THE HISTORY OF EARTH

Transcription

1 THE HISTORY OF EARTH

2 The Age of the Earth 4.6 billion years old = 4,600,000,000 Image courtesy of NASA,

3 The earth s 4.6 billion year history is divided into major units of time: Precambrian Time Paleozoic Era Mesozoic Era Cenozoic Era

4 4.6 billion years before present to 544 million years before present Longest era with a sparse fossil record (~88% of Earth time) Origin of earth s crust, first atmosphere, and first seas Earliest fossils of cyanobacteria use photosynthesis to produce oxygen Ozone layer in the atmosphere is formed from oxygen Precambrian Time

5 Precambrian Time Moon forms during this time Archaean period, when no life existed, and the later Proterozoic Period, in which life did exist. Volcanoes produce toxic atmosphere Water and water Vapor that form the oceans comes from volcanoes, asteroids and comets! Cynobacteria-changed Earth s past atmosphere of water vapor, ammonia and methane into Nitrogen and Oxygen bacteria Stromatolites are among the most famous organisms during the Precambrian era, and are formed from the growth of cyanobacteria

6 Precambrian Time

7 Paleozoic era 544 million years before present to 245 million years before present Ozone layer not fully developed: no plants on land initially Marine communities flourish Early fishes develop Origin of amphibians, insects & reptiles Recurring ice ages/ Appalachians mountains form Spore-bearing plants dominate

8 Paleozoic era 7 periods of Paleozoic Era Cambrian Period ( ) Ordovician Period ( ) Silurian Period ( ) Devonian Period ( ) Mississippian Period ( ) Pennsylvanian Period ( ) Permian Period ( )

9 Cambrian period Trilobites Clams Inland seas suggest warm Earth Land Formation: supercontinent Gondwana (Southern hemisphere) Trilobites Lived in Earth s ancient seas Extinct before the dinosaurs came into existence Cambrian Period is know as the Age of the Trilobites

10 Ordovician Period ( ) First land plants (ferns) First vertebrates: early fish appear Life moves into shallower water: Suggests ozone layer almost fully developed as life moves closer to land Laurussia seperates from Gondvana

11 Silurian Period ( ) Corals Dominate World s Oceans Warm Earth Plants move further inland Animals now moving further inland by way of water; fresh water fish North America covered by shallow sea

12 Devonian Period ( ) Fish dominate oceans First amphibians Signs of Earth beginning to cool: Water retreats forcing organisms to adapt to the new changes. More land created

13 Mississippian Period ( ) Amphibians dominate land life Earth much cooler as glaciers move southward from polar regions Cooler Earth forces Amphibians to adapt to changes; (less water-thicker skin)

14 Pennsylvanian Period ( ) First reptiles and insects Shallow seas over North America almost disappeared Cooler Earth

15 Permian Period ( ) Glaciers retreat Earth Warming back u million years before present: Supercontinent of Pangea forms 248 million years before present: MASS EXTINCTION-90 % of all known families lost! (Asteroid impact)

16 Mesozoic Era 245 million years before present - 65 million years before present The age of the dinosaurs! Gymnosperms dominate land plant/ origin of angiosperms - flowering plants Origin of mammals & birds 145 million years before present - asteroid impact? MASS EXTINCTION Pangea begins to separate/ Rocky mountains form

17 Mesozoic Era The Mesozoic Era is often known as the Age of Dinosaurs because these reptiles were the largest, the most powerful, and the most conspicuous animals of the era. Three periods of Mesozoic Era : Triassic period ( million years) Jurassic Period ( million years) Cretaceous Period ( million years)

18 Triassic Period Marks beginning of Mesozoic Era First dinosaurs and mammals appeared around 225 million years ago Atlantic Ocean Pangaea breaks up Flowering Plants appear Eoraptor, Plateosaurus and Teratosaurus

19 Triassic Period Eoraptor Plateosaurus

20 Jurassic Period ( ) Flowering Plants and Dinosaurs dominate land Birds appear Appalachian Mountains Form Dinosaurs become more diverse from basic shapes Allosaurus Stegosaurus Diplodocus Ceratosaurus

21 Jurassic Period Allosaurus Stegosaurus Diplodocus Ceratosaurus

22 Cretaceous Period (144-65) Most advanced dinosaurs: Highly specialized, most successful of all dinosaur species Modern Earth Appears Ends in Mass Extinction of Dinosaurs Tyrannosaurs, Tricerotops, Ankylosaurus, Protocerotype, Velocoraptors, Pterodactyl

23 Cretaceous Period Tyrannosaurus Tricerotops Velocoraptors Pterodactyl Ankylosaurus

24 Mesozoic Era 65 million years before present. ASTEROID IMPACT! Mass extinction of ALL dinosaurs and many marine organisms 75% of the species on Earth went extinct End of the Mesozoic era Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

25 Cenozoic Era 65 million years before present -today Present era we live in Continued evolution and adaptations of flowering plants, insects, birds, mammals Mammals dominant Major crustal movements & mountain building (Alps & Himalayan mountains form) Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

26 And during the Cenozoic era The most primitive hominid (human ancestor) evolves - approximately 4.4million years before present The first modern humans (homo sapiens) evolved approximately 100,000 years before present

27 Cenozoic Era Sabre-tooth cat Phorusrhacid Wooly Mammoth Amphicyonid Homo erectus

28 How many types of dinosaurs are known? Approximately 700 species have been named. What colors were dinosaurs? Direct fossil evidence for dinosaur skin color is unknown. Paleontologists think that some dinosaurs likely had protective coloration, those dinosaurs that had enough armor may have been brightly colored. Most dinosaurs probably were as brightly colored as modern lizards, snakes, or birds. How long could a dinosaur live? Animal lifespans relate in part to their body size and in part to their type of metabolism. Dinosaur lifespans probably varied in length from tens of years to hundreds of years.

29 Were dinosaurs warm-blooded? Scientists have conflicting opinions on this subject. Some scientists think that very big dinosaurs could have had warm bodies because of their large body size, just as some sea turtles do today. How fast could dinosaurs walk or run? One recent estimate suggests that an average person might have been able to outrun an adult Tyrannosaurus. Walkingspeed of two-legged dinosaurs vary from 4 kph to 6 kph, and peak running-speed estimates vary from 37 kph to 88 kph. What was the biggest dinosaur? What was the smallest? The largest dinosaur we know of was Brachiosaurus it reached 23 m in length and 12 m in height. The smallest dinosaurs were just slightly larger than a chicken.