Additionally, these traits do not necessarily evolve together, or at a steady rate. The various morphological characters each evolved in fits and starts, and did not evolve as a suite of characters. For example, throughout the Eocene, the feet changed little, and only the teeth evolved. Throughout the Miocene, both feet and teeth evolved rapidly. Rates of evolution depend on the ecological pressures facing the species.
New species can arise through several different evolutionary mechanisms.
Again, evolution proceeds according to the ecological pressures facing the individuals of a species and on the variation present within that species. Evolution takes place in the real world, with diverse rates and modes, and cannot be reduced to a single, simple process. Creationism utterly fails to explain the sequence of known horse fossils from the last 50 million years. To me, the horse fossils tell a magnificent and fascinating story, of millions of animals living out their lives, in their natural world, through millions of years. I am a dedicated horse rider and am very happy that the one-toed grazing Equus survived to the present.