Epihippus [SEP] parent taxon
Epihippus
Epihippus is an extinct genus of the modern horse family Equidae that lived in the Eocene, from 46 to 38 million years ago. 
"Epihippus" is believed to have evolved from "Orohippus", which continued the evolutionary trend of increasingly efficient grinding teeth. "Epihippus" had five grinding, low-crowned cheek teeth with well-formed crests. A late species of "Epihippus", sometimes referred to as "Duchesnehippus intermedius", had teeth similar to Oligocene equids, although slightly less developed. Whether
last premolar shifted in shape and function into a molar, and the crests on the teeth became more pronounced. Both of these factors gave the teeth of "Orohippus" greater grinding ability, suggesting "Orohippus" ate tougher plant material.
Eocene and Oligocene: early equids "Epihippus".
In the mid-Eocene, about 47 million years ago, "Epihippus", a genus which continued the evolutionary trend of increasingly efficient grinding teeth, evolved from "Orohippus". "Epihippus" had five grinding, low-crowned