New material of Colobomycter pholeter, a small parareptile from the Lower Permian of Oklahoma

ABSTRACT

A new specimen of the parareptile Colobomycter pholeter, from the Lower Permian Dolese Brothers Quarry near Fort Sill, Oklahoma, preserves previously unknown portions of the skull, including the premaxilla, elements of the palate, and the sphenethmoid. The premaxilla houses two teeth, of which the first is caniniform in size. The pattern and the morphology of the upper dentition indicates that C. pholeter was a small faunivore. Fortuitous damage to the dentition reveals that the large marginal teeth are polyplocodont, the simplest kind of folded teeth. The folding may have strengthened the crowns of teeth, which were otherwise relatively thin-walled in C. pholeter. Considering its small size, C. pholeter was either an insectivore that specialized on prey with hard exoskeletons, or an insectivore that was facultatively carnivorous, capable of taking other small vertebrates as opportunities arose. Folded teeth appear not to be a rare phenomenon among parareptiles, but given the lack of detailed descriptions of the dentition for many parareptiles, the evolutionary history of polyplocodont teeth in this group requires further investigation. Phylogenetic analysis of an augmented data matrix from the literature supports the hypothesis of a sister-group relationship between C. pholeter and the lanthanosuchoid Acleistorhinus pteroticus.