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''Mamenchisaurus'' ( ,() or spelling pronunciation ) is a sauropod dinosaur genus including several species, known for their remarkably long necks which made up half the total body length. It is known from numerous species which ranged in time from 160 to 145 million years ago, from the Oxfordian to Tithonian ages of the late Jurassic Period of China, and the largest species may have reached in length.〔 ==Discoveries== ''Mamenchisaurus'' was first discovered in 1952 on the construction site of the Yitang Highway in Sichuan, China. The partial skeleton fossil was then studied, and named ''Mamenchisaurus constructus'' in 1954, by the renowned Chinese paleontologist Professor C. C. Young. The type specimen had an incomplete neck with 14 vertebra preserved and none of these were complete. ''M. constructus'' has been estimated around and in length.〔Paul, G.S. (2010). ''The Princeton Field Guide to Dinosaurs'', Princeton University Press.〕〔Young, C.C. (1954), ''On a new sauropod from Yiping, Szechuan, China.'' sinica, III(4), 481-514.〕 In 1972, a second species was described, named ''Mamenchisaurus hochuanensis'', with a neck that reached up to in length.〔Paul, G.S. (1988). "The brachiosaur giants of the Morrison and Tendaguru with a description of a new subgenus, ''Giraffatitan'', and a comparison of the world's largest dinosaurs". ''Hunteria'', 2(3): 1–14.〕 This species had a complete neck preserved which contained 19 vertebrae.〔Young, C.C., and Zhao, X.-J. (1972). "''Mamenchisaurus hochuanensis'' sp. nov." ''Institute of Vertebrate Paleontology and Paleoanthropology Monographs'', A, 8:1-30.〕 This was the longest neck known until the description of ''Supersaurus'', based on a single neck vertebra, BYU 9024, with an estimated neck length of about 14 meters (46 feet). Another long-necked sauropod exceeding ''M.hochuanensis'' was ''Sauroposeidon'' which was discovered in 1994. Based on the ''Sauroposeidon'' holotype, which only preserved 4 neck vertebra, its neck was estimated to be between 11.25 and 12 meters (36.9–39.4 feet) long.〔Wedel, M.J., and Cifelli, R.L. (2005). "''Sauroposeidon'': Oklahoma’s native giant." ''Oklahoma Geology Notes'', 65(2): 40-57.〕 In 1993, ''M. sinocanadorum'' was described, which consisted of skull material and the first four cervical vertebrae. This species possessed the longest cervical rib of any described sauropod dinosaur, measuring 4.1 m (13.5 ft). This is longer than the longest ''Sauroposeidon'' cervical rib, which measures .〔"Osteology, paleobiology, and relationships of the sauropod dinosaur ''Sauroposeidon''", by Mathew J. Wedel, Richard L. Cifelli, and R. Kent Sanders (''Acta Palaeontologica Polonica'' 45, pages 343–388, 2000).〕 Additional remains attributed to this species, but not yet formally described, belong to one of the largest dinosaurs known—the restored skeleton measuring in length with a neck measuring long.〔 In 2001, another ''M. hochuanensis'' specimen was described. It had skull, pectoral girdle and forelimb material preserved, all of which were missing from the holotype. It was also found with four fused tail vertebra, which have expanded neural arches and taller neural spines, that belong at the tip of the tail. It’s thought that these could be a weapon, such as a tail club, or a sensory organ. Other Chinese sauropods, ''Shunosaurus'' and ''Omeisaurus'', are also known to have had ’tail clubs’ but they differ in shape to that of ''M. hochuanensis''. 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「Mamenchisaurus」の詳細全文を読む スポンサード リンク
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