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Christopher Columbus was wrong: The Earth is flat, at least in places. There are seemingly endless expanses of open ground, flat as the mind can imagine, found on every continent. Sometimes they are covered with grasses, ice or low shrubs that dot the land like stubble on a vast expanse of dry skin.
The great plains of Earth are truly the oceans of the land. And like the seas, it's the little green plants that make most of them work. Grasses are at the center of food webs that include rabbits, buffalo, yaks, camels, wolves and many other animals that live today on plains, or disappeared just a few thousand years ago — the blink of an eye in the history of the planet.
Lost Seas
The secret to making plains differs with the plain. The easiest way to get a plain, however, is to build it underwater. This is where the Great Plains of North America got started. More than 70 million years ago these plains were the bottom of a shallow sea. That sea had spent about 500 million years collecting sediments from 5,000 to 10,000 feet (1,500 to 3,000 meters) deep from land to the east and west. It made for a very flat, soft seabed that stretched for thousands of miles.
The uplift of that land since then hasn't changed its basically flat character. But as dry land it was new territory and habitat that helped evolve some strange creatures — like the Titanotheres, giant creatures with huge horns on their snouts. These lived 37 to 22 million years ago alongside herds of camels, rhinoceroses, tapirs and horses, which are still found elsewhere in the world.
The Great Plains today stretch from Mexico and Texas, north into Canada — 3.2 million square miles (8.3 million square kilometers) in all. Before Europeans came to North America, the Great Plains were vast open grasslands between the western end of the great Atlantic forests and the Rocky Mountains. They were too dry for trees, except in the lowest spots where water can collect. Grasses took over and made a fine home for the great American bison, or buffalo, upon which many Native American tribes depended.
No Easter Bunny
Among the things we can thank another vast plain for is the "Easter Bunny," indirectly. Bunnies of any kind, actually. It was on the plains of Mongolia in northern China that these beloved grass eaters evolved more than 20 million years ago. Lagomorphs, as these animals are called, evolved to eat the grass, and drove the evolution of a set of smaller carnivores, like foxes and eagles, that specialize in prey this size.
In all, the grassland plains of Inner Mongolia, China, encompass 306,000 square miles (792,000 square kilometers), forming a 1,000-mile (1,600-kilometer) swath of grass across Central Asia. They support tens of millions of livestock animals in addition to wildlife.
