Mastodons were large tusked mammal species of the extinct genus Mammut which inhabited Asia, Africa, Europe, North America and Central America from the Oligocene through Pleistocene, 33.9 mya to 11,000 years ago. The American mastodon is the most recent and best known species of the group.
The American mastodon, Mammut americanum, lived from about 3.7 million years ago until about 10,000 BC. It was the last surviving member of the mastodon family. It is known from fossils found ranging from present-day Alaska and New England in the north, to Florida, southern California, and as far south as Honduras and El Salvador.
http://en.wikipedia.org/wiki/Mastodon
