Procolophonids are a group of basal amniotes (the group including mammals, ‘reptiles’, birds, and extinct relatives) known from the Late Permian and Triassic periods. Procolophonids have a body plan much like that of lizards, and some species had cranial ornamentation superficially similar to that seen in horned lizards today. They also have been recently considered close relatives of the ancestors of turtles, a group that also evolved during the Triassic Period.
We report here a single partial skull of a procolophonid from the Late Triassic Period (210 million years ago) of southern Utah. This is the first relatively complete skull of a procolophonid from the western United States. Although the skull is not well enough preserved to establish whether or not it is a new or existing species, enough features are present to show that it is closely related to procolophonids known from the same time in eastern North America and Europe. This adds to evidence that suggests procolophonids were a successful and diverse group up until the end of the Triassic Period (200 million years ago).