18. Mastodons
Mastodons are distant relatives of the woolly mammoth. They migrated to North America via the Bering Strait land bridge roughly 15 million years ago. These creatures were prominent in North and Central America until they went extinct 10,500 years ago due to overharvesting by Clovis hunters.

Typically, mastodons traveled in herds and lived in cold spruce woodland areas. Their eating habits were very similar to modern elephants. They would browse and graze for mixed plants. The bulk of the mastodon diet was coniferous twigs. Mastodons in America had thick, shaggy coats like the woolly mammoth. Their tusks could reach over 16 feet in length and curved slightly upwards. These mammals reached heights up to 9 feet tall and weighed nearly 10 tons.