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''Homotherium'' is an extinct genus of machairodontine saber-toothed cats, often termed scimitar-toothed cats, that ranged from North America, South America, Eurasia, and Africa during the Pliocene and Pleistocene epochs (5 mya–11,700 years ago), existing for approximately .〔(PaleoBiology Database: ''Homotherium'', basic info )〕 It first became extinct in Africa some 1.5 million years ago. In Eurasia it survived until about 30,000 years ago. In South America it is only known from a few remains in the northern region (Venezuela), from the mid-Pleistocene.〔 The most recent remains of homotherium dates to 28,000 years BP. == Taxonomy and evolution== The name ''Homotherium'' (Greek: (''homos'', ‘same’) and (''therion'', ‘beast’) was proposed by Fabrini (1890), without further explanation, for a new subgenus of Machairodus, whose main distinguishing feature was the presence of a large diastema between the two inferior premolars 〔E. Fabrini, "I Machairodus (Meganthereon) del Val d'Arno superiore". ''Bollettino Comitato Geologico d'Italia'', 21 (1890), pp. 121–144, 161–177; esp. 176〕 ''Homotherium'' probably derived from ''Machairodus'' and appeared for the first time at the Miocene-Pliocene border, about 5 million years ago.〔Alan Turner: "The Evolution of the guild of larger terrestrial carnivores during the Plio-Pleistocene in Africa". Geobios, no 23, fasc. 3, p. 349-368, 1990.〕 During the Pleistocene it occurred in vast parts of Eurasia, North America and until the middle Pleistocene (about 1.5 million years ago) even in Africa. A fossil of ''H. crenatidens'' was inadvertently dredged from the bed of the North Sea, which was a flat, low-lying extent of marshy tundra laced with rivers during the recent glaciation.〔((BBC News) Paul Rincon, "Big cat fossil found in North Sea", 18 November 2008 ) accessed 18 November 2008〕 There has also been a discovery of 1.8 million-year-old fossils in Venezuela,〔Rincón, A., Prevosti, F., & Parra, G. (2011). New saber-toothed cat records (Felidae: Machairodontinae) for the Pleistocene of Venezuela, and the Great American Biotic Interchange. ''Journal of Vertebrate Paleontology'', 31 (2), 468-478 DOI: 10.1080/02724634.2011.550366〕 indicating that scimitar cats were able to invade South America along with ''Smilodon'' during the Great American Interchange. These remains form the holotype of ''Homotherium venezuelensis''.〔Rincón, A., Prevosti, F., & Parra, G. (2011). New saber-toothed cat records (Felidae: Machairodontinae) for the Pleistocene of Venezuela, and the Great American Biotic Interchange Journal of Vertebrate Paleontology, 31 (2), 468-478 DOI: (10.1080/02724634.2011.550366 )〕 How long they lasted in South America is not yet evident. ''Homotherium'' survived in Eurasia until about 28,000 years ago.〔 Several species (''H. nestianus'', ''sainzelli'', ''crenatidens'', ''nihowanensis'', ''ultimum'') are recognized from Eurasia, which differ mainly in the shape of the canines and in body size. But given the fluctuation range of the size of modern large cats, it is highly probable that all belong to one species, ''Homotherium latidens''. Two species described form the early Pleistocene of Africa are ''Homotherium ethiopicum'' and ''Homotherium hadarensis''. But they also hardly differ from the Eurasian forms.〔 On the African continent the genus disappeared about 1.5 million years ago. In North America, a very similar species, ''Homotherium serum'' occurred from the late Pliocene until the late Pleistocene. Remains have been found at various sites between Alaska and Texas. In the southern parts of its range the American ''Homotherium'' co-existed with ''Smilodon''; in the northern parts it was the only species of saber-toothed cat. The American ''Homotherium'' was originally described by the name ''Dinobastis''. Despite ''Homotheriums vast range and the large amount of fossil remains from Eurasia, Africa and North America, complete skeletons of this cat are relatively rare. One of the most famous sites of ''Homotherium'' remains is Friesenhahn cave in Texas, where 30 ''Homotherium'' skeletons were found, along with hundreds of juvenile mammoths and several dire wolves. The genus ''Dinobastis'' was originally named by Cope (1893). Its type is ''Dinobastis serus''. It was synonymized subjectively with ''Smilodon'' by Matthew (1910) and later with ''Homotherium'' by Churcher (1966), Schultz and ''et al.'' (1970), Waldrop (1974), Kurten and Anderson (1980), Churcher (1984) and Dalquest and Carpenter (1988).〔W. D. Matthew. 1910. Bulletin of the American Museum of Natural History 28〕〔C. B. Schultz et al. 1970. Bulletin of the Nebraska State Museum 9〕〔W. W. Dalquest and R. M. Carpenter. 1988. Occasional Papers, Museum, Texas Tech University 124〕 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「Homotherium」の詳細全文を読む スポンサード リンク
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