Udanoceratops

Udanoceratops (meaning "Udan-Sayr horned face") is a genus of large leptoceratopsid dinosaur that lived during the Late Cretaceous period of Mongolia. The holotype specimen, the partial skeleton of an adult with its bones encapsulated in calcium carbonate, was discovered in the 1980s as part of the Joint Soviet-Mongolian Paleontological Expedition, and was subsequently transported to the Paleontological Institute of the Russian Academy of Sciences. In 1992, it was described by palaeontologist Sergei Kurzanov. The sole species of Udanoceratops, also the type species, is Udanoceratops tschizhovi, named after a colleague of Kurzanov, D. O. Tschizhov. Additional remains have been assigned to Udanoceratops, though these may be misattributions.

Udanoceratops is the largest known leptoceratopsid, with some estimates placing it at about in length and in weight. Its skull, though incomplete, probably was between in length, half as long again as that of the second-largest leptoceratopsid, Montanoceratops from North America. Udanoceratops' skull was far deeper and more robust than that of other leptoceratopsids, with larger nasal cavities and presumably a heavier beak. The projections on Udanoceratops' cheek bones would have supported a large patch of keratin. The bone of its snout above the beak was completely smooth, bearing neither the horns nor the slight tubercles of related taxa. Udanoceratops had a very deep and robust lower jaw (mandible), capable of exerting a powerful bite, possibly strong enough to cleave through bone; indeed, the holotype bears damage to its mandible which may have been caused by such a bite. The lower teeth bore shelves into which the upper set would have slotted when the jaw was closed. This would have resulted in a slicing action, similar to the system present in Archaeoceratops and Leptoceratops.