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The Associated Press
In this April 28, 1993 photo provided by the San Diego Natural History Museum, a bulldozer refills the Cerutti Mastodon site in San Diego, Calif., after the excavation and salvage of fossils. In a report released on Wednesday, April 26, 2017, researchers say the southern California site shows evidence of human-like behavior from about 130,000 years ago, when bones and teeth of an elephant-like mastodon were evidently smashed with rocks. (San Diego Natural History Museum via AP)

NEW YORK — A startling new report asserts that the first known Americans arrived much, much earlier than scientists thought — more than 100,000 years ago. And maybe they were Neanderthals.

If true, the finding would far surpass the widely accepted date of about 15,000 years ago.

Researchers say a site in Southern California shows evidence of human-like behavior from about 130,000 years ago, when bones and teeth of an elephant-like mastodon were evidently smashed with rocks.

With an age that old, the bone-smashers were not necessarily members of our own species. The researchers speculate they could instead have been some species known only from fossils in Europe, Africa and Asia, like Neanderthals.

No remains of the individuals were found at the site.

The report appears Wednesday in the journal Nature.