Family SPHENACODONTIDAE
Thrausmosaurus serratidens new genus and new species
(Thrausmosaurus is formed from the neuter Greek noun, thrausma, meaning fragment, and the masculine Greek noun, sauros, meaning reptile. The specific name, serratidens, is formed from the Latin serratus, meaning serrate, and the masculine Latin noun, dens, meaning tooth. The specific name is used as a substantive in apposition with the generic name.)
Type specimen.—Fragmentary left dentary, bearing five teeth, the most posterior of which is broken at the base, KU 11120.
Referred specimens.—Fragmentary ?left maxilla, having two teeth, KU 11121; fragmentary left dentary having two teeth, KU 11122.
Horizon and locality.—From the early Permian fissure deposits in the Arbuckle limestone of the Dolese Brothers Limestone Quarry, approximately 6 miles north of Fort Sill, in sec. 31, T. 4N, R. 11 W, Comanche County, Oklahoma.
Diagnosis.—Small; teeth thecodont, compressed laterally, recurved distally, and bearing anterior and posterior cutting edges; anterior serrations limited to recurved portions of teeth, posterior serrations extending nearly entire length of teeth; lateral compression of teeth more pronounced medially than laterally; bases of teeth expanded.
Description.—The type specimen is 16 mm. long. It bears five teeth that are implanted in a straight row. Empty sockets are present between the first and second teeth, and the third and fourth teeth. The first tooth is 3.0 mm. long, the middle two are each 2.5 mm. long, and the fourth tooth is 2.0 mm. long. The fifth tooth is broken off at its base.
The empty sockets are large. The mouth of each is circular and approximately 2.0 mm. in diameter. Both sockets are 1.25 mm. deep. The bases of the teeth are expanded to fill the sockets, although the blades of the teeth arise from only the lateral portions of the bases. The edge of the dentary rises above the bases of the teeth medially, thereby producing a small depression at the junction of each base with the dentary bone.
The lateral compression of the teeth is pronounced but asymmetrical, in that the lateral surface of each blade is more convex than the medial surface.