SO far, workers on the Triassic dicynodonts1–3 have not been able to indicate how this group originated. However, Camp2 has enumerated twelve characters which he thought would be present in their ancestor. Eleven of these characters are found in the Eo-triassic genus Lystrosaurus4. The twelfth, concerning the presence of a cleithral groove, has been shown5 to be not significant. The so-called cleithral grooves found on the scapulae of Triassic dicynodonts can be better interpreted as pre-spinous fossae.