Fossil Mastodon Tooth. Mastodons lived in Florida during the last ice age (Pleistocene Epoch) and were ancient relatives of the modern elephant. These massive creatures ate leaves, twigs and brush, and had large dental cusps to grind their plant diet. We know Mastodons, along with other now-extinct animals like camels, saber-tooth cats, and giant ground sloths, roamed Florida because we find their fossilized remains. However, Florida was not always as it is today. During the Pleistocene, the world was much colder (hence the name ice age) and drier – huge amounts of water was trapped in massive ice sheets which lowered the sea level. With such a lower sea level, the Gulf coast of Florida extended about 50 miles further west which means places like Tampa Bay would have been in the middle of the state!