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ver the years, several fossils from localities in North America, Africa and Asia have been attributed to Mammut, but only the North American remains have been named and described, one of them being M. furlongi, named from remains found in the Juntura Formation of Oregon, dating from the late Miocene. However, it is no longer considered valid, leaving only 4 valid species left.
M. matthewi: Found in the Snake Creek Formation of Nebraska, dating from the late Hemphillian. Some authors consider it practically undistinguishable from M. americanum.
M. raki: Its remains were found in the Palomas Formation, nearby Truth or Consequences, New Mexico, dating from the early-middle Pliocene, between 4.5-3.6 Ma. It coexisted with Equus simplicidens and Gigantocamelus and differs from M. americanum in having a relatively longer and narrower third molar, similar to the description of the defunct genus Pliomastodon which supports its arrangement as an early species of Mammut. However, like M. matthewi, some authors don’t consider it sufficiently distinct from M. americaum to warrant its own species.
M. americanum: The American mastodon, the most known and the last species of Mammut, its earliest occurrences date from the early-middle Pliocene (early Blancan stage). It had a continent wide distribution, specially during the Pleistocene epoch, known from fossil sites ranging from present-day Alaska and New England in the north, to Florida, southern California, and as far south as Honduras. The American mastodon resembled a woolly mammoth in appearance, with a thick coat of shaggy hair. It had tusks that sometimes exceeded five meters in length; they curved upwards, but less dramatically than those of the woolly mammoth. Its main habitat was cold sprucewoodlands, and it is believed to have browsed in herds. It became extinct at the end of the Pleistocene approximately 11,000 years ago.\
A complete mtDNA sequence has been obtained from the tooth of an M. americanum skeleton found in permafrost in northern Alaska. The remains are thought to be 50,000 to 130,000 old. This sequence has been used as an outgroup to refine divergence dates in the evolution of the Elephantidae. The rate of mtDNA sequence change in proboscideans was found to be significantly lower than in primates.