This tooth, about twice life size, is from a hypsodont horse that once galloped over grassy plains in what is now South Carolina on the American east coast during Miocene times (25 to 5 million years ago).
Hypsodont teeth grow continuously for several years, as the horse grazes on tough grasses that wear its teeth down. As a consequence, they can be a record of environmental conditions over the course of their existence, much like tree rings. New research is capitalizing on that to learn more about the seasonal climate of the Miocene Epoch. Dinosaurs Guide Bob Strauss has lots more about ancient horses.
