New Materials of Protoceratops hellenikorhinus (Neoceratopsia: Protoceratopsidae) in Alxa Region, Inner Mongolia

Three new specimens of protoceratopsid skulls have been discovered recently from the Late Cretaceous Wulansuhai Formation (Campanian) at Bayan Tal locality in Alxa Right Banner, western Inner Mongolia Autonomous Region, northern China. The skull is relatively large, with premaxillary teeth absent. The craniocaudally arranged ridge on the lateral surface of maxilla is generally straight, and comparatively reduced. The ventral edge of dentary is nearly straight. These specimens show the representative characters only present in Protoceratops hellenikorhinus, thus should be assigned to this taxon. Only one genus and species of Protoceratopsidae has been confirmed, i.e. Protoceratops hellenikorhinus, at Bayan Tal locality. This locality becomes the second site yielding P. hellenikorhinus, following Bayan Mandahu locality in Urad Rear Banner, western Inner Mongolia. This protoceratopsid species was the dominant element among the dinosaur faunas at both Bayan Tal and Bayan Mandahu localities, which provides more paleontological evidences for the Late Cretaceous dinosaur faunal similarity between the two sites. P. hellenikorhinus has been only known at Bayan Tal and Bayan Mandahu localities during the Campanian, Late Cretaceous. This fact indicates that there may have existed a vast region in similar paleoenvironment across the western Inner Mongolia at that time, and that the dinosaurs could exchange easily within the region.