Jeffersonian Mammoth, Mammuthus jeffersonii
Approximately 1.5 to 1.8 million years ago the first mammoths entered North America. These mammoths came from Eurasia, crossing the Bering Strait at a time when sea level was lower than today. The first mammoths from Eurasia belonged to a species called M. meridionalis. The descendants of this species of mammoth included both Columbian and Jeffersonian mammoths.
Until recently, scientists recognized four species of mammoths (genus Mammuthus) during the late Pleistocene in North America. These were the Columbian mammoth (M. columbi), Jeffersonian mammoth (M. jeffersonii), woolly mammoth (M. primigenius), and the island pygmy mammoth (M. exilis) who lived on the Channel Islands off the coast of California. These species are defined primarily on differences in the morphology of their teeth and skeletons. However, recent genetic work on Columbian mammoths in Utah and Wyoming indicate a close relationship to woolly mammoths in Alaska, suggesting that, despite relatively large morphological differences between the two species of mammoths, genetically they were very similar (Enk et al 2011).
The Midwest was home to two species of mammoths, Jeffersonian and Woolly mammoths. Approximately 13,000 years ago all species of mammoths went extinct in North America. Mammoths, mastodons and modern elephants, are members of the order Proboscidea. The mammoths are closely related to the living elephants, especially to the Asian elephant (Elephas maximus).
Proboscidea (Elephants, Mastodonts)
Elephantidae (Elephants and Mammoths)
Height: 3.0-3.7 m (10-12 ft)
Weight: 5500-7300 kg (6-8 tons)