On the cranial morphology of the basal therapsidsBurnetiaandProburnetia(Therapsida: Burnetiidae)

The poorly known genera Burnetia and Proburnetia, which are the only members of the therapsid family Burnetiidae, are redescribed and revised generic diagnoses are provided. Both genera are similar in having a prominent antorbital depression, a parasagittal ridge on the basicranial ramus of the pterygoid that extends from the transverse processes to the basisphenoid, a small temporal fenestra with no external area for adductor muscle attachment, and the same complement of bony protuberances on the skull roof including characteristic posteriorly projecting supratemporal “horns” formed by the squamosal and parietal bones. The morphology identified here is consistent with grouping the Burnetiidae in the Biarmosuchia, rather than in the Dinocephalia or Gorgonopsia as has been previously suggested.