Cistecephalidae Broom, 1903 a

Definition: All taxa more closely related to Cistecephalus microrhinus Owen, 1876, than Myosaurus gracilis Haughton, 1917, or Kingoria nowacki (von Huene, 1942) Cox, 1959.

Taxonomic comments: The monophyly of Cistecephalidae, containing the highly specialized, fossorial dicynodonts Cistecephalus Owen, 1876, Cistecephaloides Cluver, 1974, and Kawingasaurus Cox, 1972, has never been called into question. Phylogenetic analyses including all three of these taxa (Angielczyk 2007; Fröbisch 2007; Fröbisch & Reisz 2008) strongly support this grouping.

Revised diagnosis: Autapomorphies of Cistecephalidae recognized in common by Angielczyk (2007), Fröbisch (2007), and Fröbisch & Reisz (2008) are: (1) preparietal absent; (2) postparietal contributes to the intertemporal skull roof; (3) interpterygoid vacuity absent. Extensive postcranial material is not known for Cistecephaloides, but Angielczyk (2007) recognized several postcranial synapomorphies of Cistecephalus and Kawingasaurus: (1) ossified cleithrum present; (2) acromion process absent; (3) procoracoid participates in formation of glenoid; (4) insertion of M. subcoracoscapularis on humerus extended into a distinct process; (5) trochlea and capitellum distinct.