New evidence for the unique coexistence of two subfamilies of clawed perissodactyls (Mammalia, Chalicotheriidae) in the Upper Miocene of Romania and the Eastern Mediterranean

Abstract

Chalicotheres are a peculiar group of large herbivorous mammals, closely related to extant tapirs, rhinoceroses, and horses, but with large claws instead of hooves. The family Chalicotheriidae consists of two subfamilies, the Schizotheriinae and the Chalicotheriinae. Herein we present chalicothere remains from the Upper Miocene locality of Pogana 1 in Romania, identifying the schizotheriine Ancylotherium pentelicum and an indeterminate chalicotheriine that were both found in the same stratigraphic layer. Thus, the Pogana 1 locality represents one of the very few confirmed cases of the co-occurrence of the two subfamilies within one fossiliferous horizon in the same fossil site. A detailed review of all localities where the two subfamilies have been reported to co-occur shows that this is a rare phenomenon that is almost exclusively observed in the Turolian of the Balkan-Iranian zoogeographical province. This is probably due to provincial differences in the palaeoenvironment. The data presented here support the hypothesis of a diverse mosaic environment in the Balkan-Iranian province with both closed environments and open habitats that was able to sustain a rich and diverse large mammal fauna.