What was life like in the Great Plains region 10 million years ago?

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enotechris eNotes educator| Certified Educator

The Great Plains, a huge area in the Western United States and Canada, 10 million years ago was an eastward sloping depositional plain surmounted by a few mountain masses.  Most interestingly, back then about a dozen species of what we would understand to be horses inhabited the plain. Some of these include the species Dinohippus, a single toed "horse" that grazed on grass as horses do today, Hypohippus, a two-toed "horse" that unlike the modern species, ate leaves, and a three toed "horse" Nannippus which ate both grass and leaves.  All horses in North America became extinct at the end of the last ice age, about 10,000 years ago.