Phylogenetic relationships and biogeographic history of Paradolichopithecus sushkini Trofimov 1977, a large-bodied cercopithecine monkey from the Pliocene of Eurasia

Paradolichopithecus sushkini Trofimov 1977 is a cercopithecine monkey discovered from the late Pliocene of Kuruksay, southern Tajikistan. Despite the baboon-like appearance of the skull, detailed analysis of the inner structure of the rostrum with computed tomography revealed that P. sushkini has a maxillary sinus, which occurs only in macaques among the living cercopithecoids. This observation suggests that Paradolichopithecus may belong to the lineage of the macaques rather than to that of the baboons. This fact and the fossil records of Eurasian cercopithecines together suggest that Paradolichopithecus diverged from European Macaca as early as the early Pliocene, and then dispersed into eastern Eurasia. Although the dispersal route of the Asian cercopithecines, Macaca, has so far been discussed only in the context of South Asian geographical changes, the distribution pattern of the Paradolichopithecus fossil localities may indicate a more northern dispersal route, such as via Central Eurasia rather than a southern route, such as via South Asia.