Green River Formation Dawn Horse Track Fossil

This plate contains the extremely rare track of Eohippus (meaning "dawn horse"), the earliest known horse. Also called Hyracotherium, this grazing herbivore was the size of a small dog. It had 4 hoofed toes on the front feet and 3 hoofed toes on the hind foot. However, the fourth toe on the front foot was higher on the foot and is not likely to leave an impression. Eohippus lived during the early Eocene Epoch, about 50 million years ago and ranged across Asia, Europe, and North America. Fossils were first discovered by the famous British paleontologist Richard Owen in 1841 who named it Hyracotherium (meaning "mole beast").

Similar small three toed tracks described as extremely rare horse tracks have been found near Soldier Summit as reported in the Journal of Paleontology (November 1968).