1. A Trip through Geologic Time:
Fossils

2. *Fossils are preserved remains or traces of living things.
*Most fossils form when living things are buried by sediments.
*These slowly harden into rock and preserve the shape of the organism.
*Scientists that study fossils are paleontologists .

3. *Fossils are usually found in sedimentary rocks.
*When an organism dies, its soft parts often decay quickly, leaving only the hard parts to fossilize.
*Ex: Bones, Shells, Teeth, or Seeds.

4. *KINDS OF FOSSILS. *PETRIFIED FOSSILS
*Fossils where minerals replace all or part of the organism.
ie: Petrified Wood
*When the object is buried by sediment, water rich in minerals seeps into its cells; when the water evaporates, the minerals are left behind.
*KINDS OF FOSSILS.

5. *KINDS OF FOSSILS. *MOLDS AND CASTS
* A mold is a hollow area in sediment in the shape of an organism or part of an organism.
*A cast is a copy of the shape of the organism.
*KINDS OF FOSSILS.

6. *KINDS OF FOSSILS. *CARBON FILM FOSSILS.
*Carbon films are extremely thin coatings of carbon on rock that form when materials that make up an organism become gases and escape leaving only Carbon behind.
*KINDS OF FOSSILS.

7. * TRACE FOSSILS.
*Trace Fossils provide evidence of the activities of ancient organisms.
For example – footprints, animal trails, or animal burrows
*KINDS OF FOSSILS.

8. * PRESERVED REMAINS.
*Preserved Remains are formed when an organism is preserved with little or no change
For example when organism become trapped and preserved in tar, amber (tree sap), or ice
*KINDS OF FOSSILS.

9. *To learn what past life forms were like
*WHY STUDY FOSSILS?
*To learn what past life forms were like
*To classify organisms in the order in which they lived
*To prove extinct species existed!

10. *WHY STUDY FOSSILS?
*All the information scientists have gathered is called the fossil record.
*Shows how groups of organisms have changed over time.
* Helps support the Theory of Evolution

11. One last thing…
INDEX FOSSILS

13. *Scientists use index fossils to match rock layers.
*MUST BE WIDELY DISTRIBUTED (spread out) and ONLY EXISTED BRIEFLY.
*They are useful because they tell the relative ages of the rock layers they are found in.

14. *Evolved more than 500 million years ago.
*INDEX FOSSIL-THE TRILOBITE.
*A group of hard –shelled animals whose bodies had three distinct parts .
*Evolved more than 500 million years ago.