Chapter 8.3 The Fossil Record
Dec 31, 2015
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