Fossil found in cave holds clues of ancient horse

LAS VEGAS — A well-preserved horse skull collected more than 86 years ago from a cave near Las Vegas is helping scientists identify a new type of extinct, stilt-legged horse that died out during the last ice age.

Scientists are calling it Haringtonhippus francisci after Richard Harington, an accomplished paleontologist who spent his career studying the ice age fossils of northern Canada and first described the stilt-legged horses in the early 1970s, the Las Vegas Review-Journal reported Tuesday.

A team of researchers led by famed archaeologist Mark Harrington discovered the bone in the 1930s inside the Gypsum Cave east of Las Vegas.

The fossil was initially mistaken for a modern specimen because it looked so fresh, said Paleontologist Eric Scott.

“It looked like last week’s lunch,” he said.

It turns out the horse skull is actually 13,000 years old.

It was put away in museum collections, and was not revisited until recently.

Scott tracked down the skull on a shelf at the Natural History Museum of Los Angeles County. He found it mislabeled.

“Someone had even written in pencil across the top of the skull: ‘modern sample, wild horse or burro,’” he said.

The new genus of horse was a lightly built horse with long, thin leg bones, according to a study by an international team of researchers including Scott published Nov. 28 in the journal eLife.

Using the skull found in the Nevada cave and other fossils found in Wyoming and Canada, researchers determined that the extinct horses were not closely related to any living population.

“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 the study’s senior author, Beth Shapiro, a professor of ecology and evolutionary biology at the University of California, Santa Cruz.

Mark Harrington’s expedition in the Gypsum Cave almost 90 years ago also uncovered evidence of the extinct Shasta ground sloth.

After finding so many sloth skulls, backbones, claws and even reddish-brown hair, Harrington concluded that the cave may have served as an ice age den for the animal.

From a thick layer of sloth dung that covered the cave floor, scientists were able to identify what the sloth liked to eat and what was growing in the area at the time.

The cave’s historical importance was recognized in 2010 when it was added to the National Register of Historic Places.