Fearsome giant octopus was a top predator during the age of dinosaurs

A fearsome, kraken-like octopus, potentially measuring over 60 feet, may have been the apex predator of the ancient seas 100 million years ago, new research suggests. These colossal cephalopods, boasting eight arms and elongated bodies, are now believed to have hunted alongside other formidable marine reptiles during the age of the dinosaurs.

"These krakens must have been a fearsome sight to behold," commented University of Alabama paleontologist Adiel Klompmaker, who was not involved in the study. While late Cretaceous-era waters are typically associated with sharp-toothed sharks, mosasaurs, and plesiosaurs, the role of giant octopuses has often been overlooked.

Scientists have previously studied ancient octopus relatives and smaller species that drilled into clams. However, their soft bodies rarely preserve well, making it challenging to ascertain their true size and predatory capabilities. There has also been a prevailing perception that squishy invertebrates, lacking backbones, were not formidable enough to rank among top predators, despite their tough, chitinous beaks capable of crushing shelled and bony prey.

In a groundbreaking new study, researchers meticulously analysed the jaws of 15 ancient octopus fossils previously discovered in Japan and Canada's Vancouver Island. Utilising a novel technique called digital fossil mining, which involves closely scanning rocks in cross-sections to reveal hidden fossils, they identified an additional 12 jaws from Japan. By comparing these ancient jaws to those of modern octopuses, the team estimated the creatures' immense size, ranging from 23 to 62 feet (7 to 19 metres) in length.

This illustration provided by researchers in April 2026 depicts a giant octopus that may have been a top marine predator millions of years agoYohei Utsuki via AP

The largest jaw discovered was "substantially bigger than that of any modern octopus," according to co-author and paleontologist Yasuhiro Iba with Hokkaido University. Furthermore, these massive jaws exhibited significant wear and tear, including scratches, chips, and rounded edges, strongly suggesting that "the animals repeatedly crushed hard prey such as shells and bones," Iba added. The findings were published on Thursday in the journal Science.

Without access to the octopuses' stomach contents, definitively determining their exact diet or the extent of their competition with other top predators remains challenging. They might have feasted on fish or snails, using their flexible arms to snatch prey before breaking it apart with their powerful beaks. Neil Landman, a paleontologist with the American Museum of Natural History in New York, who was not involved in the research, believes that searching for more octopus fossils globally could provide a clearer picture of their place in ancient food webs. "It's a big old planet," Landman remarked, "So we have lots to look at to piece together the marine ecosystem through time."