Archeologists find it easier to decode prehistoric life from tangible evidence rather than from something as minuscule as a footprint. Footprint sites are special because they capture a moment in time. They are followed by fossil trackways. Many trackways are made by dinosaurs, early tetrapods, and other quadrupeds and bipeds on land.
The trackways found in Mexico gave us an insight into prehistoric life. It consisted of 400 human prints including that of a toddler. Scientists documented nearly a mile of prints, making this the longest-known fossilized human trackway in the world. The tracks run north/ north-west in a straight line before disappearing into the dunes. Beside them were the remains of the return journey, seemingly by the same person.
The story from the fossil
10,000 years ago, a woman- assumed 12 years of age or a young male, together with a toddler, balanced on the hip, set out on a northward journey through Mexico. Rain may have pelted the traveler's face as their bare feet slid into the mud. They paused briefly and set the child on the ground before pressing on. Several hours later, the traveler followed the same tracks southward, this time empty-handed.
Researchers theorize that this reflects a social network, in which the person knew that they were carrying the child to a safe destination. The individual was very goal-oriented and didn’t deviate from the path. This journey taken by the individual and child was a dangerous one. Previously, wooly mammoths, giant sloths, saber-toothed tigers, and dire wolves prints had been discovered. The human footprints indicate that they were in a hurry, adding to the theory of a hostilized landscape. Beside the human tracks, footprints of a Columbian Mammoth and a giant sloth was also discovered. Scientists believe that the giant sloth depicted behavior of being aware of human presence while the mammoth remained unbothered. The prints suggest that the sloth likely took notice, reared back on two legs, possibly to sniff the human presence. This is similar to how bears behave today.
This kind of behavioral study “can’t be predicted from bones. (And it) gives us a sense of how humans existed within their ancient ecosystem”, says study author Sally Reynolds, a paleontologist at Bournemouth University.
History of the discovery
This 10,000-year-old trek is from the Pleistocene Age, revealed in present-day New Mexico White Sands National Park, which was previously Lake Otero. The lakes' muddy terrain preserved footprints for thousands of years and it eventually dried up. This particular lakebed is also home to a range of other footprints dating from 11,550 to 13,000 years ago.
The human tracks were first discovered in 2017 by David Bustos, a National Park employee. He invited a group of scientists among whom was Matthew Bennett, a geoscientist at Bournemouth University. The “ghost” footprints were previously visible for a short time after rain and in the right conditions. Now using geophysical methods, such as GPR (Ground-penetrating radar), they can be recorded, tracked, and investigated in 3D to reveal various interactions. GPR is a geophysical, non-intrusive method that uses radar pulses to image and survey the subsurface.
The prints of the new study were pressed into fine sand and a thin crust of salt was all that held their shape together. The team carefully excavated 140 of the tracks using a brush. Such fragile forms quickly break down once uncovered, so the technique of 3D Photogrammetry was used.
The human footprints show morphological variability and left-right asymmetry, due to the child balanced on the hips. This is inferred using methods based on the analysis of track outlines, and the application of geophysical imaging which includes GPR. The shape, structure, and spread of the tracks helped to unveil an intimate portrait of the persons’ walk right down to their toes slipping on the surface.
The US National Park Service released a statement regarding the findings on October 16th, 2020. Quaternary Science Reviews is a journal with a paper published by Sally Reynolds, the senior author of the new paper on the tracks. The online publication came ahead of its print publication which is to be in December.
By: Melanie Dsouza