Comparative observations on some middle and upper miocenehyaenids,Genera: PercrocutaKretzoi, AllohyaenaKretzoi, AdcrocutaKretzoi (Mammalia,Carnivora, Hyaenidae)

This study deals with the «percrocutoid hyaenids,present in Eurasia and in Africa in faunas of late Middle Miocene (Astaracian) to terminal Miocene (Vallesian, Turolian) age. These hyaenid species are characterized by certain dental apomorphies (loss of M^2/2, specialization of the carnassials P⁴/M₁, tendency for the hypertrophy of the anterior premolars) which differentiate them from other hyaenids with which they are found associated. In recent literature, these hyaenids have been attributed to the genera PercrocutaKretzoi and AdcrocutaKretzoi, the latter of which is monospecific. In fact some should be removed from the genus Percrocuta and assigned to the genus AllohyaenaKretzoi, itself subdivided into the two subgenera, AllohyaenaKretzoi and DinocrocutaSchmidt-Kittler. The genus Adcrocuta is retained and the characters which distinguish this genus from HyaenictisGaudry are discussed.This study is based on revision of all, or nearly allsuch specimens, described and figured or in collections, of which certain among them have been hardly or poorly known. Particular attention has been given to their geologic age and their distribution in Neogene mammalian faunas (Mein's zones). Their apomorphies, considered in relation to their temporal distributions, permit an interpretation of the phylogenetic relationships of their several lineages which is consistant with the proposed systematic revision of the group.The radiation of «percrocutoid hyaenids would appear to have occurred in three phases. At the beginning of the Astaracian, after the dispersal of Anchitherium, the genus Percrocuta appeared with several species of relatively small size; in Eurasia this genus does not seem to have persisted after the middle Astaracian, although it did so in the sub-Himalayan Siwaliks. At the end of the Astaracian it was apparently succeeded by the genus Allohyaena, and resulting in gigantic forms (subgenus Dinocrocuta) coincident in Eurasia and in Africa with the extension of Hipparion. The third phase of the radiation is represented by the genus Adcrocuta, which unlike the others, was monospecific. This single species, A. eximia, occurs initially, and very rarely in the upper Vallesian; however, in the middle Turolian it is common and widespread throughout Eurasia where it, perhaps, limited the expansion of Dinocrocuta.