Paleontology

Paleontology is the scientific study of life that existed in the geological past, based mainly on the evidence preserved in fossils. It reconstructs the history of living things over hundreds of millions of years, tracing how organisms appeared, changed and became extinct. The field draws on biology and geology, using the remains and traces of ancient organisms to understand the development of life and the changing conditions of the Earth.

Fossils are the preserved remains or traces of once-living things, such as bones, shells, leaves, footprints and burrows. Most fossils form when an organism is rapidly buried in sediment, which over long periods hardens into rock; minerals may gradually replace the original tissues, turning them to stone. Because sedimentary rock builds up in layers over time, deeper layers are generally older, and the fossils within them record the sequence in which different forms of life existed. Famous exposures such as the Grand Canyon reveal these layered rocks across vast spans of time.

Paleontology also studies how the Earth itself has changed. Paleogeography reconstructs the past positions of continents and oceans, which have shifted over geological time as tectonic plates moved, while paleoclimatology examines ancient climates recorded in rocks and fossils. Paleomaps are reconstructions showing where land and sea lay in earlier eras. By combining fossil evidence with the study of rocks, paleontologists build a picture of how life and the planet have evolved together.

Frequently asked questions

What is a fossil?

A fossil is the preserved remains or trace of an organism from the geological past, such as bones, shells, imprints or footprints, usually found within sedimentary rock.

How do most fossils form?

Most fossils form when an organism is quickly buried in sediment that hardens into rock over time, with minerals often gradually replacing the original material and turning it to stone.

What is paleogeography?

Paleogeography is the study of the Earth's geography in the past, reconstructing where continents, oceans and climates were located in earlier geological eras.