Early Permian chondrichthyans of the Middle and South Urals

Abstract

Very diverse Early Permian chondrichthyan assemblages occur in the Asselian to Artinskian of the Middle and South Urals. They include numerous symmoriid teeth of “Denaea” decora Ivanov, Cobelodus obliquus sp. nov., Stethacanthus and Denaea; the teeth of the ctenacanthoid Heslerodus; the teeth of the synechodontiform Synechodus antiquus sp. nov.; and the teeth of taxa of doubtful affinities – Adamantina foliacea Ivanov, Cooleyella cf. C. fordi (Duffin & Ward), Cooleyella sp. A., as well the scales and denticles of various types. Two new species, Cobelodus obliquus and Synechodus antiquus, are described herein. The Early Permian chondrichthyan assemblages of Urals include a few taxa occurring only in that interval, as well taxa which were distributed in the Carboniferous and persisted into the Early Permian, such as Stethacanthus, Cobelodus, Denaea, “Denaea”, Lissodus, Heslerodus, “Symmorium”, Petalodus, Cooleyella and Adamantina. This occurrence of a synechodontid is the oldest in the world. The symmoriid sharks disappeared in the Middle Permian. The Permian shark faunas of the Urals contain a diverse assemblage of symmoriids, ctenacanthiods and synechodontiforms, but there are no xenacanthids were common in the Permian assemblages of Western Europe