Overview
- Researchers reporting in Proceedings of the Royal Society B say the Illinois fossil Pohlsepia mazonensis is a decomposed nautiloid, not an octopus.
- Synchrotron X-ray maps uncovered a radula with 11 teeth per row, a tooth count seen in nautiloids that rules out octopuses.
- The team also used scanning electron microscopy, micro-CT, and multispectral imaging to test and overturn the original octopus features.
- Guinness World Records said it will retire the “oldest octopus fossil” title that had been linked to this specimen.
- The fossil comes from Mazon Creek, where soft tissues often survive as flat stains that can mislead, and it now stands as the oldest clear nautiloid soft-tissue find in the Paleozoic.