Fossil Formation

fossils that provide evidence of the activities of ancient organisms

Petrified Fossils

fossils in which minerals replace all or part of an organism

Fossil Formation

Molds and Casts

mold:

a hollow area in sediment in the shape of an organism or part of an organism

cast:

a solid copy of the shape of an organism

How Fossils Are Formed

petrified fossils:

Trace Fossils

trace fossils:

From fossil footprints, scientists can find answers to questions about an animal's size and behavior. Other types of trace fossils also provide clues about ancient organisms.Ex: A trail or burrow can give clues about the size and shape of an organism, where it lived, and how it obtained food.

A fossil may form when the remains of an organism become petrified. As an example, fossil tree trunks are petrified wood. These fossils form after sediment covers the wood. Then, water rich in dissolved minerals came out of the solution and hardened.

Preserved Remains

tar:

sticky oil that seeps from Earth's surface

amber:

the hardened resin, or sap, of evergreen trees

Ways to Preserve Remains:

- organism becomes trapped in tar = tar soaks into organism's bones = no decay - organism is trapped in sticky resin = more resin covers it = sealing it from air/protecting its body from decay - freezing = frozen remains of woolly mammoths have been found in very cold regions of Siberia/Alaska = has preserved even the mammoth's hair & skin