The timeline of arrival may no longer hold.

For decades, textbooks pointed to a narrow window when the first people crossed into North America. The dates were debated, but the framework felt stable. Then, preserved in layers of sediment in what is now New Mexico, a sequence of human footprints surfaced with an age estimate that stretches that timeline far deeper into the past. If the dating holds, it suggests humans were present during a period many researchers believed was unlikely. The implications reach well beyond one site.



