NEW YORK, NY, September 26, 2026 — Researchers have discovered fossil evidence of the largest invertebrate ever recorded by paleontologists. The creature was an ancient finned octopus, possibly extending to sixty-two feet long. Researchers say it would have been in direct competition with the largest marine reptiles of the time.
THE FOSSILIZED BEAKS of a strange bird help to solve the mystery of how humans evolved 1,000 kilometers north as two whiskered crested parakeets snuggle in their cage at a zoo in northeastern Taiwan.
The title species, called Nanaimoteuthis haggarti, lived between seventy-two and eighty-six million years ago. It was identified by scientists from twenty-seven fossilized beaks discovered in Japan and Vancouver Island. Beaks are one of the few hard parts that remain behind from soft-bodied cephalopods.
Researchers from Hokkaido University were the lead investigators on the study, which was published in Science. The scientists reconstructed the obscured detail inside the rock using CT scans and AI. That helped them predict the size of the creature, something they could do with significantly more certainty.
Rewriting Cretaceous Ocean History
Despite this evidence, scientists assumed vertebrates like mosasaurs ruled the seas in the Cretaceous for several decades. It implies a huge predator invertebrate competed against those top predators. At 62 feet long, the creature would have outsized by an order of magnitude even today’s largest species of octopus.
In contrast, the modern day giant Pacific octopus seldom grows larger than sixteen feet across. That puts this ancient kraken at nearly four times the size of its closest living relative today. Just the size of the creature alone compels a rethink of who has ruled more recent prehistoric oceans, researchers say.
Signs of Surprising Intelligence
The wear patterns on the fossilised beaks also showed an unexpected tidbit: two birds of this species almost always fought over food. Wear on the wearers was asymmetric, with one side of each beak showing significantly more surfacing. This lateralization — the preference for left- and right-sided brain regions to perform different functions — is associated with higher cognitive ability, scientists have said.
Lateralization indicates this long-ago octopus preferred one side of its body every time. This tendency, of course, has its roots in the brain function that comes with modern animals. It is thought that the creature used its strong jaws to crush prey with hard shells or bone.
Comparisons to Legendary Sea Monsters
The term kraken is Norse maritime folklore used to describe a sea monster who swallows ships whole. Historians think those tales were probably based on sightings of giant squid. Researchers say this new fossil species is also big enough to possibly inspire stories like that.
This ancient octopus would have had a softer, stockier body compared to its relative, the slender giant squid. At an estimated size, it could actually have overpowered smaller ships. It turns a scientific footnote on the scale of things into this centuries-old folk tale about ships and weather.
What Comes Next for Researchers
Scientists plan to search for more fossil beaks, in order to gain even better estimates of size. Since soft-bodied cephalopods do not fossilize well, the new specimen is likewise of great scientific value. The hope is that additional discoveries will uncover more details about the species’ hunting and possibly range.
It also raises new questions about competition between invertebrates and vertebrate predators. Recognizing that competition can modify larger theories about ocean ecosystems in the Cretaceous. But for the moment, Nanaimoteuthis haggarti is at least a stunning snapshot of one leg in the very deep history of the oceans.
Paleontologists say fossils of soft-bodied cephalopods are extremely scarce throughout the fossil record. The vast majority of specimens never even arrive in fossilizing conditions, instead degrading entirely beforehand. That same rarity makes each confirmed beak fossil scientifically important for scientists studying the ancient marine communities.
The research team employed imaging technology to analyze wear patterns created at microscopic scales that are undetectable by the human eye. That kind of detail lets scientists make more definitive inferences about the likely behavior of the animals. It is hoped that the same techniques may assist researchers in re-evaluating other poorly-constrained cephalopod fossils stored in museum collections.
The research could also have implications for understanding modern octopus cognition and behaviour, said the marine biologists. Data in ancient and modern cephalopod traits are compared so that researchers can better understand how intelligence evolved within the group. The study adds to a growing field of research that has highlighted octopuses as the most intelligent of invertebrates.
