PERMIAN TETRAPODS FROM NIGER REFLECT A CENTRAL PANGEAN FAUNAL PROVINCE

The Middle-to-Upper Permian rocks of South Africa's Beaufort Group provide detailed baseline regarding the composition of end-Paleozoic terrestrial ecosystems at high southern paleo-latitudes. Aspects of the Karoo vertebrate fauna can be traced, however, to coeval Gondwanan rocks at lower paleo-latitude (e.g., in Brazil, India, Tanzania, Zambia) as well as into the Northern Hemisphere (e.g., Germany, Laos, Russia). The broad geographic distribution of several genera has been considered compelling evidence for unrestricted dispersal of tetrapods across a coalesced Pangean landscape during the Permian and Triassic. Our recent work in the Upper Permian Moradi Formation of northern Niger has yielded a vertebrate fauna that is strikingly different from those known elsewhere on Africa. In contrast to the broadly distributed fauna known elsewhere, (1) Moradi tetrapods are endemic, and (2) the taxonomic composition of the fauna is unlike that of any other Upper Permian fauna. Abdundant captorhinid (Moradisaurus) and pareiasaur (Bunostegos) reptile remains have been recovered, in addition to two temnospondyl genera (Nigerpeton, Saharastega) that are most closely related to Permo-Carboniferous forms from Euramerica. Most surprisingly, dicynodont herbivores have yet to be discovered in the Moradi Formation, and therapsids as a whole are represented by only two fossils of gorgonopsians. Furthermore, sedimentological geochemical proxies of paleoclimate suggest that the Moradi Formation was deposited under a very arid climate. Based on their faunal and sedimentological similarity, we suggest that the Moradi Formation of Niger and the Ikakern Formation of Morocco together represent examples a distinct central Pangean tetrapod province, likely united by extremely arid conditions prevailing over low-latitudes during Late Permian time.