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''Avimimus'' ( ), meaning "bird mimic" (Latin ''avis'' = bird + ''mimus'' = mimic), was a genus of bird-like maniraptoran dinosaur that lived in the late Cretaceous in what is now Mongolia, around 70 million years ago. ==Description== ''Avimimus'' was a small dinosaur with a length of 1.5 m (5 ft).〔 The skull was small compared to the body, though the brain〔 and eyes were large. The size of the bones which surrounded the brain and were dedicated to protecting it are large.〔 This is also consistent with the hypothesis that ''Avimimus'' had a proportionally large brain.〔 The jaws of ''Avimimus'' were thought to form a parrot-like beak, lacking teeth, and a thorough review of the holotype specimen's anatomy confirmed that no teeth were preserved, although a series of toothlike projections along the tip of the premaxilla were.〔 However, subsequently discovered specimens have been reported to preserve small premaxillary teeth.〔 The small teeth or possible lack thereof in ''Avimimus'' suggests that it may have been an herbivore or omnivore. Kurzanov himself, however, believed that ''Avimimus'' was an insectivore.〔 The foramen magnum, the hole allowing the spinal cord to connect with the brain, was proportionally large in ''Avimimus''.〔 The occipital condyle, however, was small, further suggestive of the skull's relative lightness.〔 The neck itself was long and slender, and is composed of vertebrae that are much more elongate than in other oviraptorosaurs. Unlike oviraptorids and caenagnathids, the back vertebrae lack openings for air sacs, suggesting that ''Avimimus'' is more primitive than these animals. The forelimbs were relatively short. The bones of the hand were fused together, as in modern birds, and a ridge on the ulna (lower arm bone) was interpreted as an attachment point for feathers by Kurzanov.〔〔Kurzanov, S.M. (1981). "An unusual theropod from the Upper Cretaceous of Mongolia Iskopayemyye pozvonochnyye Mongolii (Fossil Vertebrates of Mongolia)." ''Trudy Sovmestnay Sovetsko-Mongolskay Paleontologiyeskay Ekspeditsiy'' (''Joint Soviet-Mongolian Paleontological Expedition''), 15: 39-49. Nauka Moscow, 1981〕 Kurzanov, in 1987, also reported the presence of quill knobs,〔〔Kurzanov, S.M. (1987). "Avimimidae and the problem of the origin of birds." ''Transactions of the Joint Soviet-Mongolian Paleontological Expedition'', 31: 5-92. (Russian )〕 and while Chiappe confirmed the presence of bumps on the ulna, their function remained unclear.〔Chiappe, L.M. and Witmer, L.M. (2002). ''Mesozoic Birds: Above the Heads of Dinosaurs.'' Berkeley: University of California Press, 536 pp. ISBN 0-520-20094-2〕 Kurzanov was so convinced they were attachment points for feathers that he concluded that ''Avimimus'' may have been capable of weak flight.〔 The presence of feathers is now widely accepted, but most paleontologists do not believe ''Avimimus'' could fly.〔 The ilium was almost horizontally oriented, resulting in exceptionally broad hips. Little is known of the tail but the hip suggests that the tail was long. The legs were extremely long and slender, suggesting that ''Avimimus'' was a highly specialized runner. The proportions of the leg bones add further weight to the idea of ''Avimimus'' was quick on its feet.〔 The animal's shins were long in comparison with its thighs,〔 a trait common among cursorial animals. It also had three-toed feet with narrow pointed claws. 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「Avimimus」の詳細全文を読む スポンサード リンク
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