The Fossil Record

Chapter 8.3

The Fossil Record

Paleontology = study of fossils

Fossils are the remains of an organism that lived a long time ago.

The Fossil Record

Fossils most often preserved in sedimentary rock.

Sediments cover the fossils. This slows/stop the process of decay (by bacteria) and prevents dead organisms from being eaten.

Normally only hard parts of organisms become fossilsEx. Bones, shells, teeth, and wood

Fossilization

MummificationFound in dry places

How Fossils Form

AmberHardened tree sap (amber) traps insects,

preserving it when it hardens

Tar SeepsOccurs when petroleum comes to the surface

of the EarthOrganisms get stuck in the sticky tar

FreezingLow temperatures protect and preserve

organisms in ice and frozen soil – no bacteria

PetrificationMineral solutions (ex. Silica, calcite, and

pyrite) replace the organic material, creating a mineral replica of the original organism

Imprints – ex. of leaves stems, flowers, and fish

Molds and Casts – either an empty cavity or a replica

Coprolites – fossilized dung/waste material

Gastroliths – stones in dinosaur digestive systems

Trace Fossils – ex. Tracks, footprints, borings, and burrows

Types of Fossils