Morphology and ontogeny of the humerus of the Triassic temnospondyl amphibian Metoposaurus diagnosticus

Abstract

A morphology of 22 humeri of Metoposaurus diagnosticus from Late Triassic assemblage of Krasiejow (P oland) reveals general metoposauroid conditions, being w ell-ossified with w elldeveloped processes and wide, flattened ends. These characteristics do not occur in the humer us referred to as M. diagnosticus by FRAAS, proving the improper identif ication of this specimen. In contrast to other metoposauroid species’ humeri, they exhibit a smaller de gree of torsion of the ends, unrelated to absolute size. Together with the unscre wed head shape, ob lique position of the condylus radialis, less prominent processus supinatorius and crista deltopectoralis, these indicate a paddle function of the forelimbs and therefore impl y a fully aquatic mode of life for M. diagnosticus.