Acleistorhinidae

Delorhynchus is an extinct genus of acleistorhinid stem reptile known from the late Early Permian (Artinskian age) Garber Formation of Comanche County, Oklahoma. It contains three species: the type species D. priscus is based on a series of maxillae. The second species to be described, D. cifellii, is known from a larger number of well-preserved skulls and skeletal material. The third species, D. multidentatus, is based on a fragmentary skull with several rows of teeth on its jaw.

Colobomycter is an extinct genus of acleistorhinid parareptile known from the Early Permian of Oklahoma.

Acleistorhinus (ah-kles-toe-RYE-nuss) is an extinct genus of parareptile known from the Early Permian (middle Kungurian stage) of Oklahoma. It is notable for being the earliest known anapsid reptile yet discovered. The morphology of the lower temporal fenestra of the skull of Acleistorhinus bears a superficial resemblance to that seen in early synapsids, a result of convergent evolution. Only a single species, A. pteroticus, is known, and it is classified in the Family Acleistorhinidae, along with Colobomycter (also from the Early Permian of Oklahoma).