Mastodon, a large, extinct animal resembling the elephant and mammoth. The mastodon's molars (grinding teeth) had knobby crowns and long, distinct roots. The molars of elephants and mammoths, on the other hand, are composed of a series of plates, and the grinding surfaces are corrugated (closely ridged).

The mastodonThe mastodon had long, curving tusks in the upper jaw.

Like the mammoth, the mastodon had long, curving tusks in the upper jaw. Some early species also had a set of short tusks in the lower jaw. The mastodon was covered with shaggy hair, as was the mammoth, but the mastodon's head was less dome-shaped and its body was more slender than the mammoth's. The mastodon was 7 to 9 feet (2.1 to 2.9 m) tall and 10 to 14 feet (3 to 4.3 m) in length, excluding the tusks.

The mastodon lived in Asia, eastern Europe, and North and South America during the Ice Age. It was hunted by early humans. The mastodon became extinct, for unknown reasons, about 10,000 years ago.

North American species of the mastodon are classified as Mammut americanus and M. moodiei of the family Mammutidae.