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''Oviraptor'' is a genus of small Mongolian theropod dinosaurs, first discovered by technician George Olsen in an expedition led by Roy Chapman Andrews, and first described by Henry Fairfield Osborn, in 1924. Its name is Latin for 'egg taker' or "egg seizer", referring to the fact that the first fossil specimen was discovered atop a pile of what were thought to be ''Protoceratops'' eggs, and the specific name ''philoceratops'' means "lover of ceratopsians", also given as a result of this find. In his 1924 paper, Osborn explained that the name was given due to the close proximity of the skull of ''Oviraptor'' to the nest (it was separated from the eggs by only of sand). However, Osborn also suggested that the name ''Oviraptor'' "may entirely mislead us as to its feeding habits and belie its character".〔Osborn, H.F. (1924). "Three new Theropoda, ''Protoceratops'' zone, central Mongolia." ''American Museum Novitates,'' 144: 12 pages, 8 figs.; (American Museum of Natural History) New York. (11.7.1924).〕 In the 1990s, the discovery of nesting oviraptorids like ''Citipati'' proved that Osborn was correct in his caution regarding the name. These finds showed that the eggs in question probably belonged to ''Oviraptor'' itself, and that the specimen was actually brooding its eggs, when it died at the nest. ''Oviraptor'' lived in the late Cretaceous period, during the late Campanian stage about 75 million years ago; only one definitive specimen is known (with associated eggs), from the Djadokhta Formation of Mongolia, though a possible second specimen (also with eggs) comes from the northeast region of Inner Mongolia, China, in an area called Bayan Mandahu.〔Dong and Currie, P. (1996). "On the discovery of an oviraptorid skeleton on a nest of eggs at Bayan Mandahu, Inner Mongolia, People's Republic of China." ''Canadian Journal of Earth Sciences'', 33: 631-636.〕 ==Description== ''Oviraptor philoceratops'' is known from a single partial skeleton (specimen number AMNH 6517), as well as a nest of about fifteen eggs that have been referred to this species (AMNH 6508). When living, ''Oviraptor'' was one of the most bird-like of the non-avian dinosaurs. Its rib cage, in particular, displayed several features that are typical of birds, including a set of processes on each rib that would have kept the rib cage rigid. A relative of ''Oviraptor'' called ''Nomingia'' was found with a pygostyle, which is a set of fused vertebrae that would later help support the tail feathers of birds. Skin impressions from more primitive oviraptorosaurs, like ''Caudipteryx'' and ''Protarchaeopteryx'', clearly show an extensive covering of feathers on the body, feathered wings and feathered tail fans. A tail fan is also indicated by the presence of a pygostyle in ''Nomingia'', suggesting that this feature was widespread among oviraptorosaurs. Additionally, the nesting position of the brooding ''Citipati'' specimens implies the use of feathered wings to cover the eggs.〔Paul, G.S. (2002). ''Dinosaurs of the Air: The Evolution and Loss of Flight in Dinosaurs and Birds.'' Baltimore: Johns Hopkins University Press.〕 Given the close anatomical similarity between these species and ''Oviraptor'', it is highly likely that ''Oviraptor'' had feathers as well. On the other hand, there is a problem with the use of feathers to "brood" eggs. Since feathers provide good insulation, heat cannot easily transfer between the body of an animal and the eggs if there are feathers between them. That is why many birds have a featherless patch of bare skin, known as the brood patch, to allow heat to flow freely from the bird's body to the eggs. So, if ''Oviraptor'' and ''Citipati'' were to cover their eggs with feathers, the feathers can only function to shield the eggs from the elements, such as the sun, wind or rain, but the feathers will not warm the eggs, regardless of whether ''Oviraptor'' and ''Citipati'' are endothermic or ectothermic. ''Oviraptor'' is traditionally depicted with a distinctive crest, similar to that of the cassowary. However, re-examination of several oviraptorids show that this well-known, tall-crested species may actually belong to the genus ''Citipati'', a relative of ''Oviraptor''.〔Clark, J.M., Norell, M.A. & Barsbold, R. (2001). "Two new oviraptorids (Theropoda:Oviraptorosauria), upper Cretaceous Djadokhta Formation, Ukhaa Tolgod, Mongolia." ''Journal of Vertebrate Paleontology'' 21(2): 209-213. June 2001.〕 It is likely that ''Oviraptor'' did have a crest, but its exact size and shape are unknown due to crushing in the skull of the only recognized specimen. 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「Oviraptor」の詳細全文を読む スポンサード リンク
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