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Gephyrostegus
''Gephyrostegus'' is an extinct genus of gephyrostegid reptiliomorph amphibian. It was a small animal, 22 cm in total length, of generally lizard-like build and presumably habit. It had large eyes and a large number of small, pointed teeth, indicating it was an active insectivorious hunter. The remains have been found in Nyran, Czech Republic, dating from around 310 million years ago (upper Carboniferous).〔Jaeckel, O. (1902): Über ''Gephyrostegus bohemicus'', n.g. n.sp. ''Zeitschrift der Deutschen Geologischen Gesellschaft'' no 54: pp. 127–132.〕
Originally thought to have been an seymouriamorph, the phylogenetic position is uncertain, and now it belongs to the family Gephyrostegidae, together with the genus ''Bruktererpeton''. Several phylogenetic studies indicate that ''Gephyrostegus'' is only distantly related to amniotes, more distantly than diadectomorphs, lepospondyls and seymouriamorphs were.〔
At 22 cm snout-vent length, ''Gephyrostegus'' is one of the smallest (if not ''the'' smallest) advanced reptiliomorphs found. The type species is ''Gephyrostegus bohemicus'', the type of which is the specimen with its skull and scattered elements of the anterior postcranial skeleton preserved; another known specimen is an articulated postcranial skeleton, lacking only the tail and a few phalanges.〔〔 Brough and Brough (1967) erected the species ''Gephyrostegus watsoni'' for a smaller, possibly juvenile individual, previously considered to be an individual of ''Diplovertebron punctatum''.〔Brough, M.C. and Brough J. (1967): The Genus ''Gephyrostegus''. ''Philosophical Transactions of the Royal Society of London''. Series B, Biological Sciences no 252 (776): pp. 147–165. 〕 Carroll (1970, 1972) considered the holotype of ''Gephyrostegus watsoni'' to be a skeleton of an immature individual of ''G. bohemicus''.〔〔Robert L. Carroll "Gephyrostegida, Solenodonsauridae" pp. 1-19 ''in'': Robert L. Carroll, Oskar Kuhn and L. P. Tatarinov (1972) ''Handbuch der Paläoherpetologie - Encyclopedia of Paleoherpetology Part 5B - Batrachosauria (Anthracosauria) Gephyrostegida – Chroniosuchida'' Gustav Fischer Verlag - Stuttgart & Portland, 81 pp., ISBN 978-3-89937-022-5 (web page )〕 The skeleton of the smaller individual has few of the features characterizing the skeletons of larvae of discosauriscid seymouriamorphs, and its morphology is overall very similar to that of adult specimens. Carroll (1970, 1972) states that while the skeleton of ''Gephyrostegus'' shows some adaptations for terrestrial life (e.g. in the specialization of the tarsus), it also retained some traits characteristic to aquatic non-amniote tetrapods, such the large size of the skull and the loose attachment of the vertebral elements, making it overall not as well adapted to the terrestrial environment as amniotes are. According to Carroll, ''Gephyrostegus'' probably spent a large proportion of its adult life on land, but it may be assumed that it retained aquatic reproductive habits.〔〔
Brough and Brough (1967) considered ''Solenodonsaurus'' to be a junior synonym of ''Gephyrostegus'',〔 but other authors consider them to be a separate genera. Some specimens classified by Brough and Brough (1967) as individuals of ''Gephyrostegus bohemicus'' were subsequently recognized as basal eureptilians; their "specimen I" became a holotype of ''Brouffia orientalis'', while "specimen II" became a holotype of ''Coelostegus prothales''.
==References==
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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