Footprints found in the Grand Canyon, Arizona, reveal the journey that two creatures took when they walked up the sand dunes approximately 313 million years ago. The footprints were discovered when a huge boulder fell down in the Pennsylvanian Manakacha Formation, revealing the imprinted tracks.
The footprints belonged to a couple of four-legged shelled-egg-laying creatures belonging to the same species but they didn’t go together as they traveled up the sand dunes a few hours or even days apart from each other. Researchers found 28 footprints (each row containing four footprints three inches apart) with claw marks pointing forward from one of the creatures while the other set of prints didn’t contain claw marks on the right side which may suggest that its right foot could have been injured, causing it to limp. More specifically, the first creature walked towards its right side and traveled slower than the second animal.
The footprints were found by a Norwegian geology professor named Allan Krill who was out for a hike with several of his students when they came across the fallen boulder. When they examined their “surprising discovery”, they noticed the footprints and immediately sent a picture to Krill’s colleague Stephen Rowland, who is a paleontologist at the University of Nevada Las Vegas.
Rowland explained how incredible this discovery was, “These are by far the oldest vertebrate tracks in Grand Canyon, which is known for its abundant fossil tracks.” He went on to say that “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.” Several pictures of the footprints can be seen here.
The researchers found that the creatures that left the footprints walked in a specific gait pattern called a lateral-sequence walk which means that its legs on one side would move in sequence as its rear leg would move first, followed by its foreleg, and then the two legs on the opposite side of the animal would move forward. Basically, it would look similar to when cats and dogs walk slowly. “The Bright Angel Trail tracks document the use of this gait very early in the history of vertebrate animals. We previously had no information about that,” Rowland explained. Their study on the ancient footprints can be read in full here.