Today’s horse has existed for roughly one million years. Today’s horse is a one-toed animal; however, this was not always the case. Some fifty million years ago, EOHIPPUS, ran on feet with toes. Its front feet had four hooved toes, its hind feet had three, and its weight was carried on a central pad. Several million years later, its descendant, MESOHIPPUS, had grown twice the size. All four feet had three toes, the central toe being prominent.
Another ten million years passed and the horse became MERYCHIPPUS. The MERYCHIPPUS fed on grass rather than leaves and carried its weight on a single hoof, although two side toes were present.
PLIOHIPPUS, which lived ten million years ago, was the first single-toed horse. It roamed the plains and was able to graze freely and run swiftly from its predators. Traces of the side toes were present on either side of the cannon bone.
EQUUS CABALLIS, today’s horse, is a one-toed animal. The single toe has become a part of the horse’s anatomy.
The hoof wall grows down from the coronary band. It is thick enough to have nails driven into it without splitting, and can be trimmed just like human fingernails.