Meet the 19-meter Cretaceous kraken that swam with mosasaurs
Additionally, when analyzing the beaks, the team noticed a distinct trend. The wear was not uniform. The right edge of the jaw was consistently more worn, chipped and scratched than the left. The team concluded that this asymmetry was not an accident but evidence of lateralized behavior. This is a trend seen in modern octopuses, which often favor a specific side of their body or a particular eye when performing complex tasks.
In biology, lateralized behavior is generally linked to a specialized and very sophisticated nervous system. “Of course we can’t directly measure intelligence from a fossil,” Iba said. “But the asymmetrical habit suggests that these animals may also have had advanced, individualized hunting behavior, similar in some ways to modern octopuses.”
They weren’t just huge and powerful. They were probably smart.
The evolving arms race
A highly intelligent 19 meter long cephalopod actively hunting and crushing its prey suggests that the Cretaceous evolutionary arms race was not entirely dominated by vertebrates. By launching heavy shells like those seen in early nautiloids and ammonites, the ancestors of modern octopuses traded passive defense for active attack. They gained explosive swimming speed, vast improvements in eyesight, and the neurological capacity required for advanced cognition.
“Our study highlights convergent evolution. Vertebrates and cephalopods have very different evolutionary origins, but both evolved into large, intelligent marine predators with powerful jaws, flexible bodies, high mobility and advanced behavior,” Iba said. He notes that Cretaceous marine ecosystems were probably much more complex than we thought.
Iba also hopes that the Digital Fossil Mining technique can be used to learn more about this complexity. “A major direction is to apply digital fossil mining to more fossiliferous rocks,” he told Ars. “This approach allows us to discover organisms and structures that were previously almost invisible in the fossil record.” He says the technique is particularly important for animals like octopuses and squid, which rarely fossilize.
The team ultimately hopes to reconstruct a more complete history of cephalopods. “More broadly, our goal is to reveal the hidden components of ancient ecosystems and build a much more complete picture of how past ecosystems actually functioned,” Iba said.
Science, 2026. DOI: 10.1126/science.aea6285
