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Westlothiana
''Westlothiana'' is a genus of reptile-like amphibian or possibly early reptile that bore a superficial resemblance to modern-day lizards. It lived about 338 million years ago during the latest part of the Visean age of the Carboniferous period. It is known from a single species, ''Westlothiana lizziae''. The type specimen was discovered in East Kirkton Quarry, West Lothian, Scotland in 1984. ''Westlothiana'''s anatomy contained a mixture of both labyrinthodont and reptilian features, and was originally regarded as the first reptile.〔Smithson, T.R. & Rolfe, W.D.I. (1990): ''Westlothiana'' gen. nov. :naming the earliest known reptile. ''Scottish Journal of Geology'' no 26, pp 137–138.〕 Most scientists place them among the Reptilomorpha, as a sister group to the first amniotes.〔
== Paleobiology ==
This species probably lived near a freshwater lake, and probably hunted for other small creatures that lived in the same habitat. It was a slender animal, with rather small legs and a long tail. Together with ''Casineria'', another transitional fossil found in Scotland, it is one of the smallest reptile-like amphibians known, being a mere 20 cm in adult length. The small size has made it a key fossil in the search for the earliest amniote, as amniote eggs are thought to have evolved in very small animals.〔Carroll R.L. (1991): The origin of reptiles. In: Schultze H.-P., Trueb L., (ed) ''Origins of the higher groups of tetrapods — controversy and consensus''. Ithaca: Cornell University Press, pp 331-353.〕〔Laurin, M. (2004): The Evolution of Body Size, Cope's Rule and the Origin of Amniotes. ''Systematic Biology'' no 53 (4): pp 594-622. (article )〕 Advanced features that tie it in with the reptilian rather than amphibian group include unfused ankle bones, lack of labyrinthodont infolding of the dentin, the lack of an otic notch, and a generally small skull.〔Paton R.L., Smithson, T.R. & Clack, J.A. (1999): An amniote-like skeleton from the Early Carboniferous of Scotland. ''Nature'' no 398: pp 508–513〕
Ruta & al. (2003) interpreted the long body and small legs as a possible adaption to burrowing, similar to that seen in modern skinks.〔Ruta, M.; Coates, M.I. & Quicke, D.L.J. (2003): Early tetrapod relationships revisited. ''Biological Review'' no 78: pp 251-345.(PDF )〕
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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