Definition of aetosaur
: any of an order or suborder (Aetosauria) of extinct, chiefly herbivorous, armored reptiles that lived during the late Triassic period and had a long, narrow body, a small head, and a flat, piglike snout … footprints (actually scrape marks) can also be identified as coming from two other large vertebrates: phytosaurs and aetosaurs, crocodile-like reptiles who lived around the shallow lake. — Jeanne Nicholson Siler, Washington Post, 2 Nov. 1990 Aetosaurs were low-slung animals 1 to 5 metres long with small heads and armoured bodies, built like the ankylosaurs of the dinosaur age or the extinct, car-sized armadillos that died out around 10,000 years ago. — Jeff Hecht, New Scientist, 25 Feb. 2006 ◆Aetosaurs are archosaurs that are closely related to the crocodilians.
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