Dissorophoid temnospondyl Parioxys from the Permian of Texas

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.