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''Edmontosaurus regalis'' is a species of comb-crested hadrosaurid (duck-billed) dinosaur. Fossils of ''E. regalis'' have been found in rocks of western North America that date from the late Campanian stage of the Cretaceous Period 73 million years ago. ''E. regalis'' was widely distributed across western North America, with fossil remains found from northern Alaska to Colorado. ''E. regalis'' was one of the largest hadrosaurids, measuring up to long and weighing around . It is classified as a genus of saurolophine (or hadrosaurine) hadrosaurid, a member of the group of hadrosaurids which lacked large, hollow crests, instead having smaller solid crests or fleshy combs.〔 The distribution of ''E. regalis'' fossils suggests that it preferred coasts and coastal plains. It was a herbivore that could move on both two legs and four. Because it is known from several bone beds, ''E. regalis'' is thought to have lived in groups. The wealth of fossils has allowed researchers to study its paleobiology in detail, including its brain, how it may have fed, and its injuries and pathologies. ==Description== ''Edmontosaurus regalis'' is known from several fossil specimens. ''E. regalis'' was among the largest hadrosaurids. A fully grown adult could have been long, and some of the larger specimens reached the range of to long. Its weight was on the order of . The type specimen of ''E. regalis'', NMC 2288, is estimated as long.〔Lull, Richard Swann; and Wright, Nelda E. (1942). ''Hadrosaurian Dinosaurs of North America''. p. 225.〕 The skull was roughly triangular in profile.〔Lull, Richard Swann; and Wright, Nelda E. (1942). ''Hadrosaurian Dinosaurs of North America''. pp. 151–164.〕 One specimen preserved a soft tissue crest or wattle on the head. The beak was toothless, and both the upper and lower beaks were extended by keratinous material.〔 Teeth were present only in the maxillae (upper cheeks) and dentaries (main bone of the lower jaw). They grew in columns, with an observed maximum of six in each, and the number of columns varied based on the animal's size.〔 There were 51 to 53 columns per maxilla and 48 to 49 per dentary (teeth of the upper jaw being slightly narrower than those in the lower jaw).〔 ''E. regalis'' had thirteen neck vertebrae, eighteen back vertebrae, nine hip vertebrae, and an unknown number of tail vertebrae.〔 The fore legs were shorter and less heavily built than the hind legs. Each hand had four fingers, with no thumb (first finger). The index second, third, and fourth fingers were approximately the same length and were united in life within a fleshy covering. Although the second and third finger had hoof-like claws, these bones were also within the skin and not apparent from the outside. The little finger was separate from the other three and was much shorter.〔Lull, Richard Swann; and Wright, Nelda E. (1942). ''Hadrosaurian Dinosaurs of North America''. pp. 98–110.〕 Each foot had three toes, with no big toe or little toe. The toes had hoof-like tips.〔 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「Edmontosaurus regalis」の詳細全文を読む スポンサード リンク
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