|Mounted mastodon skeleton, Museum of the Earth.|
Mastodons, with mammoths, modern elephants and various older families, are members of the order Proboscidea. As adults they stood between 2.5 and 3 meters (8-10 feet) at the shoulder and weighed between 3500 and 5400 kilograms (4-6 tons).
Stone tools and bones from a butchered mastodon were found at the bottom of a river in Florida. After a four-year investigation, researchers decided that humans lived there and made a meal of a mastodon 14,550 years ago.