Giant 'Kraken' Octopus Ruled the Ocean 100 Million Years Ago, Study Suggests

Their powerful beaks and jaws may have allowed them to eat even the largest marine reptiles of the period

A "kraken-like" giant octopus might have been one of the most formidable predators around 100 million years ago, scientists have found.

New research led by scientists from Japan's Hokkaido University, published in the journal Science on Thursday, April 23, is challenging the notion that octopuses weren't among the main marine predators during the Late Cretaceous period, when the Tyrannosaurus rex and Giganotosaurus roamed the Earth.

They studied dozens of jaw fossils that date back up to 100 to 72 million years, and found that some now-extinct octopus species may have reached lengths of up to 60 feet, resembling the legendary sea monster.

Wear patterns on their beaks indicate that they may have been able to break through shell and bone, while it's thought their strong arms allowed them to grab prey more easily.

"The most surprising finding perhaps was the extent of wear on the jaws," said Dr. Yasuhiro Iba, a paleontologist at Hokkaido University and lead author of the paper, in a press release.

The evidence of chipping, scratching, cracking and polishing on the jaws "indicates repeated, forceful interactions with their prey, revealing an unexpectedly aggressive feeding strategy," he added.

These massive mollusks may even have eaten large aquatic reptiles like mosasaurs and plesiosaurs, which were themselves believed to be among the main marine predators of the time.

The fossils were discovered in Japan and Vancouver Island, the release noted.

The release added that "the fossils belonged to a group of extinct finned octopuses, known as Cirrata," stating, "By analyzing the size, shape, and wear patterns of the jaws, the team concluded that these animals were active predators that likely crushed hard prey with powerful bites."

"Our study shows that these were not simply large versions of modern octopuses," said Dr. Iba, per The Guardian. "They were giant predators at the very top of the Cretaceous marine food web. This changes the view that Cretaceous seas were dominated only by large vertebrate predators."

The largest octopus alive today, in comparison, is the giant Pacific octopus. Per National Geographic, it tends to reach up to 16 feet in size, and though it has been known to eat larger animals like sharks and birds, it usually eats shrimp, clams, lobsters and fish.

Modern octopuses are known for their intelligence, too, with National Geographic explaining that the giant Pacific octopus has been able to solve mazes, open jars and mimic other octopuses.

The huge prehistoric octopuses may also have been intelligent creatures. One side of the biting part of the jaw was more worn than the other in the fossils examined, per the recently-published findings.

This is a type of lateralization -- the tendency to carry out a certain cognitive process on one side -- and it's associated with intelligence when observed in modern animals.

The team used grinding tomography, a 3D imaging technique, along with an artificial intelligence model, to carry out the research.

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It's hoped that combining the processes going forward will help uncover more hidden fossils.

"The research opens the door to reconstructing entire ancient ecosystems with unprecedented detail. By combining digital fossil-mining with AI, the team expects to uncover many more hidden fossils," the press release stated.

PEOPLE has reached out to Dr. Iba for comment on the study.

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