noun \ˈär-kə-ˌsr\

Definition of ARCHOSAUR

:  any of a subclass (Archosauria) of reptiles comprising the dinosaurs, pterosaurs, and crocodilians
ar·cho·sau·ri·an \ˌär-kə-ˈsr-ē-ən\ adjective or noun


New Latin Archosauria, from Greek archōn + sauros lizard
First Known Use: 1933


noun    (Concise Encyclopedia)

Any of the various advanced reptiles in the subclass Archosauria (“ruling reptiles”), including all thecodonts, pterosaurs, dinosaurs, birds, and crocodilians. The first known archosaurs appeared 242–227 million years ago during the Triassic Period. All early archosaurs possessed an ankle specialization that aided in upright posture, and most had long hindlegs and short forelimbs. Unlike the teeth of earlier reptiles, which were set in a shallow groove, the teeth of archosaurs were (and are) set in sockets.


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