FOSSILS Definition of a fossil Fossils are the

FOSSILS

Definition of a fossil: Fossils are the preserved remains of plants and animals that lived millions of years ago.

People who study fossils are called paleontologists. “paleos” means “old” or “ancient” “ology” means “the study of” so a paleontologist is a scientist who studies � life forms in ancient times.

How fossils are formed: 1. 2. 3. Fossils are formed when a plant or animal dies and decays. It is buried by sediment. Over a long period of time, the sediment hardens into ROCK and preserves the shape of the organism. Fossils are usually found in sedimentary rock.

Types of fossils:

1) molds and casts A mold is a hollow area in sediment that is in the shape of an organism. A cast is the opposite of the mold. It is in the exact shape of the organism.

Formation of a mold and cast: molds and casts animation

2) trace fossils Footprints or other trace fossils show evidence of the organisms’ activities. The mud or sand that the animal stepped in has been buried by sediment and the sediment slowly became solid rock. We can tell an organisms size and shape as well as whether it travelled alone or in a group. Dinosaur tracks Dakota Group, Dinosaur Ridge near Denver, Colorado

3) carbon film Carbonization (or distillation) preserves plants or animals as a thin carbon film, usually in fine-grained sediments (shales). As organisms decay, gas is given off, leaving behind a “photo copy of the organism. ” Fine details of the organisms may be preserved.

4) preserved fossils Some fossil remains are preserved intact in tar or amber. Fossils can also be preserved by freezing.

Otzi the Ice Man

baby mammoth

5) petrified remains fossils in which minerals replace all or part of an organism Petrified Logs from Petrified Forest. Photographed at the Smithsonian Institution Ntional Museum of Natural History, Washington, D. C.

Fossils show us the climate conditions in which they were formed such as: a) deserts b) glaciers c) forests d) inland seas fossils tell climate condition

What are fossils made of? fossilization

evolution The gradual change of an organism over long period of time.

extinction An organism becomes extinct when none of its species is left on Earth. 2 main reasons for extinction : A) habitat destruction B) climate change http: //en. wikipedia. org/wiki/List_of_e xtinct_animals#Modern_extinctions

Notes Quiz 1. What is a fossil? 2. In what type of rock are fossils found? 3. What is a scientist who studies fossils called?

4. How are fossils formed? 1) 2) 3) 5. Which is a type of fossil that is in the exact shape of the original organism? a) mold b) cast

6. Footprints that show the organism’s activities are called a) casts b) preserved remains c) trace fossils

7. Fossils that are preserved in tar or amber or by freezing are called _____________ 8. Fossils in which minerals replace all or part of an organism are called ______

9. What do fossils show us about the past environments on Earth? 10. What are fossils made of? a) bone b) stone c) soft tissues such as organs, brains, fur or hair