Udanoceratops

Udanoceratops (meaning "Udan's horned face") is a genus of large leptoceratopsid dinosaur that lived during the Late Cretaceous period of Mongolia, in what is now the Djadokhta Formation. Udanoceratops was first named and described by Russian paleontologist Sergei Kurzanov in 1992 and the type species is Udanoceratops tschizhovi. The holotype (PIN 3907/11) was collected during the 1980s at the Udan Sayr (also spelled Udyn Sayr or Üüden Sair) locality of the Djadokhta Formation in Ömnögovi Province, dating to the Campanian stage of the Late Cretaceous period. The generic name is derived from the name of the locality in which the holotype was found (Udan Sayr) and Greek ceras/κέρας meaning "horn" and -ops/ωψ meaning "face". Udanoceratops is best known from the holotype specimen, which represents a large individual comprising a large, relatively well-preserved and almost complete skull, and sparse body remains including vertebrae. In 1993 a large skull ("nearly 1 m long") assigned to Udanoceratops was reported from the nearby Bayan Mandahu Formation by paleontologist Tomasz Jerzykiewicz. However, Polish paleontologist Łukasz Czepiński in 2020 pointed out that there are no referable specimens to Udanoceratops from the Bayan Mandahu collections, and it is most likely that these remains were confused with the concurring (and relatively large) Protoceratops hellenikorhinus. In 2004 Viktor S. Tereschhenko referred a juvenile specimen (PIN 4046/11) to Udanoceratops aff. tschizhovi, from the Baga Tariach locality in Dornogovi Province, which Tereschhenko attributed to the Djadokhta Formation. Geological analyses carried out across fossiliferous localities of the Gobi Desert published by Mahito Watabe and team in 2010, indicates that this locality instead correlates best with the Maastrichtian-stage Barun Goyot Formation. The assignment of this specimen, however, has varied since then from "Udanoceratops" sp., to ?Udanoceratops sp. Udanoceratops was a large ceratopsian, estimated at to have reached nearly long with a weight of .