Question

What led to the development of grasslands?
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Answer 1

Answer:

The appearance of mountains in the western United States during the Miocene and Pliocene epochs, a period of some 25 million years, created a continental climate favorable to the evolution of grasslands. Existing forest biomes declined, and grasslands became much more widespread.

Answer 2

Answer:

Around 12000 years ago, there were major changes in the climate of the world, with a shift to relatively warm conditions. In many areas, this led to the development of grasslands. This in turn led to an increase in the number of deer, antelope, goat, sheep and cattle, i.e. animals that survived on grass.