Fossil Record Rewritten: 'Oldest Octopus' Revealed as Ancient Nautilus Relative
In a stunning scientific reversal, a 300-million-year-old fossil, celebrated as the world's oldest octopus and even featured in the Guinness Book of Records, has been unmasked as an entirely new species. This prehistoric case of mistaken identity, detailed in the journal Proceedings of the Royal Society B, resolves a decades-long puzzle in marine evolution and fundamentally alters our understanding of when octopuses first appeared on Earth.
Advanced Imaging Uncovers Hidden Truth
Researchers from the University of Reading employed synchrotron imaging, a cutting-edge technique using beams of light brighter than the sun, to peer inside the rock housing the fossil. This process, likened to a modern forensic examination for a 300-million-year-old suspect, revealed tiny, ribbon-like teeth known as a radula. The discovery proved that Pohlsepia mazonensis was not an octopus at all but is most closely related to a modern nautilus, a multi-tentacled animal with an external shell.
Dr. Thomas Clements, lead author and lecturer in Invertebrate Zoology at the University of Reading, explained, 'It turns out the world's most famous octopus fossil was never an octopus at all. It was a nautilus relative that had been decomposing for weeks before it became buried and later preserved in rock, and that decomposition is what made it look so convincingly octopus-like.'
Decay Led to Misidentification
Originally discovered in Illinois, the fossil was first analyzed in 2000 and was thought to exhibit eight arms, fins, and other features typical of an octopus, pushing back the known history of octopuses by approximately 150 million years. However, doubts persisted for years due to the lack of conclusive testing methods. The new study found that the fossil had partially rotted before fossilization, distorting its appearance and leading to the erroneous classification.
The radula discovered contained at least 11 tooth-like elements per row, a characteristic that rules out an octopus entirely. Octopuses typically have seven or nine teeth per row, while nautiloids have 13. This dental evidence matched that of a fossil nautiloid called Paleocadmus pohli, already known from the same Mazon Creek site in Illinois.
Implications for Evolutionary Timelines
This revelation not only corrects a long-standing error but also provides the oldest known nautiloid soft tissue evidence in the fossil record, surpassing the previous record by about 220 million years. Consequently, the data now supports that octopuses evolved much later, during the Jurassic period, rather than hundreds of millions of years earlier as previously hypothesized.
Scientists now believe the evolutionary split between octopuses and their ten-armed relatives, such as squids, occurred in the Mesozoic era. Dr. Clements concluded, 'It's amazing to think a row of tiny hidden teeth, hidden in the rock for 300 million years, have fundamentally changed what we know about when and how octopuses evolved.'
The findings underscore the importance of reexamining controversial fossils with modern techniques, as they can unveil minute clues that lead to groundbreaking discoveries. The Guinness Book of Records is expected to quietly remove the 'oldest octopus' entry, marking a significant update in paleontological history.
