Overview
- A peer‑reviewed paper published Wednesday in Proceedings of the Royal Society B used synchrotron X‑ray imaging to reveal a radula with at least 11 teeth in the Pohlsepia fossil.
- The tooth count and shape fit a nautiloid rather than an octopus and match Paleocadmus pohli from the same Illinois site.
- Scans found no pigment bodies in the structure once called an ink sac, undermining a key feature that had supported the octopus label.
- Researchers conclude the animal had begun to decay before burial, which likely separated or obscured its shell and left soft tissues that mimicked octopus traits.
- The reclassification removes the 310‑million‑year 'oldest octopus' claim and pushes the soft‑tissue nautiloid record back by about 220 million years, reshaping evolutionary charts and classroom references.