When you visit the White Sands National Monument in New Mexico, you will witness endless waves of bright plaster. It's great, but a team of researchers led by Cornell University scientists was more interested in what's hiding under the sand.
The team used ground-penetrating radar, which is used to detect more rocks near Stonehenge, to probe the movements of mammoths, humans and giant lizards 12,000 years ago. These trails are normally difficult to see unless conditions are perfect. Researchers call them "ghost paths".
Scientists said in a paper, "3-D radar imaging unlocks unused behavioral and biomechanical biomechanical paths," Scientific Reports magazine said on Monday.
"We never thought to look under the feet," lead author Thomas Urban said in the Cornell edition. "But it turns out that the sediment itself has a memory that records the effects of weight and momentum on the animal in a nice way. It gives us a way to understand the biomechanics of extinct fauna that we didn't have before."
The radar revealed a fascinating scene from the past that consisted of a double track of human feet extending over 2,600 feet (800 meters). It showed the movements of what was probably one person walking one way and then returning to roughly the same path. Mammoth paths cross human paths.
One of the mammoth tracks is special. It shows where the man stepped on the track later, leaving an imprint on his arm. This gives researchers a rare overview of how humans and mega-fauna can interact before all those years.
This study shows how the radar intruder can uncover previously hidden secrets from the past, even as subtle as footprints. "The technique could eventually be applied to many other fossilized footprint locations around the world, potentially including those of dinosaurs," Urban said.