If they're correct, 'rewriting the books' would be an understatement

In a provocative and controversial claim, scientists say a scattering of bones and stones suggests ancestral humans reached the New World more than 100,000 years earlier than previously thought.

Most genetic and archaeological evidence shows humans first entered the Americas some 15,000 years ago. But a study nearly 25 years in the making in this week’s Nature finds that the 130,000-year-old bones of a mastodon, an extinct relative of the mammoth, unearthed in California were split open with blows from rocks. Rocks discovered near the bones bear the hallmarks of use as hammers, the scientists report.
If correct- and that's a big 'if'- it'd change damn-near everything about how humans got to the Americas, and how, and when.