Propalaeotherium grazing on ferns while a Gastornis bird roams in background. - stock illustration

Propalaeotherium used to be called Eohippus. An early relative of the horse. There are a few species of these small and early horse relatives. They ranged in size from a foot high at the shoulder (35cm) to about two feet high at the shoulder (60cm). In the background is Gastornis, a large flightless bird that was about 6-7 feet tall (1.8-2.1 M). Luckily for the dawn horse, this bird is a vegetarian.