FossilsChapter 21.4

fossil: remains or evidence of living things

(1) original remains: the actual, unchanged remains of the organism are preserved

(a) frozen in ice

(b) preserved in amber(tree sap that has hardened

(c) mummification

(2) replaced remains: soft parts of the organism have disappeared and been replaced by minerals

petrification

(3) molds and casts of the original organism(4) trace fossils: evidence of life other than remains of an organisms activities and/or appearance

(a) footprints

(b) imprint

(c) tracks, trails, burrows, borings

coprolites: fossilized dung or waste materials from ancient animals

T-Rex Carnivore Coprolite (8 lbs.)

gastroliths: fossilized stone found within the digestive system of a dinosaur or other reptile

index fossil: fossils found exclusively in rock record of a particular geologic age•must have (4) characteristics:(1) must be easily recognizable(2) must be widespread in occurrence(3) must be limited in time(4) must be found in large numbers with the rock layer