Here's why:
* Teeth and digestive system: Horses have specialized teeth for grinding vegetation, and their digestive system is designed to break down grasses and other plant matter.
* Body structure: Horses have long legs and a slender body suited for running and grazing on open plains. Their teeth and digestive system are not adapted for catching and killing prey.
* Diet: Fossil evidence and analysis of their teeth indicate that Equus occidentalis grazed on a diet of grasses and other vegetation.
While the Equus occidentalis may have been preyed upon by larger predators like saber-toothed cats, they themselves were not predators.