Some of the oldest tracks of shelled, egg-laying animals ever recorded have just been confirmed to exist in Grand Canyon National Park.
In 2016, geology professor Allan Krill was hiking with students when he noticed a boulder lying next to the trail containing fossil footprints. He took a photo and sent it to Stephen Rowland, a paleontologist at the University of Nevada.
According to Rowland, the tracks “are by far the oldest vertebrate tracks in Grand Canyon, which is known for its abundant fossil tracks. 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.”
“Some of the conclusions likely are going to be controversial,” Mark Nebel, the paleontology program manager at Grand Canyon, told the Associated Press. “There’s a lot of disagreement in the scientific community about interpreting tracks, interpreting the age of rocks, especially interpreting what kind of animal made these tracks.”
The tracks are currently believed to be from two separate animals, who have lateral-sequence walk and move one leg at a time — the same way cats and dogs do when they walk very slowly.
The boulder had fallen from a nearby cliff-exposure of the Manakacha Formation and is visible for those who use the Bright Angel Trail. It’s unknown if the rock will stay where it is and be part of a special display or be relocated to a museum.