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''Dunkleosteus'' is an extinct genus of arthrodire placoderm fish that existed during the Late Devonian period, about 380–360 million years ago. Some of the species, such as ''D. terrelli'', ''D. marsaisi'', and ''D. magnificus'', are among the largest arthrodire placoderms ever to have lived. The largest species, ''D. terrelli'', measuring up to 〔(Ancient Fish With Killer Bite ). Science News. May 19, 2009.〕 and weighing ,〔(Monster fish crushed opposition with strongest bite ever ). The Sydney Morning Herald. November 30, 2006.〕 was a hypercarnivorous apex predator. Few other placoderms, save, perhaps, its contemporary ''Titanichthys'', rivaled ''Dunkleosteus'' in size. ''Dunkleosteus'' is a pachyosteomorph arthrodire originally placed in the family Dinichthyidae, a family composed mostly of large, carnivorous arthrodires like ''Gorgonichthys''. Anderson (2009) suggests, because of its primitive jaw structure, ''Dunkleosteus'' should be placed outside the family Dinichthyidae, perhaps close to the base of the clade Pachyosteomorpha, near ''Eastmanosteus''. Carr and Hlavin (2010) resurrect Dunkleosteidae and place ''Dunkleosteus'', ''Eastmanosteus'', and a few other genera from Dinichthyidae within it. (Dinichthyidae, in turn, is made into a monospecific family). New studies have revealed several features in both its food and biomechanics, as well as its ecology and physiology. Placodermi first appeared in the Silurian, and the group became extinct during the transition from the Devonian to the Carboniferous, leaving no descendants. The class persisted in the fossil record for at least 70 million years, in comparison to the 400-million-year-long history of sharks. In recent decades, ''Dunkleosteus'' has achieved recognition in popular culture, with a large number of specimens on display, and notable appearances in entertainment media like ''Sea Monsters - A Walking with Dinosaurs Trilogy'' and ''River Monsters''. Numerous fossils of some species have been found in North America, Poland, Belgium, and Morocco. The name ''Dunkleosteus'' combines the Greek ''osteus'' (οστεος), meaning "bone", and ''Dunkle'', in honor of David Dunkle of the Cleveland Museum of Natural History. ==Description== Due to its heavily armoured nature, ''Dunkleosteus'' was probably a relatively slow but powerful swimmer. It is thought to have dwelt in diverse zones of inshore waters. Fossilization tends to have preserved only the especially armoured frontal sections of specimens, thus it is uncertain what exactly the hind sections of this ancient fish were like. As such, the reconstructions of the hindquarters are often based on smaller arthrodires, such as ''Coccosteus'', that had hind sections preserved. The most famous specimens of ''Dunkleosteus'' are displayed at the Cleveland Museum of Natural History. Others are displayed at the American Museum of Natural History and in the Queensland Museum in Brisbane, Queensland. Instead of teeth, ''Dunkleosteus'' possessed two pairs of sharp bony plates which formed a beak-like structure. ''Dunkleosteus'', together with most other placoderms, may have also been among the first vertebrates to internalize egg fertilization, as seen in some modern sharks.〔Ahlberg, Per, et al. "Pelvic claspers confirm chondrichthyan-like internal fertilization in arthrodires." Nature 460.7257 (2009): 888.〕 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「Dunkleosteus」の詳細全文を読む スポンサード リンク
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