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''Eogavialis'' is an extinct genus of gavialoid crocodylian. It superficially resembles ''Tomistoma schlegelii'', the extant false gharial, and consequently material from the genus was originally referred to ''Tomistoma''. Indeed, it was not until 1982 that the name ''Eogavialis'' was constructed after it was realised that the specimens were from a more basal form. ==Species== The genus was first described by Charles William Andrews in 1901 when Andrews named a new species of ''Tomistoma'', ''T. africanum'', on the basis of a specimen found from an outcrop of the Qasr el-Sagha Formation in Egypt, about 20 miles northwest of Faiyum, dating back to the Priabonian stage of the late Eocene 37.2 to 33.9 million years ago. Other specimens were later found from the Gebel Qatrani Formation, slightly younger than the Qasr el-Sagha dating back to the Rupelian stage of the early Oligocene 33.9 to 28.4 million years ago, and near the locality where the original specimen of ''T. africanum'' was found in the Faiyum depression. A new species was also found from this locality and named ''T. gavialoides'' by Andrews in 1905. One of the first papers to identify the differences between these two species and others within ''Tomistoma'' was published in 1955 by J. A. Kälin.〔Kälin, J. (1955). Crocodilia. In J. Piveteau, ed., ''Traité de Paléontology'' 5:695-784; Paris: Masson.〕 Other papers were written in the following decades that also questioned these species' relationships within Tomistominae.〔Langston, W. Jr. (1965). ''Fossil crocodilians from Columbia and the Cenozoic History History of the Crocodilia in South America''. Publications in the Geological Sciences 52. Los Angeles. University of California.〕 Eric Buffetaut proposed the genus name ''Eogavialis'' in 1982 and reassigned both ''T. africanum'' and ''T. gavialoides'' to it. A third species was assigned to ''Eogavialis'' in 2003 from material found in the 1990s from the lower Nawata Formation of the Turkana basin outcropping in Lothagam, Kenya. The strata from which the material was found dates back to the late Miocene and early Pliocene, around 11.61 to 2.59 million years ago. This extends the fossil range of the genus by approximately 17 million years. It was named ''E. andrewsi'' for Charles Williams Andrews.〔Storrs, G. W. (2003). Late Miocene-Early Pliocene crocodilian fauna of Lothagam, southwest Turkana Basin, Kenya. In: ''Lothagam: The Dawn of Humanity in Eastern Africa'' pp. 137–159. New York. Columbia University Press. ISBN 0-231-11870-8.〕 The holotype consists of a well preserved, nearly complete skull. One reason why ''Eogavialis'' was initially placed within ''Tomistoma'' was due to the fact that the premaxilla and nasal bones made contact with one another, a feature also seen in ''Tomistoma''. However, this characteristic has since been shown to be present in other extinct gavialids, meaning that premaxilla and nasal contact is a plesiomorphic trait of all tomistomines, including basal ones. ''Eogavialis'' also has a very similar cranial anatomy when compared to ''Tomistoma'', having the same proportions, rostral length, and tooth number, leading to the conclusion by some authors of papers published after 1982 that ''Eogavialis'' is synonymous with ''Tomistoma''.〔Tchernov, E. (1986) ''Evolution of the Crocodiles in East and North Africa''. Cahiers de Paléontologie. Paris. Centre National de la Recherche Scientifique.〕 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「Eogavialis」の詳細全文を読む スポンサード リンク
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