Diversity of Amphicyonidae (Carnivora, Mammalia) in the Middle Miocene Halamagai formation in Ulungur River area, Xinjiang, Northwestern China

Amphicyonidae is one of the most widely distributed families of Carnivora in the Early and Middle Miocene, yet the fossil record of this family is extremely poor in Eastern Asia. In this study, we report an unanticipated diversity of Amphicyonidae from the Middle Miocene Halamagai Formation in Ulungur River area, Xinjiang, Northwestern China. At least five species of very different size: Amphicyon ulungurensis (including Amphicyon cf. ulungurensis), Gobicyon zhegalloi, Cynelos cf. bohemicus, Cynelos aff. helbingi and cf. Cynelos sp. based on rare teeth and postcranials were found in the Halamagai Formation. Such diversity of amphicyonids from East Asia is previously unrecorded and indicates the probable presence of a representative Mid-Miocene amphicyonid guild. The geographic location of these species supports the existence of a Palaearctic Neogene faunal exchange of amphicyonids between Europe and East Asia during the early Middle Miocene interval.