Fossils help in deciding the evolution of species.We can identify some similar features of the fossils with the living species.We can see that evolution that has taken place in different species.For example,the fossil of a tiny dinosaur Archaeopteryx show that it has wings(small),the main purpose was for insulation.But the dinosaurs for different reasons tried to fly.This gave rise to Birds.After the dinosaurs extinction, large birds have come into scenario.Due to reasons like natural selection, adaptation,genetic drift .Birds have evolved,actually birds have evolved from reptiles.
The roles of fossils are:
1. They tell us about the similarities.
2.They tell us approximately how long ago these species evolved from old species.