1. Fossil Records – Clues to the Past
Chapter 8.3

2. Key Terms
Fossils: The remains or traces of plants and animals that live in the past (not yesterday…the distant past… a different geological time period)
Paleontologist – cool guy (or girl) that studies fossils
Index Fossils – Fossils that occur only in rock layers
Fossilization – The process by which plants and animals are preserved against decomposition (usually the squishy parts decompose though)

3. Why are Fossils Important?
Fossils reveal secrets of the past
Organism development and evolution
Climate & other environmental changes
Add video here

4. How fossils form….or don’t
BACTERIA is the enemy of fossil development..
So are other animals
If dead organisms are not protected by an environmental factor, bacteria will break down the organism and it will decompose
Animals may come and see the dead organism as an easy meal…

5. Formation methods Amber Mummification A covering of plant sap.
Preserves very delicate features
Occurs in dry places
Most bacteria does not survive well in these areas
Generally lack internal organs
Exception: Bog Bodies – many have preserved skin and organs
Tar Seep
Area of petroleum covered by water
Acts a trap when animals fall in
Tar surrounds and preserves the animal
Egyptian Mummy
Bog Body Mummy

6. Freezing Petrification
Little bacteria here – its too cold
Low temperature preservation
Dinosaurs didn’t live in the cold, so finding one in Antarctia meant that is was once a warm mild area
Minerals, such as silica, calcite and pyrite replace the organic material and create a near perfect replica.
200 million year old tree found in Arizona

7. Types of fossils Trace Fossils Carbon Film
No actual organism is left behind, only an imprint.
A “picture” or residual printed into the stone

8. Smooth stones found by prehistoric remains
Gastroliths
Smooth stones found by prehistoric remains
Used to help grind and digest food (like a bird uses)
Molds & Casts
Shells press into a soft muddy area which eventually hardens, the shell fills with mud, once the shell decays, the cast & mold are left behind
Coprolites
Can we say poopy? – coprolites are petrified waste material which can be used to determine feeding habits