What is "acleistorhinidae"

Acleistorhinidae is an extinct family of Early Permian-aged ( Artinskian to Kungurian stage) lanthanosuchoid parareptiles. Presently, the clade consists of only two taxa, Colobomycter and Acleistorhinus, both collected from the Permian of Oklahoma. Sister taxa include Chalcosaurus, Lanthaniscus and Lanthanosuchus.

Acleistorhinidae is notable for being the oldest-known parareptilian clade. The family is diagnosed by the presence two synapomorphies: (1) the largest tooth is located far anteriorly on the maxilla; and (2) cranial ornamentation consists of sparse and shallow circular dimples.