How Did The Large Ungulates Roamed Western North America?

Large ungulates roamed western North America up until about 7000 years ago. The herds included woolly mammoths, oxen, bison, horses, burros and camels. As the landscape of western North America evolved, animal species coevolved to take advantage of the rangeland vegetation.
When the first people came to this part of the world, woolly mammoths, bison and other grazers still roamed. Evidence shows Native Americans hunted the large ungulates, as well as the saber tooth cat and other carnivores. These hunter-gatherers learned to use fire to drive animals as part of their hunting technique. They also discovered that the use of fire on rangelands increased the availability of desirable plants and maintained habitat for game animals.
After Spanish explorers Cortez and Coronado brought domesticated horses to the southwest in the 1500s, Native Americans obtained and bred horses, built up their herds, and equines joined the ranks of animals grazing western rangelands.
On their epic journey from St. Louis to the Pacific Ocean and back from 1804-1806, Lewis and Clark reported on many different grasses, forbs, and woody plants. In fact, Lewis described prairie dogs, sage grouse and other animals still common today on rangelands. Lewis’s woodpecker, Clark’s nutcracker and several plant species bear the names of the explorers. Lewis and Clark’s reports of their discoveries sparked increased interest in these uncharted lands. The idea of making dreams come true in the west appealed to many easterners. As a result, the first wagon-traveled road- called the Oregon Trail- crossed the country in the 1840s. Over the next twenty years, there was a mass western migration. The discovery of gold in California in 1849 helped to bring about even more