What did prehistoric horses eat?

Answer 1

Before the flood everyone were vegetarians!! probably ate what horses eat today.

Answer:

The very early ancestors of horses such as Condylarth, were a dog-sized, five-toed creature that lived about 75 million years ago during the early Eocene period. These evolved into the predecessor of modern horses (Eohippus) which inhabited the open grasslands. From that time unto this horses have been vegetarians living on a diet composed mainly of grass.

Answer 2

The earliest horses were browsers, much like modern goats are. They would eat leaves, bark, a little grass, and weeds. As they evolved horses began to eat more and more grass, just like modern horses do now.