Protorohippus

Protorohippus (Latin: "before" (pro), + Greek: "mountain" (oros), "horse" (hippos)) is an extinct genus of equid that lived in the Eocene of North America.

== Palaeobiology == Based on oxygen and carbon isotope analysis of the teeth of P. montanum, the species is believed to have had two distinct birth seasons per year, a result of the diminished seasonality during the Early Eocene. It is possible that this phenomenon held for other early equids as well.thumb|left|Restoration by Charles R. Knight thumb|left|Skeleton cast