Fossil Reclassified: Oldest Known Octopus Revealed as Ancient Nautilus

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The paleontology world is abuzz with a fascinating revelation that challenges our understanding of ancient marine life. A 300-million-year-old fossil, Pohlsepia mazonensis, previously identified as the oldest known octopus, has now been reclassified as an ancient relative of the nautilus after scientists used a synchrotron to peer into its secrets and discover an unusual radula, or ribbon of teeth.

Why it matters

This discovery not only corrects the historical record but also has significant implications for our understanding of cephalopod evolution. The initial octopus identification suggested an earlier emergence of that species, but the nautilus reclassification leaves a vast gap in the fossil record, raising new questions about the timeline of cephalopod diversification.

The details

Scientists at the Field Museum in Chicago used a powerful synchrotron to analyze the Pohlsepia mazonensis fossil in detail. They found that the creature had an unusual number of rows of teeth on its radula, a feature that is characteristic of nautiluses rather than octopuses. This simple but crucial detail shattered the previous octopus identification, leading researchers to reclassify the fossil as an ancient relative of the modern nautilus.

• The Pohlsepia mazonensis fossil dates back approximately 300 million years.
• The fossil was initially identified as the oldest known octopus in the early 2000s.

What’s next

The reclassification of Pohlsepia mazonensis as an ancient nautilus relative rather than the oldest known octopus will prompt further research into the evolution and diversification of cephalopods, as the gap in the fossil record between this specimen and the next oldest octopus fossil is now much wider.