Scientists say the world’s oldest octopus fossil isn’t an octopus after all

Key Points:

• A 300-million-year-old fossil previously recognized as the world's oldest octopus, Pohlsepia mazonensis, has been reclassified as a relative of the nautilus, a shelled cephalopod, according to new research by University of Reading zoologist Thomas Clements.
• Using advanced synchrotron imaging, researchers discovered the fossil's radula (teeth ribbon) had 11 teeth per row, inconsistent with octopuses which have seven or nine, indicating it is not an octopus but a nautiloid.
• The fossil was originally misidentified due to decomposition that caused the loss of its shell before fossilization, complicating earlier analyses and leading to its octopus classification in 2000.
• As a result, Guinness World Records has removed Pohlsepia mazonensis from the title of the earliest known octopus, with the next oldest octopus fossil dating back only about 90 million years.
• The Field Museum in Chicago, which houses the fossil, views the reclassification positively, highlighting that the specimen is now the oldest known soft tissue nautilus and reflects advances in fossil analysis technology.