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''Stegosaurus'' (, meaning "roof lizard" or "covered lizard" in reference to its bony plates〔(【引用サイトリンク】url=http://www.etymonline.com/index.php?term=stegosaurus&allowed_in_frame=0 )〕) is a genus of armored dinosaur. They lived during the Late Jurassic period (Kimmeridgian to early Tithonian), some 155 to 150 million years ago in what is now western North America. In 2006, a specimen of ''Stegosaurus ungulatus'' was announced from Portugal, showing that they were present in Europe as well. Due to its distinctive tail spikes and plates, ''Stegosaurus'' is one of the most recognizable dinosaurs. Several species have been identified in the upper Morrison Formation, represented by the remains of about 80 individuals.〔Turner, C.E. and Peterson, F., (1999). "Biostratigraphy of dinosaurs in the Upper Jurassic Morrison Formation of the Western Interior, U.S.A." Pp. 77–114 in Gillette, D.D. (ed.), ''Vertebrate Paleontology in Utah''. Utah Geological Survey Miscellaneous Publication 99-1.〕 A large, heavily built, herbivorous quadruped, ''Stegosaurus'' had a distinctive and unusual posture, with a heavily rounded back, short fore limbs, head held low to the ground, and a stiffened tail held high in the air. Its array of plates and spikes has been the subject of much speculation. The spikes were most likely used for defense, while the plates have also been proposed as a defensive mechanism, as well as having display and thermoregulatory functions. ''Stegosaurus'' had a relatively low brain-to-body mass ratio. It had a short neck and small head, meaning it most likely ate low-lying bushes and shrubs. It was the largest known of all the stegosaurians (bigger than genera such as ''Kentrosaurus'' and ''Huayangosaurus'') and, although roughly bus-sized, it nonetheless shared many anatomical features (including the tail spines and plates) with the other stegosaurian genera. == Description == The quadrupedal ''Stegosaurus'' is one of the most easily identifiable dinosaur genera, due to the distinctive double row of kite-shaped plates rising vertically along the rounded back and the two pairs of long spikes extending horizontally near the end of the tail. Although large individuals could grow up to in length,〔Holtz, Thomas R. Jr. (2012) ''Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages,'' (Winter 2011 Appendix. )〕 the various species of ''Stegosaurus'' were dwarfed by their contemporaries, the giant sauropods. Some form of armor appears to have been necessary, as ''Stegosaurus'' species coexisted with large predatory theropod dinosaurs, such as ''Allosaurus'' and ''Ceratosaurus''. Most of the information known about ''Stegosaurus'' comes from the remains of mature animals; more recently, though, juvenile remains of ''Stegosaurus'' have been found. One subadult specimen, discovered in 1994 in Wyoming, is long and high, and is estimated to have weighed 2.3 metric tons (2.6 t) while alive. It is on display in the University of Wyoming Geological Museum.〔''Stegosaurus''. University of Wyoming Geological Museum. 2006. Retrieved October 6, 2006. (University of Wyoming Geological Museum ) 〕 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「Stegosaurus」の詳細全文を読む スポンサード リンク
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