Fossils give evidence about:
(a) The organism and their paleobiology
(b) Even an organism’s behaviour can be inferred to some extent. For instance, palaeontologists have discovered a site with more than 10,000 Hadrosaurus dinosaur skeletons. This suggests that the dinosaurs were a herd animal.
(c) Fossils shed light on how animals and plants have developed over time (for instance, palaeontologists have discovered that whales had evolved from goat-sized land-dwelling animals called Pakicetus).