Early humans roamed North America about 23,000 years ago

The footprints were found in a dry lake in White Sands National Park, which was first observed by a park manager in 2009. Scientists from the US Geological Survey recently determined their approximate age by analyzing seeds trapped in footprints, which was between about 22,800 and 21,130 years ago.

Most scientists believe that the ancient migration came via the now-submerged land bridge that connected Asia with Alaska. Based on a variety of evidence – including stone tools, fossil bones and genetic analysis – other researchers have offered a range of possible dates for human arrival in the Americas, between 13,000 and 26,000 years ago or more.

The current study provides a more solid baseline of when humans were definitely in North America, although they may have arrived earlier, the authors say. Fossil footprints are more indisputable and direct evidence than “cultural artifacts, modified bones, or other traditional fossils,” he wrote.

“What we are presenting here is proof of a certain time and place,” he said.

Based on the size of the footprints, researchers believe that at least some were made by children and teenagers who lived during the last ice age.

The research was published Thursday in the journal Science.

Earlier excavations at White Sands National Park have uncovered fossil tracks left behind by saber-toothed cats, dire wolves, Colombian mammoths and other ice age animals.

This story has been published without modification in text from a wire agency feed. Only the title has been changed.