A mastodon (mastós 'breast' + odoús 'tooth') is any proboscidean belonging to the extinct genus Mammut (family Mammutidae) that inhabited North and Central America during the late Miocene or late Pliocene up to their extinction at the end of the Pleistocene 10,000 to 11,000 years ago. Mastodons lived in herds and were predominantly forest-dwelling animals. They survived on a mixed diet and obtained food by browsing and grazing, somewhat similar to modern elephants, but probably with greater emphasis on browsing.
M. americanum, the American mastodon, and M. pacificus, the Pacific mastodon, are the youngest and best-known species of the genus. Mastodons disappeared from North America as part of a mass extinction of most of the Pleistocene megafauna, widely believed to have been caused by a combination of climate changes at the end of the Pleistocene combined with overexploitation by Paleo-Indians.