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The Columbian mammoth (''Mammuthus columbi'') was a species of mammoth that inhabited North America as far north as the northern United States and as far south as Costa Rica during the Pleistocene epoch. It was one of the last in a line of mammoth species, beginning with ''M. subplanifrons'' in the early Pliocene. The Columbian mammoth evolved from the steppe mammoth, which entered North America from Asia about 1.5 million years ago. The pygmy mammoths of the Channel Islands of California evolved from Columbian mammoths. The closest extant relative of the Columbian and other mammoths is the Asian elephant. Reaching at the shoulders and in weight, the Columbian mammoth was one of the largest species of mammoth. It had long, curved tusks and four molars, which were replaced six times during the lifetime of an individual. It most likely used its tusks and trunk like modern elephants—for manipulating objects, fighting, and foraging. Bones, hair, dung and stomach contents have been discovered, but no preserved carcasses are known. The Columbian mammoth preferred open areas, such as parkland landscapes, and fed on sedge, grass, and other plants. It did not live in the Arctic regions of Canada, which were instead inhabited by woolly mammoths. The ranges of the two species may have overlapped, and genetic evidence suggests that they interbred. Several sites contain the skeletons of multiple Columbian mammoths, either because they died in a single incident such as a flash flood, or because these locations were natural traps in which individuals accumulated over time. Before they went extinct, Columbian mammoths coexisted in North America for a few thousand years with Palaeoamericans, who hunted them for food, used their bones for making tools, and depicted them in ancient art. Columbian mammoth remains have been found in association with Clovis culture artefacts; these remains may have stemmed either from hunting or from scavenging. The Columbian mammoth disappeared at the end of the Pleistocene around 11,000 years ago, most likely as a result of habitat loss caused by climate change, hunting by humans, or a combination of both. ==Taxonomy== The Columbian mammoth was first scientifically described in 1857 by Scottish naturalist Hugh Falconer, who named the species ''Elephas columbi'' after Christopher Columbus. The animal was brought to Falconer's attention in 1846 by Charles Lyell, who sent him molar fragments found during the 1838 excavation of the Brunswick Altamaha Canal in Georgia, in the southeastern United States. At the time, similar fossils from across North America were attributed to woolly mammoths (then ''Elephas primigenius''). Falconer found that his specimens were distinct, confirming his conclusion by examining their internal structure and studying additional molars from Mexico. Although William Phipps Blake and Richard Owen believed that ''E. texianus'' was more appropriate for the species, Falconer rejected the name; he also suggested that ''E. imperator'' and ''E. jacksoni'', two other American elephants described from molars, were based on remains too fragmentary to classify properly. More complete material that may be from the same quarry as Falconer's fragmentary holotype molar was reported in 2012, and could help shed more light on that specimen, since doubts about its adequacy as a holotype have been raised. In the early 20th century, the taxonomy of extinct elephants became increasingly complicated. In 1942, Henry Fairfield Osborn's posthumous monograph on the Proboscidea was published, wherein he used various genus and subgenus names that had previously been proposed for extinct elephant species, such as ''Archidiskodon'', ''Metarchidiskodon'', ''Parelephas'', and ''Mammonteus''. Osborn also retained names for many regional and intermediate subspecies or "varieties", and created recombinations such as ''Parelephas columbi felicis'' and ''Archidiskodon imperator maibeni''. The taxonomic situation was simplified by various researchers from the 1970s onwards: all species of mammoth were retained in the genus ''Mammuthus'', and many proposed differences between species were instead interpreted as intraspecific variation. In 2003, palaeontologist Larry Agenbroad summarised current views about North American mammoth taxonomy, and concluded that several species had been declared junior synonyms, and that ''M. columbi'' (the Columbian mammoth) and ''M. exilis'' (the pygmy mammoth) were the only species of mammoth endemic to the Americas (as other species lived both there and in Eurasia). The idea that species such as ''M. imperator'' (the imperial mammoth) and ''M. jeffersoni'' (Jefferson's mammoth) were either more primitive or advanced stages in Columbian mammoth evolution was largely dismissed, and they were regarded as synonyms. In spite of these conclusions, Agenbroad cautioned that American mammoth taxonomy is not yet fully resolved. 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「Columbian mammoth」の詳細全文を読む スポンサード リンク
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