TETRAPODS FROM THE GERMAN BUNTSANDSTEIN (TRIASSIC: OLENEKIAN-ANISIAN): EVIDENCE ON TETRAPOD DIVERSIFICATION IN LAURASIA FOLLOWING THE END-PERMIAN EXTINCTION

Following the end-Permian biotic crisis, reptiles rapidly diversified and dispersed across the globe at the beginning of the Triassic Period. Non-mammalian synapsids became much less abundant and had massive losses in diversity during the end-Permian event. To date, the fossil record of continental tetrapods has largely been restricted to the Karoo of South Africa and European Russia. In the Central European Basin, Early and early Middle Triassic continental red beds are collectively referred to as the Buntsandstein Group. Whereas the strata of the Lower Buntsandstein are largely unfossiliferous, those of the Middle and Upper Buntsandstein have yielded many tracks and trackways representing a great diversity of tetrapods and occasionally skeletal remains of tetrapods. Temnospondyl stem-amphibians were common with a variety of ecomorphs. A sandstone quarry at Rotfelden in the Black Forest region (Germany) exposed a 6-to-8-m-thick section within the top of the Röt 4 Subformation. Tetrapod remains have been recovered from several horizons in this section. Previously, Amotosaurus rotfeldensis, a tanystropheid archosauromorph and the temnospondyl Eocyclotosaurus lehmani have been reported from this locality. New discoveries include a new Euparkeria-grade archosauriform and a rhynchosaur. The latter is documented by a group of three juvenile skeletons. The absence of unambiguous records of non-mammalian synapsids in the Buntsandstein is possibly related to environmental factors. The growing number of tetrapod taxa from the Buntsandstein suggests that assemblages of continental tetrapods had already recovered to a considerable extent 6-7 million years after the end-Permian extinction.