1. Fossils and Geologic Time Scale Chapter 17

2. What’s It All About Essential Question: Can relative dating and relative frequency be a trusted thing? Objectives: Describe the fossil record Sate the information that relative dating and radioactive dating provide about fossils Identify the divisions of the geological time scales

3. Fossil Formation Provides evidence about the history of life on Earth Shows how different groups of organisms, including species have changed over time The fossil record is incomplete because just the right conditions must occur.

4. How Fossils Form Water carries small rock particles to lakes and seas. Dead organisms are buried by layers of sediment, which forms new rock. The preserved remains may later be discovered and studied. See page 418!

5. Interpreting Fossil Evidence Relative Dating—Age of a fossil is determined by comparing its placement with that of fossils in other layers of rock Estimate of the age Radioactive Dating—Calculate the age of a sample based on the amount of remaining radioactive isotopes it contains Accurate Age

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

7. Division of Time Era—One of several subdivions of time between the Precambrian and present Period—Unit of time in which eras are subdivided

8. Draw a big table that looks like this: Glaciations; mammals increased; humans Mammals diversified; grasses Aquatic reptiles diversified; flowering plants; mass extinction Dinosaurs diversified; birds Dinosaurs; small mammals; cone-bearing plants Reptiles diversified; seed plants; mass extinction Reptiles; winged insects diversified; coal swamps Fishes diversified; land vertebrates (primitive amphibians) Land plants; land animals (arthropods) Aquatic arthropods; mollusks; vertebrates (jawless fishes) Marine invertebrates diversified; most animal phyla evolved Anaerobic, then photosynthetic prokaryotes; eukaryotes, then multicellular life Cenozoic Mesozoic Paleozoic Precambrian Time Quaternary Tertiary Cretaceous Jurassic Triassic Permian Carboniferous Devonian Silurian Ordovician Cambrian 1.8–present 65–1.8 145–65 208–145 245–208 290–245 363–290 410–363 440–410 505–440 544–505 650–544 Key EventsEraPeriodTime (millions of years ago)

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

10. 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

11. 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

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