Giant Cretaceous Octopus Nanaimoteuthis haggarti May Have Reached 19 Metres

In seas where mosasaurs and plesiosaurs usually dominate depictions of the Cretaceous, another giant may have sat at the summit of the food chain. Fossilised jaws suggest that a finned octopus grew to almost 19 metres, wielding a formidable beak to crush prey and compete with the largest hunters of its time.

A real kraken swam alongside giants

The animal belonged to the species Nanaimoteuthis haggarti and lived in the Cretaceous, while dinosaurs still inhabited the continents. According to a study published in the journal Science, this extinct octopus may have reached between 7 and 19 metres in length, exceeding even the modern giant squid at the upper end of the estimates.

Yasuhiro Iba, a palaeontologist at Hokkaido University and co-author of the research, says the finding reshapes the conventional picture of those oceans. Rather than being ruled solely by large marine reptiles and fish, these waters may also have contained enormous, intelligent invertebrates able to compete for the most desirable prey.

Fossilised jaws expose a formidable predator

As octopuses have neither bones nor tough external shells, almost their entire bodies vanish after death. Their beaks, hard structures comparable to the jaws of living species, are what remained. Researchers examined 27 fossil specimens recovered in Japan and on Vancouver Island, Canada.

The remains showed heavy wear, particularly at their tips and on only one side. The authors say these marks suggest the animals used the full power of their jaws to break shells, carapaces and other hard structures, rather than feeding solely on small or soft-bodied creatures.

How did researchers reconstruct this monster?

The team matched the size of the ancient beaks against the proportions of finned octopuses alive today. By examining the relationship between the jaw, mantle and arm length, they were able to estimate an approximate size range for creatures that disappeared tens of millions of years ago.

• Nanaimoteuthis jeletzkyi may have measured between 3 and 8 metres;
• Nanaimoteuthis haggarti may have reached between 7 and 19 metres;
• Some jaws had lost up to 10% of their tip through use;
• The oldest fossils are about 100 million years old.

At its maximum estimated size, N. haggarti would rank among the largest invertebrates ever identified. It may have surpassed a 12-metre giant squid and matched the length of mosasaurs that grew to nearly 17 metres, although length does not necessarily mean equal weight or strength.

Watch the video shared by the YouTube channel Macaco Despido, which shows the real-life “kraken” that lived in the Cretaceous era.

Was the giant octopus really the king of the ocean?

The authors believe its size, jaw wear and possible lateralised behaviour point to an effective hunter that could have occupied a high position in the food chain. The uneven wear may reveal a preference for one side while feeding, a behaviour associated with a sophisticated nervous system.

Other specialists urge caution. René Hoffmann of Ruhr University Bochum and Christian Klug of the University of Zurich note that the body size was calculated from isolated jaws. In their view, the animal was undoubtedly large and efficient, but the 19-metre figure represents the outer limit of a highly uncertain range.

The discovery reshapes the history of ancient seas

The fossils also push back the known record of octopuses by around 5 million years, and that of finned octopuses by roughly 15 million years. This indicates that the group already included huge, specialised representatives far earlier than previously believed, despite its almost invisible fossil history.

Further jaws may establish whether this kraken truly rivalled the largest Cretaceous reptiles or was smaller than the highest estimate suggests. Until then, the discovery leaves one compelling certainty: we still know only some of the monsters that once dominated the oceans, and every small fossil may force the rewriting of an enormous story.