Scientists Reclassify World's Oldest Octopus Fossil as Nautiloid from Illinois
Key Takeaways
- Pohlsepia mazonensis reclassified as a nautiloid, not an octopus.
- Findings published in Proceedings of the Royal Society B.
- Synchrotron and X-ray imaging drove the reinterpretation.
Fossil Reclassification
The fossil previously celebrated as the world's oldest octopus has been reclassified as a nautiloid.
“The world’s oldest octopus fossil isn’t an octopus after all, scientists say The world’s oldest octopus fossil isn’t an octopus after all, scientists say LONDON (AP) — A 300-million-year-old tentacled sea creature has lost its crown as the world’s oldest octopus, after scientists found evidence that it’s not an octopus at all”
Thomas Clements explained that the fossil has long been the subject of scientific debate.
The team discovered a radula with 11 teeth per row, whereas octopuses have either seven or nine.
The world's oldest octopus is actually a fossil nautilus, not an octopus.
Guinness World Records said it will no longer list Pohlsepia as the earliest known octopus.
Scientific Debate and Technology
The original identification of Pohlsepia as an octopus in 2000 upended ideas about cephalopod evolution.
The classification remained controversial.
The breakthrough came with synchrotron imaging.
The discovery of the radula's tooth count was the key to reclassification.
The fossil's decomposed state likely caused the loss of its shell before fossilization.
Implications for Evolution
The reclassification pushes the record of nautiloid soft tissue back by around 220 million years.
“The story of a 300-million-year-old fossil has been rewritten after scientists discovered that it doesn’t actually belong to the world’s oldest octopus as previously thought”
The fossil's radula matched that of Paleocadmus pohli, an ancient nautiloid already known from the site.
Pohlsepia was never a distinct species.
The Field Museum now has the oldest soft tissue nautilus in the world.
The research demonstrates the power of new technologies to advance scientific understanding.
Reactions and Future Research
Guinness World Records called the discovery fascinating.
Paul Mayer said he was a little surprised.

The museum plans to continue studying the fossil and other specimens.
The reclassification highlights the importance of ongoing scientific scrutiny.
Questions had persisted since 2000.
More on Other

OIC Condemns Israel for Approving 34 New West Bank Settlements as War Crimes
11 sources compared

OIC Condemns Israel's Approval of 34 New West Bank Settlements
10 sources compared

Netanyahu Orders Direct Talks With Lebanon to Disarm Hezbollah Amid Ongoing Strikes
14 sources compared

Israel Strikes Beirut Killing Over 250 Despite US-Iran Ceasefire
20 sources compared