Other sites contributed to an accumulating picture.

Debra L.

Friedkin in Texas produced pre-Clovis tools dated to approximately 15,000 to 16,000 years ago.

The Meadowcroft Rockshelter in Pennsylvania had been controversial since the 1970s, with claimed dates in the range of 14,000 to 19,000 years — dates that were contested for decades before some researchers concluded the evidence was genuine.

Bluefish Caves in Yukon, Canada, produced cut-marked animal bones tentatively dated to approximately 24,000 years ago, though the evidence remains debated.

Each of these sites pushed the timeline back in ways that the Clovis-first model struggled to accommodate.