North America’s oldest fossil footprints tell us about early humans
Fossil footprints found in White Sands National Park in New Mexico in 2009 now prove that humans walked across North America about 23,000 years ago. A recent analysis of seeds trapped in the fossils helped scientists at the US Geological Survey date the footprints, which may help prove when people first arrived in the Americas. The analysis is explained in a study published this week in the journal Science.
Scientists believe ancient humans arrived in the Americas via a now submerged land bridge that once connected present-day Siberia to Alaska. But the exact date when humans first arrived here is still unknown, and scientific estimates vary.
These fossils help refine it, indicating that the imprints were made between 22,800 and 21,130 years ago. This reverses an earlier theory that the first humans did not reach southern Canada until the glaciers melted between 16,000 and 13,500 years ago.
Before the seeds allow these fingerprints to be dated, the the oldest known footprint in the Americas was found in Chile in 2011, and was only (only!) 15,600 years old.
David Bustos, resource program manager at White Sands National Park, was the first to spot the footprints in 2009.
“We knew they were old, but we had no way of dating the footprints until we found some with (tiny seeds of aquatic plants) on top,” he told The Associated Press. .
The prints are so fragile that the researchers had to examine them carefully.
“The only way to save them is to save them – to take a lot of pictures and create 3D models,” Bustos said.
The size of the prints indicates that most were probably made by children and adolescents.