The Miocene was a time of drastic change in environment, with woodlands transforming into grass plains. This led to evolutionary changes in the hooves and teeth of equids. A change in surface from soft, uneven mud to hard grasslands meant there was less need for increased surface area. The foot was fully supported by ligaments, and the middle toe developed into a hoof that did not have a pad on the bottom. In some "Merychippus" species, the side toes were larger, whereas in others, they had become smaller and only touched the ground when running. The transformation into plains also meant "Merychippus" began consuming more phytolith rich plants. This led to the presence of hypsodont teeth. Such teeth range from medium to intense crown height, are curved, covered in large amounts of cement, and are characteristic of grazing animals