Why were bovids able to thrive on fibrous plant foods?

Bovids are able to thrive on fibrous plant foods primarily because they are ruminants, possessing a specialized, four-compartment stomach that facilitates the digestion of cellulose—a material most animals cannot break down on their own.12

The largest of these compartments, the rumen, acts as a fermentation vat where microorganisms break down fibrous plant material. This process produces volatile fatty acids, which serve as a primary energy source for the animal. To maximize this efficiency, bovids engage in the behavior of "chewing the cud," where they regurgitate and rechew partially digested food to further break it down and distribute ruminal fluid.12

This evolutionary adaptation allowed bovids to exploit grasslands and other open habitats that became more prevalent during the Miocene Epoch. By tailoring their digestive systems and feeding apparatuses to these environments, bovids became highly efficient at extracting nutrients from diets that would provide little nourishment to nonruminant animals.32