1. 4.1 - Fossils  Essential Questions: 1. What Are Fossils? 2. What Are the Kinds of Fossils? 3. What Do Fossils Show?

2. What Are Fossils?  Fossils are the preserved remains or traces of living things.

3. What Are Fossils?  Most fossils form when living thing die and are buries by sediment. The sediment slowly hardens into rock and preserves the shapes of the organisms.

4. What Are Fossils?  Most fossils form from animals or plants that lived near water where sediments build up.  Normally only the hard parts of organisms are fossilized.

5. What Are the Kinds of Fossils?  Fossils found in rock include:  Molds and Casts  Petrified Fossils  Carbon Films  Trace Fossils  Preserved Remains

6. Molds and Casts  A mold is a hollow area in sediment in the shape of an organism or part of an organism.  Forms when an organism is buried in sediment, then water deposits minerals in the cast forming a cast.  A cast is a solid copy of the shape of an organism.  This preserves fine details.

7. Petrified Fossils  Petrified – Turned into stone.  Petrified fossils are fossils in which minerals replace all of an organism or a part such as a dinosaur bone.  Water deposits minerals into the organism’s cells.  The water evaporates leaving the minerals behind.

9. Carbon Films  Carbon films are extremely thin coatings of carbon on rocks.  An organism’s thin carbon outline preserves delicate parts of plants and animals.

10. Trace Fossils  Trace fossils provide evidence of the activities of ancient organisms.  Footprints  Nests Chirotherium footprints in Triassic sandstone.

11. Preserved Remains  Organisms that become trapped in tar, ice, or tree resin (amber) do not decompose.

12. What Do Fossils Show?  Scientists who study fossils are called archeologists.  The fossil record provides evidence about the history of life and past environments on Earth. The fossil record also shows how different groups of organisms have changed over time.

14. Fossils and Past Environments  Fossils can tell whether an area was a shallow sea, an ocean bottom, or a freshwater swamp.  Past climates can also can detailed.  Coal in Antarctica.

15. Changes and the Fossil Record  Older rocks contain fossils of simpler organisms.  Younger rocks show both complex and simple ones.

16. Changes and the Fossil Record  The fossil record shows how life on Earth has evolved.  Evolution is the change in living things over time.  Millions of different types of organisms have evolved.  Many have become extinct, which means they no longer exist on Earth.

17. Changes and the Fossil Record  Fossils can be used to find relationships between former organisms and current organisms.