1. Put the following events in order… A. Body slowly decays and minerals fill in the cavity. B. Sediment covers the body (rapid burial) C. Geologic processes bring fossil to surface. D. Organism Dies Fossil Formation Video Clip

2. I. Fossils  A. Fossil: the remains of physical evidence of an organism preserved by geological processes. How Fossils Form Simulation

3. Examples of Fossilization

4. Other Types of Fossils B. Trace Fossil a fossilized mark that is formed in soft sediment by the movement of an animal. Ex: Footprints Burrows Dinosaur footprint Crustacean burrow

5. C. Using Fossils to interpret the Past 1. Only a fraction of the organisms that have lived during geologic time have been preserved as fossils. 2. However fossils can indicate a record of environmental change.

6. Question?  Why is it difficult for fossilization to occur?  Answer : Environmental conditions may not be favorable.  2 Requirements of Fossilization:  Rapid burial  Possession of hard parts.

7. D. History of Changing Organisms  By studying the relationship between fossils, scientist can determine how life has changed over time. -Paleontologist look for similarities between fossils, or between fossilized organisms and their closest living relatives.

8. II. The Geologic Time Scale  Divisions in the time scale mark times when rapid changes happen on earth. -Rise of a dominant organism -Mass Extinction

9. A. Precambrian Time 1. Accounts for 88% of Earth’s History 2. Early life forms on Earth 3. Cyanobacteria appeared 3 billion years ago.

10. B. Why would cyanobacteria be important?  1. Release Oxygen into the oceans and air  2. Formed ozone layer, which absorbs harmful UV radiation from the sun.

11.  Extinction Extinction Describes a species that has died out completely. Mass extinction periods when many species suddenly became extinct. Over 99% of organisms that have ever lived on Earth are now extinct! What Caused the Extinction of the Dinosaurs? What evidence supports this? K-T Extinction Event Video Clip What caused the extinction of the dinosaurs?