paper 1066, Al- A.48. Rhodes, F. H. T. (1952). A classification ofpennsylvanian conodont assemblages. J. Paleont. 26, Sandberg, C. A., and Gutschick, R. c. (1979). Guide to conodont biostratigraphyof Upper PALEOECOLOGY AND PALEOBIOGEOGRAPHY 169 Devonian and Mississippian rocks along the Wasatch Front and Cordilleran hingeline. Brigham Young Univ. Geol. Studies 26: to7_ (1984). Distribution, microfauna, and source-rock potential of Mississippian De[e Phosphatic Member of Woodman Formation ton Group (Ordovician) in New york, southern Ontario and Quebea. N. Y. State Mus. Sci. Seru. Bull. 405, l-1o5. Geol. Survey, Tech. Information Ser. 14, l-:-l. Sweet, W. C. (1979.). Conodonts and conodonr biostratigraphy of post-tyrone Ordovician rocks of the Cincinnati Region. U. S Geol. Sum. Prof,. Paper t066-g, ct--g26. - (1979). Late Ordovician conodonts and biostrati$aphy of the western Midcontinent Proince. Brigham YounR t-lniv. Geol. Studies 26, Sweet, W. C., and Bergstriim, S. M. (1974). provinciatism exhibited by Ordovician conodont faulnas. Soc. Econ. Paleont. Mineral. Spec. publ. 2r, (1984). Conodont provinces and biofacies of the I-ate Ordovician. Geol. Soc. Am. Spec. Paper I 96, Sweet, W. C., Turco, C. A., Warner, E., Jr., and Wilkie, L. C. (1959). The American Upper Ordovician Standard. I. Eden conodonts ftom the Cincinnati Region of Ohio and Kentucky. "/. Paleont. 33, yon Bitter, P. H. (1972). Environmental control ofconodont distributon in the Shawnee Group (Upper Pennsylvanian) of eastern Kansai. graphische Bedeutung. Abh. Hess. Landesamtes Bod.enforsch. 3t, 1-l 66.

177 ra e8pfply'qsg pue'dutotsolqjun-tg letusl eql Jo slcolq alosnur Jo seuloloûl padeqs-uojôl{3 eql qll,!\ semt"ej rell?l eseql tuueduoc ur snounec.i(let udordd" sraa ( 86I) 'p le s8ltug qtnoqqv 'suaurrjeds JnoJ IIEJo su?d rouelsod orll ls?ot le Jo sjpts eql Jq ol psleldjelut or? l?q^{ gzuelc?j?qc suorsserdurr pad"qs-a '8uI -uedo,{ljouelsodjo souos pu" 'seô luesejdel,{"ru " uerurcods qsnlocs auojo eqol clpqdec 0q1 Jo Jo u d rouefod oqt ur slods {Jep Jo ll?d Y 'Iel eql Jo,teqduod eql Surpunouns sug Jo s^?j eql eq 01 polojfuet -ui suo$sejdur a{iebuuj 'peperlp i(llouelsod 'uoqsjo sles Fur8Jerrr sreoq pu? lurod pepunol fnunlq e ol sradet 'sueurceds o^{t ur ssel Jo Jroru u^\oqs pu? ^ljeolc JIel oql se PJlaJd -relur 'pue elrsoddo eql 'eloqr\? s ueulr3eds eql Jo leql 01 asre^su?jt sox? Buol Jleql qllf\ polueuo ele qcrqa\ 'sluauale luopouocjo e8?lq -uress? I?Jnleu elolduroj ue sgpnlcul puz 'peqo[q 'popu?dxe fpq8qs ^Jl?rluosse st '3qol 3II"qd -af, E se palajdrelur 'ugrurceds euo Jo pug ouo 'opud rurrr 8'I 01 Z'l pue Suol luul et ol 0t 'sursl -u?fuo perpoq-uos,(llu?uruop'e4quro,t''e1e6 -uolejo sul"uer eql ej" suourr$ds pejolle pus pessejduroc esoql lbreulur enlq el?djo seqq"d Sur,tlJeô qlra{ eju?lsqns eurllelsdrc qsluîojq e se pe^jeserd sr leuel?ru cru?8ro,{ eultuo qcii^\ ul suorssojduoo IJe eje '?Jeue3 lualej -Jrp oû tseel l? tuosejder ol lqanoql pu s^,r tuaragrp ur pe^ressjd q8noqlf 'sueur -Jeds qsr[ocs ^DqtrF JnoJ eql'g Jetd"qC ur pelou sv 'uorlelejdjelu ' L'a no/( JI 'Jo uollelncods.{ll?al sr lser eql [Iv suorlco oc luelxe ui sueu -roeds elerosrp Jo suol lu,{ll?j5lll ui elq?le^" sr serceds gggy se,(u?tu se luesojdal ol lq?noql slueurele pezrl?jeurrrr Jo ejnlcruls plrjslfi pu? ed"qs oqt uo aouepl\e pue :sretsnlc pssru pue seeelqulesse lejnl"u 00S ueql ojour,{q pepl^ -ojd sr sluopouo5 euros Jo snl?j?dd" lelele{s aqljo uorlgoduoc eql 01 s" ejuepho lcajro '[ Jeloeqc ur ecuephe l?qt Jo,{l"rlIuns peprôjd e^?q " 0/I I 'sluopouo3 Jo,{uol"uE,(poq-Uos pu? 'ezls 'ed?qs eql ol sp e^?rl e,!r a3ueprô pejlp {Iuo eql eplôrd (/86I '13 le qfurs :q9861 'ES86I "p la llf{ir{) utsuojsl^\ tuo{ ujturjads snpodpu'd rr"unlrs efuls e pw (986I) 'Ie re espfptv pu? ( 86t) 'p le aug,{q pequcs -ep sueurroads ueunlu"n qsrllocs JnoJ eql 'fu eôcslp luecal.iijibj,{[soru pue Joqurnu ui.aroj ele sedruse tlsol -orq rroql lnoq? (seseqlod[q Jo) suo4?inseds Surl?nl? s ur InJesn 0J? leql sluopouoc lnoq? spejjo suos eql 'Iooq srqljo sudd snonajd ur,(ipeleadej pezrseqdue ueeq s"q sz 'puy 'sls?q I"np?J sll Jo {c34 dea{ 01 lueuodur s,("/r\ -Je sr 1r tnq 'ÊoloPotnour JUIluotJs Jo luouod -ruoo lueuodurr u" si ti pu? 'unj si uo$slnjeds alc"j Jo lueullselur turgul e qcns uo+ llnsej uowfceds Jo urntej elesgloq,lt e qons lq8rur ejuercs ur lnq eslo ersqrt\ :pgjapuoli\ 0q ueq \ sluopouoojo seriusb c olorq oql uo suorurdo lnoq? tuqu,{r ueaq e^?q lqelu ureraj {JeI I sraljarbqj luopouoj Jo drbuurns Z'8 'euliii luo{ lojlp sebru$" c olorq uo suorsnlcuoc esoq.& 'sjor{lo,{q pezrsbqdura esoqt olur osle tnq 'uml,(qd pudxe-8uol pue luep -uedopur ue sb uraql tuipjeesj JoJ suos?el,(ur olur,(luo Lou lqarsul auos epl{ojd pu" 'sluopouoc ^qejeqt Jo sefrug" c6ololq oql ot s" suor -urdo snorêjd elenl?ag pue loj ecueprê eql /{er,\er ol snqt sr Jaldeqc IEUU srql Jo uorssru aqj 'dnor8 3rSolorq Joqlo eruos ol peu8lss? ro 3o UPd pereplsuoc 'qll^\ peiw ueoq raêu e^"q sluopouos eql leql Jo s?iq f,ru saj qs euofueê l?ql uorssejdurr 0q1 e^?a[ ol llzjun eq plno^l lr 'reê^roh 'uinl,{qd 'IuEr lseq8lq " oqtjo,{lquo rruouox4 e se dnol8 eql l?ejl 01 si 'reld?qc srql Jo olru eql,{q popufis <s?iq legj 'sluopouoc aql Jo se4rulg" cltolorq aql 8uI -ujoouoc sprq l(ru qlra\ Jerlrru"J eje no,(,!1ou,tg sb!{ [suosred Y l'8 VINOqONOJ hin'iahd AHJ '8

178 THE PHYLUM CONODONTA 111 al. (1986) describe these features as "somites" without further justification and this evidently figured prominently in their ultimate determination that the affinities of the conodonts are with the chordates. Also indicated with varying degrees of fidelity on all four Scottish specimens is a pair of subparallel longitudinal lines, which extend from a point (in one specimen) not far behind the cephalic lobe to a point near the posterior end of the tail. Aldridge et al. (1986) point out that these lines might represent "... a septum dividing the body somites longitudinally, a mesentery separating compartments of the body cavity, a major longitudinal blood vessel, a stiffening rod or notochord, a nerve chord, the gut." They note that the gut is the one of these structures most likely to be preserved; however, they also note that ifthe pairs oflongitudinal lines do representhe outlines of the gut, the fact that they extend almost to the posterior end ofthe tail in two specimensuggests that the animal lacked a postanal segment, or true tail. As noted in Chapter 2, the intemal structure of conodont elements indicates they are composed of two parts, crown and base, which must have been completely enveloped by (or embedded in) secretory tissue at least during times of growh. Apatite crystallites in lamellae of crowns are oriented with their prism surfaces parallel to the direction of growth. Bases are less densely mineralized, and the framework of organic material may be thicker. In a nonmarine. The first true conodonts are from Upper Cambrian rocks, the last from strata of latest Triassic age. Conodonts have been recovered from virtually all types ofsedimentary rocks. and records of conspecific specimens frorn rocks representing many diferent depositional envionments are common. Especially significant (to me, at least) is the fact that most conodont genera are represented somewhere in the world in black shale deposits, which commonly lack remains of benthic organisms but in many places include well-preserved specimens of pelagic ones. 8,3 Conodonts as Ilvertebrates In the 130 years since their first formal recognition, the conodonts have been referred at one time or another and with various degrees ofsenousness to most ofthe major phyla of invertebrate animals. The hypotheses represented by many ofthese referrals are easily dismissed, but some others are not so readily discounted and should at least be mentioned in this ooinion polt Arthropod and Annelid connections Even before Pander's original diagnosis ofconodonts was published in 1856, Murchison, Barrande, and Carpenter had registered the opinion that the tiny fossils were the tip-ends of some parts of tlre trilobite carapace, and thus were arthropod, not chordate, fragments. And, few specimens, the basal portion may include a not long after Pander's monograph appeared, plug of bonelike material v/ithin which Barskov, Moskalenko, and Starostina (1982) have be analogous with the "... spines, hooklets, or Owen (1860) suggested that conodonts might identified structures interpreted as osteoblasts. denticles, of naked rnolluscs or Annelids." Among the other characters that havo been Although no one seems to have followed up considered in speculations on the biologic affinities ofconodonts, I should also mention their parts ofa trilobite carapace, two authors (Har- on the interpretation of conodont elements as geographic and stratigraphic distribution and ley, 186l; Simpson, in Newberry, 1875) suggested that conodont elements might b crus- the cosmopolitan occurrence of many species in rocks representing a wide variety of sedimentary facies. Conodonts are common indig- proved particularly appealing, largely, I sustacean remains. These suggestions have not enous fossils in rocks that contain the remains pect, because the variety of element types of of animals such as brachiopods and echinoderms, which are exclusively rnarine at present the array of spines that rim crustacean most natural assemblages is not duplicated in and apparently always have been. They have carapaces. been found only as reworked or redeposited Owen's suggestion that conodonts might be specimens in rocks that might be interpreted as a group of the Annelida received serious atten-

179 -uojêqc eql lpql tse8ilns osle 'suorurcads 'elnlcruls I"uJelur ui sluopouos luopouoc qsnlocs aql Jo sauq êql prxe eqljo luec luo+ {lptueuepunj rejrp 'splleuu? ele"qc^lod -srururej suorlsod e^?q seleoôjopn?c ureuao Jo ernlns Jo s,["f I$soJ oqt 'sluopmelocs leqt pe/{oqs l?iuo^pru eql pue serls"souelos tur oq/( '(186I '1" 10 )lrelj ud rellnl I,{q pelues -,tq;o e,too:t pped eql terll pu" :s!"d [Eculetu -grd s?,r\ uoncefqo 8u{lot ejou V,{ eujolur -ru^s o,rt otur popr^rp sr plerqs I?Jo oql 'ejorld eteqdsoqd urnrjpj elejres ot elqeun,{ltuejed -oc?ldv euros Jo sllnp? ro ae e[ eqt reqlre -de ej" sp{euu BuIAI l"ql sr uorlcafqo roferu ur lbql :stuopouoc snojejruoqjej qsruocs 3 lew (euop o^?q sroqlo s?) lno palurod osp aql se gzrs eurbs eql lnoq? ej? suejoqdoceld? eq 'stuopouoj loj pleuus upjo JO^BJ ur 8ur^rT l?ql lcej eql elr3 JrnJ puz JorlII 'uos eruephe tuoj$ rajo ^trul$",(eql,{la^rpejloc t?ql -ueduloc e qrns tudsettns ui 'suejoqdoo?ldeaql qll^\ pelsl ^{er^ lsnf sluournej? oq1 Jo uobsns oleaôjopnej snoue^jo esoql qlrry\ uosupduroj -srp sq pepnlcuoc (t96i) sepoqu qtnoqlyy elrû suorurcod snojojruoqjej qsrllocs oql 'unlqc Jo peolsur Jo sojnleoj,{ueu t?qt Auuse8itns,(q $Isn our eq elpqdsoqd urnrol?c Jo ep?u s,,\{ef ql!t\ tq8ru sluopouo3 l?ql srsaqlod^q eql pearaoj pqeuu? ue oleflsod ol ^le8jel,(ljorujoj upql lf g eêq (986T) Jrnf, pu? relllrj ',(nuocer tuea -Jrp ssel suree snql 1I 'eqnl ro 'elc4nc l?ujelxs 'pelelej ^lesolc lsorrj oje sluopouoj eqt Jo ssolouroq ortolors^qd aje s,!\zf prleuue qcq^{ ot dnojs rofeui aql luesejdej ol l"ql elqrssod surees lr 'urauo ur le"polllols snql -un ele ejueq pue al"qdsoqd qcnur IJa./\ elajcas ^lellr ere pue ujepotce cluo,fuqula eql Jo uoq?u6p^ ol peddmbe lou er? $lsn our -ur,{q uroj surro^\ eseqljo xua?qd pue Buhrl Îlm6olors,{qd tsolu 1?q1 '(516l) uosleqcol pelsea Imonq eql JI 'soqnl Jo urroj aqt ui el"qdsoqd ^trêc -8ns'qcund tnoloou)l eql uar0 s".{ l?q^r ^q peppe (186I ''p te {J?lJ ur) rollnw.lou rrjnrcpc olejces spqeuu? eleeqc,{lod oluos. op sluoul 'J"e^r Jo sua$,{lejej'joô,{rog'suljo^\ -ei3 luopouor seoreq.r 'l?ei Jo ecuoprê elq? îoqs -Japrsuoc aoqs i(poururoc êql leql Jo..stueuodruoJ,r?f 8urdsel3,, eqj 'qteet orul pue s,{loj se uonrunj lou plp pculeullu,ft ur pgbu"jje ^lqer.reûr lsorxle ej? êql l?qt slsesens stueur -ale luopouos lsoru uo JD3,1d Jo {cei aqj ' qleel relnp?r 1?q1 pu? '(..snourlrqc,,) 3ru?Ero 'salpjqsue^ ISOUr ozuep"jeqc,{isrnuo ere $lsn orrr Jeqlo pu" slwus Jo qleel leql srrrjo Je1(ol pu? Joddn eql tou pu? sjred [ErelDI luesojder ot Jelnp?J eql s?areq^{ 'c!.eqdsoqd oj? slueur tuees sas"lquass? esaqljo slueuele par?d. -ele luopouoj teql sjlou oste JH slljqs pod 'spqeuue eloeqc^lod Jo sesnlerpdde -o-4set luzpunqz ur?tuoc l?qt slrsodep,(uzru A{ef luesejdej 01 unaodl se8eqtuess? luocej pu? ur punoj lou ele sluopouor leql pue spod IrssoJ ur esoql olquras ses"lquess? I rnleu ur -ojts?t tur^rl Jo rlleol relnp?r aql Suoru? su?d -retunot cl8oloqfuolll lcel slueurole luopouoc Jo sod,q Lsoru leqt selou 'spodojls?e Jo qteet JelnpEl eql eq lq8rur sluouela tuopoum leql tuerun8r? eql Euuetunoc ur'(ts6i) sepoqu 's1u0urole luopouoc uljojruoo ureuec pu? spodols"s 8ur^rl Jo sluelliele relnp?r eql Jo uosu?duoc slueuelo luouoduroc oril Jo urjoj ur uorleu? pu? 'Jequnu 'luoluoeu?lj? IeJeueE oqj ' 'qleel el?jqaue^ Jo PJrdiq.{lr^?c dfd eql {cei slueuelo luopouoj pue 'slueuod -rxoo.\\?f prtouue Jo osoql ol J?Irurrs ej? sluaur -ele luopouoc Jo ejnfruls pu? rrrjoj erlj. 'sturod tul,noljoj eql sepnlc -ur fu?uiurns srh 'splouue oje sluopouoc leql crsoloqfuou ssoj8 uo suorsnlcuoc reqt pos?q srognc pu?'tlojs'uoqou pue I0 rzjo s,!lel^ urog,r,\ Jo IIe'(9 61) sruoo.i pu? '(t88i) selli?t oql uo stueururoc pu? srsll (ts6i) sopoqu '(Sr8I ',ftiaq/aen ur) es:o141,(q peuoddns se1'{ 'selep 1l lnq 'stsl8olotuoepd ot PeFedd" lou -roqj oql Euuo^?J esoqt Jo leû,fueruud sql seq uoqse8ensrqj 's1sn11oru3o û?ru dnort euos go uajq s?q,.serlru$? luopouoj Jo srsaqlod,{q qloel r?lnp r eql eq lq8ru 1?gl,{lrTqrssodpqouu?,, eql 'slee,{ aqt q3norqt 'peepul'peuop eqt pesrcr oqe (9991) uo,r\o êql 'dno$ pqeuu" ub -u?q? ueaq e^?q ol ur00s se4rulu? pqeuu? Jo lueserdar lq8ruj sluoulele luopouoo lsql flflrq sesaqlod,tq uoq,,.r's0s6i elpprur oql lllun (ts6i -rssod eqt petse8ilns aq t?ql eceld oul"s oql ui 'sepoqu: t6i 'srognc :t 61 'ltocs '3 e) s1s6 -ololuoel?d Jeqto Jo tudlurql eql peoue suoujauuoj ud)sn oi4[ 7 t 8 -nuur pu? (988I) uoqou û?ur pw pll.rz uro{ uou VINO(ONOJ IIHI zll

180 THE PHYLUM CONODONTA t7f shaped impressions, which are such strikine and mollusks, which have already been discussed, these include the lophophorata (or features of the Scortish specimens. mighr corl respond either to the dorso-ventral muscle series of the Solenogastres or to the chewonlike wormlike animals as various aschelminthes, tentacutala) and such disparate groups of arrangement of dermal spicules thal characterizes the dorsal side ofother aplacophoran mol- about the only major invertebrate phyla that gnathostomulids, and chaetognaths. In fact, lusks. According to Tiltier and Cuif, features have not been suggested as the parental group interpreted as fin rays in the tail region of two for the conodonts are the Archaeocyathida Scottish specimens might also be duplicated in (which were largely or entirely extinct before certarn prochaetodermatids by very long sp! conodonts appeared), and the porifera, Bryozoa, Echinodermata, and Hemichordata. cules in the posterior region. Tillier and Cuif further suggesthat the cephalic apparatus ofthe Scottish conodonts may (1976) have either directly or indirectly sug- Lindstriim (1973) and Conway-Morris be analogous in arrangement and erren rn mrneralogy to the radular teeth and, particularly, group of the invertebrate superphylum termed gested that conodonts might be an extinct the buccal mandibles ofthe Aplacophora. They Irphophorata or Tenkculata by various authors and composed at present of the phyla note, as I have in a previous paragraph, that the principal reason for rejecting a rnolluscan affinity for conodonts is the argumenthat mollusks way-morris's suggestion is based on his inter- Brachiopoda, Bryozoa, and phoronida. Con- are incapable of secreting phosphatic hard pretation of a curious little fossil from the famous Middle Cambrian Burgess Shale of parts. However, Tillier and Cuifhave subjected the radular teeth and buccal mandibles of British Columbia as a vagrant tophophorate, Chevroderma turnerae (a prochaetodermatid and on his interpretation ofimpressions in the caudofoveate) to both X-ray microdiffraction supposed lophophore of that oryamsm as conodont elements. Unfortunately, the conical ele- and microprobe analysis and have discovered that both teeth and mandibles include substantial amounts ofcalcium phosphate, as is prob- lophophore of the creature Conway-Morris ments supposed to have supported lobes ofthe ably also the case with the radular teeth of at named. Odontogiphus omalius have all been least certain scaphopods. (Gastropod radulae dissolved away, and the fossil is from rocks far studied thus far seem to lack phosphate, and older than those yielding the oldest specimens the external spicules of the Aplacophora are I would regard as conodonts. Thus, in addition aragonitic. ) to questioning the real significance ofa vagrant, The features just summarized led Tillier and or swrmming, lophophorate, I disqualify Odontogriphus as a seious contributor to our under- Cuif to comment that if conodonts were aplacophoran mollusks, it would be normal for the standing of conodont affi nities. phosphatic buccal mandibles, at least, to be fossilized even though the aragonitic dermal pointed out features that suggest conodont ele- Lindstrijm (1973), on the other hand, spicules might recrystallize and be unrecognizable as conodont elements. They therefore re- noted a general tendency in the evolution of ments were internal (not external) structures; gard the Conodonta as a potential class of the conodonb toward an increase in surface area of Mollusca, most closely related to one or another ofthe groups included in the paraphyletic surfaces of certain conodont elements might elements; and suggested that pits in the upper Aplacophora. have been the sites of muscle attachment. These observations led him to suggest that conodont E.3-3 Connections with other invertebrates elements might have served as intemal Miiller (in Clark et al., l98l) lists a large number ofadditional invertebrate groups that have been considered appropriate, for one r ason or another, as taxonomic receptacles for the conodonts. In addition to the arthropods, annelids, supports for a muscle-operated tentacular apparatus, or lophophore, and this led to the further suggestion that anceslors of the co[odont stock and those of the brachiopod stock were closely related at some relatively late

181 Jo ernpruls I"IUelul ul rqrluopr J?eu pu" uo4nq -lrlslp ur se4uelrulrs a,{rlcflll? elrdsop 'er{l?ua -of?qj eql ol sluopouos ar$ turusrsss qlr,y' 'Jeê,{roq 'surolqojd snojournu ejp eloql 'slooj.sluopouoc 091 pejeôcsp p"q a^r leql Pepnlcuoc ^[l"ug ûeur ',(pn$ lu?eolo s,rjlsla?ru?zs Jo aiu?jeod -d" ogl qll.{ 'puy 'sluopouoj ueruoôq pu? uerchopjojo uollnqulslp aqt ur pj^rajrad o^\ selleruoue ureuec urcidxe ol loporu E turplrnq ur dnoje teql Jo uounqulsrp pud slrqeq eql pesn peq I pue uoppes afuoeo IL6l ur esnsj -oq?ql?u8oleeqj erd Jo se^qeiaj crozosal^l pu" orozoeled oq ol lno urnl lgftur sluopo ^ljee -uo3 orll lsql eql 01 petce4le -cru?d sea\ I'ql?utole"qo ^llrqrssod tur^ll E'(JI'8 ^ljeln 'trc),llr3rs Jo sourds Eurds?rA eqt pue (npotbtotld ol peuersse,rou) slueurela rrsojruoc uelsr^ -opro,{ll?e pue uelrqurej alel ulzuec uee.t\t -eq ejnloruls ui,qu?[iu]rs EuDtuls E palejls -uoursp (286 I ) rlls.{rau?zs ueqa oroqc Jo fuoeelec eq1 arueceq dno pet"losr i(lpc -rsolooz sql pue 'eqleueofeqj Ûeuq unl,(qd oqtjo suuol{,adojje Surlr ol pelqar eq lqtur sluopo -uoc laql petsetilns oslb eêq sjoqln" leraês 'p01csl0j. Îr -J"ruurns ool 0q louu?c uoucrulsuorer s.rug4s -purl os,,'4jr,, Jeql?J osl? q suaurcads qsn -locs er0jo sejnleal oruosjo uoqqsjtuolur leql Jeld?rIJ srql ur JaIEI palou eq,rr lr'je e,'{'oh 'el?joqaloqdol u^{odi,{ub rj"r{l uouezruea -Jo ur luojeiglp,fia^ sleurrue Jo dnore e elecrp -m plno,t\ (flo^rlosdsor 'suu lepnsj pue seurol -o/(ru s" ''A e) pelojfuolur ^lloaloc Jr 'qcq^\ '(sug peuoddns-êj :sejnlcn4s psd?qs-uor -Aeqc'palEeder' t'e) sreqlo epnlcur pue ojoqd -oqdol E se lojfuelur plno,r I leql em1"ej {ue {cel suoruoods esoql ' 86I Irlun pequcsap lou ojel\ rljjqr'['suorssejdujr u"unur N qsrllocs 3ql Jo senleoj qlw\ psrbnbs eq ()1 speeu sejnl -?ej osoql uro{j PecnPep aq tepou, p:r1aq1od -^r{ eqr r"ql luaruluoc ot lsjg eql oq 'pedsns I 'plno^r lnq' t6i ur u^lou){ sluopouocjo sojnl -?oj IIe lunocce olur {ool,{llnjor"j urolspurt 'gji qsnojql cluod{ueld peureruel sluopo -uoc lsoul seeleqa'ol$sos eueceq'e8qs parel truol -ryqd e.roge 'spodorqcbrq eql esn"joq ps^lo,{e socuojoj -JIp IsluetuBpury aql leql pu? 'ueuqoecojd eql Jo o8els -oi(j) pue (g):socrnos snoue^.,,o.{t un*rped (v)(eqreuao,eqc,,"- ôr*"9fg,t"ot:q}r#xi5i# -oqcu,{qu) ouruoruou ofrel.d. e'calrauauopan (g) :(elepjoqj) eleluprcp 8urÎ,(..snxorqduv,, ro\ olaotsotlll -rr.rbr(v) eluopouoj oql roj sefollsoder se peraprsuoa ueeq oêq leql sdnor8 IEJoês Jo $a^nquosolded.i.g.l!tr iil::: Itri t$r VJNOOONOJ IIHI tll

182 THE PHYLUM CONODONTA Phakelodus and, Sagia4 elements. I am not c r_ rmens and concluded that they were,,... frag_ tain that any ofthese problems is fatal, but thev ments of the hard, crustaceous ends of all the diclate caurion. For example. the graspin! segments of some trilobite.,, In apparent spines def_ ofall living chaetognaths are entirely or_ erence to that opilrion, which he ganic did not at_ in composition, whereas all specirnens tempt to refute, Pander remarked somewhat that I regard as skeletal elements ofconodonts wistfully that (my translation)..... Complete are thoroughly phosphatized. Furthermore, al_ conviclion that these remains are really teeih though of Bengtson (1976) has outlined the steds extinct fishes could be reached only if by which similar the transition from organisms wiih elements like those of phakelodus structures could be demonstrated in living an_ to those with imals of the sarne class." elements with the internal structure of all known conodonts might have been made, that transition has not yet been objectively docu_ E.4.2 Newberry, Hinde, Huxley and Myxine mented. Thus it is my perhaps ultraconserya_ Newberry (1875), on his trye conclusion that phakelodus own account. and and other or_ Hinde (18?9). on the advice gamsms of Huxlev. concluded apparently from shape with skeletal elements of similar lntemal structure (the paraconodontida and luster alone of the that the conodont elements they Treatise examined classjfic.ation) are not conodonts. If were so closely similar to the teeth of the that is hae_ the case, then identity in structure of frsh, Myxine (Fig.8.2). as to be indistinsuishable. In fact. Huxley is reported ro have Phakelodus and Sagi a elements has no bear_ lng on the question in_ of conodont affinities. although it may suggesr thal roots oflhe Chae_ tognatha are to be found in the paraconodon_ tida, a goup formerly assigned to the Cono_ donta on the basis of gross morphology of skeletal elements. Fig Myxine glutinosa, a hagish (o, slime eel), reprcsents the chordate division to which many believ; conodonts to be mosl closely related. Redrawn from Miiller (1836). lls 8.4 Conodonts as Chordates Only a few students ofconodonts haye taken a firm stand regarding the biologic affinities of condonls. and most of them favor an assign_ ment rn or near the phylum Chordata. It is thus ofinterest to look criticalty at the evidence on which that assignment has been based The opinions of pander Pander (1856), who coined the name and pro_ vided the first diagnoses and descriptioni of conodonts, included those diagnoses and de_ scnptrons rn a monogaph that dealt Drimarilv with fossil 0shes. Throughout rhai pioneei monograph, Pander treated conodonts as the hard parts, possibly the teeth and jaws, of a group of extinct fisbes, prirnarily, it seems to me because that is what they looked like to him. Pander did not seriously consider assign_ rng the conodonts to any group other lhan the Chordata, but he noted that Murchison, Bar_ rande, and Carpenter had examined some sdec_

183 i(ueur prp I s? pue) Jorlreo sjee,{,r\ej e euop ej? suorsnlsuoc asoql 'snoeuoue Jo elq?uoq p?q Ir.D{ se 'roê.{oq 'elou prp poluos -sonb Jeqlro sr l(llu$e luopouoj uo suorsnlj -ejd Jeâu sea\ qolr{.r 'ecueplê ôql o^rsnpuoc -uoc s.ou?ljqc?tral JoJ srseq r^?rl ol pjrur"lc pue sjqss J^nruud Jo qleel 1enpe3 aw q?noqr ueê leq1 'reêmoq'elon sl"rurue eseql JoJ Jql se slujurjle luopouoj Jo uorlqajfujlul pesodojd dnor Jueuot"Jdns lslg eql 'sluopo eql ur perjncuoc ( 6I) Iqew pue uosu"jg -uoo roj,fuo8olec dnoje-jepjo ue Jo luauqsq 'suleurar el?jqeue^ eja^\ sueurcods oql l"ql -q?tse prrrjoj eql eq uo4nquluoc elq?jo pu? euoq oje,r sal?id IBs?q oql t?ql sjoqln oj -rueuj lsour S.au?IJEJO?IAI ^"ur '!oqs uj 'euueuuou sq pu? 01 pelse88ns 'sls?lsoelso pue ers,t\ oqo ôlsj?g Pu? {JoA ur pepouoc uoeq p?q 'se!{coelso'slselqoelsol pue ozrs sluopouoc q3rq,r uro{ ^\en salsqs lc"lq u?ruoêo ur puodsauoc ol reodd? ^SoloqdJorrr leql semtcruts qt!.{r eql l"ql poless? osle eq 1"q1 tupou,{q peseejc raqletol 'sess?ur oseqj 'euolspues Surpr"H -ur lou s sorlrulu? luopouoc Jo lueussess? aql ur peluesojdsj osl" sr l?ql s.ausirsjseiai ui ecuopguoc 'snourlrgs er" r4lel st.ue? e'snpoapj ^nu?punq? 01 peu8lss? sluelliola IeJe es oql seejeq,,\a 'snoej?cl?j ej? JerrrroJ oql leql se,ra Jo seleld les?q eql ui sesseur peq os qleel euolsolc,{c pu? sluopouoc uee^\leq pelou -ep (286I) eullsor?ls pue 'o]uoplsolî ^8uods 'ôls ojusrsgrp,{iuo eqt pue 'qy{\ojajo oporrr ro 5rn1 -J"g 'Jelel sj?e^,{ueur'reaea{oh sluopouoc -Jruls IEuJJlur lnoqe peuollueu se,r AurqloN IJP JpntJur ol uolsnlsuoj s[{l pualxe 01 Surltr/$ 'qfet,{ardruq pue qsgteq ;o s8ul,{r?jp pezrte -un selyr eq 1nq 'srrrjopocsjlso Jo su?d qlnoul -:auat f1-relrurs qlr^\ djeq,'aen pu? apurh,4q uesq eêq 1q3[u sluetuele luopouoj eu]os sjsded uro{ pecz.rt stueluele tuopouoc Jo s8ur leql uorurdo eql ol urx pel suou"^resqo eseql -^\sjp eurt epruc SuueduroJ,tq pel?lej.{lesolc 'euoq urjopocejlso pol?rcoss? eql 01 relsnl eje^\ (sêrdurel pu? seqsg8?q ''a'r) sorfiolsolo^t pue rolot ur J"lrur$ pejsedde t?ql atuqsqns B pu? sluopouoc l ql uorsnlcuoc sq pouoddns ol es?q eql le peq3el13 erc,{\ sluetuele luopouot euelj?jcet\l'(seluoz,{urorlad repro) sêrdruel eqljo euos leql p01ou oslb ah opeloloj [Erl pue (seprouuî I ropro) soqsgt?q aqt pet 8e -uecjo euolspu?s EurpJsH uerchopjo atpprl l -IeJ osle eq qcrq/rr ot (?t?urepocq?i eqt) fro8 aro ui srrrjepocs4so u^{ou)lllea erll qlr.!\ Jncco -el?c e^rsueqejduroc ajour E ol peu8rsss s?a\ slueurele tuopouoc teql pauoder (6261) Irr,) q3rq,{r 'seluopouoj ropjo ue ur raqlesol sluopo -uoc eql podnoj8 'slueuruojrûo Jel?aq${ ui p!d t2tu tuoq psoq Io uouoratdtaut pud tuaôjste g (SI r'g 8 '3lC)(?lemoqcu^qu) srrrror u?euruoru -eu[xo+ pe^loâ sel"rqeue^ aql l"ql /(oqs ol pepuotur Iooq snounc? ui '( Z6I) euelj-ej3sl,il 'repu?d[q Felep ur Jeô pojopuod pup pequcs uolpauuoj -0P ejnpruls leruelur uj secuojejrp lsrlu?ls udautuawau aqt pud auoudljpw F'r'8 -qns eqt Jo lunocc",{u?{ool legl ocuopr -â ou pug u?c I 'osounry8 auut7r[ êql 'qsutur{ eqr Jo qlejr eql pup 'sueqs Jo soletd pulep pup ilnjer?c os uooq p?q êfnh l?ql plnold 'rerlrurej qleel eqt 'slueluele luopouoc SuorrJ? ed?qs pu se^\ eq qjrq^\ qll/( qsg Jeqlo ro -relxe ur,bu?irurs ssojt 3 Jo esnsceq (,{lejrlua (auqtl I) seqsgg9\jo esoql ellun /(lr?elc ûp ero^\ lou Jr),(F?urud uorsnlcuoc slql peqreer 13ql slueuela luopouoc ur sernlcruls pujel l?rll 'Joô.!\oq'J?op sr 1I dnoje eul"s eqljo êql -ur poqucsap Jepu"d 'oslv 'cru"fuo oj? II?,(lu?sseceu lou 'seqsg a^rlrrrrrjd Jo sat"ld pru qsgaeqjo esoql seejoq l'r4?qdsoqd ^lejuue ar? sluopo -rep pu" ql.eel eql ej? sluopouos -uorjo slueluele eql 'esmocjo'pue:(gt'8 pup leql.jerteq,, eql possordxe osle (9z6l) relss?g pu? qrujn Vt 8 'tlc) arnlculs ur lueje.up etmb erp,teqt 'ts?el le ',{?ujelul snoeolouoq glp seqsu8eq nlssp{ pud qrulnlolalpq aqj h'r'g JO.,qleel, eql pu? slueurelo luopouoc 1?q1 UOrlE4SuOurep ûjoq aûcefqo JOJ elnlr$qns flpl?q uec lueurolsls? qcns l"ql 'JeAeA\oq'lno '(986 t "le le e8plrplv "3 a) ^lruue luopo lurod ol dl?sseceu lou f,lq?qojd si 1I..' ' 'repro -uoc uo sjeded lumal lsour erll Jo euo ur elnoj srql Jo seqsg 01 Suoleq lou prp lueje.urp JerlleJ? [q por{c"ej seuo eql flosl'erd êql leql aôrd 01lJncIUp aq plno,{lu ',, leql epurh peuroj YINOCONO] EHJ 911

184 8.4.6 Composition and growth of etements Following description of three additional Ellison (1944), and Hass and Lindberg (1948) specimens in 1986, however, Aldridge and his cleared up long-standing confusion about the colleagues concluded that conodonts represent chemical composition of conodont elements a group ofjawless, craniate chordates sedarate and pointed out that the phosphatic minerals from previously described groups but perhaps they identified were the same as those in fossil rnost closely related to the hagfishes (Myxinoidea). A similar conclusion is expressed, but and recent bones and teeth. However, Gross (1954), a student offossil fishes, made the important determination that conodont elements that the hypothetical animal..s" he proposes as just in passing, by Jeferies (1986), who notes are not composed of dentine and lack features the first "crown vertebrate,, resembles the Scottish Carboniferous conodont animal described that could be interpreted as either a purpa or dentine channels. Furthermore, Gross prepared thin sections ofthe Pa elemenls of Ozar- three pages Jetreries devotes to listing the char- by Briggs et al. (1983). However, in the nearly kodina murchisonl (Pander) and determined acters of this hypothetical creature, I find onlv frorn the arrangement oftheir lamellae that the six that might be more or less objectively represented in (or by) the Scottish specimens (ma- elements must have grown by accretion ofnew material to their outer surfaces, not by addition rine habitat, eel-shaped body, head-trunk-tail, ofnew lamellae on the inner surface ofthe element, as Pander (1856) had concluded was the suggesthat, as Jefferies intimates, the resem- rasprng tee1h,?lensless paired eyes,?somites). I case. Gross vr'as thus able to assert with some blance between hypothetical animal..s,'and confidence that conodont elements were not the Scottish conodonts may be so striking because the latter were used as a general model the teeth or derrnal scales of vertebrates. nor were they components of the vertebrate endo- for the former. In reaching their conclusions on conodont af- skeleton, which should show evidence of ossification about a core of spongy, cartilagenous tissue. Gross concluded from his studies that conodonts were primarily soft-bodied chor_ dates assignable to a distinct branch ofthe Aenatha. lt is ironic. I suppose, that his detail; studies led Gross to conclusions very similar to those advanced by Huxley, Macfarlane, and THE PHYLUM CONODONTA years later), that many ofthe elements they collected from the Middle Ordovician Hardins comparative gross morphology. Ulrich and Bassler on little evidence other than Sandslone oicentral Colorado were attached ai the base to a substance that "... appears bony but does not have the structure of ordinary Interpretations of the Scottish bone." Branson and Mehl's (1933) comment C arb onife rous s pec i mens that "... the materials to which the conodonts are attached could not be from annelids or from anlthing but vertebrates..." takes on considerable importance because it was the conclusion of a pair of trained vertebrate paleontologists; but it can hardly be accepted as peated reference. Briggs et al. compared the specimens, to which I have already made re- evidence ofaffinity in the absence offurther description, illustration, or histologic analysis. specimen with the cephalochord.ate Branchio- first-discovered and best-preserved Scottish Possibly they were referring to material such as stoma (FiE.8.lA),the ammocoete larva of lampreys, and artow worms of the invertebrate that described from Siberia by Barskov, Moskalenko, and Starostina (1982), but this will always be phylum Chaetognarha (Fig. 8.lC). Their con- uncertain. t't7 The most recent discussions ofconodont amnities (Briggs er al., t983; Aldridge er al., 1986) are concemed primarily with appropriate interpretation of the four Scottish Carboniferous clusion was that neither a chordate nor a chaetognath model "... provides a satisfactory answer to the question ofconodont amnity." finities, Aldridge er al. (1986) and Jefferies (1986) clearly identiry with Pander, Huxley, Newberry, Macfarlane, and Ulrich and Bassler, although their reasoning is somewhat different. Because the Scottish specirnens lack any evidence ofjaws or a bony skeleton, it is the opinion of Aldridge and his coauthon that

185 8Ll uersls sdo^tau tettuaz :t-tv ld -rvlillo tlvld lvsv8

186 THE PHYLUM CONODONTA 179 the chordate feature to which the conodont appamtus shows the greatest similarity is the lingual structure of hagfishes... in which the rows ofteeth are not opposed when at resl, but are evefted by protractor muscles in such a way thal the action is bilateral rather than vertical. Since this is also the chordate feature to which Huxley, Newberry, Macfarlane, and Ulrich and Bassler assigned conodont elements, and a feature of Jeferies' (1986) hypothetical animal "s," the first cro\ln vertebrate, a briefreyiew of its characters is in order The lingual apparatus ofvyxine Figure 8.3 includes ventral views ofthe head of Myxine glutinosa, a typical hagfish, drawn to show the toothed lingual structure everted (left, above) and retracted (right, above). The sagittal and transverse sections below these two views provide schematic information on the anangement of supporting plates and principal rnuscles. According to Dawson (1963), the lingual slructule of Myxine has four primary components. Above the mouth there is a single, backwardly directed palatal tooth, which is median in position and firmly attached to an overlying plate of palatal cartilage. The laterally compressed, slitlike mouth is flanked by flaps of mucous membrane, which are continuations of the cephalic epidermis and fold into and line the oral cavity. Embedded in the mucous membrane on either side of the oral cavity are two longitudinal rows of seven to nine yellowishbrown, horny teeth, which are conical in shape and joined at their bases to form a tooth comb- When the lingual apparatus is retracted (Fig. 8.3, upper right), the tooth combs lie flat, and apices of their component denticles point inward and posteriorly. The lingual teeth of Myxine are firmly attached to a cartilaginols dental plate (FiE. 8.3), which is a troughlike structure of V-shaped cross section that lies just below the mucous membrane of the oral cavity. Its longitudinally keeled underside moves forward and backward in the grooved upper surface of a cartilaginous basal plate, which supports the floor of the mouth and is the rigid, immovable site of at_ tachment ofthe jaw muscles. Contraction of prolractor muscles attached, to its anterior end causes the dental plate to slide forward in the grooved upper surface of the basal plate. As it does so, its sides flatten and the rows of lingual teeth above it are raised, spread laterally, and eyerted from the mouth (Fig. 8.3, upper left). Dawson (1963) likens this sequence ofevents to the opening of a book. Contraction ofmuscles attached to the posterior end of the dental plate efects retraction of the plate, closing of the book, and approximation of the teeth in a grasping move_ ment. Repeated protraction and retraction of the lingual apparatus altemately spreads and approximates the rows of teeth and is effective in tearing food and conducting it into the mouth. During these ripping motions, the lone palatal tooth may serve as a gaff by impaling chunks of foodstuff and thereby keeping them from slipping out ofthe mouth during prorractive moyements ofthe dental plate. Individual lingual teeth of Myxine glutinosa (Fig. 8.4A) are complex structures made up of an outer horn cap separated by an epithelial layer from an inner cone that includes distinctive, goblet-shaped pokal cells.in the center of each tooth is a mesodermal pulp cavity. The base of the outer horny cap is embedded in a groove in the mucous membrane of the oral cavlty, except laterally, where it joins adjacent teeth. Dawson (1963) notes that several authors believe that growth of the horn cap takes place by cell division and keratinization in this basal groove. Cells in the epithelial layer between the apex ofthe horn cap and that ofthe inner pokal-cell cone appear pl/.led. apart, as if they had been stretched between a horn cap that giew more rapidly than the underlying pokal-cell cone. The latter, composed ofwhite, opaque, resilient ectodermal cells, is peculiar to the Myxinoidea and surrounds a small pulp, which contains blood vessels and nerve fibers. Various authors have speculated that the pokal-cell cone might be a replacementooth, Fig Myxine glutrroja. Top two views show venrral side of head, with lingual apparatus extended (left) retracted (dght). and central and bottom figures are tralsverse and sagittal sections -of t}re rieao to strow musculature erem'enti a.j ofthe lingual ' apparatus. Rledrawn from oa*son fts65i_

187 -epul pedoleêp uaeq eêq lqalllj sed,{l eseql Jo sosnlpredde leql Euncedsns ul ( 961) uos/(ieq ûejo urof l (elnper u?tsn oul 3ql pu sâjd -urel D1 p) SurdseJ lno-pue-ul pu? :(arl rxtl4j el?) Surdsert l"ret l :AuI^leqJ u^loppue-dn-pooj lsoeur,(ys1zrur11n pu? 'dser 'pejqs 'J?el ol peu?rsap sqej?dde l?cjnq D ur uorlc? Jo sad,{l,(le{i aelql,{[uo oj? areql'esjnmjo JerlunC 'st?iluec s" Palelfuel -ur eq lqaru leql uoisej peoq eql ur Buqlûe se^reserd sueurceds snojejruoqj"j qs4locs oql Jo pelresejd lsoq aql Jou uaurlreds ueu -nlrs u?3uetlly eql Jeqlou 1nq 'snouaselq:zc ueeq oêq pfoqs r{c[q/'\ 's^?l ug s? pelartual -ur ueeq eêq leq/(jo puj rouolsod 3ql t? suors -sejdrrrr a^rasard sueulcods qslllocs aql Jo o.{! 'sr l?qj Jeqlre 'uou?aresojd Jo sepnlrssrol^ aql ol lsnf elq4nql4l? sr stt{l 1?q1 ojns os lou Iue I'aulxtw ur uoqcunj snteedde oql e)pul ol porrnbar er" teql saleld I s q pue 'IEluep 'l?13 qed snourselpec eqljo ec"jl,(u?{c?l '1?J snql peljelloc sluopouoo pe^jasard,(lelaldllioc lsotu eql aj? qcq^{ 'suoruroeds u?unlrs uecueruy pue qs41o3s aql'jeê \oh'u^\oqs eêrl (186I) 'le 1e qlrus pue (t86i) sfflug pue'fqrolq 'qtrrus 'eapupiv se 'stuopouoc Jo snlej?d -d? orteqdec eq1 Jo uodzlejfuotur 'pclueqceru Jo'IBuorlounJ JoJ Iepour SurnErIuI u? 'poap -ul 'q aulxtw Jo sv?jedd? IEnSuI oql Jo uod3" turdsera eprs-ot-oprs er{i socqlns Jotno JI3q1 ol JsltaLuE[ pezllejsuluj JÎSSJJJnS JO UOl',tlSOd -d? fq,(uoeoluo Suunp pebjelue osl? pus pezrl -uelcs fllnols eje^r qcrqnd 'slueuele luopouoc elelduroc rii u?djolunoj ou sr ojeql 'aulxtj;\[ Jo qleol Fntul eql ui euoc llac-p{od eqljo ocu?cr -Jrufis oql reêleq,t\ 'lueurdoloêp Jo epour ui ',{IqeunseJd'pu? arnpruls I?uJelur ui secuejej -Jrp snolrqo pue punojojd or? ajeql lualrlelo luopouoc urojluoc e qtlt^ Dsou\ry8 autxth[ Jo qlool IEnEurt? er?dtuoo I t'8 '31{ ui.,'ojiijo epour cdrs"ftd e ot uo-rleld?pe pn -pr^rpur ue ar? feqllpqlpu? qte peulcpc pue qleel osoql uee^feq uoqjeuuoc apeuesol^qd ou sl ereqt l?ql,{lql lsolu si li ' ' ',, l"ql8upou Kq qlp,et auutw lo uorssncslp Jsq sezueulums ( 96I) uos^\bc'ur uec IIE l3 lou sl sql lnq 1I/6I) rure on pu" rollntr l ruojd uonces leulpnl uol ui osl"'luopouoo ejo lueuela urrojruoc lecrd^j (g) 1 961) uos.rec (uo{ uoqces l ulpnrlfuolldl austtll Jo rllool FnBurI (V) 't'8't!d v Art^s? dlnd esojnut tejo- VJNOCONOJ IIHJ 08r

188 THE PHYLUM CONODONTA l8l pendently many times. If so, similarity in mechanical action, even if real, may not imply very much about biologic afiniries Summary offeaturcs indicating chordate qlfinities (1982) from the basal plate of several Middle Ordovician elernents from Siberia, it should be In summary. evidence taken by previous authors to suggest chordate (or vertebrate) affiriparable parts of any of the conodont elemeqts noted that no such features were noted in cornties for conodonts consists of (l) similarity in studied by owig (195t), Gross (1954), Miiller chemical composition of conodont elements and Nogami (1971), or in the closely similar elements of Archaeognathus rccently analyzed in and the mineralized tissues of yertebrates; (2) the shapes ofconodont elements, which suggest detail by Klapper and Bergstrtim (1984). The that they functioned as teeth or jaws; (3) the affinities of Coleodus, to which the Siberian presence within the basal plates of several Siberian Ordovician specimens of structures among conodonts; and the Siberian fossils are specimens have been assigned, are unknown such as those that characterize vertebrate bone; diferent enough from the tlpe of Coleodus to (4) tlte chevron-shaped impressions in the posterior half of seyeral Scottish Carboniferous lication. In short, the features noted by Barskov raise at least modest doubt about their identi- specimens, which have been interpreted to be and his coauthors may indicate that the basal myotomes comparable to those of Branchiostoma (:Amphiorus); and (5) imptied similar- them are bone. But it is not entirely clear that plates of the specimens in which they found ity of function between lhe cephalic apparatus the specimens are conodont elements! Nor of conodonts and the lingual apparatus of have those features been seen in the basal Myxine and. other hagfishes. plates of elements representing other species. With respect to compositional similarity, it Orvig (1951) noted that some ofthe conodont has been noted repeatedly that phosphate elements in his collection from the Silurian of mineralization is widespread within the animal Estonia and the middle Devonian ofohio have kingdom and hence is not, ofitsell evidence of "a base consisting ofa substance which differs anything more than an enzymatic system that... frorn... material of the tooth-like cusps... has not been completely modified to permit accumulation ofcarbonate minerals. Note, in this any kind of bone tissue." He also pointed out but in this substance one is not concerned with regard, the recent determination by Tillier and that the Middle Ordovician Harding Sandstone Cuif(1986) that the buccal elements of certain of Colorado, which yields elements of Coleodus aplacophoran and scaphopodan mollusks are phosphatic. With respecto shape, I need only point out that teeth, grasping spines, copulatory hooklets, and the like, have similar shapes in whatever animal body they are formed because those are the shapes that do the job, not because all organisms with teeth, grasping spines, and copulatory hooklets are closely related. In addition to those formed in various ways by diferent groups ofchordates, structurcs that are similar to chordate teeth in form and function are found in distantly related groups such as mollusks, arthropods, trematodes, nemertineans, gnathostomulids, and chaetognaths. It is thus no surpnse that someone, sometime, has considered one or another ofthose groups as either the repository for the Conodonta or its sister group. Without in any way minimizing the possible signilicance of the bonelike features reported by Barskov, Moskalenko, and Starostina and a great variety ofother types ofconodonts, also yields specimens assigned to the ostmcoderms Astraspis and. Eriptychius that exhibit practically all the types ofhard tissue known in vertebrates. To my mind, this statement is significant because it suggests that conodont elements with superficially bonelike materials a1 the base and specimens composed of real bone occur in collections from the same beds and that tbey may be readily distinguished by one with a trained eye. Finally, anyone familiar with the elegant illustration of Myxine glutinosa in Miiller's (1836) famous monograph on the hagfishes (Fig. 8.2) is bound to be struck by the many features that seem to be shared with the best Dreserved of lhe Scottish Carboniferousoecimens

189 -ur prerl sllll 1"q^{ pue 'paj?druoc uaeq,tfour -(uoc e?q qslq r qlu{\ sdnoje olepjoqc 0q1 Jo senl"ej êrll lbrluosse {rq sluauele plel3{s Jreql 'sseuenbun Jreql azs?qdue u"ql ejorrr elll{ auop seq esle Suqleuos sluopouoc olelu ol Eurfu Jo.funluac e ueqt ajorll Jouq ui (EJaocoqcu^qU oql ueê Jo '?Trtrld uepodorgue oqljo euo '?lelulep -ourqcg eqt ''3'o) IUBJ urnl^qd Jo sdnoj8 reqlo olur seprs IeJe es uo puelq lnq 'eper8..elep -rogt,, aqt Jo lueu;^jrqje luapujdapur ploj - seûeluesajdej Eur rt osoq^r salelqel -r0^ ^?ur pue selerqofoûr Jo uo4erapejuoc ibpqs B usql ejoru ou,{lqrssod sr 4epJoqJ olq?je -ua^ 0rl1 ueê t3q1 pelsoetns ueeq saurl IeJeAes seq U puy 'sdnoj8 qcns eq osl? l{eru slelnuo] pu? spuolllurol eql pu? 'o^r^rns ol pelrsj leqt (iluopauq ejdua u" ueô ro 'q^qd) sopbja puo4?zluesro l?uoqrppe luesejdej peelsur f,"ru 'sa^rlpluosejdej SurAI[ qlhr?l,4r{d l"ulrue Prcôs Ol uonclûoc SnOhqO lnoqlr,h peuals -s? ueeq e ri qcrqnd 'seunej ed^l-ejejerpe Jo slequreur euszrq eql 13q1 ( g6l,leqcqros),{lluajor pelse8llns uaaq sbq 1I u?uqur?j eql a r Jns ot polej '"qt?,{roeeqcjv eql 'sjep"j?qj u"u?pruc ^lluophe pu? uelejuodjo uorleurq -I'uoc SulsnJuoc p qlr^\ dnolt laôl-ujnl^qd euo N?el 1? lbrll pu? :"I^qd Euorue uoê uol4ezrldeb Jo uourunf psrop pedpqs- ro ernlelnosnur -Jo Jo sepat ere ejoql t?ql :seurlt Jo requrnu e I?4ue^-osrop Ieues eql tuesejdsj lq8ru,{oql.{fuepuodspur peqceel uoq?zruebro Jo ap?j8 e 'petsoe:lns eêq (9861) JrnJ pu? rertll s? 'ro sr..podorqu",, l?qt (.tlqeuojruocun teq^\ouos 'eleproqj eqrjo dnor relsrs eq1 se (rl6i'r2ur lroql?) sepr oqlqly( e q ol peru"el eêq ea\ 1ll,t : Z6I 'euelrejc?y.{ :/88I ' 88I 'lqcerqnh 'sjo^rllns eql sel?jedes,r\ou qcrqa\ l?ql "3'a) sroqlne snojeurnu,{q pesodord ueeq s?q ueql sssl qcnur ueaq a^?q,(?ur sop?re esor{l l"ql selejqeueûr al"uroleocejo dnors '(gi 8 uaolyqeq..ecublsrp clurouoxsl,, eql leql pue 'ErC) sueauruoueu " Jo tne oql uro4 qcu?jq 'pelrlrns oêq uerp lno peul sep"jt l"uorlez lsql ef rue^lp snojerfinu er{l Jo esoql eq -ruz8ro qcns elou,{ubur OJOÎ gjeql uorlerpel e^t se lsnflr{8ruj suorssejdun pedeqs-a pal"od u?oz?lerr Jo crozoel?d -ej agl leql '(uortrrûoc snouos lnoqlr^\ -erd elq aql ui êp,(eq leql aq 1q3nu,{er^ ^ljee-ueuquec elsruelp ue lnq) ^lleues aldur?xe JoJ 'lruqns I'ecueprê e^ncof 'Je,\e,,AoH'u?rcrôplo eqljo alppru aql lnoq" -qo s? elq?ldecj" lou sr uou"lejfualur ue '(Jel ecurs (popejlqns ro) pepp? ueoq seq euou l?iu srql uo al$",r\,{jarns'986i''i" re etpgply pu? orozoapd eql ur Jo ueuquerejd eql pu?) saurolo.(u se pogquopr ej? uelu ui elq esoj? elfqd se fepot ^lj?e ezrutooer a^\ sap?ja -Iceds Jellel eql ur suorssajdrur ^lpeuoc ped?qs- erll I?UOrlEzrueSJo Jof?u aql Jo lsoru lpql uod Jr uoê l"ql purlli ur dee{ osl" lsnru euo 'JeAe -Jrûos pelels-uauo oql [q '^llueprô 'pepm8 -,'AoH ueurrceds qs4loos aq1jo JI"q Joualsod ' I,{qd elaqaloûr oql Jo Jeqlou? lo euo otur el{l rn suorssojdru poderls-a etft pue aurxtw Jo el"pjoqj eql otw sluopouoj eql Jnls ol Jo seuolo,(lu ped?qs-a eqt use.&loq &uell 8ulful uooq el?q e/r{,funluoc e ueql ojorrr Jog -ujrs oql fq lcruls,{lelns sr euo '(epr,4a ruc z pue Auol rlrc 0 tnoqe s auutj,i I?crd& E) parou!oûg.rj's'8 'qlee1 Jo 'seuroloûr'proqcolou Jo?J"Jl.{ue qc?[ IrssoJ ter{l qanogl uoê '(986I) rahu"i pu" pun'i,q pequcsop f,iluecoj IIssoJ aql ur u^roqs sernl?ej lueuruojd êjdu?l lsoru aql oje seqcnod U eql Jo slueursle 'Jo s^\oh 'Ielluelod uo4e^josojd 1(ol,fue^ 3 oêq sejnl"ej qcns? 'ejns eq oi 'el"proqj aql o1 -rsnqtua pu",(ie^rlrsod os poue$s? ore ^ljbcrls" sluopo -uoj ejojeq seuo ueunlrs uscueurv Jo qsnlocs eql se qcns sueurceds ur peguuepr eq plnorls sel"proqc W sagrd& l"ql (ErJs Ilrt 'proo e^reu I?srop 'pjoqcolou) semleoj oqljo euo 1se0l lejo uonejrpur lcojlpur SuoJls Jo 'ejuepr^ e^rlrsod flemg 'sreqlo,tq tsol ro pagrporx uoaq -d? e^?q tnq sol?progc,(u?ur ^lluered ^q soojaep snor -JeA ot podoleêp eje 'e{i eqt pue 'sruals/k aull -Pretq 'se/(e Feurd perred 'seurolo,(ur se q3ns 'sernl"ej Jeqlo ',(poq cruo,tuquro aqljo gjejjns I"sJop aql Jo EuploJur,{q sdoleêp lsql ruel -s^s sno^jeu J"lnqnl Ale^qrurlsrp E pue '(..stqs t3,,) suelc poeu.,tueqd Jo seues e 'proqcolou? eêq selepjoqc 'ûasoluo reql ur reqlou" ro e8els ouo lv eleproqc oql elrun sejnt"oj Jrs?q aejqt lsqt pullu ur dee{ plnoqs euo ',(ll?nl'cv '$lsn[ioiu uejoqdoc?ld? Jo sefcrds lerruep Jo sles -Er sr JIRrs JI '( 86 t) 'le lr sfflug ^q pelulsnlll YJ,NO(IONO] 3HJ z8r

190 THE PHYLUM CONODONTA 183 formation we have on soft-part anatomy Branson, E. B., and Mehl, M. G. (1933). Conodont Studies No. l. Univ. Missouri Studies t, speaks to us in several tongues. Thus, I am comfortable in considering the Conodonta an Briggs, D. extinct phylum E. G., Clarkson, E. N. K., and Aldridge, of small. solitary marine animals, with compressed or depressed vermifom 16,t-14. R. J. (1983). The conodont aqimal Lethaia bodies that were soft except for a variously differentiated assemblage of phosphatized epithe- Klapper, G., Austin, R. L., Rhodes, F. H. T., Ctark, D. L., Sweet, W. C., Bergstriim, S. M., lial elements in the cephalic lobe. Mtiller, The elements K. J., Zieg)er, W., Lindstriim, M., Miller, J. F., and Harris, A. G. (1981). Conodonta. Pt. W, Suppl. 2 il Trcatise on Inverte- by which conodonts are represented in the fossil record may have functioned as grasping brate Paleontology (ed. R. A. Robison), Geol. spines and buccal or pharyngeal teeth. And the Soc. America and Univ. Kansas, 202 pp. cosmopolitan and broadly facies-independentconway-morris, S. (1976). A new Cambrian lophophorate distribution ofmany speciesuggests they were from the Burgess Shale of British Columbia. Palaeontology pelagic 19, animals, probably nektonic, although Dawson, J. A. (1963). The oral cavity, the'jaws' others, of more limited distribution and facies and the horny teeth of Myxine glutinosa. Pp. dependence, may have been nektobenthic or il The Biology of Myxlze (ed. A. Brodal and R. Fange). Universitetsforlaget, Oslo. even benthic. Conodonts were probably a minor phylum. never parlicularly Dubois, E. conspicuous P. (1943). Evidence on th nature of conodonts. components of Paleozoic or Triassic marine "L Pal Ellison, S. P., Jr. (1944). The composition ofconodonts. J. Pal. le, faunas. Their ultimate extinction at the end of the Triassic was probably the cumulative result Gross, W. (1954). Zur Conodonten-Frage.,Serrckenbergiana Lethaea 35, of a long decline through the Carboniferous and Permian and a gradual reduction in genomic diversity. In spite of their probable rarity Harley, J. (1861). On the Ludlow bone-bed and its crustacean remains. Q. L Geol, Soc. London 11, in Paleozoic and Triassic seas, conodonts are abundant and common as fossils right up to the top ofthe Triassic, probably because they were blessed with heala, chemically resistant skeletal elements that provided them a place in posterity denied to other less suitably endowed groups. Hubrecht, A. A. W. (1883). On the ancestral form References of the chordate. Q. J. Microsc. Soc. 23, Aldridge, R. J., Briggs, D. E. c., Clarkson, E. N. - (1887). The relation of the Nemertea to K. and Smith, M. P. (1986). The amnities of the Vertebrata. Q. J. Microsc. Sci.21, conodonts-new evidence from the Carboniferous of Edinburgh, ScotLand. Lethaia 19, -l 4. helminthes and Rhynchocoela-The acoelo- Hyman, L. H. (1951). The Invertebrqtes: Plqty- Aldridge, R. J., Srnith, M. P., Norby, R. D., and mate Bilateria.y.lL Mc Graw-Hill. New York. Briggs, D. E. G. (1987). The architecture and 550 pp. function of Carboniferous polygnathacean conodont apparatuses. Pp in Palaeobiology mate Groups. V. 5. Mc Graw-Hill, Ne\ry York, - (1959). The Invertebrates: Smaller Coelo- of Conodonts (ed. R. J. Aldridge). Ellis Horwood, Chichester, 180 pp. James, U. P. (1884). On conodonts and fossil an- 783 pp. Barskov, I. S., Moskalenko, T. A., and Starostina, nelidjaws. Cincinnati Soc. NaL Hist. J L. P. (1982). NorTe dokazatel'stva prinadlezhnosti konodontoforid k pozvonochnym. Pal Jefferies, R. P. S. (1986). The Ancestry ofthe Ver Zhur. 19E2, [English translation in Paleontologicalournal 1982, pp. tebrates. Carnbidge Univ. Press, Cambridge, Bengtson, S. (1976). The structure of some Mid- Kirk, S. R. (1929). Conodonts associated with rhe dle Carnbrian conodonts, and the early evolution of conodont structure and function. Iethaia 7, s2. Hass, W. H., and Lindberg, M. L. (1946). Orientation of crystal units ofconodonts. J. Pal.20, Hinde, G. J. (1879). On conodonts from the Chazy and Cincinnati group of the Cambro-Silurian, and from the Hamilton and Geneseeshale divisions ofthe Deyonian in Canada and the United States. 0. "/. Geol. Soc. London 35, Ordovician fish fauna of Colorado-A prelimrnary roe. Am. J. Sci. Ser. 5, 18(108), Klapper, G., and Bergstriim, S. M. (1984). The

191 .9 I_801,9I,.I)I.sfrld_.rel{ 'reqstun4rs ''ss!11 'pdlv.tutdg.uetuopo -uoc reqll (9881)' 'f 'uogou pub.v.),telrz '299-t99 'lgl uopuo7 'Jos pae.,srsn 7 our,, ueuq -rubj[ij?ejo uorssncslq.a,uosleqco^ 19/6I) -I ' 9 -lzt,' 6,' o1 r'selejqaue^ eql ây Jo srolsecq elqrssod pu? seurleuren (tf6l) N g TooZ toj pjeue8 ur salejqoue leaol 'ralunr/t\ Jo s3nss4 ^Dlty pj?q eql uo s{&ruej qlr r.uololels 'dd 9 'zl -opue eqj :J 'sqcuhqousqe 'Uv '89 'Jotd 'sny[ '1"1I lrssoj pu suuep S'n serceds u"rddrssrs -oceld Jo sednts cfolotslh 'fi961) soa 'tuug -sii I pu? u?ruoêq u?cueluv Jo suo4ducsep 'gb-tt 'Z'U'7 'tde['taung pad otqo'seqsv qlr/a 'sluopouoc'slrssoj elrnlool sqljo uollscg -Fs"Ic V (9261)'S U 'rolss"g pu?..g,qculn IrssoJ Jo suo4ducseo (9rgT).S.f,,{roq^\aN O '88-l '8 'lgjeull^l 'loed'res 'at9-lz9'll 'ras 0 srr"d '!rs pdsv 'tjs JDI 'UaI4[ 'ueluopouoc ^tun optx Jop n?qurej 'U, ioroqdojqdv snbsnllo^ un l-lse atuopo -uoc-puru?..i{9g6l) 'd-f uep Jeqn '(116l) 'I 'rureson pue Jmc pup.s.reltttl ''f )'rellnl/{ 'dd 0ZI 'ulfeg 'l'uapnuutw ' '9S?2d sluopo Dp atwotduv apuaqrqqn/1 (9 8t).f,rotInI/,I -uocolojd u?uquec tuorus pezrusoc seurds Surds?-f ql?u?ola?qc.h,qs,neu?zs 98-8t'II 1Z96 I ) 'g'rel 'uopuot 'JoS tog suo.u ' tld 'ysn 'z9z-9zz'6210d 'ursuojsrl\ Jo u"unlrs Je^ro.I 3r$ urorj 4orq 7'opejoloCJo (u?rcrôpro alppq^d uorfrrroc po^resejd,([?uolderrc /t\eu SurpreH eqt ruo{ sluopouoc (956I.J.A\,lee^\S V (qsg6l) - ) 'dd 081 'retsaqcrqc 'pooûoh slllg (e8puplv.f.lll_gtl.gzz ua?25 'elorq porpoq-gos ueunlrs 'l 'pa) V (?S86I).I yop siuopouoj lo tsoptqoaolod ui t0 I - I 6 -uessenlx pu? 'C A O 's8'ilug'c 'dd 'sluopouoc.(i,cf{li I pquopojepued Jo ejnpelrqcj? 'dd ISt snlej"dde aql pue 'VSn 'ursuocsrd\ Jo u"unj 5lroi 'uel\utcbw'unap4 -ad ^\an Io -rs re^\ol eql uo{ nnos aql l urue luopouoj saqsll GZ6i 'I{ 'f 'eu?lr Jc"J I V'0961) 'zsg-lr9'g)6r 'I'U 'e8pupmu ''9 A C 's33ug,d.i^t,qrrus.torgoac(.5gg,91 V'S'n) eusluoj l 'qolno reegjo (u u staots -nru N) snojojruoqjbc Je^ro.I 0q1 uo{t,{ejd otd 14!4\ sljd4sqy ''wv 'Jos Tort suoqcun -lii?l puojes V (9961) d 'rerûef pue ' U 'pun I -xe ueoz?teur u?uqu?cerd ( g6l) 'v 'Jeqcqres 'v99-899'0t'lod 'r ' '9t 7rd sluopouor roj ppour Aspodols?8 stuopouoc erv (9 61) 'D'C 'isuroo.i c oloce uv '(116l)'J l!\ 'teelrrs pub 'C 'uoppes 'It 'sst-gtt,g.sluopouoc I reo"d 72d 7 aqljo 'cads Ecueruv 'cos 'Ioog (sepoqu sdrqsuorteler lecraolooz eqj (t 61).A\.H,ltocs.J.C.pe) H {SoloozoalDd tuopouoc q 'z9n-6w'62 Z0l-99 dd 'sluopo i{aur Trt8lsluoPouoc eqljo -uot Jo sertlulge eql uo '(tr6l) 'w 'rrrqrlspun seuruub l?c otooz eql (ts6i) 'I 'I{ 'J 'sepoqd '916-6t6'@)BS.dd IoJ 'I 's?4erqel 16.Bnqea@d ts -re^ Pu? sluopouoc ol suollslej slr pup sn {12.3 ''ss!a 'pryv 73?aot 'stuaureuje noc ueqjsrl -oadq)tv FssoJ uercrôpjo ayppr1,r1 cqeur8rue lsq-qrsrssru Jep stiie$^s ueqcsunlrs sep oqjsrc uelssoj rep erqdatouol l (9SgI) 'H 'J 'repu?d 'dd E9t 'q3.,nqulpg 5lcelg pub sru?pv 'suotpp.t lortsol -oa8 JDtlt puo slou uo putua Io [,nwu,ms p -ua6ts D.to 4SoloiuoaDtDd (OggD pre\ce{,ue,ro nsn-tz,e '(dz YINOCONOJ 3HJ t8r

192 APPENDIX A. A SUMMARY CLASSIFICATION OF THE CONODONTA Phylum Conodonta Pander, 1856 Class Car.idonti, new Order Proconodontida. new Family Proconodontidae Lindstr6m, t970 E o c o n o d o nt us Miller, 1980 Proconodontus Miller, 1969 Family Cordylodontidae Lindstriim, r970 Cambrooistodus Miller, I 980 Cordylodus Pzndet 1856 I apetognat hus Ianding, 982 Family Fryxellodontidae Miller, l98l Fryxel lodo ntus Miller, I 969 Family Pygodontidae Bergstriim, 198 I N er i c o dus Li'j.ds1'Jom, 955 Polonodus Dzik, 1976 Pygodus I-amont and Lindstriim, 1957 Order Belodellida, new Family Belodellidae Khodaleyich and Tschernich, 1973 B e I o d e I I a Ethi'lgtoll, 1959 Coe loc erodo ntus Ethington, 1959 Dvorakia Klapper and Barrick, 1983 Stoladus Lindstrdrn, 1955 Il a I I i s e r o dus Serpagh, 967 Family Ansellidae Fihraeus and Hunter, 1985 Ansella Firhtaeu;s and Hunter, Hamarodus Yiira, 1975 Family Dapsilodontidae, n w B es selodus AJdridge, 1982 Daps i lodus Cooper, 9-l 6 Class Conodonti Branson, 1938 Order Protopanderodontida, new Family Protopanderodontidae Lindsrrtim, 1970 G ly pt o c o nus KenJc,dy, 1980 M onocost odus M.rller, 1980 O neot odus Lindstriim, I 955 Parutahconus Landing, 1982 Pr ot opanderodus Llndstriim, I 97 I 2 Pseudooneotodus Drygant, 1974 Scabbarde I Ia Orchard, I 980 Se miaconti odus Miller, I 969 Stauferella Sweet, Thompson, and Satterfield, Strachanognat hus Rhodes, 1955 Teridontus Miller, 1980 Tropodus Kennedy, 1980 Utahconus Miller Vaiabiloconus Landing, Bames, and Stevens Family Clavohamulidae Lindstrdm, t970 C lav ohamulus Fumish, 938 H i r s ut o d o nt u s Mjlle\ 969 S eftat ognat hus I-fJe, 970? Paraserratognat hzs Yang, 1986 Family Acanthodontidae Lindstrtim, t970 Acant hodus Fu;mish, 938 C o r nu odus F ahrircrs, 966 D repanodus P ander, 1856 P arapal todus Stov$e, 1984 Scalpellodus Dzik, 1976 U lric hodina Furnish, 938 Family Drepanoistodontidae Fihraeus and Nowlan, 1978 D repanoist odus Lindstrdm, I 97 I Paltodus Pande\ 1856 P aroistodus Lindstrttm, I 97 I Order Panderodontida, new Family Panderodontidae Lindslriim, r9'10 B e I o di na EthilJigton, 959 Culumbodina Moskalenko, 1973 N e o p an d er o dus Ziegler and Lindstrtim, 1971 Panderodus Ethinglon, 1959 Parabelodi na Sweet, 9'l 9 P arapanderodus Stouge, I 984 P legagnathus Ethington and Fumish, 1959 P s eudobe lodina Sweet, 1979

193 Z86I '4r"I I pu? ^qdrnw DlltI ve6l 'IqoI I pue uosu?rg snqpusolddy 926 J'relss?g e?prugporuoud,{yrueg gl6l.{rzq uoporttoltg 61 lqot{ pue uosuerg snpowst.tg EE6I '1tIoI I pu? uosu?rg snqpusoqn)i E 6I 'lqew pup uosu"rg snqpu&o.tlq) tt6l 'tqetl pue uosuprg eepqleueojtlc,{lrulec Jeplo ^\au'?prurporuolrd El6l 'AurppeH uopohad I t6 I'ruo.rlspurl rutpaltdz on n 0L6I'ruoJlspurl e?pnuopouod 196l,uosueJg ^lrluej pu" 'HeI I 'uosuerg snqpusopldltly V L6 l' rlgedjes, snltdusouaol lsbd g t/61.sraqlo pue rllo.nstuag szry pusttpdldddv T86I 'tuo4spur.i eepql?ueoprdqu t[6i ÎrueC 1qo],,r{ pu? uosuujg snpousdtqd s 6 T'reJnels ralpotud{.l g L 696I'sssH s?prluopohou^j,(lrurec Eg6l,uV snpouoqssuojl S E6t' renljp.ls, npo uldtr S I t6l' l JJnels, Du tpo I Jal d (sluetuale d elsuused qlia\ sorceds roj snuat ^{ou)..snqqu3oplldy,,,{au'eeprupotcald,tlrui?c fs96i 'srjjeh pue srjj?h snpo\uozdald z86r 'Ir?lJ pu? uofurqle snporuoudzjdd 9961 'sr.rreh pu" sureh snpo$toupuloan 8 6I 'uosiinj ffpotslo! nr[ [t6t 1g0r l pu? uosubjg srt ryrru8ottq)ofia7 n96r 'sureh o?puuopotsrouflî,(iurdg S 6 I'reJnBrS er?rdusojvldlqod 996l' re\llell snqpusordldo g 86I 'uro4stueg sn WDuBDqDqo) I86I 'ulojlsajeq e?pql?uaoceld^lod,{ urpc 6t6I 's?uroql sn rywusstlapd z96 'relllt.l^l snpou)uan J 8t6I \qaw pu? uosuerg snpourl g/61,ôtaudr-i snqpu8otuv I.56I.JEIINW pue rollnn e?pnuopoucl AIIlu"C 6961 'lpu?c pu? sljec, utpojdpunpv Lr6l 'uosuejg pue uosuerg snpoluolsl(j zl6l <ejruq pue Iur.I snqfiusosstttoj I86I 'redd?i),i eepnuopoujolsro,,(fruej 086I 'rodded{ pue oual,n nxololdalg L L6l \ M?-)d-IV Dt uudruauuo s I /6I 'drtrqd pue reddela stopa4 ES6l 'sepoqjdo apou)j,reu'eepq1epouc1,{gureg L96l 'rejdlru){ ou ttuopo tsos 9961 leoas pu? urojls8jeg s lry tvu Sosap oqtr z86r 'seuj?g pub ue'ljejjain sntuopoxton 086I 'sauj?g pue 'uelaon ' u.)3e r)ciî snq I Du 3 t U J0 u.td g 9 L6t'l,:tz(I snpoxaflruoj I L6l 'urojtspur:1 snpowo og tt6r 'lqatral pue uosuag snwdusovdl ouy 656l 'sseh eeprgl"usoleg,tlnu?c 958 I' repued snpot uo r td S 6l IuuoJJ.sprdr-I snpol iao 5Z6I 'Jelsseg e?plluopoluoud (e861'ldy snpoqolunv ^[ru]q 'lcud t/6i 'qaetueg, snqtousoudnt z9 6l'srrJerl Dnapor I s t H I86I 'ulollsfuog e"urqleu?ouenf,{iiu JqnS 696 1' sn po d t tj ^\E\sperg 861 'uofurqlg pue Dlslodeu szpossoy,raeu'a?uquopodrja,(jrruz;qng e L6l'\s IJW snpoqortdotot ê d 9S8l '$pued ffipotslo vl6l 'l.rdjb1} ^ ue^ snpopuopo 0L6l 'ruo4spul'i 3?urluopolsro,(IuJeJqnS 016I'rrJoJtspur.I e"pquopolsro 9/6I.)[Izc?pDuoporuoud ^truec rsplo VJNOCONOJ AHI 98r

194 A SUMMARY CLASSIFICATION OF THE CONODONTA t87 Hibbardella Bassler, 1925 I dioprioniodus Glnnell, 1933 Kl adognat hus Rexroad, I 958 Oulodus Brarson and Mehl, 1933 Prio ni odina Bassler, 1925 Pristognathus Stone and Furnish, 1959? Ligo nodina Bassler, 1925? Lonc hodina Bassler, 1925 Fam ily Baclrognalhidae Lindstriim, t9'70 Bactrognathus Branson and Mehl, 194l Doliognathus Branson and Mehl, t94l Dollymae Hass, 1959 Eotaphrus Pierce and Langenheim, t97 4 E mbay s gnat hus Metcalfe, I 98 I Scaliognalhus Branson and Mehl, t94l Staurognat hus Branson and Mehl, 194l Family Ellisoniidae Clark, 1972 EllisoniaMij.ller, 1956 Furnishius Clark, 1959 G ladigondo I el Ia Miiller, I 962 Hadrodontina Staesche, I 964 Metillina Kozur and Mock, 1974 P ac hycladina Staesche, I 964 Sweelina Wardlaw and Collinson, 1986 Family Gondolellidae Lindstrdm, l9'10 CarinellaBt trov,1973 Cypridode I la Moshey 1968 E pigondo I el la Mosher I 968 Gondolella Statffer and Plummer, 1932 Misikella Kozur and Mock, 1974 Mosherella Kozur, 1972 Neogondolella Bender and Stoppel, r965 Neosp at hodus Mosher, I 968 Platyvillosus Clark, Sincavage, and Stone 1964 Pseudolurnishius van den Boogaard, 1966 Xaniognat hus Sweet, 1970 Order Ozarkodinida Dzik, 1976 Family Spathognathodontidae Hass, l9s9 Amydrotaxis Klapper and Murphy, 1980 Ancyrodella Ulich and Bassler, 1926 A ncyrode I loides Bishoff and Sannemann, 1958 Aphelognathus Branson, Mehl, and Branson, l95l B isp at hodus M.ilrlle4 962 E ognat hodus Phllip, 965 Lochriea Scott, 1942 Mehlina Y oungquist, 1945 Ozarkodina Branson and Mehl, 1933 Pa ndori nel I i na M;jller and Miiller, t95'l?" Plectodina" (new genus for specres without pastinate P elements) Polygnathoides Branson and Mehl, t933 P seudopolygnat hus Branson and Mehl, 1934 Rhachistognat hus Dunn, I 966 Scaphignathus Helms, 1959 Torlodus Weddige, 1977 Vogelgnathus Norby and Rexroad, 1985 Yaoxiano gnat hus An, 985 Family Kockelellidae Klapper, l98l A ncoradel I a W zlliser, 1964 Kocke I el la W alliser, 195'1 Family Pterospathodontidae Cooper, 1977 Apsidognalhus W alliser, 1964 Astropentagnat hus Mostler, 1967 Aulacognat hus Mostler, 1967 Carniodw Wallisel 1964 Jo hno gnat hus Mashkova, I 977 Pt er ospat hodus W alliser, I 964 Family Polygnathidae Bassler, 1925 Ancyrognal hus Branson and Mehl, 1934? A ncyro I epis Ziegle Polygnathus Hindq 879 Polylophodonta Branson and Mehl, t934 Family Palmatolepidae, new Klapperina l-ane, Miiller, and Ziegler,1979 Mesotaxis KlaEEer and Philip, 1972

195 6I 'lqol/{ pu? uosu?rg snuozoalalsl tt6l 'lqel l pu" uosuerg snpoap)oan 9S6l 'lsel;l.s snuoronwi. g6l 'lr{el\i pue uosuer[ s7tpozloj 8 6I 'uosrflnj snq pusoaor.ljtv tt6l 1qen pue uosu"rg ebprluopooloj u.rrou)lun ^lltu?d leplo 9 L6l 'ôe$lolv pu? snqldubrdtd'j ôlsuv LS6l goqcsrgsnrytdusotsary I86I 'sopoqd pue udsnv oeplqleueolsaw.[iiiuec w6l 'lqatral pue uosuag snqpusotr.lddj 6961 'ernlq pue uusnv 'sepo\[ snqpusotlod 696I'atnjc pu" u nsnv'sapoqg m 4 uu E o pt1 2 s L6r 'fieqcuw pue u4snv snqpusnqsotj g6l 'quo^\sauiioh pue srrjee flqpu8sn^d) 9/6I.IIAqCIIIÎ pue urtsr Snq pu8 ou I o JrtdoC L96l 'euy\ snqrdusoppv 186l 'sapoqu pue ur$nv e?pllleutsn^?j Z L6 l' ryzlj snqpu8 otaats ^lrued g L 6 l, mzo>l s ll tdu 3! a qd V Z L6l'. )4J lj snpoqtdu8 ofi at Foa N I L6l 'Jrrzo.) onajd.tdsi 916I 'pz?a-ruilttr"u pu" 'refsol I 'nzoa snq ousouotl 9g6 l' ralill sn[dusoudttouro H I L6l 'llural I pu" rnzo) snpoqpusoldte 986I'roue{ oeplqlbutolee,4rs,(iru?c vt 6I lqa4 pue uosuerli snpoudtuqqns L v96l 'qsrunc pu? psojxed snpoapulh 16['uu"Iueseeg s?mpqpv u6r 5lrelJ e?prluopoql"u8rqcuv ÎIueC z 6I 'roururnld pu? ra.un?ls sr,rporypusotda4s OL6l 'uunq snpoqpusoan t[6i 'qloarstulloh pue sure[ sapoxpdusorp J I 6t 'lleuun9 srp orlldusotpl 9961'r]!nq snpoqpusouq)ao 6I 'qiloastullloh pu? suj"h eepuuopoqt?u8orpl /(Fu?d 696 l' r.ieerz s-np otl td ub o I o t d gsgt 'repldp-d snpoqpu),neu'esprl.uopoqlbuo vn6l ÎIIu"C 'Iqol l pu" uosubrg Dllapouotldts r86l 'Sreqpues pue reltelz sflqtousoudqv 186l 'sopoqu pue uqsnv eeplql"usoplla,(lrurec 996 I' relaerz snq p u 3 o tp t w r S 9Z6r 'relss?g pu" rijuln sldappuldd VINOCONOJ :IHl, 88r

196 APPENDIX B. STRATIGRAPHIC RANGE CHARTS In charts on the next 14 pages I indicate the References slraligraphic ranges of 562 conodont species in Higgins, A. C., and Austin, R. L., editors (19E5). a biostratigaphic framework that includes 156 A Strutigraphkal Index of Conodonts. Ellis conodont-defined biozones and, in the Lower Horwood, Chicheste\ 263 W. and Upper Carboniferous, several intervals for Klapper, G., and Johnson, J. G. (1980). Endemism and dispenal of Devonian conodonts. "[ which there are currently no widely accepted conodont-biozonal schemes. In choosing which PaL 54(2), Klapper, G., arld Ziede\ W. (1979). Devonian of the nearly 5000 named conodont species to conodont biostratig.raphy. Spec. Papers in Poinclude in the following charts, I followed no Iqeont. 23, particular guidelines. By and large I have included species whose first and/or last occurphische Reichweite der wichtigsten Conodon- Kovacs, S., and Kozur, H. (1980). Stmtigarences define boundaries in the biozonal framework, and I haye omitted species with r0(2),4't-'18. ten (ohne Zahnreihenconodonten) der Mittelund Obertrias. Geol. Paliiont. Milt. Innsbruck exceptionally long ranges and/or poorly known I-ane, H. R., Sandberg, C. A., and Ziegler, W. or morphologically nondescript apparatuses. (1980). Taxonomy and phylogeny of some Representative specimens of many of the species included are illustrated in Chapter 5. Lower Carboniferous conodonts and preliminary standard post-siphonodella zonation. Geol. et Palaeont. 14, ll'l-168. I-ane, H. R., and Struka, J. J., (1974).I-ate Mississippian and early Pennsylvanian conodonts, Mark Kleffner, a doctoral student at The Ohio State University, generously abstracted information on the ranges of important Silurian spe- Spec. Paper 152, 144 pp- Arkansas and Oklahoma. Geol. Soc.America cies from the much more inclusive composite Ritter, S. M. (1986). Taxonomic revision and phylogeny of post-early Permian crisis bisseliwhitei Zone conodonts with comments on Late slandard section he has assembled by graphic means. In compiling other charts in this appendix I have supplemented my own records with 165. Paleozoic diversity. G eol et Palaeo nt. 20, information from sources listed below. Thus Wardlaw, B. R., and Collinson, J. W. (1986). Paleontology and deposition of the Phosphoria authors of those rcports must be credited for Formation. Contr. Geol. Univ. Wyoming 24(2), most of the hard work that went into building to the charts in which their data are used. Of course, they must also share some ofthe blame for any errors! le9

197 06t puo ria stivôrd.p.rpef,*ol ur serrods luopouoc uercrôpro pu" u uqu'j ele-j por""r". Jo "nau"d"t1jgfl5 sl Fril :_ i_i t s![: ifgio i-s-3-e-s snluopouoso)d sna eojd s paujolul tuosuejg xaa-sntec!pejpeno lilt F s, ir i t eeueq _suelpo!'s s S P- o- s!suauoqluew c-o !unuwoc snulpuv-epueuee t tuossnueef -epuejv 9râe'l -wnlloqelj I suojltllv e sonu!s = * es -od. d -R- -i 6 -q -t ^q e 3 F d _B -6-3 d": B* EtetuapopH,snsonxelJ_ d. st9uall^spuau! Paa/vS eleelncv sn lcepljpeno es9ajduoc $o o I t F It os -F+ ;l snlepun s!nua! 9UAnUUOC s!dsnc!laa snlsnqoa stpuejg suaojaa!e!azleqg S t

198 -;o; -: t9 3 S e-g ;6 gs s o *-.E 191

199 z6l 'socu!^ord epntrlefqfiq u?nhoplo ur serceds luopouqc palcelas Jo s38ueu.z ueqj g-.-e- _3_S 3 h\ -b -5 :- s6-'o RS -i'-d 6-a

200 tl tl S s t l{ I.S _t-*- ss 's*.: ^" *'s s e s t A s o o" { i { E 3 s E { 3 t E F a. Chart 3. Ranges ofselected Silurian conodont species.

201 b6i '(sa3od 3u plrd {a serjeds tuopouoc uewo^oo olppq^l pud ro,{oj pelrolas Jo so8ued.t IErIJ snjadsah oo re* i -;'-P-S-= [$-$$;:o 'i.:g; _i'f e! q$ 9tsu$lun3 eao s!^e9 ed l!'! ; -d snleclng <_Q_R i-s-$.$;c E, 5!etpu!, "#j1s$ suecstqao JI- F_$_i s $!6Jequo.to a_ 6. s nl elsoc4 e1 -snstaaul snuuojos i\ o si IF) $ ti o t$ tr n 5 S= I snlnted nj i snt etsoc =: ts 6A ll qi- $* e" $-d-g *t t t ; slle4snv snueuoxcox 7 stsue9us w sncjea 7 sryelspg n -tuuew.lah s!/!reds!o uapuoo $t t o ; T t ss n H st

202 -E Ss e B s!!f * 3 s - F-,3 33.i-4. il Q ar * - d-;-r re d E + 195

203 961 '(sa8dd tqsu puo ta sercods tuopouoj u?ruo^eo ele-j pepeles Jo sosueu 'S ubqc J_r_L F 1 w snc!4auwtrsv JJe $ ; >: de8 d sljenoueuj'cuv ; T to 7 IIT]R$;giB s I i 9. "ro1g ;t E s-$ g-r'j BJ Vun s i $$ q-f ',6:tds 1 Fts 7 - 'wd n w eprcajc ls^.s*d J q r s"d ; l P,E k 1 - eaptoquoqa n, 6' n r.i 1!Gl i_*: B ;ol q Fr11l B x. d s! ry ejaltubjew n ejat/(qce4 i n 7 - n 7 etalsod n esuedxj I t FE ltr st ; 1 n eleclnsoejd ;

204 -s- \ _ di- E-F s-e Bi e-9 s< h6 s* 6i-s { E- t q- s- - E- s $ s 0- T;: s s Ad. = Ancyrcdella Anc. = Ancytognalhus 8i. = Eispathodus Pan. = Pando nellina Pe. = Pelekysgnalhus Pgn. = Protognathodus Pn. = Palmatolepis Po. = Polygnathus Ps. : Pseudopolygna thus Py. = Polylophodonta { s d, S e l9'7

205 861 '(ta8dd llstt pud [al)serjjds luopouoj (uerddrssrssrl ) sn oral ruoqrej,{ FE3 pjjjljsjo sjbueu '9 ubqj *.o ep g-! -F-B- s,e $a R \-! 99 + id ;.6 elelnuuc'7 eltepouotldls = snqeuootstqceqa = ls qa snqteudilodopnosd = sd snqteuoitod = od snpoqleuootojd = u6d snqteuoojted =?ed eullleulopued = ued snqteuoojsahl = aw eelrrlcol = 01 snpoopulh : lh snpoqteu9 = ue sntleuoeplp = 7c snqleudsn^ec = snpotltds!8 = ^ec!8 snqteudoqceq = u6e o b -s -s-s' a S -9- S t F s' f d s : ^s l sauoz paztu6ocaa,{pp!/ti

206 t99

207 002 '(sa3od,tl3u puo {a tle$.uro'jj -so(l - WC :uololv = JV serreds luopouoc (uerue^llsuuod) snolejruoqje] ele-i pelceles Jo s.8ueu., UEqJ s lt).; s$ llll i_f_s_g o i S N t I I a Ll_ 3 0s. td LE 9ts 6l$ lsi 'Ra oo SS R* -x-* Si; SF g; d s -:- -8- d S a l_s iar is as snw!jd snlnutw -s4enuls snc!tlouwls ualsses snsonu/s uoddelx snxaauoc stsuoltqceno 3 \ B E x d o o(o N. o a, a o N o E * o T t tr = il 6 o si E tt Ft il B

208 tl re ts ij ie ig il l RA Fr.Rs 201

209 z0z 'sanods luopouoc u?[ured pepolos Jo setu9x 'g UErIJ u, \ I * t \! o $ tt t $t c s A.

210 s -* ṡ -8 E L tl l-l (5 s- 6 s- e _ 3 * Chrfi 9. Ranges of selected Triassic conodont species.

211 Index Absaroka sequ nce, 132, Acanthodontidae, 54, le5 Acanthodus, 54, l85, FiE. 5.7 Acodus, 6l "Acodtu," 60 Acontiodus,53 Adcarinal trough, 100 Adenticulate process, I 6 Adetognathus, 120, l2l, 122, 136, 137, 160, 16l, 163, 188, Fig. 5.s7 Aethotaxis, ll5,ll7,137,161, 164, I87, Fig Agnatha, 177 Alate g niculate coniform el ment, 16 Alat nongeniculate coniform element, 16 Alale ramiform element, 17 Albid (crowns), 13, 14,52 Alternognathus, 89,96, IO1, loe, 188, Fig pseudoslrigosus, 107, 108, Fig Ambalodus galerus,99 Ammocoete lawa, 177 Amoryhognathus, 63, 64,7l, 134, 156, 165, 186, Fig. 2.11,5.15 ordovicicus, 26 Afi p h ioxus. S ee B ruhc htostoma Amydrctaxis, 89, 93, 95, 99, 135, 187, Figs. 5.39, 5.40 Anchiglathodontacea, I I 7 Anchignarhodontidae, 90, 92, 1t 5, I17, 188 Ahchignathodus, l17 typicalis, ll7 Ancoradella,89, 93, 98, 187 ploeckehsis, 98 Ancyrodella, 89, 96, 106, 135, l4l, 187, Figs. 5.39,5.41 Ancyrodelloides, 89, 93, 95, 96, 98, 99, 106, 135, l4l, 187, Fiss. 5.39, 5.40 Ancyrognalhus, lo2, 187, FiE, 5.46 Ahcyrclepis, 187 Angulate pectiniform element, 2l Annelids, l7l, t72 Ansella,49,50, 167, 185, Fig 5.3 Ansellidae, 42, 49, 185 Anterior process, 16 Antler flysch trough, 157 Antognathus, 69, 10, 186 Apatognathus, 81, I16, 186, Fig Aphelognathus, 73,91,93, 134, 154, 155, 156, 187, Fig "Aphelognathus," 9l, 86 gigas,9l kimmsv/ickensis, 9l Aplacophora, 172, 173 Appalachignathus, 15, 16, 186, Fie Apparatuses, 38 laboration of, 142 reduction of, 143 Apsidognathus, 99, 187, Fig Archaeocyathida, 173, I82 Archeognathus, 123, l8l, 188, Fig Aschelminthes, 73 Ashlock Formation, 155 Aslraspis, l8l Astropentaghathus, 99, 187, Fig Altachment surfac.e, 40 Aulacognathus, 99, 187 Au lobodui, 186 Bactrognathidae, 83, 145, 156, 187 Bactrognathus, 83, 84, 136, 159, le1, Fig. 5,32 anchorarius, 84 excavatut, 84 hamatus,84 Balognathidae, 63, 64,1l,15, 144, 186 Balognalhus, 63 Baltoniodus,63, 64, 65, 186, Fig Baltoscandic Eovince, 167 Bars, 15, 16 Basal cavily, 13, 15, 40 Basal filling, 12 Basal pit, 13, 22 Basal plate, 179 Base, 13, 15 Belodella, 45, 49, 185, Fig. 5.3 B lodellida, 42, 45, 49, 133, 185 Belodellidae, 42, 49, 185 Belodi a,18,55,57, 58, 141, 185, Fig.5.10 calciprcminens, 57 comprcsso, 58 monilorcnsis, 58 Berys!rcemoghathus, 75, 76, 186, Fig.5.26 extensus,l6 Besselodus,50, 51, 185, Fig. 5.3 Bimembrate skeletal appalatus, 24 Bip nnate iamiform element, 18, 24 Bnksleldia, 65 Bisegminiscaphat pectiniform element, 22 Bispathodui, 89, 90,94,96,97, 136, l4l, 159, 187, Figs.5.39,5.41 aculealus, 96 biswthodus,96 spinulicostat s,96 stabilis,96,97, 109, I12, Fie utahensis, 96, 159 Blades, 15,

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213 INDEX 207 Distacodidae, 36 Distacodontacea, 41, 42, 5l Distacodontidae, 36, 5l Distacodus, 51,54 Distomodontidae, 67, 68,11, 134, l4l, 144, 167, 186 Distomo&rs, 66, 61, 68,1 l, 98, 186, Fie kentuckyensis, 61, 68 Diversity cycles, 130 firsr-order, 130, 132, 133 long-term, 130, 132, 133 second-order, 13 l, 133, l 40, 146 Dolabrate coniform elemcnt, l8 Dolabrate ramiform elemenl, 18, 24 Doliognathus, 83, 84, 136, 159, 187, Fig Do ytnae, 83, 136, 187 Drakes Formation, 154 Drcpanodus,54, 185, Fig. 5.? slrkttus,56 Drepanoistodontidae, 54, 185 Drepanoistodus, 54, 55, 59, 134, 57, 185, Fig. 5.8 sp. aff. suberectus, 23 Dvorakia, 45, 149, 185, Fig. 5.3 Echinodermata, 173, 182 Einfache Zahne, 15, 35 Element, I I Elictognathidae, 89, 96, 106, 136, 188 E lictoghathus, 106, 107 Elltsonia, 83,85, 86, 89, 137, 138, 139, 161, 163, 187, Fig.5.33 teichefti, Il7 ttiassica,86,87 Ellisoniidae, 83, 85, 142,166, 187 Embaysgnathus, 84, 18?, Fig Enanliognathus, 18, 83 Eobelodina,5T Eoconodontus, 46, 47, 185, Fig. 5.2 Eognathodus, 89, 93, 94,95, 96,91, 135, l4l,181, Fies.2.11,5.39, 5.41 sulcalus, 26,96 Eoneop oniod s,72 Eop I acog nat hus, 1 l, 72, 102, 43, 186, Fie Eotaphrus, 83, 136, 159, 187 Epigondolella, 87, l3'1,142,146, 187, Fig. 5.35,g/rkd, 81, 186, Fig divaricala, 8l Eriplychius, l8l Eismod s, 18,79,81, 134, 186, Frg quadridactylus, 79 Erratrcodon, 78, 79, 81, 85, 186, Fig.5.29 palu, 79 Euconodont element, 42 Euconodonts,4l Evolutionary index.,see Index ofevolutron Exoc ho gnot hus exwnsu-s, 68 Extensiform digyrate element, 18, 24 Fairview Formation, 155 Falcodus, lo4, 106, loj anguhts, lo7 Fibrous elements,?9, 81, 165 Fibrous struclure, 14 Flotant marsh, 164 Form taxonomy, 5, 35 Free blade, I13, ll7 Fryxellodontidae, 48, 185 Fryxellodontus, 48, 185, Fig. 5.2 Fumishinacea, 42 Furnishiut,85, 86, 138, 187, Fig Fus d cluster, 24, 3?, 41, l7l GamachighalhrLt, 64, 65, 67, 186, Fig Geniculate coniform element, 15, 16, 25 Germanic Province, 168 Gladigondolella, 87, 138, l8?, Fig meeki, 81 tjty?toconus, )J, l6)! frg. ).) quadruplicatus, 53 Gnathodontidae, 89, 95,96, lo9, ll2,i13, 135, l8e Gnathodus, 109, Ill,ll2, 136, 14l, 159, t88, Fig austi L lll bilineatus, IIO, I I t, 112, Fig anneifurmis, 109, Fig delicarus, 109, t1l, Fig.5.50 girtyi, l l l,137, Fig praebilineatu,s, lll p nctalus, lo9,i10, Fig semiglaber, 111, Fig texaws,lll,fit 5,50 typicus, 109, I10, Fig Gnathostomulids, 173 Gondolella, 81,88, 89, 137, 138, 142, 16I, 162, 163, 165, 166, 187, Fig navicula, 1'l Gondolellacea, 41, 42, 78 Gondolellidae, 78, 83, 87, 88, 89, 138,142,146, 166, 187 Gondwana glaciation, 134 Grant Irke Formation, 155 Grier Member (of Lexington Limestone), 155 Habit (ofconodon$), 148, 150 benthic, 152 nektobenthic, l5o, 152, 164 pelagic, 150, 152, 164 Hadrcdoatina,85, 86, 138, 187, Fig.5.33 Hadrcgnalhus,68, l4l sta rcgnathoides, 68 Hagfrsh. See Myxine Hamarcdus,49,50, 185, Fig. 5.3 Harding Sandstone, l?7 Hemichordata, 173 Heterochrony, 145 H ibbardella, 11, 8, 82, 84, 187, Frg angulata, 8l Hibbardellacea, 42, 7E Hindeodus,l15, l16, l17, l18, 120, 137, 139, I40, 159, 160, 16l, 164, 188 uassidenlatus, I 15, 116, Fig cr lstulus, 16, I l'1, Fig jufensis, I 17 minulus, li7

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215 INDEX Neogondolella, 87, 88, 137, 138, 142, 146, 187, Fig. bisselli, 131, 138 clorki, 137 mofiberye sis, 138 pfaed6te t, tt I Neomuhioistodus,2L, 72,73, 186, FiE 5.22 clypeus,73 Neopanderodus, 55, 57, 185 Neoptioniodus, 82,83 Neospathodus, 87, 137, 138, 142, le7, Fig Neostteptognathodus, ll7, ll9, 131,138, 188, Fig Neoteny, 146 Ne codl,ts,48,185 Neurodontiformes, 14, 36, 79, 81, 155 Noixodonlus,64, 186 Nongeniculate coniform elemenl, 15, 16 Nonh American Midcontinent Province, 167 Nonh Atlanric Provinc, 167 Nolhognathella, 104 Octimembrate apparatus, 64 Odo ntog tiphus, 28, l'l 3 omolius,173 Oelandodus, 61,185, Fig Oepikodut,63, 186, Fig Otrshore fauna, 165 Ohio Valley Province, 167 Oistodontidae, 42, 50, l4l, 186 Oistodontinae, 61, 186 Oistodus, 61, 186, Fig. 5- l3 Oneotodontidae, 52 OneotodtLt, 52, 53, 185, Fig.5.5 Origination-extinction ratio. See Index of evolution Ostracoderms, 176 Oulodw 18,81,154, 155, 156, l81,fie se atus,8l Outside shale, 161, 163 Ozarkodina, 91, 92,93, 95, 96, 98,99, l2o, 115, 142, 187, Figs. 5.38,5.39 abrupta,97 confluens,33 inclinata,92,94 murchisoni, 177 n. sp. of Bergstritm, 9l renscheideksis, 95 sannemana,96 se$,93,94,95,99 semialtemens,93, 106 tortilis, 37 Ozarkodinida, 42, 45, 75,89,90,lJ4,135, 140, l4l, 187 P position (or element), 24 Pa position (or element), 24, 30 Pachycladina, 85, 86, 138, 187, Fig Paedomorphosis, 145, 146 Palatal tooth, 179 Palmatodella, lo4 Palmatolepidae, 89, 102, 106, 135, 187 Palmatolepis, 102, 104, 105, 135, 136, 145, 188, Figs. 5.44,5.4',7 pe obata,105 rugosa, 105 rugosa ampla, 105 rugosa lrachyleru, 105 Itia gula s, lo5 PaLodus, 53,54, 185, Fig. 5.8 Pander, Christian Heinrich, 3 Pander Society, 7 Panderodontacea, 4l Panderodonlida, 42, 45, 55,56, l4l, 185 Panderodontidae, 56, 167, 185 Panderodus, 55, 57, 58, 59, l4l, 156, 167, 170, 185, Fig.5.9 berystrcerni,56, 58, 141 gr4cuts, zj, rte z.t sulcatus,5l unicostatus, 32, 57, Frg. 3.3 Pahdetulepis, lo5 Pandotinellina, 92,93, 95, 96, 107, 123, 136, 142, 59, l8?, Fis insita,93,96, l2l, 123 Parubelodiha,18, 55, 58, l4l, 185, Fig.5.l0 denticulata, 56, l4i Paruchtognathus, 79 Paraconodonta, 4l Paraconodontida, 41, 42, 45, 175 Paraconodonts, 28, 41, 42 Paragnalhodus, lll Parupaltodus, 54, 185 Parupandetudus, 55, 56, 185, Fig. 5.9 asymmetf icus, 56, 51 striatus, 56 Parapet, 109 Paruprioniodus, 73, 134, 186, Fie costalus,73, l4l Paraserutog nat hus, 185 Psroistodus,54, 55, 185, Fig. 5.8 horridus, 55 Porutahconus, 53, 185 Pastinate p ctiniform element, 2l Pastiniscaphate pectiniform element, 22 Patrcgnathus,96, 120,122, 136,I88, Fig Pb position (or element), 24, 30 Pectinat t eth, 19 Pectiniform elem nt, 15, 20, 24, 36 Peda s, 65, 66, 67, 68,7 L, 134,135,146, l86,fi& 5.18 lalialalus,7i Pelelcysgnathus, 60, 65, 65,69,70,71, 135, 136, l4l, 142, t46, t86,fie csakyi,lo inclinatus,70 index, 70, Il, l4l "Pelekysgnathus," 7o Peiodon, 18, 35, 16, 77, 156, 186, FLl acuteal4, to, t t Jlabellum, '17 gtanats,

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217 INDEX 2tl Rabeignathus, 117, I19, 188, Fig Radular teeth, 172 Ramiform element, 15, 16, 24 Rastrat element, 15, 18, 55, 57 Recapitulation, 145 Recurrent group, 39, 40, 4l Red River Province, 167 Rhachistognathus, 97, 136, 137, l4l, 187, Figs. 5.39, 5.41 Rhipidognathidae, 62,75, 99, 186 Rhrpidog4athu:, 15,16, 155, 156, 157, l86,figs.2.ll, 5.26 \ slmmetricttl;,l54 Rhodesognathui564, 134, 156, 186, Fig Rhynchocoela, 3l! 176, 182 Robtglicoslatus stiock (of Polygnalhus),99, 100, l0l Rossod s,53,60,61,133, 186, Fig Rostral ridge, 102 Rostrum, 102 Rotundacodina, 67, 68, 186, Fig.5.19 dubius,68,7l,146 S position (or element),24, 25, 30 Sa position (or element), 25 Sagiua, 41,174, l'l5 Sagittodohtina, 64, 67, t86, Fig.5.l5 Sannemannia, 65, 66, 186 pesanse s, 66 Sauk sequence, 132,133, 134 Sb position (or element), 25 Sc position (or element), 25 Scabbardella, 53, 185, Fig. 5.5 kaliognath s, 33,84, 159, 187 Scalpellodus, 54, 185, Fig. 5.7 Scandodus, 54 Scaphale attachment s!fiace, 15,22 Scaphignathus, 96, 107, 123, l4l, 187, Fig Schmidtognathus, 102, 104, 106, 135, 188, Fig Scolopodontidae, 52 Scolopodri, 53 gracilis,56 Sclttula, lo4 Scyphiodtu, 73,'14, 143, 186 primrs,74,fig Sd position (or element), 25 Secondary process, 21 Segminate pectiniform element, 22 sefitacon oaus, )2, )J, )o, t6), l.lg. ).) Septimembrate skeletal appamtus, 24 Serratognalhus, 53, 185, Fig. 5.6 Seximembrate sk letal apparatus, 24 Siphonodella, 89,96, 99, 106, 107, 108, 136, 188, Figs. 5.48,5.49 duplicala, 109 pruesulcata, 107, 108, 109 sulcato, 107, IO9 Siphonognathui, 106 Skeletal appararus, 23, 37, 38 Skeletal elemenl, 11 Solenogastres, 172, 173 Somites, 29, l7l Spathodus,ll5 Spathognathodontidae, 89, 90, 91, 94, 95, 96, 97, 106, tt2, t34, 116, t4t, 144, 167, t87 Spathognalhodtls,ll5 Spatula, I I? SlauflercL\a,53, 185, Fig. 5.5 Staurcghathla,83, 84, 136, 187, Fig Stellate pectiniform element, 21 Steptotaxis,65, 66, 186, Fig fumishi grotrp, l4l Steteocohtls, 123, 188, Fig Stolodus,49, 185, Fig. 5.3 Sttuchahoghath s, 185 Strcptognathodl,ts, ll4, ll5,137,146, 150, l6l, 163, 188, Fig. 5.52, 5.53 Subbryantodus, I 15, 116, 188 Survivorship curves, 139 Sweetina, 85, 137, 38, 187, Fig Sw erognathidae, 90, 92,96, ll2,ll7, 188 Sweetognathinae, I l7 Sweelognathus, 89, 117, l19, 137, 138, 188, Fig menilli, l19,131 whitei, IL9,l2O Symmetry, classes of, 25 Symmetry-tran$ition series, 22 Synpioniodina, lo4 Tanglewood Member (of Lexington Limestone), 155 Tangshanodus, 186 Taphrognalhus, l2o, 122, l88, Fle Tenraculata. See Lophophorata Teridonlidae, 52 Teridontus, 45, 52, 5!, 133,142, 157, 185, Fig. 5.5 Tertiopedate ramiform element, l7 Tethyan Prcvince, 168 Tippecanoe sequence, 132, 134 Tooth comb, 179 Tortodus,93,94, 187, Figs. 5.39, 5.41 Ttiangulodus, T2 Trichonodello, 11 2expansa,68 T gonodur,12 Trimembrate skeletal apparatus, 24 Tipodellus, IO5 Tripodontinae, 62, 186 Tripodus, 60,61, 62, 63,72,13,75, 133, 14l, 185, Fig. 5.t2 deltotus, '12 Trisegminiscaphate pectiniform element, 22 I ropodus, )5, lu), nrg. ).) complus,53 Truchercgnalhus, 79 True conodonts, 4l Ulrtchodina,54, 185, Fig. 5.? Unimembrate skeletal apparatus, 24 Utahfonus,53, 185, Fig. 5.5 "Utica" Shale, 155

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