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Letognathus
''Letognathus'' is a genus of rhizodont tetrapodomorph that lived during the Carboniferous period.〔Brazeau, M.D. 2005. A new genus of rhizodontid (Sarcopterygii, Tetrapodomorpha) from the Lower Carboniferous Horton Bluff Formation of Nova Scotia, and the evolution of the lower jaws in this group. ''Canadian Journal of Earth Sciences'' 42:1481–1499〕 Its remains come from the Blue Beach Member of the Horton Bluff Formation, near Hantsport, Nova Scotia. Like most rhizodonts, it was of relatively large size, had a large recurved fang at the symphysis of the lower jaw, and a row of three coronoid fanks along the length of the jaw in addition to its marginal dentition. ''Letognathus'' is important for rhizodont systematics because it retains a number of primitive features, such as ossified Meckel's cartilage, are not found in the genera ''Rhizodus'' and ''Strepsodus''. == Taxonomic History == The members of the Rhizodontida have nearly all had complex taxonomic histories〔Jeffery, J.E. 2006. The Carboniferous fish genera ''Strepsodus'' and ''Archichthys'' (Rhizodontida: Sarcopterygii): clarifying 150 years of confusion. ''Palaeontology'' 49: 113-132〕 due to earlier use of the genus ''Strepsodus'' as a wastebasket taxon. The taxon was originally assigned to the genus ''Rhizodus'' by John William Dawson and later to ''Strepsodus'' by Arthur Smith Woodward. A new genus was erected for the Horton Bluff material based on a number of differences from either ''Strepsodus'' or ''Rhizodus''.
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「Letognathus」の詳細全文を読む
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