Nasal anatomy of Paradolichopithecus gansuensis (early Pleistocene, Longdan, China) with comments on phyletic relationships among the species of this genus.

ABSTRACT

Paradolichopithecus was a large cercopithecine primate that existed in Eurasia from the middle Pliocene to the early Pleistocene. Para. arvernensis from the late Pliocene of Senèze, France, shows no maxillary sinus, whereas Para.sushkini from the late Pliocene of Kuruksay, Tajikistan, has this feature. In this study, we examined a new maxillary specimen of Para. gansuensis from the early Pleistocene of Longdan, China. The Longdan maxilla had lost its facial part, which exposed the internal floor of the nasal region. The nasal floor expands laterally, making the maxillary body thin at the P3-M2 level and thick at the M3 level and extending to the maxillary tubercle. Such a topography is seen in the Senèze and Kuruksay crania. The Longdan maxilla shows no evidence of the formation of a maxillary sinus within the inferior portion of the thick maxillary body, as is seen in the Senèze cranium. Such a configuration could reflect the absence of a maxillary sinus in the Longdan specimen. Eastern Para. gansuensis might have dispersed eastward retaining a primitive condition, while central Para. sushkini would have acquired this feature independently in central Eurasia.