Did aspects of a horse's anatomy evolve over hundreds of years to suit their environment or millions of years to suit their environment

The evolution of a horse's anatomy occurred over millions of years in response to changes in their environment and ecological pressures. Different aspects of their anatomy, such as their teeth, limbs, and digestive system, evolved to help them adapt to various habitats and feeding strategies. The evolution of the horse can be traced back over 50 million years, with numerous adaptations occurring throughout this long period of time.