1. Tracing Evolutionary History CHAPTER 15

2. 15.1 • Fossils chronicle the evolutionary timeline • Eras in geologic time • Precambrian • Paleozoic • Mesozoic • Cenozoic

3. Precambrian Era • 4.6 billion ya- 542 mya • First fossils- prokaryotic cells (3.5 billion ya) • Diverse invertebrates (600 mya) and algae • Oxygen builds up in our atmosphere as the result of photosynthetic bacteria

5. Paleozoic era • 542 mya-251mya • Cambrian explosion – many new animals • Colonization of land by arthropods and land plants • Fish • Tetrapods (amphibians) • Seed plants, Reptilian adaptive radiation • Major extinction of many organisms

7. Mesozoic Era • 251 mya-65mya • Cone bearing plants • Radiation of dinosaurs • Origin of mammals • Flowering plants • Major dinosaur extinction at end of era

9. Cenozoic Era • 65 mya-present • Radiation of birds and mammals • Origin of primates • Origin of hominids • Ice Ages

11. 15.3 Continental drift • 1912- Alfred Wegener suggested that all the land masses were once a single mass called Pangea • Pangea broke apart and the continents drifted to there current locations creating geographic isolation

13. 15.5 Mass Extinctions • Permian mass extnction (boundary between Paleozoic and Mesozoic) 96% of all marine life • Volcanic eruption in Siberia ? • Creataceous mass exntinction – dinosaur extinction • Asteroid collision? Climate change ?

14. Convergent Evolution • Likeness suggests relationships . . .however some likeness is the result of living in a similar environement NOT common ancestry • Streamlined appearance of both whales (mammals) and sharks (cartilage fish)

16. Scientific naming • Linneaus – 18th century – Latin naming system • Domain • Kingdom • Phylum • Class • Order • Family • Genus + species = organism’s scientific name

18. 15.8 Cladistics • Forming family trees based on shared traits • New branches have derived traits • “family trees” – cladograms