A New Eryopid Temnospondyl From Early Permian Germany

An Eryops-like interclavicle from the Early Permian of the Saar-Nahe Basin, and a discussion of temnospondyl interclavicle characters

Authors:

Witzmann et al

Abstract:

A large, isolated temnospondyl interclavicle from Rockenhausen, Rhineland-Palatinate, is described that is derived from the Early Permian Meisenheim Formation of the Saar-Nahe Basin, south-western Germany. The element resembles closely the interclavicle of the North American genus Eryops in the following characters that justify its assignment to an eryopid temnospondyl: (1) The broad-ovate shape with a narrow, convex anterior margin and slightly convex or straight anterolateral margins, and the length-to-width ratio of approximately 0.7; (2) the ventral surface with a raised triangular field and the irregular dermal sculpture consisting of transversely oriented ridges, furrows and pits; (3) the anteroposteriorly shortened clavicular facets. The interclavicle from Rockenhausen represents the first unambiguous remain of an eryopid in the Saar-Nahe Basin. In contrast to dissorophoid and stereospondylomorph temnospondyls that constitute autochthonous faunal elements in the lakes of the Saar-Nahe Basin, eryopids seem to be allochthonous and might have been washed in from more distant habitats. Comparison of the morphologies and proportions of temnospondyl interclavicles suggests that the plesiomorphic state for temnospondyls is a proportionally small interclavicle equal in length and width or slightly longer than wide. Interclavicles that are broader than long are a derived character of zatracheids, certain dissorophoids (branchiosaurids) and Eryops and the specimen from the Saar-Nahe Basin, but evolved convergently in these groups. The much enlarged, elongate interclavicles appear to be a synapomorphy of stereospondylomorphs.