‘Kraken’ fossils show enormous, intelligent octopuses were top predators in Cretaceous seas
Fossil jaws from colossal octopuses place them at the top of a prehistoric marine food chain
Giant octopuses may have been apex predators in the Late Cretaceous period.
Yohei Utsuki: Department of Earth and Planetary Sciences, Hokkaido University
Step aside, megalodon; a new ancient marine predator may have taken the crown. An analysis of fossilized octopus jaws from creatures that lived between 100 million and 72 million years ago during the Late Cretaceous period suggests these octopuses were not only the largest ocean animals but also highly intelligent, rivaling sharks and marine reptiles in predatory capability. These findings challenge the traditional view of the roles played by soft-bodied organisms in marine ecosystems and provide insights into how large size and intelligence developed among ocean inhabitants.
Historically, large vertebrates have been considered the apex predators of the marine food chain for around 370 million years, with creatures like sharks, ichthyosaurs, plesiosaurs, and whales occupying the top spots. In contrast, invertebrates were thought to have been primarily prey. During the Late Cretaceous, while land was dominated by fearsome dinosaurs like Tyrannosaurus rex, the seas were believed to be ruled by giant marine reptiles known as mosasaurs, without any significant challengers.
However, a recent study indicates that invertebrates may have competed with mosasaurs. Shin Ikegami from Hokkaido University in Japan and his team examined fossils of enormous octopuses, dubbed “krakens” after the legendary sea monsters of Norwegian folklore. These ancient octopuses, similar to modern-day octopuses and squids, possessed a “beak” made of two chitinous jaws. By analyzing fossilized jaws and their wear patterns, the researchers reconstructed the sizes and feeding habits of these ancient creatures.
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The fossils, found in Japan and Vancouver Island off Canada’s Pacific Coast, were identified as belonging to two finned octopus species, Nanaimoteuthis jeletzkyi and Nanaimoteuthis haggarti. Calculations reveal that N. haggarti, the larger of the two, could grow up to 18.6 meters in length, similar to an articulated bus. This surpasses today’s giant squid, which can reach up to 13 meters. N. haggarti might have been the largest creature in the Cretaceous seas.
These ancient octopuses were not only massive but also formidable predators. Scientists have long known about the existence of large-bodied octopuses in prehistory, but their diet and position in the food chain remained a mystery due to the lack of preserved stomach contents. Ikegami’s team approached the diet question by examining beak damage caused by feeding. The wear patterns on the fossil jaws suggest that N. jeletzkyi and N. haggarti were carnivorous, crushing the shells and bones of their prey. Although they lacked the elongated jaws of mosasaurs and other top vertebrate predators, they likely used their long, flexible arms to capture large prey and dismantle it with their strong beaks. The asymmetrical wear on the krakens’ jaws hints at specialized brain regions for different tasks, suggesting advanced cognitive abilities in these invertebrates.
The study’s authors note that both large marine vertebrates and cephalopods independently evolved similar adaptations. Both developed jaws to enhance feeding efficiency, with vertebrates losing body armor and scales for smoother skin, while cephalopods shed their external shells. These changes improved swimming performance, increased body size, and enhanced cognition, resulting in predators from both groups that held dominant positions at the top of the ocean’s food chain.
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