Oldest 'octopus' fossil reclassified as nautiloid
A fossil long hailed as the oldest octopus, Pohlsepia mazonensis from Mazon Creek (~311–306 million years ago), has been re-examined with advanced imaging. Using synchrotron X-ray, micro-CT, SEM, and multispectral imaging, researchers found no octopus features (no eight-arm anatomy, no internal shell, no ink sac, no hooks) and no ocular pigments. They identified a preserved radula and dental pattern that match nautiloids, revealing it died, decomposed, and was flattened into mud, preserving soft tissue as two-dimensional stains. This makes Pohlsepia the oldest confirmed nautiloid soft-tissue fossil in the Paleozoic, and the study suggests other Mazon Creek fossils could yield similar revelations.
