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''Stokesosaurus'' (meaning "Stokes' lizard") is a genus of small (around three to four meters (10-13 ft) in length), carnivorous early tyrannosauroid theropod dinosaurs from the late Jurassic period of Utah. ==History== From 1960 onwards Utah geologist William Lee Stokes and his assistant James Madsen excavated thousands of disarticulated ''Allosaurus'' bones at the Cleveland-Lloyd Dinosaur Quarry in Emery County, Utah. During the early seventies Madsen began to catalogue these finds in detail, discovering that some remains represented species new to science. In 1974 Madsen named and described the type species ''Stokesosaurus clevelandi''. Its generic name honours Stokes. The specific name refers to the town of Cleveland, Utah. The holotype (UUVP 2938) was uncovered in the Brushy Basin Member of the Morrison Formation dating from the early Tithonian stage, about 150 million years old. It consists of a left ilium or hip bone, belonging to a juvenile individual. Madsen also assigned a paratype, UUVP 2320, a 50% larger right ilium. Additionally he referred a right premaxilla, UUVP 2999.〔 However, this was in 2005 referred to ''Tanycolagreus''.〔K. Carpenter, C.A. Miles, and K.C. Cloward, 2005, "New small theropod from the Upper Jurassic Morrison Formation of Wyoming", In: K. Carpenter (ed.), ''The Carnivorous Dinosaurs''. Indiana University Press, Bloomington pp. 23-48〕 ''Stokesosaurus'' and ''Tanycolagreus'' are about the same size, and it is possible that the latter is a junior synonym of the former. However, the ilium (the best and perhaps only known element of ''Stokesosaurus'') of ''Tanycolagreus'' has never been recovered, making direct comparison difficult.〔Foster, J. (2007). ''Jurassic West: The Dinosaurs of the Morrison Formation and Their World''. Indiana University Press. 389pp.〕 In 1976 Peter Malcolm Galton considered ''Stokesosaurus'' to be a second species of the British possible early tyrannosauroid ''Iliosuchus'', that he named as ''Iliosuchus clevelandi''. This has found no acceptance among other researchers;〔 in 1980 Galton himself withdrew his opinion.〔Galton, P.M. and Powell, H.P., 1980, "The ornithischian dinosaur ''Camptosaurus prestwichii'' from the Upper Jurassic of England", ''Palaeontology'', 23: 411-443〕 Some later finds were referred to ''Stokesosaurus''. This included some ischia and tail vertebrae in 1991,〔Britt, B., 1991, "Theropods of Dry Mesa Quarry (Morrison Formation, Late Jurassic), Colorado, with emphasis on the osteology of ''Torvosaurus tanneri''", ''Brigham Young University Geology Studies'', 37: 1-72〕 and a partial braincase in 1998. Another, very small ilium referred to ''Stokesosaurus'', found in South Dakota, is lost but may actually belong to the related ''Aviatyrannis''.〔Oliver W. M. Rauhut. (2003). "A tyrannosauroid dinosaur from the Upper Jurassic of Portugal". ''Palaeontology'' 46(5): 903–910〕 More fragmentary remains possibly referable to ''Stokesosaurus'' have been recovered from stratigraphic zone 2 of the Morrison Formation, dated to the late Kimmeridgian age, about 152 million years ago.〔Turner, C.E. and Peterson, F., (1999). "Biostratigraphy of dinosaurs in the Upper Jurassic Morrison Formation of the Western Interior, U.S.A." Pp. 77–114 in Gillette, D.D. (ed.), ''Vertebrate Paleontology in Utah''. Utah Geological Survey Miscellaneous Publication 99-1.〕〔Foster, J. (2007). "Appendix." ''Jurassic West: The Dinosaurs of the Morrison Formation and Their World''. Indiana University Press. pp. 327-329.〕 A second species, ''Stokesosaurus langhami'', was described by Roger Benson in 2008 based on a partial skeleton from England.〔Benson, R.B.J. (2008). "New information on ''Stokesosaurus'', a tyrannosauroid (Dinosauria: Theropoda) from North America and the United Kingdom." ''Journal of Vertebrate Paleontology'', 28(3):732-750. .〕 However, further study showed that this species should be referred to a new genus, which was named ''Juratyrant'' in 2012. Benson and Stephen Brusatte concluded that not a single bone had been justifiably referred to ''Stokesosaurus'', and that not even the paratype could be safely assigned, leaving the holotype ilium as the only known fossil of the taxon.〔Brusatte, S.L. and Benson, R.B.J. (In press). "The systematics of Late Jurassic tyrannosauroids (Dinosauria: Theropoda) from Europe and North America." ''Acta Palaeontologica Polonica'', (in press). 〕 The holotype ilium is twenty-two centimetres long, indicating a small individual. Madsen in 1974 estimated that the adult body length was about four metres.〔 In 2010 Gregory S. Paul estimated the length at 2.5 metres, the weight at sixty kilogrammes.〔Paul, G.S., 2010, ''The Princeton Field Guide to Dinosaurs'', Princeton University Press p. 100〕 In 2012 Benson and Brusatte established a single unique derived trait or autapomorphy of ''Stokesosaurus'': the normally vertical ridge on the outer blade surface of the ilium, above the hip joint, was strongly inclined to the back and reached the upper rim of the blade.〔 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「Stokesosaurus」の詳細全文を読む スポンサード リンク
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