1. Chapter 15 Section 4 Fossils

2. Fossil Preservation Five main ways fossils are preserved: o Rocks o Amber o Petrifaction o Asphalt o Ice

3. Fossils in Rocks Organism dies, quickly covered by sediment, decay slows dramatically When sediment becomes rock, the hard parts of the organism are preserved – The shell, teeth, bones Preservation in sedimentary rock is the way most fossils are preserved

5. Fossils in Amber Amber is hardened tree sap Insects are caught in the liquid sap, sap hardens, insects is preserved

7. Petrifaction Minerals replace the organism’s tissues Example – Petrified wood

9. Fossils in Asphalt Asphalt forms pools at the Earth’s surface Plants and animals become trapped and preserved Example – La Brea Tar Pits (California) Trapped organisms for the past 38,000 years

12. Frozen Fossils Very cold (freezing) temperatures slow decay Cold climates have very little decomposing bacteria Fossils in ice are very well preserved Example – Woolly Mammoth

14. Other Type of Fossils Trace Fossils – Tracks (footprints) – Marks left by a dinosaur’s tail – Burrows – Coprolite: preserved animal dung

15. Other Types of Fossils Mold (see vocab) – Cavity left by decayed organism Cast (see vocab) – Created when sediment fills mold and becomes a rock Index Fossil (see vocab) – Fossil from a specific time, used to date surrounding rock layers

16. The Fossil Record A rough sketch of the history of life on Earth Incomplete because most organisms never become fossils

17. Uses of Fossil Record Environmental Change – Marine fossils help scientists reconstruct ancient coastlines and sea depths. Marine fossils found on Canadian mountaintop! – Plants and Animals help reconstruct past climates. Can tell if an area was cooler or wetter than it is now. Changing Organisms – Relationships between fossils Interpret how life has changed over time