Fossils What is a fossil Fossils are any

Fossils!

What is a fossil? Fossils are any evidence such as the remains, imprints, or traces of once living organisms (plants & animals) preserved in rocks.

Fossils provide clues to past geologic events and evolution of life forms.

PALEONTOLOGIST A Scientist that studies fossils to learn about Earth’s past. Paleontologists arrange fossils in the order in which they lived, from earliest to latest. All the information gathered about past life is called the fossil record.

What are the different kinds of fossils? Original Remains Petrified Remains (wood) Carbon Films Trace Fossils Molds and Casts

What is an Original Remain? Original Remains: Fossils that are the actual bodies or body parts of an organism. Some processes preserve the remains of the organisms with little or no change.

A. Mummification (drying)Because most bacteria cannot survive without water, the mummified organism does not decay.

B. Amber- Many insects have been found preserved in hardened resin or sap called amber.

C. Tar - Formed by thick petroleum oozing to the Earth’s surface. The tar beds are often covered with water. Animals that came to drink the water became trapped in the tar and were preserved.

D. Ice. Most bacteria cannot survive freezing temperatures, organisms buried in frozen soil or ice do not decay. The frozen remains of relatives of elephants called woolly mammoths have been found in very cold regions. Freezing has preserved even mammoth’s hair & skin.

How do organisms become petrified (mineralized)? Petrified organisms are fossils in which minerals replace all or part of an organism, changing the organism into stone. The most common organism that becomes petrified is wood.

Describe a Carbon Film A thin film of carbon residue that forms an outline of the original organism leaving behind fine, delicate details. When sediment buries an organism, the weight of the sediment squeezes almost all of the decaying organism away. Eventually, only a thin film of carbon remains.

Hold up a fossil and tilt it back and forth in the light. If it has a shiny, black appearance, then its a “carbon film” fossil.

Trace Fossils that contain no part of an organism, but show evidence of their existence.

A. Imprints When an outline of an organism is pressed into soft sediment (mud) and the sediment turns into stone preserving the outline, such as the footprint of an animal or the outline of a leaf.

B. Coprolites- Fossilized waste material a. k. a poop!

Casts and Molds Often organisms are buried by sediments. If the sediments turn into rock and the organisms decay, empty cavities are left behind. These empty cavities are called molds. Sometimes the molds are filled with sand mud that later hardens forming a replica of the original organism. These replicas are called casts. A cast is the opposite of a mold.

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