Chapter 17 The History of Life

1. Chapter 17The History of Life Section 17-3Evolution of Multicellular Life

2. The Fossil Record • Documents • Evolutionary Histories • Climate • Geography • Life Forms

3. Precambrian Time • Covers 90% of Earths History • During This Period: • Simple Anaerobic Life Formed • Then Photosynthetic Organisms • Released Oxygen • Aerobic Life Formed • Eukaryotes Developed • Multicellular Organisms Appeared Start Finish

4. Paleozoic Era Key Concept: Early In The Paleozoic Era, The Fossil Record Became Rich With Evidence of Many Types of Marine Life Paleozoic Weblink Age of the Trilobites

5. Cambrian Period • Cambrian Explosion • Huge Numbers of Multicellular Life Forms Developed • Shells, Outer Skeletons, Appeared • Trilobites, Brachiopods, Invertebrates Arrived • Burgess Shale in British Columbia is a famous fossil site for this event

6. Ordovician & Silurian Periods • First Appearance of: • Octopus, Squid • Aquatic Arthropods • Vertebrate • Jawless Fishes (suckers) • Insects • Plants

7. Devonian Period Ferns Appear Fish Proliferate Sharks Appear Amphibians Evolve

8. Devonian Period Key Concept: During The Devonian, Animals Began To Invade Land

9. Carboniferous & Permian Periods • Life Expands Across The Continents • Reptiles • Winged Insects • Dragonflies, Cockroaches • Giant Ferns, Swampy Forests • Laid Down Coal Deposits

10. Carboniferous & Permian Periods Key Concept: The Mass Extinction At The End Of The Paleozoic Affected Both Plants & Animals On Land & In The Seas. 95% Of Complex Ocean Life Forms Disappears

11. Permian Extinction • Killed Off • Trilobites • Many Amphibians • What Survived • Most Fishes • Numerous Reptiles Extinction Link

12. Mesozoic Era Key Concept: Events During The 180 Million Years Of The Mesozoic Era Include The Increasing Dominance Of Dinosaurs. The Mesozoic Is Marked By The Appearance Of Flowering Plants

13. Mesozoic Era

14. Triassic Period • Made Up Of The Organisms That Survived The Permian Extinction • Cone Bearing Plants Appear • “AGE of REPTILES”

15. Triassic Period • Mammals Appear In The Late Triassic • Small Shrewlike Organisms

16. Jurassic Period Dinosaurs Still Rule First Birds Appear Archaeopteryx

17. Cretaceous Period • Dinosaurs Still Dominant • T. rex • Flying Reptiles • Became Extinct During Cretaceous • Seas Contained • Turtles • Crocodiles • Plesiosaurs

18. Cretaceous • Appearance of: • Leafy Trees • Shrubs • Small Flowering Plants • True Seeds • Often Enclosed In Fruit

19. Cretaceous Extinction • 65 Million Years Ago • > 50% of All Plant & Animal Groups Wiped Out • Including ALL the Dinosaurs

20. Cenozoic Era The Age of Mammals Key Concept: During The Cenozoic, Mammals Evolved Adaptations That Allowed Them To Live In Various Environments – On Land, Water & Air.

21. Tertiary Period • Climates Warm & Mild • Whales & Dolphins Evolve • Grasses Evolve • Grazing Animals Evolved • Some Mammals & Birds Became Very Large

22. Tertiary Mammals

23. Quaternary Period • Climate Cooled • Several Ice Ages Occurred • Sea Levels Dropped By Over 100 Meters (300 Feet) • 20,000 Years Ago • Climate Warmed • Ice Packs Melted • Sea Level Returned

24. Ice Age

25. Quaternary Period • 4.5 Million Years Ago • Our Primate Ancestors Evolved • 100,000 Years Ago • Genus Homo Arose In Africa • Migrated Across The World