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''Troodon'' ( ; ''Troödon'' in older sources) is a genus of relatively small, bird-like dinosaurs known definitively from the Campanian age of the Cretaceous period (about 77 mya), though possible additional species are known from later in the Campanian and also from the early (and probably late〔''Dinosaur distribution (Late Cretaceous;North America;Yukon Territory, Canada).'' In: Weishampel ''et al.'' Page 578〕〔''3.12 Wyoming, United States; 9. Ferris Formation.'' In: Weishampel, ''et al''. (2004). Page 585〕) Maastrichtian age. It includes at least one species, ''Troodon formosus'', though many fossils, possibly representing several species have been classified in this genus. These species ranged widely, with fossil remains recovered from as far north as Alaska and as far south as Wyoming and even possibly Texas and New Mexico. Discovered in 1855, ''T. formosus'' was among the first dinosaurs found in North America. The genus name is Greek for "wounding tooth", referring to the teeth, which were different from those of most other theropods known at the time of their discovery. The teeth bear prominent, apically oriented serrations. These "wounding" serrations, however, are morphometrically more similar to those of herbivorous reptiles, and suggest a possibly omnivorous diet.〔Holtz, Thomas R., Brinkman, Daniel L., Chandler, Chistine L. (1998) Denticle Morphometrics and a Possibly Omnivorous Feeding Habit for the Theropod Dinosaur Troodon. Gaia number 15. December 1998. pp. 159-166.〕 A partial ''Troodon'' skeleton has been discovered with preserved puncture marks.〔Jacobsen, A.R. 2001. Tooth-marked small theropod bone: An extremely rare trace. p. 58-63. In: ''Mesozoic Vertebrate Life''. Ed.s Tanke, D. H., Carpenter, K., Skrepnick, M. W. Indiana University Press.〕 == Description == ''Troodon'' were small dinosaurs, up to in height, in length,〔Holtz, Thomas R. Jr. (2008) ''Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages'' (Supplementary Information ) 〕 and up to in mass. The largest specimens are comparable in size to ''Deinonychus'' and ''Unenlagia''. They had very long, slender hind limbs, suggesting that these animals were able to run quickly. They had large, retractable sickle-shaped claws on the second toes, which were raised off the ground when running. Their eyes were very large (perhaps suggesting a partially nocturnal lifestyle), and slightly forward facing, giving ''Troodon'' some degree of depth perception. 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「Troodon」の詳細全文を読む スポンサード リンク
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