WHITE SANDS NATIONAL PARK, New Mexico: Early humans walked across North America some 23,000 years ago, researchers said on Thursday, after analyzing fossilized footprints discovered in New Mexico.
While the first footprints were found on a dry lake bed in White Sands National Park in 2009, scientists from the U.S. Geological Survey recently analyzed seeds stuck in the footprints to determine their approximate age, which range from 22,800 to 21,130 years ago.
The question of when the first people arrived in the Americas from Africa and Asia could be potentially answered by the discovery, with most scientists believing ancient migration was made possible by a now-submerged land bridge that connected Asia to Alaska.
Various pieces of evidence, such as stone tools, fossil bones and genetic materials, have led researchers to suggest a range of possible dates for the arrival of humans in the Americas, ranging from 13,000 to 26,000 years ago.
However, the current study provides a more accurate estimation of this date, as fossil footprints are more indisputable than "cultural artifacts, modified bones, or other more conventional fossils," its authors stressed in the journal Science, which published the study on Thursday.
"What we present here is evidence of a firm time and location," they added. Based on the size of the footprints they think some were made by children and teenagers.
"We knew they were old, but we had no way to date the prints before we discovered some with seeds on top," said David Bustos, resource program manager at White Sands National Park.
The footprints were very fragile, as they were made of fine silt and clay, so the researchers had to work quickly to gather samples, he added.
Earlier excavations at the park also uncovered fossilized tracks left by a saber-toothed cat, dire wolf and Columbian mammoth.