Scientific classification
Mastodons are members of an extinct genus of the order Proboscidea, and were herbivores who resembled modern elephants. The American mastodon (Mammut americanum) lived in North America beginning almost four million years ago, becoming extinct approximately 10,000 years ago. They were furry, and had a height of about three meters. They differed from mammoths mainly in the structure of their teeth, which were more suited to chewing leaves rather than for grazing. From their tooth structure they acquired the name mastodont (Greek μαστός and ὀδούς, "nipple tooth"), which was later shortened to the more familiar "mastodon."

Mastodon skeleton

Their tusks sometimes exceeded five meters in length. Their meat was a food source for early humans, and archeologists are still trying to determine what role, if any, the early human settlers of North America played in the extinction of the mastodon.