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''Bactrosaurus'' (; meaning "Club lizard," "baktron" = club + ''sauros'' = lizard) is a genus of herbivorous dinosaur that lived in east China during the late Cretaceous, about 70 mya. The position ''Bactrosaurus'' occupies in the Cretaceous makes it one of the earliest known hadrosauroids, and although it is not known from a full skeleton, ''Bactrosaurus'' is one of the best known of these forms of hadrosaurs predecessors.〔"Bactrosaurus." In: Dodson, Peter & Britt, Brooks & Carpenter, Kenneth & Forster, Catherine A. & Gillette, David D. & Norell, Mark A. & Olshevsky, George & Parrish, J. Michael & Weishampel, David B. ''The Age of Dinosaurs''. Publications International, LTD. p. 131. ISBN 0-7853-0443-6.〕 ==Description== A typical ''Bactrosaurus'' would have been long〔 and high when standing on all fours, and weighed , with an femur. It was an early relative of ''Lambeosaurus'',〔 perhaps a predecessors, as it shows a number of iguanodont-like features, including three stacked teeth for each visible tooth, small maxillary teeth, and an unusually powerful build for a hadrosaur. It shows features intermediate between those of the two main hadrosaurid groups, and may represent an ancestral form that evolved from an earlier iguanodontid dinosaur. ''Bactrosaurus'' was originally described as lacking a crest, which would be typical for an iguanodont, but anomalously primitive for a lambeosaurine like itself.〔 However subsequent study of ''Bactrosaurus'' remains uncovered pieces of what appear to be the base of an incompletely preserved crest.〔 In 2003, evidence of tumors, including hemangiomas, desmoplastic fibroma, metastatic cancer, and osteoblastoma was discovered in fossilized ''Bactrosaurus'' skeletons. Rothschild ''et al.'' tested dinosaur vertebrae for tumors using computerized tomography and fluoroscope screening. Several other hadrosaurids, including ''Brachylophosaurus'', ''Gilmoreosaurus'', and ''Edmontosaurus'', also tested positive. Although more than 10,000 fossils were examined in this manner, the tumors were limited to ''Bactrosaurus'' and closely related genera. The tumors may have been caused by environmental factors or genetic propensity. 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「Bactrosaurus」の詳細全文を読む スポンサード リンク
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