And here was the problem: the original dating of the Manis site was not airtight.

Radiocarbon dating in the late 1970s and early 1980s, while well-established as a technique, had limitations that more modern methods addressed.

Dates from bulk carbon samples or poorly preserved material were subject to contamination that could shift the apparent age in either direction.

And if the dates were off — if the mastodon was actually younger than the radiocarbon numbers suggested — then the spectacular claim of pre-Clovis hunting could be simply a dating error.

Skeptics raised legitimate questions.