Knowra Dinosaur Dinosaur A member of Dinosauria, a diverse reptile lineage that arose during the Triassic Period. Non-avian dinosaurs went extinct about 66 million years ago; birds are living dinosaurs.
Dinosauria : The clade comprising dinosaurs and all their descendants, including birds. This is the evolutionary group to which every dinosaur belongs.
Dinosaur fossil : Preserved remains or traces of a dinosaur, including bones, teeth, eggs, and footprints. Fossils provide the direct evidence used to identify dinosaur anatomy and behavior.
Triassic Period : The geologic period from about 252 to 201 million years ago, preceding the Jurassic. Dinosaur origins lie within this period's changing ecosystems.
Tyrannosaurus : A genus of large predatory theropod dinosaurs from the Late Cretaceous of North America. Its fossils exemplify the anatomy of a giant, late-appearing predator.
Cretaceous–Paleogene extinction event : A mass extinction about 66 million years ago that eliminated non-avian dinosaurs and many other groups. It ended the era of non-avian dinosaurs while leaving birds alive.
Archosaur : A reptile in the lineage that includes crocodilians, pterosaurs, dinosaurs, and birds. Dinosaurs are one branch of this broader reptile lineage.
Cladistics : A method of classifying organisms by shared derived traits and inferred evolutionary relationships. It helps reconstruct dinosaur family trees from anatomical characters.
Ischigualasto Formation : A Late Triassic rock formation in Argentina preserving some of the earliest known dinosaurs and their relatives. Its fossils document dinosaurs near the beginning of their evolutionary history.
Triceratops : A genus of large, horned ceratopsian dinosaurs from the Late Cretaceous of North America. Its skull illustrates the elaborate defenses and display structures of some herbivores.
Chicxulub crater : A large impact crater beneath Mexico's Yucatán Peninsula, formed about 66 million years ago. Its impact is strongly linked to the extinction of non-avian dinosaurs.
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