Paleontology Glossary

Adaptive Radiation

The rapid diversification of an ancestral lineage into many ecological niches following an opportunity such …

Archosauria

The group that includes dinosaurs, pterosaurs, crocodilians, and birds. Archosaurs are distinguished by skull openings, …

Autapomorphy

A derived character state unique to a single taxon, not shared with close relatives. The …

Convergent Evolution

When unrelated organisms independently evolve similar features. Dolphins, ichthyosaurs, and sharks all evolved streamlined body …

Dinosauromorpha

The group containing dinosaurs and their closest relatives. Includes dinosauriforms like Marasuchus and Silesaurus that …

Homoplasy

The independent evolution of similar features in unrelated lineages. Crests evolved independently in multiple dinosaur …

Monophyletic

A grouping that includes an ancestor and all of its descendants, forming a complete natural …

Mosaic Evolution

The concept that different features of an organism evolve at different rates. Archaeopteryx shows a …

Paraphyletic

A grouping that includes an ancestor but excludes some of its descendants. 'Reptilia' in its …

Phylogenetics

The study of evolutionary relationships among organisms. Cladistic analysis of anatomical and molecular data reconstructs …

Plesiomorphy

An ancestral character state retained from earlier ancestors and shared broadly across a group. Five-fingered …

Polyphyletic

A grouping whose members do not all share the same immediate common ancestor, assembled from …

Sister Group

The closest evolutionary relative of a given taxon, sharing an immediate common ancestor. Birds and …

Synapomorphy

A shared derived character state inherited from a common ancestor, used to define a clade. …