Ice age fossils from Yukon help identify new horse genus

DNA analysis has prompted researchers to re-think the horse family tree. The new genus — Haringtonhippus francisci — was an evolutionary dead-end, unrelated to any modern horse or donkey species.

Stilt-legged horses — extinct since the last ice age — are unrelated to modern horses, donkeys and zebras

A family of stilt-legged horses in Yukon, during the last ice age. Researchers have concluded that the now-extinct genus was an evolutionary dead end. (Jorge Blanco)

Some ancient horse fossils from the Yukon's Klondike goldfields have helped researchers identify a previously unknown genus of stilt-legged horses that went extinct at the end of the last ice age, about 17,000 years ago.

The researchers say their discovery alters the known family tree of North American horses, by revealing the new genus — Haringtonhippus francisci — as an evolutionary dead-end, unrelated to any modern equine species.

Stilt-legged horses once roamed North America and were previously thought to be related to modern horses, donkeys, and zebras.

But according to a study published by the online journal eLife, DNA analysis of bones from Yukon, Nevada and Wyoming prompted researchers to rethink the horse family tree.

"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," said senior study author Beth Shapiro, in a statement. Shapiro is a researcher from the University of California.

The scientists chose to name the genus after paleontologist Richard Harington, of the Canadian Museum of Nature. Harington was a frequent visitor to the Klondike region from the 1960s to the 1980s, searching for fossils and talking to placer miners about things they found.

In a statement, Harington said he was "delighted" to have his name attached to the extinct genus.

He said he'd been curious for years about the identity of a horse bone he found in the Klondike, and another from Lost Chicken Creek in Alaska. The new research shows they belong to his namesake genus, he said.