Ancient oceans were dominated by powerful predators, but new evidence suggests a giant octopus may have rivaled them at the top of the food chain. Marine reptiles like mosasaurs once ruled these waters, yet researchers now point to another formidable hunter lurking in the deep.
Scientists have identified a species called Nanaimoteuthis haggarti, described as a 60-foot “kraken” of the Cretaceous seas. The study, published in Science, suggests this animal could reach about 60 feet (18 meters) in length, making it one of the largest invertebrates ever known.
Beaks reveal the scale of ancient octopuses
The findings rely on fossilized beaks, one of the few parts of octopuses that can survive for millions of years. Unlike soft tissues, these hard structures preserve well and offer clues about the animal’s size.
Researchers used the relationship between beak size and body size in modern species to estimate the scale of N. haggarti. The results suggest it was significantly larger than today’s giant squids.
“It challenges the common view of an ‘age of vertebrates’ in marine ecosystems,” said Yasuhiro Iba of Hokkaido University, a co-author of the study.
Artificial intelligence uncovers hidden fossils
To support their findings, Iba and his team analyzed 15 well-preserved beak fossils from Late Cretaceous deposits in Japan and on Vancouver Island. They also used artificial intelligence to scan sediment samples and detect hidden fossils inside rocks.
The method, called digital fossil mining, allowed researchers to identify 12 additional beaks. Several belonged to very large individuals, strengthening evidence for giant cephalopods.
“Using this approach, we were able to discover fossil jaws that would have been nearly impossible to find using conventional techniques,” Iba said.
Finned octopus relatives reached extreme sizes
Further analysis linked the fossils to species within the genus Nanaimoteuthis. Scientists now place these animals within Cirrata, a group of deep-sea octopuses with small fins and webbed arms.
The fossilized lower jaw of an adult Nanaimoteuthis haggarti. The largest beak found by the researchers was 1.5 times as large as those of today's giant squids. pic.twitter.com/YP7fvGNbtt
— Tom Marvolo Riddle (@tom_riddle2025) April 28, 2026
The discovery suggests that these finned octopuses once reached far larger sizes than their modern relatives. A related species, Nanaimoteuthis jeletzkyi, likely grew to about 26 feet (8 meters) in length. Its fossils extend the known history of octopuses by millions of years.
Evidence points to powerful feeding behavior
The fossilized beaks show clear signs of wear. Researchers observed chipping, scratching, and rounded edges, indicating repeated crushing bites. Some beaks had lost up to 10% of their length.
Scientists interpret this damage as evidence that these animals fed on hard or resistant prey. Their strong beaks likely allowed them to break apart tough shells and possibly even bone.
Scientists urge caution on size estimates
Some experts remain cautious about the largest size estimates. Christian Klug of the Natural History Museum at the University of Zürich said the proposed length of 60 feet is “quite extreme.”
He noted that conclusions rely on limited fossil evidence. “Of course, we have only the jaws, so there is some uncertainty,” he said.
Adiel Klompmaker of the University of Alabama Museums said more data is needed to confirm what these animals ate and how they lived.
Deep oceans may hold more secrets
Most of the fossils were found in shallow marine deposits. Scientists say this raises questions about what may have lived in deeper parts of the ocean during the Cretaceous.
Researchers believe further discoveries could reshape the understanding of ancient marine ecosystems. The study highlights how much remains unknown about life in Earth’s prehistoric seas.
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