Giant Octopus Fossil: 60-Foot Deep-Sea Monster Discovered

Scientists just published a study that rewrites what we thought we knew about prehistoric seas. On April 23, 2026, a paper landed in the journal Science with a claim that stopped paleontologists mid-sentence: a giant octopus the length of a city bus once stalked the Cretaceous ocean, roughly 100 million years ago — and it was bigger than any squid alive today.

Not a squid. Not a shark. An octopus.

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The Creature Nobody Saw Coming

For a long time, the Cretaceous ocean had a cast of famous monsters — mosasaurs, plesiosaurs, enormous sharks. Soft-bodied cephalopods like octopuses barely registered. They don’t fossilize well. No hard skeleton, no teeth, no scales. Just muscle and intelligence, dissolving into sediment.

So when researchers began re-examining fossilized jaws — specifically, 15 ancient octopus beak fossils previously recovered from Japan and Canada’s Vancouver Island — the picture that emerged was unexpected. By comparing those ancient jaws to the beaks of modern-day octopuses, paleontologist Yasuhiro Iba of Hokkaido University and his co-authors were able to estimate body size. Then they went further: using a technique called “digital fossil mining,” they identified 12 additional jaws from Japanese collections that had been sitting unexamined.

Twenty-seven jaws. One pattern. The animals they belonged to ranged from 23 to 62 feet in length.

The largest of them — now formally named Nanaimoteuthis haggarti, the so-called “Cretaceous kraken” — stretched an estimated 60 feet, or roughly 18 to 19 meters. For comparison, the largest giant squid ever recorded falls about 20 feet short of that. N. haggarti wasn’t just a big octopus. It may have been one of the largest invertebrates to have ever existed on Earth.

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What the Jaws Reveal

Fossilized jaws don’t just tell you size. They tell you behavior.

The beaks recovered from the largest individuals showed significant wear: scratches across the surface, chipped edges, rounded tips. That kind of damage doesn’t come from catching soft prey. It comes from repeatedly crushing things — shells, bones, armored marine animals. Whatever N. haggarti was eating, it was going after hard targets.

Modern octopuses are already formidable hunters. They use their beaks to crack crab shells and pierce through tough mollusks. Scale that behavior up to a 60-foot animal, and you have something capable of taking on prey that would have made other Cretaceous predators cautious.

The wear patterns across multiple specimens suggest this wasn’t occasional. It was a dietary strategy — consistent, repeated, and apparently successful for millions of years. The ocean floor during the Cretaceous was rich with ammonites, large crustaceans, and shelled creatures. N. haggarti appears to have made a living dismantling them.

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The Family Tree Gets Redrawn

Here’s the part that surprised even the researchers.

For years, fossils like these had been loosely categorized as relatives of the vampire squid — that strange, deep-sea animal that sits somewhere between octopus and squid on the evolutionary tree. It was a reasonable assumption, given the age of the fossils and the limited material available for study.

The new analysis overturns that. Nanaimoteuthis haggarti and its relatives are now classified as ancient members of the finned octopus lineage — the group that includes today’s “Dumbo octopuses,” named for the ear-like fins they use to glide through deep water.

That reclassification matters more than it might seem. It means the finned octopus lineage is far older and far more diverse than anyone previously estimated. What we think of today as a relatively niche group of deep-sea animals was, 100 million years ago, producing giants. The Dumbo octopus you might see in a nature documentary, drifting quietly through the dark — its evolutionary ancestors were crushing bones on the Cretaceous seafloor.

Evolution doesn’t always move toward larger and more dominant. Sometimes a lineage shrinks, retreats to the deep, and survives quietly for millions of years while the giants disappear.

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Why This Discovery Matters Right Now

Paleontology has a soft-body problem. Animals without hard skeletons leave almost nothing behind. The fossil record for cephalopods — octopuses, squid, nautiluses — is riddled with gaps that have historically led researchers to underestimate how large and ecologically important these animals were.

The “digital fossil mining” technique used in this study offers a way around that. By systematically re-examining museum collections using computational comparison methods, researchers were able to pull meaningful data from specimens that had been catalogued and largely ignored. Twelve additional jaws, sitting in Japanese collections, waiting.

This is the implication that should interest anyone who follows paleontology: the record isn’t fixed. There are almost certainly more specimens like these in existing collections around the world — fossils that were identified, stored, and never fully analyzed. The tools to extract new information from old material are improving rapidly. N. haggarti may be the first of several Cretaceous giants we didn’t know we already had evidence for.

The question isn’t just “what lived in the ancient ocean?” It’s “what else are we missing that’s already in a drawer somewhere?”

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Final Thought

Nanaimoteuthis haggarti didn’t need a dramatic discovery moment — no expedition to a remote dig site, no accidental find. It emerged from 27 fossilized jaws, a comparison method borrowed from modern biology, and a technique called digital fossil mining applied to museum collections in Japan and Canada. The giant octopus was already there. It just needed someone to look properly.

The April 2026 Science paper doesn’t just add a new species to the Cretaceous roster. It reframes what we thought we understood about soft-bodied animals in deep time — and raises a harder question for the field: if a 60-foot apex predator stayed hidden in plain sight until now, how many other giants are still waiting in catalogued collections, mislabeled and underexamined, for the right tool to find them?

Frequently Asked Questions

How big was the Cretaceous giant octopus?
The largest specimen, named Nanaimoteuthis haggarti, stretched an estimated 60 feet (18-19 meters) in length, making it potentially one of the largest invertebrates to have ever existed on Earth, surpassing the largest giant squid by about 20 feet.

How did scientists discover a giant prehistoric octopus fossil?
Researchers re-examined 27 fossilized octopus jaws from Japan and Canada’s Vancouver Island, using a technique called digital fossil mining to identify previously unexamined specimens and estimate body size by comparing them to modern octopus beaks.

When did the giant Cretaceous octopus live?
Nanaimoteuthis haggarti lived approximately 100 million years ago during the Cretaceous period, sharing the ocean with famous prehistoric creatures like mosasaurs, plesiosaurs, and enormous sharks.

Recommended Reading

Explore these hand-picked resources to dive deeper into this topic:

• The Fossil Hunter by Helen Scales
• Monsters of the Deep by Richard Ellis
• National Geographic Fossil Excavation Kit

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Sources

• https://apnews.com/article/kraken-cretaceous-octopus-fossil-ab911a3fcae1f32443770308348cfbe6
• https://www.nationalgeographic.com/science/article/cretaceous-kraken-giant-octopus
• https://abcnews.com/Technology/wireStory/massive-kraken-octopus-prowled-seas-age-dinosaurs-132322984
• https://m.economictimes.com/us/science-tech/kraken-like-giant-octopuses-as-large-as-semi-trucks-ruled-oceans-100-million-years-ago-study-finds/amp_articleshow/130484017.cms
• https://www.sciencenews.org/article/kraken-octopus-largest-invertebrate