PALEONTOLOGY

Paleontology—The Study of Past Life The history of the Earth would be incomplete without knowledge of the organisms that have inhabited our planet and the conditions under which they lived. The science involved with the study of past life is called paleontology. Paleontologist study fossils, which are the remains of organisms preserved by geologic processes.

Fossils

Fossil Preserved remains of a past organism

FORMATION OF FOSSILS Fossilized- the process of becoming a fossil. Fossils are evidence of past life, preserved in rock. Most fossils form when living things die and are buried by sediments. The sediments slowly harden into rock and preserve the shapes of the organisms.

What do fossils tell us? Fossils provide evidence of how life has changed over time. Fossils help scientists infer how Earth’s surface has changed. Fossils are clues to what past environments were like.

The Fossil Record and life The fossil record is the complete body of fossils that shows how species and ecosystems change over time.

Types of fossils Petrified fossils Molds and casts Carbon films Trace fossils Index fossils Preserved remains

Petrified Fossils Fossils in which minerals replace all or part of an organism. How does this happen? Water rich in dissolved minerals seeped into spaces, evaporated, leaving the hardened minerals behind. Example – petrified wood

Molds and casts Most common type of fossil. Both copy the shape of the organism. A mold is a hollow area of sediment in the shape of the organism. A cast is a copy of the shape of an organism.

Carbonization Leaves extremely thin coating of carbon film outline on rock. How does this happen? All organisms are made of carbon. When they are buried, the materials that make up the organism evaporates. These gases escape leaving carbon behind.

Trace Fossils Trace fossils are a fossilized mark that is formed in soft sediment by the movement or actions of an animal. Examples A footprint provide clues about the size and behavior, the speed, how many legs it walked on, lived alone or with others. A trail or burrow can give clues about the size and shape of the organism, where it lived, and how it obtained food.

Index Fossils An index fossil is a fossil found in a narrow time range but widely distributed around the earth; used to date rock layers. Example Trilobite: a marine organism that has become a fossil. Ammonite

Preserved remains Preservation of remains with little or no change.

Preserved remains Tar The sticky oil that seeps from Earth’s surface. Tar soaks into the organisms bones, preserving the bones from decay.

Preserved remains Amber The hardened resin, or sap, of trees. The amber seals the organism from the air protecting it from decay.

Preserved remains Ice Ice Fossils are actual flesh remains of the organism. They become trapped in ice and remain frozen until t hey thaw. Good example of a ice fossil are Wooly Mammoths, which are often found in the Arctic.

Fossil Brochure Cover Fold your guided notes in a brochure on the front cover create a design that will show me you understand what fossils are and the types of fossils