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''Oplosaurus'' (meaning "armed or weapon lizard" or "armoured lizard"; see below for discussion) was a genus of sauropod dinosaur from the Barremian-age Lower Cretaceous Wessex Formation of the Isle of Wight, England. It is known from a single tooth usually referred to the contemporaneous "wastebasket taxon" ''Pelorosaurus'', although there is no solid evidence for this. ==History and taxonomy== In 1852 geologist Thomas Wright reported the find of a large reptilian tooth from the ''Wealden Clay'' near Brixton Bay on Wight. Wright had presented the find to several experts, among them Richard Owen, David Forbes, George Robert Waterhouse and Samuel Pickworth Woodward but only Gideon Mantell came with a useful suggestion pointing to a similarity with the teeth of the dinosaur ''Hylaeosaurus''. Not convinced by this, Wright concluded that the tooth, in view of its sharpness, belonged to a carnivorous reptile of unknown affinities.〔Wright, T. (1852). Contributions to the palaeontology of the Isle of Wight. ''Annals and Magazine of Natural History'' 2:87-93.〕 Wright had also asked the French paleontologist Paul Gervais for his opinion on the fossil. Gervais in 1852 based the type species ''Oplosaurus armatus'' on it. The generic name would normally read as "armoured lizard" from the Greek ''hoplon'', "body armour". The usual story about the — given the fact that ''Oplosaurus'' is not known to be armoured — odd choice of name is that Gervais named this large, well-preserved tooth (holotype BMNH R964) under the mistaken belief that its owner was an armoured dinosaur like ''Hylaeosaurus'' following Mantell's suggestion.〔Naish, D., and Martill, D.M. (2001). Saurischian dinosaurs 1: Sauropods. In: Martill, D.M., and Naish, D. (eds.). ''Dinosaurs of the Isle of Wight''. The Palaeontological Association:London 185-241. ISBN 0-901702-72-2〕 However, (recent research ) by Ben Creisler shows that Gervais compared it to ''Mosasaurus'', not ''Hylaeosaurus'', and that the name may have been intended as "armed lizard", with the teeth as the weapons of a carnivore, as ''hoplon'' can also mean "weapon" (although this would make the specific name redundant, as ''armatus'' too means "armed" in Latin).〔Gervais, P. (1852). ''Zoologie et paléontologie française (animaux vertébrés)'' (1st edition). A. Bertrand:Paris, 271 p. ()〕 Richard Lydekker (1888) suggested that a maxilla with a tooth (BMNH R751), also from the Isle of Wight, was another exemplar of this animal, but this opinion has not been substantiated. Lydekker also used the improved spelling "Hoplosaurus" but the original ''Oplosaurus'' has priority. The tooth is large, 85 mm (3.35 in) tall in total, with a spatulate crown 52 mm (2.05 in) tall, comparable to ''Brachiosaurus''; it has a pointed tip, a slightly compressed form "cheek" to tongue, a slight convexity to the base of the tongue-facing side, and wear facets.〔〔 It is vaguely like a ''Brachiosaurus'' tooth, which is why the genus has for a time been referred to the Brachiosauridae.〔McIntosh, J.S. (1990). Sauropoda. In: Weishampel, D.B., Dodson, P., and Osmólska, H. (eds.). ''The Dinosauria''. University of California Press:Berkeley 345-401. ISBN 0-520-06727-4〕 Earlier, ''Oplosaurus'' was typically referred to ''Pelorosaurus'' following an opinion of Friedrich von Huene in 1909, although ''Pelorosaurus'' is based on fragmentary remains that do not include teeth, making it impossible to prove the identity. (See Naish and Martill (2001) for a good review of ''Oplosaurus'' and Wealden sauropods in general; (here ) is a more recent informal summation of the state of work.) Given how poor the ''Pelorosaurus'' holotype material is, and that it doesn't include teeth, recent reviews have retained ''Oplosaurus'' as a potentially valid but poorly known genus.〔Upchurch, P.M., Barrett, P.M., and Dodson, P. (2004). Sauropoda. In: Weishampel, D.B., Dodson, P., and Osmólska, H. (eds.). ''The Dinosauria'' (2nd edition). University of California Press:Berkeley 259-322. ISBN 0-520-24209-2〕 Darren Naish, a British palaeontologist familiar with Wealden sauropods, has (suggested informally ) that the genus may be a turiasaur but also co-authored an article concluding it was a member of the Camarasauridae. In any case, it likely belongs to the more general Macronaria. 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「Oplosaurus」の詳細全文を読む スポンサード リンク
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