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''Smilodon'' , is an extinct genus of machairodont felid. It is perhaps one of the most famous prehistoric mammals, and the best known saber-toothed cat. Although commonly known as the saber-toothed tiger, it was not closely related to the tiger or other modern cats. ''Smilodon'' lived in the Americas during the Pleistocene epoch (2.5 mya–10,000 years ago). The genus was named in 1842, based on fossils from Brazil. Three species are recognized today: ''S. gracilis'', ''S. fatalis'' and ''S. populator''. The two latter species were probably descended from ''S. gracilis'', which itself probably evolved from ''Megantereon''. The largest collection of ''Smilodon'' fossils has been obtained from the La Brea Tar Pits. Overall, ''Smilodon'' was more robustly built than any extant (living) cat, with particularly well-developed forelimbs and exceptionally long upper canines. Its jaw had a bigger gape than that of modern cats and its upper canines were slender and fragile, being adapted for precision killing. ''S. gracilis'' was the smallest species at in weight. ''S. fatalis'' had a weight of and height of . Both of these species are mainly known from North America, but remains from South America have also been attributed to them. ''S. populator'' from South America is perhaps the largest known felid at in weight and in height. The coat pattern of ''Smilodon'' is unknown, but it has been artistically restored with plain or spotted patterns. In North America, ''Smilodon'' hunted large herbivores such as bison and camels and it remained successful even when encountering new prey species in South America. ''Smilodon'' is thought to have killed its prey by holding it still with its forelimbs and biting it, but it is unclear in what manner the bite itself was delivered. Scientists debate whether ''Smilodon'' had a social or a solitary lifestyle; analysis of modern predator behavior as well as of ''Smilodon''s fossil remains could be construed to lend support to either view. ''Smilodon'' probably lived in closed habitats such as forests and bush, which would have provided cover for ambushing prey. ''Smilodon'' died out at the same time that most North and South American megafauna disappeared, about 10,000 years ago. Its reliance on large animals has been proposed as the cause of its extinction, along with climate change and competition with other species, but the exact cause is unknown. ==Taxonomy== During the 1830s, Danish naturalist Peter Wilhelm Lund and his assistants collected fossils in the calcareous caves near the small town of Lagoa Santa, Minas Gerais, Brazil. Among the thousands of fossils found, he recognized a few isolated pieces as belonging to a hyena, which he named ''Hyaena neogaea'' in 1839. After more material was found (including teeth and foot bones), Lund realized the fossils belonged to a felid larger than any extant species, and named the animal ''Smilodon populator'' in 1842. The genus name ''Smilodon'' means "tooth shaped like double-edged knife" in Ancient Greek, from the words , (''smilē'') and (''odoús''). The species name ''populator'' means "he who brings devastation". By 1846, Lund had acquired nearly every part of the skeleton (from different individuals), and more specimens were found in neighboring countries by other collectors in the following years.〔(σμίλη ), Liddell, H. G.; Scott, R. ''A Greek-English Lexicon'', on Perseus〕 Though some later authors used Lund's original species name ''neogaea'' instead of ''populator'', it is now considered an invalid ''nomen nudum'' ("naked name"), as it was not accompanied with a proper description and no type specimens were designated.〔 Some South American specimens have been referred to other genera, subgenera, species, and subspecies, such as ''Smilodontidion riggii'', ''Smilodon'' (''Prosmilodon'') ''ensenadensis'', and ''S. bonaeriensis'', but these are now thought to be junior synonyms of ''S. populator''. Fossils of ''Smilodon'' were discovered in North America from the second half of the 19th century onwards. In 1869, American paleontologist Joseph Leidy described a maxilla fragment with a molar, which had been discovered in a petroleum bed in Hardin County, Texas. He referred the specimen to the genus ''Felis'' (which was then used for most cats, extant as well as extinct) but found it distinct enough to be part of its own subgenus, as ''F.'' (''Trucifelis'') ''fatalis''. The species name means "fate" or "destiny", but it is thought Leidy intended it to mean "fatal". In an 1880 article about extinct American cats, American paleontologist Edward Drinker Cope pointed out that the ''F. fatalis'' molar was identical to that of ''Smilodon'', and he proposed the new combination ''S. fatalis''.〔 Most North American finds were scanty until excavations began in the La Brea Tar Pits in Los Angeles, where hundreds of individuals of ''S. fatalis'' have been found since 1875. ''S. fatalis'' has junior synonyms such as ''S. mercerii'', ''S. floridanus'', and ''S. californicus''. American paleontologist Annalisa Berta considered the holotype of ''S. fatalis'' too incomplete to be an adequate type specimen, and the species has at times been proposed to be a junior synonym of ''S. populator''. Swedish paleontologists Björn Kurtén and Lars Werdelin supported the distinctness of the two species in 1990.〔 In his 1880 article about extinct cats, Cope also named a third species of ''Smilodon'', ''S. gracilis''. The species was based on a partial canine, which had been obtained in a cave near the Schuylkill River in Pennsylvania. Cope found the canine to be distinct from that of the other ''Smilodon'' species due to its smaller size and more compressed base. Its specific name refers to the species' lighter build. This species is known from fewer and less complete remains than the other members of the genus. ''S. gracilis'' has at times been considered part of genera such as ''Megantereon'' and ''Ischyrosmilus''. ''S. populator'', ''S. fatalis'' and ''S. gracilis'' are currently considered the only valid species of ''Smilodon'', and features used to define most of their junior synonyms have been dismissed as variation between individuals of the same species (intraspecific variation).〔 One of the most famous of prehistoric mammals, ''Smilodon'' has often been featured in popular media and is the state fossil of California. 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「Smilodon」の詳細全文を読む スポンサード リンク
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