The index fossil are the fossils that are of animals and plants that remained preserved in the rock of the earth. It describes the particular span of the geological time or the environment. An index fossil can be easily recognized, is widely distributed and abundant.
The index fossil is the basis for defining the boundaries of the geological time scale with the correlation of the strata.
Those organisms which exhibited the short vertical range that is the life span on earth and the wide lateral range that is geographic distribution can be included as index fossil.
These fossils are indicative of the environment in which the organism used to live.
