Colobomycter pholeter from the Lower Permian of Oklahoma: A parareptile, not a protorothyridid

Reexamination of the holotype of Colobomycter pholeter and description of a new specimen, from a Lower Permian fissure fill near Richards Spur, Oklaho ma, reveals that this small enigmatic reptile is not the youngest known pro torothyridid, but instead is one of the earliest parareptiles. Parareptilia n apomorphies that are present include an anterior lateral maxillary forame n, a transversely broad antorbital buttress formed by the prefrontal and la crimal, and a single median posterior emargination of the skull roof. The l ast feature is recognized for the first time as a parareptilian synapomorph y. The anterior lateral maxillary foramen of parareptiles is confirmed to b e the lateral egress of a canal that opens into the nasal chamber Colobomyc ter is the sister taxon of the parareptile Acleistorhinus pteroticus, known from the Lower Permian South Grandfield locality of Oklahoma. Together the se two taxa comprise Acleistorhinidae, the oldest known parareptilian clade . The group is diagnosed by two synapomorphies: (I) the largest tooth is po sitioned far anteriorly on the maxilla; and (2) cranial ornamentation compr ises sparse, shallow circular dimples.