It is exactly the kind of environment where a reservoir effect might be expected to occur.

If the Ruppia seeds had incorporated a significant amount of old dissolved carbon, the dates could be artificially inflated — and the actual age of the footprints could be substantially younger than 23,000 years.

This was not a fringe objection.

It was a mainstream scientific concern raised by legitimate researchers using standard analytical frameworks.

And it was serious enough that it required a serious answer.

The question was: could researchers find a way to test the dates using different materials that were not subject to the same potential contamination?