Parioxys ferricolus is a long-neglected taxon of dissorophid temnospondyls from the early Permian (Cisuralian) of Texas. Reexamination of the original material and preparation of a previously undescribed specimen sheds some light on ontogeny and reveals numerous eucacopine features. P. ferricolus is characterized by (1) a preorbital region 1.5 times as long as the posterior skull table in juveniles and twice as long in adults, (2) parietal only two-thirds the length of the frontal, and (3) interpterygoid vacuities shorter than half the skull length, (4) choanae posteriorly extended, and (5) vomer with enlarged, V-shaped medial depression. P. ferricolus is found nested with Kamacops acervalis, with which it shares synapomorphies in the palate, within the dissorophid clade Eucacopinae.

Character-taxon matrix and description of morphological characters.

Data set was analyzed with TNT.