1. Geologic Time Scale Chapter 17

2. Formation of Earth 4.6 billion years old Took 100 million years to form

3. Formation of Earth Early atmosphere: CO 2, CO, H 2 O, N 2, H 2 S, but no O 2 ! First life was simple one celled prokaryotes about 3.5 mya

4. Miller and Urey Experiment simulated Earth’s early atmosphere Created organic compounds necessary for life—amino acids

5. Geologic Time Scale Used by paleontologists Represents evolutionary time Mark major changes in fossils

6. Cenozoic Era Quaternary Period 1.8-present Glaciations, mammals increased, humans Tertiary Period 65-1.8 Mammals diversified, grasses

7. Mesozoic Era Cretaceous Period 145-65 Aquatic reptiles diversified, flowering plants, mass extinction Jurassic Period 208-145 Dinosaurs diversified, birds Triassic Period 245-208 Dinosaurs, small mammals, cone-bearing plants

8. Paleozoic Era Permian Period 290-245 Reptiles diversified; seed plants; mass extinction Carboniferous Period 360-290 Reptiles; winged insects diversified; coal swamps Devonian Period 410-360 Fishes diversified; land vertebrates (prim amphibs) Silurian Period 440-410 Land plants; land animals (arthropods) Ordovician Period 505-440 Aquatic arthropods; mollusks; vertebrates (jawless Cambrian Period fishes) 544-505 Marine inverts diversified; most animal phyla evolved

9. Precambrian Time Vendian Period 650-544 Anaerobic, then photosynthetic prokaryotes; eukaryotes, then multicellular life