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''Bunostegos'' ("knobbly () roof"〔) is an extinct genus of pareiasaur parareptile from the Late Permian of the Agadez Region in Niger. The type species, ''Bunostegos akokanensis'', was named from the Moradi Formation in 2003. It was a cow-sized animal with a distinctive skull that had large bony knobs, similar in form to those of other pareiasaurs but far larger. The species appears to have lived in a desert in the centre of the supercontinent of Pangaea. Analysis of the limb bones (including the scapulocoracoid, humerus, radius, ulna, pelvis, and femur) was published in 2015, and revealed that ''Bunostegos'' walked upright on four limbs, with the body held above ground. This new information directly suggests that it could be the first tetrapod with a fully erect gait.〔(【引用サイトリンク】url=http://www.sciencedaily.com/releases/2015/09/150917110007.htm )〕 ==Description== The animal has been described as about the size of a modern cow with a knobbly skull and bony plate armor on its back."〔 Its teeth show it to have been a plant eater. It lived in an isolated desert region of the supercontinent of Pangaea some 260 million years ago. Its home region appears to have supported a distinctive fauna, in contrast to the rest of the supercontinent, where species were broadly distributed. It is particularly notable for the large bony knobs on its head, bigger than any seen in other species of pareiasaur. In life they were probably skin-covered horns or ossicones similar to those of modern giraffes. They are thought not to have served a protective function but were probably purely ornamental, perhaps aiding recognition between or within particular species. ''Bunostegos'' may have been part of a relict population that clung on in central Pangaea, isolated from other more advanced species by the hyperarid conditions in which it lived. It is more closely related to older and more primitive pareiasaurs. The centre of the supercontinent appears to have been a very dry desert, which prevented population exchanges between the interior and exterior and kept ''Bunostegos'' in reproductive isolation.〔 Only a few million years later, however, ''Bunostegos'' and most of the other pareiasaurs died out in the Permian–Triassic extinction event of 252 million years ago. The evidence ''Bunostegos'' walked upright: * the shoulder part (scapulocoracoid) where the upper arm bone moved is oriented more downward and to the back than off to side as in other pareiasaurs, allowing a greater vertical movement. * the humerus (upper arm bone) does not fit into a spread out posture * the elbow joint allows a front to back movement as in an animal standing upright. Near vertical hind limbs were usual for pareiasaurs, but ''Bunostegos'' was more advanced in having all four limbs vertical.〔 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「Bunostegos」の詳細全文を読む スポンサード リンク
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