Cliff collapses in Grand Canyon, revealing 313 million-year-old footprints, park says

A geology professor hiking in the Grand Canyon made a “surprising discovery” — the oldest recorded tracks of their kind.

After a cliff collapsed in Grand Canyon National Park, a boulder with fossilized tracks was revealed, park officials said in a Thursday news release. The fossil footprints are about 313 million years old, according to researchers.

“These are by far the oldest vertebrate tracks in Grand Canyon, which is known for its abundant fossil tracks” Stephen Rowland, a paleontologist at the University of Nevada, Las Vegas, said in the news release. “More significantly, they are among the oldest tracks on Earth of shelled-egg-laying animals, such as reptiles, and the earliest evidence of vertebrate animals walking in sand dunes.”

The tracks were in plain view for many hikers, but weren’t discovered until Allan Krill, a Norwegian geology professor, was hiking with students and saw a boulder containing “conspicuous fossil footprints,” park officials said.

Researchers said the footprints show two separate animals passing on the slope of a sand dune, which is significant because of the “distinct arrangement of footprints.”

“The researchers’ reconstruction of this animal’s footfall sequence reveals a distinctive gait called a lateral-sequence walk, in which the legs on one side of the animal move in succession, the rear leg followed by the foreleg, alternating with the movement of the two legs on the opposite side,” Grand Canyon officials said.

They “previously had no information about that,” Rowland said. The fossil also shows the earliest-known use of sand dunes by vertebrate animals, park officials said.