New Data on Trematosauroid Labyrinthodonts of Eastern Europe: 5. Genus Thoosuchus Efremov, 1940

Abstract

Abstract: The trematosaurid genus Thoosuchus Efremov, 1940, which is the type genus for the subfamily Thoosuchinae, is revised and its diagnosis is emended. This genus includes T. yakovlevi and T. tuberculatus, previously identified from the Rybinskian Regional Stage (Lower Triassic, Lower Olenekian), and the new species T. abbasovi sp. nov. The morphotype of the latter species is characterized by a number of apomorphic characters typical of more recent trematosaurid subfamilies: Platysteginae and Trematosaurinae (widely spaced orbits, the absence of an anteromedial projection of the postorbital, a narrowed middle ear cavity, a flattened depressor part of the lamina ascendens, and a well-developed crista posterior on the pterygoid), which is consistent with the later (Sludkian) age of the new species.