Unravelling the origin of the brown hyena (Parahyena brunnea) and its evolutionary and paleoecological implications for the Pachycrocuta lineage

Abstract

The dentition of several species of hyenas within the lineages leading to Parahyaena brunnea and Pachycrocuta brevirostris was analysed from a multivariate point of view. The probable origin of these lineages can be traced back to China in the late Miocene or early Pliocene, from an initial stock that dispersed across the Old World during the Zanclean. This ancestral stock is believed to comprise Parahyaena howelli and Pliocrocuta perrieri from the Zanclean and is suggested to be grouped into Pachycrocuta pyrenaica. The subsequent Pliocrocuta perrieri arose from such a stock and is proposed to be reassigned to Pachycrocuta perrieri. The findings obtained substantiate the hypothesis that Pachycrocuta bellax represents a species distinct from Pachycrocuta brevirostris. Pachycrocuta perrieri is posited as the ancestor of Pachycrocuta brevirostris in Eurasia, and Parahyaena brunnea in Africa. The sequence Pachycrocuta pyrenaica, Pachycrocuta perrieri, and Pachycrocuta brevirostris delineates an evolutionary trend marked by greater specialization in the scavenging niche, manifested through augmented overall dentition size and development of bone-breaking part of the dentition at the expense of a reduction in its cutting region. Present-day forms of Parahyaena brunnea also exhibit such specialization, but the size of the dentition is similar to that of Pachycrocuta perrieri. ‘Hyaena’ prisca is considered a basal form of Parahyaena brunnea, akin to specimens recovered from Elandsfontein approximately 1 million years ago, which recolonized Europe following the extinction of Pachycrocuta brevirostris. The degree of divergence of the extant forms of Parahyaena brunnea from ‘Hyaena’ prisca justifies their classification as distinct species. A proposal is made to integrate both the brown hyena and ‘Hyaena’ prisca into the genus Pachycrocuta.