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''Arrhinoceratops'' (meaning "no nose-horn face", derived from the Ancient Greek "a-/α-" "no", rhis/ῥίς "nose" "keras/κέρας" "horn", "-ops/ὤψ" "face") is a genus of herbivorous ceratopsian dinosaur. The name was coined as its original describer concluded it was special because the nose-horn was not a separate bone, however further analysis revealed this was based on a misunderstanding.〔 It lived during the latest Campanian/earliest Maastrichtian stage of the Late Cretaceous, predating its famous relative ''Triceratops'' by a few million years, although it was contemporary with ''Anchiceratops''.〔 Its remains have been found in Canada.〔 ==Discoveries and species== Described by William Arthur Parks in 1925, ''Arrhinoceratops'' is known from a partially crushed, slightly distorted skull which lacked the lower jaws. The remains were collected from the Neill's Ranch site, along the Red Deer River in Alberta by a 1923 expedition from the University of Toronto.〔Parks, W.A. (1925). "''Arrhinoceratops brachyops'', a new genus and species of Ceratopsia from the Edmonton Formation of Alberta". ''University of Toronto Studies, Geology Series'' 19:1-15〕 Parks named the type species ''Arrhinoceratops brachyops''. The generic name is derived from Greek α~, "without", ῥίς, ''rhis'', "nose", κέρας, ''keras'', "horn", and ὤψ, ''ops'', "face" as Parks had established that no separate nose-horn was present. The specific name means "short-faced" from Greek βραχύς, ''brachys'', "short".〔 The holotype is ROM 796 (earlier ROM 5135), which was found in a layer of the Horseshoe Canyon Formation dating from the latest Campanian or perhaps earliest Maastrichtian. It consists of the original skull. Other material from Utah, found in the 1930s, was posthumously named ''Arrhinoceratops? utahensis'' by Charles Whitney Gilmore in 1946. It is based on holotype USNM 15583. The question mark indicates that Gilmore himself had doubts about the identification.〔C.W. Gilmore, 1946, "Reptilian fauna of the North Horn Formation of central Utah", ''United States Department of the Interior Geological Survey Professional Paper'' 210-C: 29-53〕 In 1976, Douglas A. Lawson transferred the species to ''Torosaurus'', as a ''Torosaurus utahensis''.〔D.A. Lawson, 1976, "''Tyrannosaurus'' and ''Torosaurus'', Maestrichtian dinosaurs from Trans-Pecos, Texas", ''Journal of Paleontology'' 50(1): 158-164〕〔Hunt, R.K. and Lehman, T.M. (2008). "Attributes of the ceratopsian dinosaur ''Torosaurus'', and new material from the Javelina Formation (Maastrichtian) of Texas". ''Journal of Paleontology'' 82(6): 1127-1138.〕 Apart from the holotype skull little fossil material of ''Arrhinoceratops brachyops'' has been found. In 1981 Helen Tyson in a revision of the genus, provisionally referred specimen ROM 1439,〔Tyson, H., 1981, "The structure and relationships of the horned dinosaur ''Arrhinoceratops'' Parks (Ornithischia: Ceratopsidae)", ''Canadian Journal of Earth Sciences'' 18: 1241-1247〕 but in 2007 Andrew Farke moved this to ''Torosaurus''.〔Farke, A.A., 2007, "Cranial osteology and phylogenetic relationships of the chasmosaurine ceratopsid ''Torosaurus latus''", pp 235-257 in: K. Carpenter (ed.), ''Horns and Beaks: Ceratopsian and Ornithopod Dinosaurs'', Bloomington, Indiana University Press〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Arrhinoceratops」の詳細全文を読む スポンサード リンク
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