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A thagomizer is the distinctive arrangement of four to ten spikes on the tails of stegosaurid dinosaurs. These spikes are believed to have been a defensive measure against predators.〔Holtz, T. R., (2000) "Classification and Evolution of the Dinosaur Groups" (pp. 140-168) in ''The Scientific American Book of Dinosaurs'', edited by Gregory S. Paul, New York: St Martin's Press ISBN 0-312-26226-4〕 The arrangement of spikes originally had no distinct name; the term ''Thagomizer'' was coined in 1982 by cartoonist Gary Larson in his ''The Far Side'' comic strip, and thereafter became gradually adopted as an informal term within scientific circles, research, and education. ==Paleobiology== There has been debate about whether the spikes were used simply for display, as posited by Gilmore in 1914, or used as a weapon. Robert Bakker noted that it's likely that the stegosaur tail was much more flexible than those of other ornithischian dinosaurs because it lacked ossified tendons, thus lending credence to the idea of the tail as a weapon. He also observed that ''Stegosaurus'' could have maneuvered its rear easily by keeping its large hindlimbs stationary and pushing off with its very powerfully muscled but short forelimbs, allowing it to swivel deftly to deal with attack. In 2010, analysis of a digitized model of ''Kentrosaurus aethiopicus'' showed that the tail could bring the thagomizer around to the sides of the dinosaur, possibly striking an attacker beside it. In 2001, a study of tail spikes by McWhinney et al., showed a high incidence of trauma-related damage. This too supports the theory that the spikes were used in combat. There is also evidence for ''Stegosaurus'' defending itself, in the form of an ''Allosaurus'' tail vertebra with a partially healed puncture wound that fits a ''Stegosaurus'' tail spike. ''Stegosaurus stenops'' had four dermal spikes, each about long. Discoveries of articulated stegosaur armor show that, at least in some species, these spikes protruded horizontally from the tail, not vertically as is often depicted. Initially, Marsh described ''S. armatus'' as having eight spikes in its tail, unlike ''S. stenops''. However, recent research re-examined this and concluded this species also had four. 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「thagomizer」の詳細全文を読む スポンサード リンク
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