Index Fossil Definition Geologic Time. List of index fossils and geologic time scale · see more » inoceramus. [ ĭn ′dĕks′ ] the fossil remains of an organism that lived in a particular geologic age, used to identify or date the rock or rock layer in which it is found.
Index fossils must have a short vertical range, wide geographic distribution and rapid evolutionary trends. List of index fossils and geologic time scale · see more » inoceramus. An index fossil is a fossil representing a plant or animal that existed for a relatively short duration of time.
Rocks formed during the proterozoic eon may have fossils of relative simple organisms, such as bacteria, algae, and wormlike animals.
First appearances of new species ; A fossil usually with a narrow time range and wide spatial distribution that is used in the identification of related geologic formations examples of index fossil in a sentence The fossil remains of an organism that lived in a particular geologic age, used to identify or date the rock or rock layer in which it is found. List of index fossils and geologic time scale · see more » inoceramus.