Biology COMPARATIVE VERT. ANATOMY WEEK 4, Amniote Skeleton. Assignments. Learning Goals

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1 Biology COMPARATIVE VERT. ANATOMY WEEK 4, Amniote Skeleton Assignments Readings Kardong & Zalisko: 5: 47-52, Work Use my notes as a guide for what you should see & examine, but you must use the lab manual or text for explanatory information & supplementary images. You will be expected to know the terms used in my laboratory notes; use my notes as the guide for what to learn in Kardong & Zalisko. Participation Each team will present key features of 2 of these skeletons: cat, bird, lizard & alligator to another team. The TAs will show groups the special items: bat, penguin, and snake vertebrae. They will also explain how to ID the long ungulate bones. Coloring! Color code the black-white diagrams in your lab notes & these in Kardong & Zalisko: Fig pg. 57, 5.20 pg. 58, Fig pg. 64, & Box 5.2 pg. 65, to distinguish dermal bones: Dermatocranium (dermal bone) - red Quiz Yourself Test your knowledge using the unlabeled images in notes or links & the unlabeled diagrams in the Student Art section of Kardong & Salisko: Fig. 5.11, 5.13, 5.14, 5.19, 5.20, 5.22, & Quiz 4 Quiz 4 will be at the end of the lab on Thursday. Topics will be announced in class on Tuesday. Learning Goals 1. Know the Clades listed & their shared, derived features. 2. Know which skeletal elements are dermal vs endochondral in evolutionary origin. 3. Know the regionalization of the vertebral column & the function of each region: cervical, trunk (vs thoracic & lumbar regions), sacral & caudal. 4. Know these parts of anamniote vertebrae & their functions: centrum, pre & post-zygapophysis, neural spine, neural canal, transverse process, pre & post-zygapophysis, hemal canal & hemal spine. 5. Identify the shape of the centrum in different vertebrae: acoelous, procoelous or opisthocoelous. 6. Know these pectoral girdle bones: suprascapula, scapula, coracoid, clavicle & interclavicle. a. Identify the unique parts of the mammalian scapula: scapular spine, acromion process & coracoid process. b. Which of these bones are dermal vs endochondral in origin? 7. Know these pectoral limb bones: humerus, radius, ulna, carpals, metacarpals & phalanges. a. Identify the olecranon process on the ulna in mammals. 8. Know these pelvic girdle bones: ilium, ischium & pubis. In mammals, these 3 bones fuse into a single innominate in adults. 9. Know the pelvic limb bones: femur, patella, tibia, fibula, tarsals, metatarsals & phalanges. 10. Be able to identify individual (non-articulated) long bones of a variety of mammals: humerus, radius, ulna, femur, tibia & fibula. a. You won t need to know who a bone belongs to but you can suggest type of locomotion in some cases. 11. Know the foot posture terms used with mammals: plantigrade, digitigrade & unguligrade. Type of Material Strings of vertebrae or separate vertebrae Articulated, dry skeletons Individual bones or limbs Articulated wing display Specimens to Examine Varanid lizard, snake, bird, human, cat, dolphin, whale, misc. ungulates Iguana, Teiid lizard, alligator, birds, cat, rabbit, bat, opossum, human Alligator, seal, dolphin, many "ungulates", porcupine, human... Bat, penguin

2 Additional Information ALLIGATOR Savalli UM Vertebrate Anatomy: Alligator Skeleton. BIO 370, Vertebrate Zoology. Arizona State Univ. BATS Savalli UM Vertebrate Anatomy: Rat Skeleton. (+ dog, bat, more) BIO 370, Vertebrate Zoology. Arizona State Univ. Univ. of California - Berkeley, Museum of Paleontology Chiroptera: More on Morphology. Univ. of Edinburgh What do bats look like? BIRDS Univ. of Wisconsin La Crosse Lab 10: Tetrapod Vertebrates. Zoo Lab, Dept. of Biology - go to bird skeleton #28 Ksepka D March of the Fossil Penguins. A Map for Our Tour of the Penguin Skeleton Savalli UM Vertebrate Anatomy: Pigeon Skeleton. BIO 370, Vertebrate Zoology. Arizona State Univ. Shearwater.nl Seabird Osteology. Skullsite.com Bird Skull Collection. (includes many skeletons) CATS Heithaus, P Cat Anatomy Tutorial. Kenyon College. Univ. of Wisconsin La Crosse Lab 10: Tetrapod Vertebrates. Zoo Lab, Dept. of Biology - go to Cat skeleton #29 Perkins M Cat Skeletons. Bio 185: Diversity of Organisms. Orange Coast College. HUMANS or PRIMATES Kappleman J The eskeletons Project. Univ. of Texas, Austin. Loyola Univ. Med. Education Network Bone Box - Human skeleton. Strauss JA Skeletal System. Biol. 29. Human Anatomy. Penn State Univ. Savalli UM Vertebrate Anatomy: Hominid Skeletons. BIO 370, Vertebrate Zoology. Arizona State Univ. Wissmann P Photographs of the Human Skeleton. Santa Monica College. MISC. OTHER MAMMALS Articulated Equine Skeletons Photo Gallery. Myers P, et al Procyon lotor: Guadeloupe raccoon (skeleton, labeled) The Animal Diversity Web. Univ. of Wyoming Virtual Bison. Univ. of Kentucky Electronic Field Trip to a Horse Farm. College of Agriculture. &

3 Major Clades & Shared Derived Traits in Amniote Skeleton (Features in living taxa, observed in lab) Amniota Synapsida Sauropsida Mammalia Squamata Archosauria Theria Aves Metatheria Eutheria Squamata Crocodylia Aves (Opossum) (Human, cat ) (Snakes & Lizards) (Alligator) (Birds) Snakes: Zygosphene & zygantrum processes on vertebrae Theropoda: Heterocoelous centra in neck Furcula Aves: Keeled sternum Synsacrum Carpometacarpus Tibiotarsus Theria: Lose interclavicle Posterior coracoid a process on scapula Scapular spine Mammalia: Astragalus on top of calcaneus Tibio-tarsal ankle joint Rod-shaped ilium > 2 cervical vertebrae > 2 sacral vertebrae Posterior coracoid added

4 Introduction In living amniotes, the centrum is solid, but it may have a curved surface to articulate with anterior/posterior vertebrae. The procoelous centrum is concave on anterior side of centrum & the opisthocoelous centrum is concave on posterior side. These designs give equivalent flexibility to the vertebral column, and both designs may be found in Lepidosaurs & Archosaurs. Heterocoelous centra are saddle-shaped meaning each surface is both concave & convex. This design is extremely flexible in all directions & is most readily seen in the neck vertebrae of birds. Living mammals have centra that are relatively flat so they are called acoelous or amphiplatyan. The flexibility in mammalian vertebrae depends on the compression of intervertebral discs that contain remnants of the notochord. Large mammals with long necks often have opisthocoelous centra that give their necks more flexibility. Amniote vertebrae (as in all tetrapods) have paired pre & post zygapophyses that allow vertebrae to articulate with each other, provide additional support and limit the total range & direction of body movement. In mammals the zygapophyses begin to curve, so that pre-zygapophysis facets curl upward & inwardly & the post-zygapophyses curl downward & outwardly. This usually gives the mammalian body increased dorsal ventral flexion. In large ungulates, the zygapophyses are so curved that they interlock tightly, limiting movement of the trunk. Snakes have also reduced the mobility of their vertebral column. With the loss of their legs, the trunk & tail propel the body by pushing against the ground, but this may tend to make the body twist or roll. Snakes evolved an additional set of processes on the vertebrae to limit torsion. These unique structures are called the zygosphenes (which projects out on the anterior side of a vertebra, above the pre-zygapophyses and the zygantrum, the cavity the zygosphenes fit into on the posterior side of snake vertebrae. The cervical (or neck) region has an atlas vertebra with large facets articulate with occipital condyle(s). It has a large neural canal because of the reduction, then loss of the centrum. Amniotes also have another specialized cervical called the axis that fits into the atlas. This vertebra has a large neural spine & an odontoid [odon = tooth, oid = like] process or dens that allows the atlas & thus the head to rotate. The cervical vertebrae have small ribs. In birds & mammals these ribs fuse completely to the vertebrae forming small passageways called transverse foramina that protect blood vessels to the brain called transverse foramina. The trunk region is not differentiated in lepidosaurs or snakes. The archosaurs, birds & mammals have divided the trunk into two functional regions: thoracic & lumbar. The thoracic vertebrae retain true ribs. These vertebrae have visible transverse facets where the rib s 2 heads articulate. Lumbar vertebrae are posterior to the thoracic vertebrae and lack ribs. The absence of ribs increases the dorsal/ventral flexibility of the body and provides clearance room for the hind limbs in amniotes with upright posture. Lumbar vertebrae have very large transverse processes. Amniotes have 2 or more sacral vertebrae that attach to the pelvic girdle. Birds and mammals have fused many of these vertebrae to form a stronger more stable brace for the hind legs. Birds have a synsacrum made up of fused sacral vertebrae to some of the thoracic, lumbar & caudal vertebrae. The caudal vertebrae are greatly reduced in size & number in birds & mammals. Although lizards and most archosaurs have large hemal spines, birds and mammal have greatly reduced the caudal vertebrae so their caudals have small neural canals, reduced neural spines & rarely have hemal arches. Among amniotes, considerable variation occurs in the skeleton of the pectoral girdle. Their dermal bones include the clavicle & interclavicle. The interclavicle is an unpaired bone in the midline. Birds have fused the clavicles & interclavicles to form a structure called the furcula. The furcula braces the wing & in some species gives the chest some elasticity that may aid birds in flying or during ventilation. Therian mammals have lost the interclavicle. Large ungulates have lost the clavicle entirely, while cats & dogs retain just a remnant of the clavicle that is no longer attached to the rest of the pectoral girdle & floats in muscle tissue. The endochondral series of bones in amniotes may include a scapula, suprascapula & anterior coracoid & posterior coracoid. Both coracoids are often labeled just coracoid in many illustrations, and we will use the same simpler labeling. Features of Therian Mammal Skeletons to Know Scapular spine Unique to Therian mammals. It looks like a midline keel down the scapulas superficial surface. The spine increases the surface area for muscles. Coracoid process The only remnant of the coracoid bone. Its size varies in different species. It fused onto the scapula just above the articulation for humerus. Acromion process This is the articulation point for the clavicle. It s a projection at the distal end of the scapular spine. Olecranon process This process is the elbow region of the ulna. It is posterior to the articulation between ulna & humerus.

5 Squamate Vertebrae Varanid lizard string of vertebrae Vertebral regions: cervical, trunk, sacral (2-3) & caudal in lizard. The atlas, the first cervical vertebra is missing, but identify the axis, the second cervical. Structures on all vertebrae: neural spine, neural canal, transverse processes, pre-zygapophyses, and post-zygapophyses. Additional structures on caudal vertebrae: hemal canals & hemal spine (chevron bones). Shape of the centrum: procoelous. Cervical (atlas missing) Varanid Lizard Vertebrae Trunk (anterior to the right) axis Small articulation facets for cervical ribs Sacral large articulation facets for larger ribs Caudal (with hemal spines) Limbless Locomotion: Snakes: Locate the pre & post-zygapophyses. Locate the unique features: zygosphene & zygantrum. Posterior & Lateral views zygantrum Posterior & Anterior views zygosphene

6 Squamata: Iguana & Teiid Lizards (Whole, Articulated Skeletons) Ribs: both the small cervical ribs & the larger ribs on the trunk vertebrae. Sternum Pectoral Girdle: Dermal bones: clavicles & interclavicle (imbedded in sternum). Endochondral bones: coracoid, scapula & suprascapula. Pelvic Girdle: ilium, ischium & pubis. Foreleg: humerus, radius, ulna, carpals, metacarpals & phalanges. Hind leg: femur, tibia, fibula, tarsals, metatarsals & phalanges. Iguana Pelvis & hind limb. Iguana Pectoral Region clavicle ( ischium out of view) ilium pubis Anterior to the left: Il - ilium, iss - ischium, pus - pubis interclavicle sternum scapula suprascapula cl - clavicle, cor - coracoid, icl - interclavicle, sc - scapula, st - sternum

7 Aarchosauria: Alligator: Fully Articulated & 1 partially articulated Vertebral regions: cervical, trunk, sacral (2-3) & caudal in lizard. Alligator has divided trunk into thoracic & lumbar. The atlas, the first cervical vertebra is missing, but identify the axis, the second cervical. Structures on all vertebrae: neural spine, neural canal, transverse processes, pre-zygapophyses, and post-zygapophyses. Additional structures on caudal vertebrae: hemal canals & hemal spine (chevron bones). Shape of the centrum: procoelous. Cervical Vertebrae (atlas missing) with cervical ribs Thoracic Vertebrae (anterior to the left) axis Lumbar & Sacral Vertebrae (with pelvis) ilium transverse processes show articulation facets for ribs Osteoderms over the skeleton of a dead alligator pubis ischium Ribs: small cervical ribs & the larger ribs on the thoracic vertebrae. Sternum: It is very thin & cartilaginous. Gastralia: thin, membranous "ribs" in the ventral abdominal region tend to attach to the sternum anteriorly & to the pubis posteriorly. They are a special type of dermal bone derivative or osteoderm (i.e. bone that forms within the skin). Pectoral Girdle: Dermal bone: interclavicle Endochondral bones, scapula. Pelvic Girdle: ilium, ischium & pubis. Forelimb: humerus, radius, ulna, carpals, metacarpals & phalanges. Hind limb: femur, tibia, fibula, tarsals, metatarsals & phalanges. Gastralia

8 Archosauria: Aves: Rock Dove or Chicken Whole, Articulated Skeletons Regions of the vertebral column: cervical, thoracic, synsacrum & caudal. The tail ends in a pygostyle that is made of fused caudal vertebrae. Ribs: large ones on thoracic vertebrae. Sternum: Locate the large keel that provides room for flight muscles. Pectoral Girdle: Dermal bones: clavicles (paired) fuse to form furcula [furc = fork]. In some birds a wishbone area is apparent in the midline of the furcula - this is the interclavicle. Endochondral bones: coracoid & scapula. Pelvic Girdle: Ilium has a broad attachment to the synsacrum. Ischium is large & fused along the posterior edge of the ilium. Pubic bones are thin & small & face posteriorly. Wing: humerus, radius, ulna, carpometacarpus (fusion of carpals & metacarpals) & phalanges. Hind leg: femur, tibiotarsus (fused tibia & some tarsals), fibula, tarsometatarsus (fused tarsals & metatarsals) & phalanges. Anterior view of pectoral girdle showing furcula made of paired clavicles & large coracoid.

9 Archosauria: Aves (Birds) Miscellaneous Bird Vertebrae, loose Vertebral structures: neural spine, neural canal, pre- & post- zygapophyses, and transverse foramina. Shape of centrum: heterocoelous (cervical vertebrae are extremely flexible with this centrum shape). Flattening of centrum in thoracic/lumbar vertebrae to stiffen body & limit movement. Fusion of vertebrae in tail forms a pygostyle. Cervical; anterior views Thoracic, anterior, posterior & lateral views Cervical, dorsal views; anterior to the left Synsacrum with ilium (anterior to the right) Caudals with pygostyle; anterior to the right Mammalia: Eutheria: Human Skeleton: Special Features Bones are same as the cat with these specializations. Caudal vertebrae are greatly reduced & fused into a structure called the coccyx. Clavicles are large & easy to identify. Human Pectoral Girdle Human sacrum clavicle coracoid process acromion process Coccyx

10 Mammalian Vertebrae Mammalian Vertebrae: miscellaneous Cat vertebrae are on strings are on every each table. Miscellaneous other vertebrae may be on special demo tables. Regional types of vertebrae: cervical, thoracic, lumbar, sacral & caudal. Atlas & axis of the cervical vertebrae. Structures on all vertebrae: neural spine, neural canal, transverse processes, pre & post zygapophyses. Additional structures on cervical vertebrae: transverse foramina. Additional structures on some of the caudal vertebrae: hemal canal & hemal arch. Shape of the centra: acoelous (cat, human, whale) & opisthocoelous (large ungulate cervical vertebrae). Cat Cervical Ungulate Cervical & Axis Human Atlas & Axis Mammal Thoracic with intervertebral discs Human Thoracic Ungulate Thoracic Cat Lumbar Unknown Mammal Sacrum Human Lumbar Opossum caudal vertebrae with hemal arches. Cat caudal vertebrae with hemal arches.

11 Mammalia: Metatheria: 1 Opossum Articulated Skeleton Most bones can be identified using the cat list. Features NOT seen in Cat skeletons: Large clavicles that are useful braces in climbing. Epipubic bones that support the marsupial pouch, in addition to the other pelvic girdle bones. Opossum clavicle Opossum pelvis with epipubic bones

12 Mammalia: Eutheria: Cat & Rabbit Articulated Skeletons Articulated skeleton Regional types of vertebrae: cervical, thoracic, lumbar, sacral & caudal. Atlas & axis of the cervical vertebrae Structures on all vertebrae: neural spine, transverse processes, pre & post zygapophyses. Ribs: in thoracic region Sternum Pectoral Girdle: Dermal bone: clavicles small, suspended in muscle in cat & rabbit. Wired on in some cats, glued to humerus in rabbit. Endochondral bone: scapula with its coracoid process, acromion process & scapular spine. Forelimb: humerus, radius, ulna, carpals, metacarpals & phalanges. Pelvic Girdle: ilium, ischium & pubis regions of the innominate. Hind limb: femur, tibia, fibula, tarsals, metatarsals & phalanges.

13 Mammalia: Specialized Foot Postures Plantigrade Digitigrade Unguligrade Primitive, non-cursorial Cursorial, small body size Cursorial, large body size [Planti = sole of foot] Walk on tarsals, metatarsals & phalanges [Digit = finger, toe] Walk on all 3 phalanges [Ungui = nail, ungul = hoof] Walk on 1 or 2 terminal phalanges Human, opossum, bear Cat, dog Horse, cow, deer Human Cat Horse Humerus Radius Ulna Femur Tibia Fibula Individual Mammalian Long Bones: demo tables. It has a rounded head at the proximal end, but its head is less uniformly round, and may often be oval shaped or flattened than the head of the femur. The head should be in line with the articulation point at the distal end. Its proximal end has a flattened, rounded disc. In ungulates, the radius is greatly enlarged & the rounded disc is less visible. An olecranon process, or "elbow" extends posteriorly behind ulna's articulation with the humerus. The ulna may be large or reduced distally. It has a very round head that usually projects off the side of the main shaft on a short "neck". Its distal articulation has 2 large condyles that are ~ at 90 degree angles to the position of the head of the femur. The proximal end is fairly flat, with 2 facets that articulate with the femur's distal paired condyles. The proximal end has a triangular shape because of the anterior ridge that runs down the midline. It articulates with the sides of the tibia so it has 2 small articulation points along the side of the bone, near the top & bottom. The bone is often reduces or fused onto the tibia & its articulations are small & face off to the side. Seal humerus, posterior Seal femur, posterior Deer ulna; radius- ulna Porcupine tibia & fibula

14 Eutheria: Horse & other large ungulates: Disarticulated Be able to identify the major limb bones (but not to distinguish individual carpal bones from tarsals). Leg Bones: Enlarged radius & smaller ulna partially fuse. Enlarged tibia & reduced fibula. Reduce rotation of legs. Foot Bones: Metatarsals & metacarpals are elongated; with 2-3 fused & others reduce/lost. Tightly locking joints hold the digits. Why do large ungulates lack clavicles? Horse radius/ulna Deer metacarpal Horse tibia Horse metacarpals What is the benefit of these distal lock & key joints? Cow? Humerus with relatively flat heads that limit lateral movement of the leg & locking socket for olecranon process of ulna. Springbok femur

15 Eutheria: Bat Skeleton & Wing Identify the major wing elements: humerus, large radius, reduced ulna, carpals, elongated & very thin metacarpals & phalanges. Close-up of elbow showing reduced (& broken) ulna

16 Marine Tetrapods Eutheria: Seal limbs Forelimb: humerus, radius, ulna, carpals, metacarpals & phalanges a greyhound (dog), b True Seal, c Eared Seal Hind limb: femur, patella, tibia, fibula, tarsals, metatarsals & phalanges Why are the humerus & femur short, while phalanges are elongated? Eutheria: Cetacean Vertebrae & Forelimb Front limbs are now fins. They have greatly shortened the humerus, radius & ulna and added extra phalanges on each digit. The ulna & radius are unable to rotate at the elbow & are flattened. Why are the bones so different in size compared to the seal? Anterior (1 st digit is the long, slender one at the bottom) Pilot whale forelimb (note additional phalanges) Cervical vertebrae are thin & may fuse to reduce the movement of the neck. See their 3D atlas Whale lumbar vertebra Zygapophyses are greatly reduced/absent. Forelimb bones: humerus, radius, ulna, carpometacarpus & phalanges. Aves: Penguin wings What are 2 differences between this wing & the wing of flying birds?