Abstract

The aardwolf Proteles cristatus is the only known hyaenid, living or extinct, to exhibit an extremely reduced dentition related to its termite-specializing diet. The fossil record of aardwolves is essentially nonexistent, rendering it difficult to place this unusual hyena in the broader evolutionary context of small-bodied hyaenid species in Eurasian Neogene deposits. Here we describe a new genus and species of a small-bodied hyaenid, Gansuyaena megalotis, representing the closest morphological link to aardwolves to date. This new fossil hyena is based on a skull with associated mandible, a rostrum preserving several teeth, and several referred specimens. The new specimens were discovered in Neogene deposits in Linxia Basin, Gansu Province, China. Phylogenetic analysis indicates that among early hyaenids, Gansuyaena megalotis is most closely related to the living aardwolf. Also recognized in Gansuyaena are the fossils previously referred to “Protictitherium” aff. gaillardia from Pasalar, Turkey, and “Plioviverrops” guerini is interpreted to represents a second Gansuyaena species. In addition to the living aardwolf, Proteles cristatus, our analyses suggest that the proteline lineage includes the extinct genera Gansuyaena, Mesoviverrops, and Plioviverrops. Although the precise timing and geographic location of evolutionary divergence between the aardwolf and Gansuyaena remain elusive, critical new morphological information provided by Gansuyaena specimens contradicts previous molecular phylogenetic analysis suggesting a hyaenine origin for Proteles. Instead, our analyses suggest the aardwolf lineage has a more ancient origin from small-bodied stem hyaenids prior to the appearance of large and robust bone-cracking hyaenines.