Members of this genus where slightly larger than Mesohippus (around 50 kg) and had a longer skull and limbs. They lived in what is now North America, alongside Mesohippus before the latter became extinct.
Its lateral toes were reduced even further and they probably only touched the ground during fast running or when moving on soft ground. Miohippus was the first Equid to have the typical ridges on their molars which we can see in modern horses and which facilitated grinding coarse plant based diets.
Up until now, only one or two Equid genera were present at a time. Miohippus was the origin for the first larger diversification of horse species and it gave rise to at least three genera with many different species, some living in the forests, some on the open plains.