A huge Pachycrocuta from the middle pleistocene loess in Luoning County, central China, and the evolution of mandible within Pliocrocuta-Pachycrocuta lineage

Abstract

ABSTRACT The giant hyena Pachycrocuta is one of the iconic components in Eurasia Pleistocene faunas. This genus largely went extinct near the Early-Middle Pleistocene boundary in Europe, but continued to flourish till the early Middle Pleistocene in eastern Asia. However, the Middle Pleistocene Pachycrocuta in eastern Asia is only well represented in Loc. 1, 9 and 13 of Zhoukoudian, and the geographic variation is unknown. Here, a complete mandible is reported from the Middle Pleistocene loess in Luoning, Henan Province, central China. The mandible is similar to that of Pachycrocuta from Zhoukoudian in dental morphology, but is markedly larger, being the largest Pachycrocuta known (the estimated skull total length reaches 385 mm, and the estimated body mass is 150.3 kg). It also displays several unique mandibular traits, e.g., strongly curved toothrow, and elevated condyle. This suggests the presence of geographic or chronological differences between the populations of Pachycrocuta across Asia during the Middle Pleistocene. A gradually increasing depth is observed in the Pliocrocuta-Pachycrocuta lineage during its evolution, until its final extinction.