The gigantic sharks and reptiles that infested the world’s oceans during the Cretaceous Period were joined by another top predator, write Japanese paleontologists in Science. Between roughly 100 million years and 72 million years, giant octopuses were already swimming around, which could grow up to nineteen meters long. They conclude this based on the discovery of well-preserved fossil mandibles. The wear marks on those jaws indicate that early eight-armed squids could crack their prey with force.
Octopuses have undergone some dramatic changes over the course of evolution. For example, at the end of the Triassic, around 200 million years ago, the hard ‘shell’ on the outside of the body disappeared. A disadvantage for paleontologists, because less hard material remains that can fossilize – but fortunately the chitin-rich jaw parts of octopuses are also resistant to the test of time.
Previously, paleontologists had found fossils of large ‘krakens’ from the Cretaceous: octopuses of at least two meters that crushed their prey between their chitin jaws. Because the prey was harder than the jaws, the crushing left traces in the chitin – this is also the case with modern squids.
But the current finds are even bigger: the Japanese researchers describe the jaws of octopuses that were estimated to be between seven and nineteen meters in size. Some of the jaws had already been discovered, but the paleontologists now also found new fossils using an advanced technique: digital ‘mining’ of fossils, in which rocks are scanned in high resolution and thus hitherto hidden remains can be studied.
The new fossils turned out to belong to the suborder Cirrata: octopuses with two small fins on either side of the head. This also includes, for example, the modern-day Dumbo octopuses of the genus Grimpoteuthis: because of their appearance they are compared to the flying Disney elephant. At over 72 million years old, the Cretaceous specimens are the oldest known fin octopuses to date.
The mega-squatters were also smart, the Japanese think. The wear marks indicate that the carnivorous squids routinely crushed hard shells and bones with their jaws, which they probably held together with their long arms. The asymmetry of the tracks also reveals that many of the octopuses had a ‘preferred side’ with which they crunched their prey. This has been linked in previous research to a highly developed brain.
