Colosteus scutellatus (Newberry) : a primitive temnospondyl amphibian from the Middle Pennsylvanian of Linton, Ohio. American Museum novitates ; no. 2770

Abstract

"Colosteus scutellatus (Newberry), known exclusively from the classic Coal Measures locality of Linton, Ohio, is the genotype and youngest representative of the Colosteidae, an archaic group of temnospondyls that also includes Pholidogaster and Greererpeton. The colosteids are a monophyletic group distinguished from other temnospondyls by massive stapes and no otic notch; elongate prefrontal contacting narial border, premaxilla, and maxilla; intertemporal reduced or absent with broad postorbital-parietal contact; single pair of premaxillary tusks; and single, elongate Meckelian fenestra. The use of the superfamily Colosteoidea (Tatarinov, 1964) is recommended in the absence of shared derived characters indicating a close relationship between the colosteids and any other known temnospondyls. The structure of the stapes and skull roof suggests that the colosteoids may represent the sister group of all other temnospondyls. An overview of the status of the Temnospondyli indicates that exclusion of the loxommatoids is justified, but that a possible microsaur-temnospondyl relationship circumvents the possibility of temnospondyl monophyly"--P. 2.