Fossils-the remains of an animal or plant preserved from an earlier era inside a rock or other geologic deposit, often as an impression or in a petrified state.
-The age of fossils can be estimated by the depth of layers or rock
-It can also be estimated by the isomers of the fossil contained rocks
-They help up the study and know about those species which are no longer alive
-They also help in forming of pathway on animals through their way of evolution
-Thus we can find the types of organims be it plants animals and microbes that existed at a particular geological time and reconstruct evolutionary process