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}} ''Coelophysis'' ( or ;pron.: or ) is an extinct genus of coelophysid theropod dinosaur that lived approximately 203 to 196 million years ago during the latter part of the Triassic Period in what is now the southwestern United States. It was a small, slenderly-built, ground-dwelling, bipedal carnivore, that could grow up to long. ''Coelophysis'' is one of the earliest known dinosaur genera. Scattered material representing similar animals has been found worldwide in some Late Triassic and Early Jurassic formations. The type species ''C. bauri'', originally given to the genus ''Coelurus'' by Edward Drinker Cope in 1887, was described by the latter in 1889. The names ''Longosaurus'' and ''Rioarribasaurus'' are synonymous with ''Coelophysis''. Another dinosaur genus, ''Megapnosaurus'', has also been considered to be a synonym. This primitive theropod is notable for being one of the most specimen-rich dinosaur genera. ==Description== ''Coelophysis'' is known from a number of complete fossil skeletons of the species ''C. bauri'', which was a lightly built dinosaur which measured up to in length and which was more than a meter tall at the hips. Paul (1988) estimated the weight of the gracile form at , and the weight of the robust form at .〔 ''Coelophysis'' was a bipedal, carnivorous, theropod dinosaur that was a fast and agile runner. Despite being an early dinosaur, the evolution of the theropod body form had already advanced greatly from creatures like ''Herrerasaurus'' and ''Eoraptor''. The torso of ''Coelophysis'' conforms to the basic theropod body shape, but the pectoral girdle displays some interesting special characteristics: ''C. bauri'' had a furcula (wishbone), the earliest known example in a dinosaur. ''Coelophysis'' also preserves the ancestral condition of possessing four digits on the hand (manus). It had only three functional digits, the fourth embedded in the flesh of the hand. ''Coelophysis'' had narrow hips, forelimbs adapted for grasping, and narrow feet.〔Tykoski, R.S. & Rowe, T. (2004). "Ceratosauria": In: 〕 Its neck and tail were long and slender.〔 The pelvis and hindlimbs of ''C. bauri'' are also slight variations on the theropod body plan. It has the open acetabulum and straight ankle hinge that define the Dinosauria. The hindlimb ended in a three-toed foot (pes), with a raised hallux. The tail had an unusual structure within its interlocking prezygapophysis of its vertebrae, which formed a semi-rigid lattice, apparently to stop the tail from moving up and down. ''Coelophysis'' had a long narrow head (approximately ), with large, forward-facing eyes that afforded it stereoscopic vision and as a result excellent depth perception. Rinehart ''et al.'' (2004) described the complete sclerotic ring found for a juvenile ''Coelophysis bauri'' (specimen NMMNH P-4200), and compared it to data on the sclerotic rings of reptiles and birds and concluded that this Coelophysis was a diurnal, visually oriented predator." The study found that its vision was superior to most lizards' vision, and ranked with that of modern birds of prey. The eyes of ''Coelophysis'' appear to be the closest to those of eagles and hawks, with a high power of accommodation. The data also suggested poor night vision which would mean this dinosaur had a round rather than a split pupil.〔 ''Coelophysis'' had an elongated snout with large fenestrae which helped to reduce skull weight, while narrow struts of bones preserved the structural integrity of the skull. The neck had a pronounced sigmoid curve. The braincase is known in ''Coelophysis bauri'' but little data could be derived because the skull was crushed.〔 Unlike some other theropods, the cranial ornamentation of ''Coelophysis'' was not located at the top of its skull. Low, laterally raised bony ridges were present on the dorsolateral margin of the nasal and lacrimal bones in the skull, directly above the antorbital fenestra.〔 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「Coelophysis」の詳細全文を読む スポンサード リンク
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