Cotylorhynhcus romeri (Stovall 1937) Kungurian, Middle Permian, ~265 mya, ~6 m in length, was the largest sister to Casea and Ennatosaurus. It was the largest land animal of its time.
Distinct from Casea, the skull of Cotylorhynchus was smaller and the torso was larger. The skull and mandible were both taller. The jugal was smaller. The squamosal was larger. The nasals were broader anteriorly.
All prior reports nested Cotylorhynchus with the synapsids, but here it nests more parsimoniously with Saurorictus, Australothyris and other plant-eaters in this new clade, many of which share a lateral temporal fenestra.