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Rhynchosaurs (meaning "beaked lizards") were a group of unusual herbivorous quadrupedal archosauromorphs that lived during the Triassic period. Rhynchosaurs ranged in size from the 50 cm long Rhynchosaurus to the 2 meter (6 feet) long Hyperodapedon, with the average size being 1 meter (3.3 feet). Rhynchosaurs were a widespread and worldwide taxon, being found all across the supercontinent of Pangaea. Rhynchosaur fossils have been found in Britain, South Africa, Zimbabwe, Tanzania, Madagascar, India, Brazil, Argentina, Canada and the United States, although they are poorly represented in the Northern Hemisphere fossil record. 15 species are currently regarded as valid, and another five are valid taxa still in need of a name. In some fossil assemblages, several taxa lived alongside one another, as evidenced by the four contemporaneous species were contemporaneous in the Upper Triassic Santa Maria Formation of Brazil. Rhynchosaurs went extinct during the Permian-Triassic extinction event that marked the end of the Carnian stage of the Late Triassic. Rhynchosaur fossils are very abundant in some assemblages (in some fossil localities accounting for 40 to 60% of specimens found) and the anatomy and ontogeny of a few species is comparatively well known. Early primitive forms like Mesosuchus and Howesia were more typically lizard-like in build, and had skulls rather similar to the early diapsid Younginia, except for the beak and a few other features. (Read more...)

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