Burnetiidae derived from a sister to Hipposaurus, the Burnetidae were basal kynodont therapsids from the Middle to Late Permian that evolved bizarre skull ornamentation.
Rubidge and Sidor report, "The systematic position of the Burnetiidae has been unsure
largely because of a poor understanding of the cranial morphology
of these two enigmatic skulls. In the past they have
been considered gorgonopsians (Boonstra, 1934; Haughton and
Brink, 1955; Sigogneau, 1970), dinocephalians (von Huene,
1956), and more recently, biarmosuchians (Hopson and Barghusen,
1986; Sigogneau-Russell, 1989). Like Gorgonopsids, this clade has anterior facing nares and a proparietal by convergence.
Ictidorhinus martinsi (Broom 1913) is the most primitive bernetid. It was also transitional between Hipposaurus and Biarmosuchus.
Herpetoskylax hopsoni (Sidor and Rubidge 2006; CGP/1/67; Late Permian) had a longer rostrum and a more gracile cheek arch. Note the progressive lengthening of an overlapping spur of the lacrimal on the jugal.
Lemurosaurus pricei (Broom 1949, Sidor and Welman 2003; BP/1/816, NMQR 1702) developed tall ridges over the eyes and had intermeshing teeth. The nubbin like boss is the supratemporal. The postcanine teeth bore a coarsely serrated
posterior margin. Several antorbital fossae appear.
Proburnetia viatkensis (Tatarinvov 1968, Rubidge and Sidor 200; PIN 2416/1) had a wider skull and larger protrusions including supratemporal horns in the back.
Burnetia mirabilia (Broom 1923, Rubidge and Sidor 2002; BMNH R5397) had a flatter, wider skull with exceptional skull ornamentation. The premaxilla was essentially toothless. The squamosal cheeks flared widely.