Giant Octopus Fossil Ranks Among Largest Invertebrates Ever Discovered, Scientists Say
A newly analyzed giant octopus fossil is reshaping what scientists thought they knew about size limits in the animal kingdom — revealing a new species of finned octopus that ranks among the largest invertebrates ever documented.
Stretching up to 62 feet long, the ancient predator dwarfed modern giant squid and may have rivaled some of the most formidable hunters of the Cretaceous oceans.
The findings were published Thursday, April 23 in the journal Science.
Bigger Than Any Invertebrate Scientists Expected
The larger of the two newly identified species, Nanaimoteuthis haggarti, reached an estimated length between 22 and 62 feet. That upper range puts it more than 20 feet longer than today’s giant squid, which tops out around 39 feet.
A second species, Nanaimoteuthis jeletzkyi, was smaller but still massive, measuring up to 25 feet long.
Together, they represent some of the largest invertebrates ever discovered — a category long thought to be dominated by squid.
“These animals were remarkable… they represent what could be described as a real ‘Cretaceous Kraken,’” lead researcher Yasuhiro Iba told Reuters.
A Giant Finned Octopus Built for Power
Unlike most modern octopuses, these ancient giants were finned octopuses, using paddle-shaped appendages on their heads to move through the water.
They lived between about 100 million and 72 million years ago, overlapping with dinosaurs like Tyrannosaurus rex, Triceratops and Velociraptor on land.
In the oceans, they shared territory with massive marine reptiles such as mosasaurs and plesiosaurs, as well as sharks comparable to today’s great whites.
And based on the evidence, they weren’t just coexisting. They were competing.
The Giant Octopus Had Jaws Built to Crush
The giant octopus fossil evidence comes from beaks — the only hard part of an octopus’s body that can fossilize.
Those beaks tell a clear story about how these animals fed. They show heavy wear patterns consistent with repeatedly crushing hard prey like shells and even bone.
“In the largest specimens, about 10% of the total jaw length appears to have been lost due to wear,” Iba said. “This is more severe than what is typically seen in modern octopuses… that feed on hard prey.”
Their diet likely included fish, shelled cephalopods and clams — prey that required both strength and precision to capture and consume.
And, like modern octopuses, these ancient species were likely highly intelligent.
Researchers found uneven wear patterns on the fossilized jaws — a sign of lateralized behavior, similar to handedness in humans. That suggests these animals weren’t just powerful, but also adaptable hunters.
Combined with their size, long arms and crushing beaks, they would have been formidable predators.
Challenging What We Thought We Knew
For decades, scientists believed the top of the ocean food chain was dominated by vertebrates — first fish and sharks, then marine reptiles and eventually whales.
This discovery complicates that picture.
“Their existence changes how we view ancient oceans,” Iba said. “Instead of ecosystems dominated solely by vertebrate predators, we now see that giant invertebrates such as octopuses also occupied the very top of the food web.”
In short, this wasn’t just a large animal. It was a top predator — a true Cretaceous kraken.
Finding Something That Generally Doesn’t Fossilize
Octopuses are notoriously difficult to study in the fossil record because their bodies are almost entirely soft tissue. That’s what makes this discovery so rare.
Researchers reexamined 15 previously known fossilized jaws and identified 12 additional specimens from sedimentary rock in Japan and on Vancouver Island in Canada.
Using advanced 3D imaging techniques — including grinding tomography and AI-assisted reconstruction — they were able to build detailed models of the animals, a process the team calls “digital fossil mining.”
“We were surprised. The fossil record of octopuses is extremely limited, so finding animals this large… was beyond our expectations,” Iba told CNN.
What’s Next for the Cretaceous Kraken?
Researchers hope to expand this “digital fossil mining” approach to uncover more hidden species that don’t typically fossilize.
“Our goal is to reveal the hidden players of ancient ecosystems and build a much more complete picture of how past ecosystems really worked,” Iba said.
If this discovery is any indication, there may be more giant invertebrates — and more prehistoric “krakens” — waiting to be found.
This article was created by content specialists using various tools, including AI.
