new aardwolf-line fossil hyena from Middle and LateMiocene deposits of Linxia Basin, Gansu, China

he aardwolf Proteles cristatus is the only known hyaenid, living or extinct, to exhibitan extremely reduced dentition related to its termite-specializing diet. The fossil record of extantaardwolves extends to 2 to 4 million years ago, but records that inform its evolutionary originsare essentially nonexistent. Such circumstance renders it difficult to place this unusual hyena inthe 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 basedon a skull with associated mandible, a rostrum preserving several teeth, and several referredspecimens. The new specimens were discovered in Neogene deposits in Linxia Basin, GansuProvince, China. Phylogenetic analysis indicates that among early hyaenids, G. megalotis is mostclosely related, but unlikely ancestral, to the living aardwolf. Also recognized in this new speciesare the fossils previously referred to “Protictitherium” aff. P. gaillardi from Pasalar, Turkey.Additionally, “Plioviverrops” guerini from Los Mansuetos, Spain is interpreted to represent asecond Gansuyaena species. In addition to the living aardwolf, Proteles cristatus, our analysessuggest that the proteline lineage includes the extinct genera Gansuyaena, Mesoviverrops, andPlioviverrops. Although the precise timing and geographic location of evolutionary divergencebetween the aardwolf and Gansuyaena remain elusive, critical new morphological informationprovided by Gansuyaena specimens reinforce findings from recent genomic analyses that theaardwolf lineage has an ancient origin from small-bodied stem hyaenids prior to the appearance oflarge and robust bone-cracking hyaenines.