A 60-foot octopus roamed the seas as a predator during the age of the dinosaurs, showing its bony jaws

The top predator that roamed the oceans during the time of the dinosaurs 100 million years ago may have been the octopus.

New analysis of fossilized jaws reveals that large, kraken-like octopuses were once hunted along with other marine predators. They boasted eight arms and long bodies that stretched more than 60 meters, rivaling other carnivorous marine reptiles.

“These krakens must have been terrifying to behold,” University of Alabama paleontologist Adiel Klompmaker said in an email. He had no part in the new study.

Dinosaur fans know that the waters of the late Cretaceous period were dominated by sharp-toothed sharks and marine reptiles known as mosasaurs and plesiosaurs.

Why are octopuses left out of the mix? Scientists have studied relatives of giant octopuses that roamed where the dinosaurs were, and they have studied small octopuses that burrowed into clams. But since their soft bodies are not well preserved, it is difficult to determine how big the creatures were.

There’s also the idea that squishy invertebrates – creatures with no backbone – weren’t strong enough to join the ranks of top predators. But octopus beaks made of hardened chitin are strong enough to crush shells and bones.

In the new study, researchers studied the jaws of 15 ancient octopus fossils found in Japan and Canada’s Vancouver Island. They also identified 12 more jaws from Japan using a technique they developed called digital fossil mining, which probes through rocks in cross-sections to reveal fossils hidden within.

They compared the jaws to those of modern octopuses to gauge how large the creatures were, and determined that ancient octopuses ranged from 23 to 62 in length. The largest jaw was much larger than that of any modern octopus, co-author and paleontologist Yasuhiro Iba of Hokkaido University said in an email.

Iba told Reuters that the predator is one of the largest invertebrates in history.

“Until now, the largest known invertebrate has been the modern giant squid, which can reach about 12 meters (39 feet) in length,” Iba said.

The researchers also found that the jaws of the largest creatures were worn and torn including scratches, chips and rounded edges, suggesting that “the animals repeatedly crushed hard prey such as shells and bones,” Iba said.

Without access to the stomachs of octopuses, it is difficult to know for sure what they were eating or whether they were actually competing with other top predators for their diet. They could eat fish or snails, grab prey with their flexible arms and tear it apart with their beaks.

“Our findings show that powerful jaws, along with the loss of external bones, transformed cephalopods and marine animals into intelligent large predators,” the researchers said of the findings published Thursday in the journal Science.

Looking for octopus fossils elsewhere may help scientists get a clearer picture of how they fit into the ancient food web, said paleontologist Neil Landman of the American Museum of Natural History in New York.

“It’s an old old planet,” said Landman, who was not involved in the new research. So we have a lot to look at in order to integrate the marine ecosystem over time.

Earlier this month, what was previously thought to be the world’s oldest octopus was discovered reorganized as anotherafter scientists discovered that the fossils actually belonged to a different type of sea creature. It turns out that the fossil listed in Guinness World Records as the oldest known octopus belongs to a relative of the nautilus, a cephalopod with tentacles and a shell.