Aerosaurus wellesi, new species, a varanopseid mammal-like reptile (Synapsida : Pelycosauria) from the Lower Permian of New Mexico

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Abstract
Aerosaurus wellesi n. sp. is based upon two nearly complete articulated skeletons from the Lower Permian deposits near Arroyo del Agua, New Mexico. Study of these superbly preserved specimens indicates that the genus Aerosaurus is distinguishable from most other pelycosaurs, including Varanops and Varanodon, in having fewer maxillary and dentary teeth, all of which are more laterally compressed and more strongly recurved. The parasphenoid is uniquely expanded laterally and posteriorly, and bears rows of teeth on ridges. Aerosaurus also differs from all other pelycosaurs in which the braincase is adequately known in the formation of the dorsum sellae mainly from the basisphenoid. Aerosaurus was probably an aggressive predator of lizard-like habitus, with an unusually long tail for a pelycosaur. Aerosaurus, Varanops, and Varanodon are the only pelycosaurs that can be included in the family Varanopseidae with certainty; however, Basicranodon may also be a varanopseid. The possibility that the alleged antorbital fenestra in Varanodon may be artificial casts further doubt on the suggestion that Varanodon, and by extension the Varanopseidae, was involved in the ancestry of archosaurs.