A new dissorophoid temnospondyl from the Allegheny Group (Late Westphalian, Carboniferous) of Five Points, Mahoning County, Ohio (USA)

A small temnospondyl skull from the Upper Carboniferous Allegheny Group of Five Points, Ohio, is referred to a new dissorophoid, Palodromeus bairdi n. gen n. sp. The complete skull with mandibles is preserved in counterparts. It is characterized by (1) elongated slit-like choana, (2) postfrontal, postorbital, and supratemporal bearing a distinct ridge, and (3) reduced parietal only two-thirds the length of the frontal. Phylogenetic analysis confirms a dichotomy between amphibamiforms and olsoniforms and places Palodromeus bairdi at the base of the olsoniforms, revealing an early stage in the evolution of that clade.