Acleistorhinus pteroticus (Daly 1969) Early Permian, ~3.5 cm skull length was consiered by DeBraga (2001, 2003) to be a Parareptile related to Lanthanosuchus, which is a mismatch. Here Acleistorhinus is derived from a sister to the RC14 specimen of Milleretta and phylogenetically preceded Eunotosaurus.
Distinct from RC14, the skull of Acleistorhinus was further downturned anteriorly. The maxilla ascended to cut off the lacrimla from the naris and to contact the prefrontal. The jugal separated from the squamosal creating a lateral temporal fenestra. The supratemporal was enlarged. The second half of the skull was expanded laterally, rotating the orbits anteriorly for better binocular vision.
Since both Eunotosaurus and Milleretta had expanded ribs, it is likely that Acleistorhinus did so too.