When the discovery of fossilized footprints made in what’s now New Mexico was made public in 2021, it was a bombshell moment for archaeology, seemingly rewriting a chapter of the human story. Now new research is offering further evidence of their significance.
While they look like they could have been made yesterday, the footprints were pressed into mud 21,000 to 23,000 years ago, according to radiocarbon dating of the seeds of an aquatic plant that were preserved above and below the fossils.
This date dramatically pushed back the timeline of humans’ history in the Americas, the last landmass to be settled by prehistoric people.
The 61 dated prints, which were discovered in the Tularosa Basin, near the edge of an ancient lake in White Sands National Park, were made at a time when many scientists think that massive ice sheets had sealed off human passage into North America, indicating that humans arrived in the region even earlier.
However, some archaeologists questioned the age of the footprints established by those initial findings. The skeptics noted that aquatic plants such as Ruppia cirrhosa the one used in the 2021 study can acquire carbon from dissolved atoms in the water rather than the air, which can result in a misleadingly early date.
In a follow-up study published Thursday in the journal Science, researchers said they have produced two new lines of evidence to support their initial dates.
“Even as the original work was being published, we were forging ahead to test our results with multiple lines of evidence,” said Kathleen Springer, research geologist at the US Geological Survey and co-lead author on the new Science paper, in a news release.