Trending Now - Ancient Fossil Misidentified as Oldest Octopus, Experts Confirm

WHO:

AP News - Thomas Clements, zoologist at the University of Reading, is the lead researcher behind the new findings.

AP News - The fossil Pohlsepia mazonensis was originally identified by paleontologists in 2000.

AP News - The fossil is named after its discoverer, James Pohl.

AP News - Adam Millward, Managing Editor of Guinness World Records, commented on the discovery.

WHAT:

CBS News Science - A 300-million-year-old sea creature previously thought to be the world's oldest octopus is actually a nautilus relative.

AP News - The fossil Pohlsepia mazonensis has been reclassified and will no longer be listed as the earliest known octopus by Guinness World Records.

AP News - The next oldest-known octopus fossil is approximately 90 million years old.

AP News - The fossil measures about the size of a human hand.

WHERE:

AP News - The fossil was found in the Mazon Creek area of Illinois, about 50 miles southwest of Chicago.

AP News - The fossil is in the collection of the Field Museum in Chicago.

WHEN:

AP News - The research findings were published in the journal Proceedings of the Royal Society B in April 2026.

AP News - The fossil was originally identified as an octopus in the year 2000.

WHY:

AP News - The identification of the fossil as an octopus was questioned due to its unusual characteristics and the significant gap in the fossil record of octopuses.

HOW:

AP News - Researchers used a synchrotron to examine the fossil, which allowed them to look inside the fossil rock and discover a ribbon of teeth known as a radula.

AP News - The radula found in the fossil had 11 teeth per row, which is inconsistent with octopuses that have either seven or nine teeth.

(UPDATED April 9, 2026 15:24 UTC)

A recent study led by Thomas Clements, a zoologist at the University of Reading, has revealed that the 300-million-year-old fossil Pohlsepia mazonensis, originally thought to be the world's oldest octopus, is actually a relative of the nautilus. This reclassification means it will no longer hold the title of the earliest known octopus, with the next oldest fossil dating back approximately 90 million years, and the discovery was made possible through advanced imaging techniques that uncovered a unique ribbon of teeth inside the fossil. The fossil, which measures about the size of a human hand, was originally found in the Mazon Creek area of Illinois and is currently housed at the Field Museum in Chicago.