Oldest human footprints in North America identified -10,500-year-old footprints smash record
// January 12th, 2014 // Geology and Archaeology News
In 1961, during a highway construction project in northeastern Mexico, less than 200 miles from the Texas border, a pair of tracks, one left and one right, were uncovered in the Chihuahuan Desert. The tracks were excavated and taken to a local museum (Saltillo’s Museo del Desierto) for study. Now, over 50 years later, researchers have determined that the tracks are a mind-boggling 10,500 years old, smashing the previous record by thousands of years.
The tracks were preserved in Travertine, a sedimentary rock that contains minute traces of uranium, providing scientists the means to use the element’s radioactive decay rate (uranium decays into thorium at a predictable rate) to determine the specimens’ ages. Researchers returned to the area of the discovery but unable to determine the precise location (the exact location of the find has been lost to history), did not find additional specimens. They did however, uncover 11 other prints in a Cuatro Cienegas quarry that date back about 7,250 years.
According to Discovery Magazine:
“The difference in age suggests that, while both sets of prints were made possible by the basin’s marshy, carbonate-rich sediments, the 11 recently discovered tracks are not from the same precise location as the pair found in the 1960s.
Although rare, other fossil human footprints have been found elsewhere in North America, from Nicaragua to California. But those tracks are at least a thousand years younger than the newly studied samples. The oldest known human print in the Western Hemisphere is the tiny track of a child’s foot in Chile dated to 13,000 ago — adding fodder to the ongoing debate about when humans first migrated to the New World.”
The oldest previously reported human fossil evidence in the area were coprolites — fossil feces — found in a rockshelter dated to about 9,000 years ago. What’s more, analysis of the 7,200-year-old tracks also turned up traces of ancient pollen from trees like pecan and willow, suggesting that the region was cooler and wetter than it is today. But analysis also yielded pollen from prickly pear cactus, a staple of the Coahuiltecans in historic times, as recorded by the Spanish when the groups first encountered each other in the 1500s.
Taken together, these clues suggest that the person who left the 11 ancient footprints was traveling through a changing landscape — one that was gradually becoming more arid, and more challenging, requiring adaptations that still persist among native people in the Chihuahuan Desert, centuries after the rest of Coahuiltecan culture itself disappeared.
Sources: Discovery Magazine, Wikipedia
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