A new dissorophid (Temnospondyli, Dissorophoidea) from the Early Permian of New Mexico (United States)

Abstract

An amphibian skull and partial skeleton found from the El Cobre Canyon Formation of New Mexico, USA, is identified as a new species of the dissorophoid temnospondyl genus Broiliellus. Significant anatomical features include: a relatively long, narrow preorbital region, with both nasals and vomers no more than half as wide anteriorly than posteriorly; extended ventral projection of the postorbital; a unilaterally retained lateral exposure of the ectopterygoid (in addition to the normally present lateral exposure of the palatine); supratemporal lacking a semilunar flange; highly vaulted vomers forming a median internasal septum; and an angular with a swollen posteroventral keel. Phylogenetic analysis strongly supports a sister group relationship with Broiliellus brevis and clearly distinguishes it from another dissorophoid, ‘B.’ novomexicanus from New Mexico. The medially restricted supraneural osteoderms are more similar to those seen in Cacops than Broiliellus, which reinforces the importance of avoiding using single ‘key features’ to discriminate taxa.