LOS ANGELES, Nov. 28 (Xinhua) -- A new analysis of ancient DNA from fossils reveals a previously unrecognized genus of extinct horses that once roamed North America during the last ice age.

According to the new discovery, conducted by an international team of researchers, this extinct species of North American horse, now named Haringtonhippus francisci, appears to have diverged from the main trunk of the family tree leading to Equus some four to six million years ago.

The new findings, published Tuesday in the journal eLife, are based on an analysis of ancient DNA from fossils of the enigmatic "New World stilt-legged horse" excavated from sites such as Natural Trap Cave in Wyoming, Gypsum Cave in Nevada, and the Klondike goldfields of Canada's Yukon Territory.

Prior to this study, these thin-limbed, lightly built horses were thought to be related to the Asiatic wild ass or onager, or simply a separate species within the genus Equus, which includes living horses, asses, and zebras. The new results, however, reveal that these horses were not closely related to any living population of horses.

"The evolutionary distance between the extinct stilt-legged horses and all living horses took us by surprise, but it presented us with an exciting opportunity to name a new genus of horse," senior author Beth Shapiro, professor of ecology and evolutionary biology at University of California, Santa Cruz, was quoted as saying in a news release.