Paleontology Glossary

The rapid diversification of a single lineage into many species, each adapted to different ecological niches.

An extinct group of marine cephalopod mollusks with coiled shells, important index fossils for Mesozoic rocks.

The use of fossil organisms to date and correlate sedimentary rock layers.

The rapid appearance of most major animal phyla in the fossil record approximately 541 million years ago.

A classification method based on shared derived characteristics to reconstruct evolutionary relationships.

The independent evolution of similar traits in unrelated lineages subjected to similar environmental pressures.

Fossilized feces that provide information about the diet and behavior of ancient organisms.

The physical, chemical, and biological processes that alter sediments after deposition and during lithification.

The largest division of geologic time. The four eons are Hadean, Archean, Proterozoic, and Phanerozoic.

The complete disappearance of a species when no individuals remain alive anywhere on Earth.

The totality of fossils, both discovered and undiscovered, representing a chronological archive of life on Earth.

A southern supercontinent comprising South America, Africa, Antarctica, India, and Australia that existed from the Neoproterozoic to the Jurassic.

The time required for half of a radioactive isotope to decay. Used in radiometric dating to determine absolute ages.

A fossil species used to define and correlate the age of rock strata, ideally widespread and short-lived.

A sedimentary deposit that exhibits extraordinary fossil preservation, either in quality (conservation) or quantity (concentration).

The geologic era spanning 252-66 million years ago, subdivided into the Triassic, Jurassic, and Cretaceous periods. Known as the 'Age of Reptiles'.

The branch of paleontology dealing with the study of fossil plants.

The study of ancient ecosystems, including the relationships between fossil organisms and their environments.

A supercontinent that included most of Earth's landmasses, assembled in the late Paleozoic and began rifting in the Triassic.

A fossilization process in which minerals are deposited in the cellular spaces of organic remains.

A technique using the decay rates of radioactive isotopes to determine the absolute age of geological materials.

Layers of sedimentary rock deposited over time, forming the physical record studied in stratigraphy.

The principle that in an undisturbed sequence of sedimentary rocks, the oldest layers are at the bottom and the youngest at the top.

The study of the processes of fossilization, from death and decay through burial and diagenesis.

An extinct group of marine arthropods that thrived throughout the Paleozoic Era, important as index fossils and among the earliest known complex animals.