The type and only species was described by R. C. Fox in 1962, from three fossilized jaw fragments bearing teeth.

[1] The specimens were recovered from the fissure-fill deposits uncovered in a Limestone Quarry, north of Fort Sill, Comanche County, Oklahoma, USA.

[2] Thrausmosaurus was designated by Fox to belong to the family Sphenacodontidae based on the structure and curvature of the teeth.

[2] In 1986 the type specimen was reassigned to Synapsida incertae sedis by R. R. Reisz, who was unable to identify the relationship of the material to other synapsids.

However they were unable to determine enough distinct characters to maintain the species Thrausmosaurus serratidens, and thus declared the name nomen dubium.