A Real-Life Kraken? Fossils Reveal Ancient Octopuses Up To 61 Feet Long

Giant Octopuses May Have Been Among the Smartest Predators in Dinosaur-Age Seas

For centuries, sailors whispered about the Kraken, a massive tentacled beast capable of dragging ships beneath the waves. Later generations chalked those tales up to overactive imaginations, with the supposed monster reaching roughly 33 to 40 feet. But a new fossil discovery points to something even bigger: octopuses possibly up to about 61 feet long that appear to have been top predators in oceans shared with giant marine reptiles roughly 100 to 72 million years ago.

Published in Science, an international team of researchers has identified the earliest known octopuses from rocks in Japan and Canada’s Vancouver Island. Based on exceptionally well-preserved fossilized jaws and telltale wear on those jaws, these ancient finned octopuses appear to have been powerful shell-crushers that actively hunted hard-bodied prey. Their calculated body size rivals marine reptiles often cast as the dominant predators of those seas, including bus-length mosasaurs and long-necked plesiosaurs. Those size estimates are based on scaling relationships observed in modern relatives rather than intact ancient specimens, meaning they represent informed reconstructions, not precise measurements.

Wear patterns on the jaws aren’t even on both sides. One side is consistently more ground down than the other, a feature researchers link to a preference for using one side of the body, similar to being right- or left-handed. Researchers suggest these ancient giants may have been not just enormous and powerful, but genuinely smart, though they caution that inferring cognitive ability from jaw wear alone has inherent limits.

How Fossil Octopus Jaws Survived Millions of Years

Octopuses are notoriously difficult to find in the fossil record. Their soft bodies decay quickly and almost never leave a trace in stone. But their jaws, hard beak-like structures made of a tough biological material called chitin, can survive millions of years under the right conditions. Researchers studied 27 fossil jaws. Fifteen had been previously reported from rocks in Japan and Vancouver Island. Twelve were newly discovered using “digital fossil-mining,” which combines high-resolution grinding, shaving rock away in ultra-thin layers and photographing each slice, with an AI model that scans massive image sets to spot hidden fossils.

All 27 specimens came from calm, deep-water deposits far from shore, meaning the heavy damage on the jaws wasn’t caused by tumbling along the ocean floor but by the animals themselves, by the repeated, forceful crunching of hard prey. Because all specimens came from a specific depositional setting, the findings offer a snapshot rather than a complete picture of their range.

Giant Octopus Fossils Reveal Record-Breaking Predators

Researchers identified two species: N. jeletzkyi and N. haggarti. Both belong to the finned octopuses, a subgroup that today lives mostly in the deep sea. Modern finned octopuses are relatively modest in size. Their ancestors from the age of dinosaurs were anything but.

By comparing fossil jaw size to the known relationship between jaw size and body size in living finned octopuses, the team calculated that N. jeletzkyi reached a total length of roughly 9 to 25 feet. The larger species, N. haggarti, reached an estimated 22 to roughly 61 feet. Because no complete soft-body fossils have been found, these calculations assume proportional relationships in living species apply to their ancient relatives, and the broad range reflects that uncertainty. At its maximum, N. haggarti would have been comparable to the largest known bony fish, shark-like predators, plesiosaurs, and mosasaurs of its era.

Growth marks on the fossil jaws, somewhat like tree rings, revealed that N. haggarti grew both larger and faster than N. jeletzkyi. Since N. haggarti appears in younger rock layers, this suggests these octopuses were getting more gigantic over time, becoming increasingly dominant toward the end of the dinosaur era.

Ancient Jaw Wear Reveals Giant Octopus Diet and Intelligence

Both species show unmistakable signs of heavy use on their largest jaws: originally sharp tips ground to blunt nubs, rounded and chipped edges, and outer surfaces polished smooth where fine natural grooves have been worn away. Scratches crisscross those polished surfaces, and chips and cracks suggest moments when the jaw bit down on something so hard it nearly fractured.

In modern octopuses and cuttlefishes, this type of wear is a hallmark of animals that regularly crush hard-shelled prey like crabs and clams. Wear on these ancient jaws exceeded what researchers typically see even in modern shell-crushers, with lost jaw material amounting to about 10 percent of total jaw length. Because no stomach contents have been found, the top-predator interpretation rests on jaw wear and body size calculations rather than direct observation.

Wear showed up only on adult jaws, not on juveniles, and was absent from squid jaws found in the same rock layers. In both species, the right edge was more worn than the left. Researchers interpret this as evidence of “handedness,” a behavioral one-sidedness closely linked in modern brain science to a highly developed brain with specialized regions, raising the possibility that the roots of octopus intelligence run extremely deep in evolutionary time.

Although they lived far too early to inspire the Kraken legend, these animals show that something strikingly kraken-like really did prowl those seas, armed with powerful jaws and a level of intelligence no one expected to find 100 million years in the past.

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