A recently completed inventory of ancient animal tracks in a remote area of Death Valley National Park reveals that three species of horses once roamed the region in gentler climatic times.
The tracks, left up to 5 million years ago, were catalogued by paleontologist Torrey Nyborg, of Loma Linda University.
It took Nyborg four years to complete the work, creating a careful record of the numerous tracks spread across five square miles.
He used high-definition cameras and GPS technology to create the record.
The tracks he found were matched to mastodons, one species of tapir, five species of cats, five species of camels and three species of horse. There were bird tracks from 12 species, too.
Some of the prints tell a story. One set shows that a horse once slipped on soggy ground and landed on its rump.
Public access to the little-known canyon, which is peppered with the ancient tracks and is known informally as The Barnyard, is restricted.
Just 100 members of the public are allowed to visit annually, under careful supervision. The National Park Service is reportedly looking at options to allow greater access, but must first put in place formal plans to manage and protect the fossilized footprints.
The canyon is home to one of the largest, most diverse and well-preserved deposits of prehistoric mammal and bird tracks known to exist, according to the Los Angeles Times.
“This canyon is as good as it gets — there are fossil tracks almost everywhere you look,” Nyborg told the Times.
The prints were laid down in successive layers of mud that settled alongside what was once a spring-fed lake that drew migrating mammals and birds.
Tectonic activity pushed the landscape upward and the tracks changed to mud stone.