Ancient diets, ecology, and extinction of 5-million-year-old horses from Florida

Six sympatric species of 5-million-year-old (Late Hemphillian) horses from Florida existed during a time of major global change and extinction in terr estrial ecosystems. Traditionally, these horses were interpreted to have fe d on abrasive grasses because of their high-crowned teeth. However, carbon isotopic and tooth microwear data indicate that these horses were not ail C -4 grazers but also included mixed feeders and C-3 browsers. The late Hemph illian Florida sister species of the modern genus Equus was principally a b rowser, unlike the grazing diet of modern equids. Late Hemphillian horse ex tinctions in Florida involved two grazing and one browsing species.