Life Science Dictionary10 terms

Paleontology Terms

Paleontology studies the history of life through fossils. These terms cover how fossils form and are dated, the geologic time scale, landmark events such as the Cambrian explosion and the mass extinctions, and the dinosaurs and early humans known from the fossil record.

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C

Cambrian explosionPaleontologyThe Cambrian explosion is the relatively rapid appearance of most major animal groups in the fossil record, beginning about 540 million years ago.

D

DinosaurPaleontologyA dinosaur is a member of the reptile group Dinosauria, which dominated life on land for most of the Mesozoic Era and survives today as the birds.

E

ExtinctionPaleontologyExtinction is the permanent loss of a species, which happens when the last living individual of that species dies.

F

FossilPaleontologyA fossil is any preserved evidence of past life in rock or sediment, from bones, shells and leaves to footprints and burrows.

G

Geologic time scalePaleontologyThe geologic time scale divides Earth's 4.6-billion-year history into eons, eras, periods and epochs, marked by events in the rock record.

H

HomininPaleontologyA hominin is any member of the human lineage, the group of species, including modern humans, that are more closely related to us than to chimpanzees.

I

Index fossilPaleontologyAn index fossil is the fossil of a widespread, short-lived species used to identify and match rock layers of the same age in different places.

M

Mass extinctionPaleontologyA mass extinction is an event in which a large share of Earth's species, often three-quarters or more, dies out in a geologically short time.

R

Radiometric datingPaleontologyRadiometric dating is a method of finding the age of rocks, fossils or artifacts by measuring how much of a radioactive isotope in them has decayed.

T

Trace fossilPaleontologyA trace fossil is preserved evidence of an ancient organism's activity, such as a footprint, burrow or dropping, rather than a part of its body.

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