Palaeontology

Fossils are formed when plants and animal remains are preserved in rocks due to the organisms dying and layers of sediment being deposited on top of the plant or animal remains over time.Each stratum represents a different geological era.Older fossils are found in lower strata and the most recently fossilised organisms are found in the top strata.Fossils of the simplest bacteria are found in the oldest rocks whilst fossils of more complex organisms are found in more recent rocks.The sequence matches their ecological links; plant fossils are found before animal fossils.Scientists can study the similarities between the anatomy of fossils and build up a picture of evolutionary relationships.Fossils allow relationships between extinct and extant(living) species to be determined.