New research suggests that ancient octopuses were gigantic predators that thrived alongside dinosaurs, challenging previous beliefs about their evolutionary history and role in the Late Cretaceous marine ecosystem.
Octopuses’ earliest relatives may have been formidable predators that roamed the oceans during the age of dinosaurs, according to groundbreaking research from Hokkaido University.
Traditionally, scientists believed that the first finned octopuses emerged around 15 million years ago. However, a recent study published in the journal Science reveals that fossilized jaws discovered in Late Cretaceous rock samples indicate these creatures existed approximately 100 million years ago.
Due to their soft-bodied nature, octopuses do not fossilize well, making it challenging to trace their evolutionary history. The researchers explained that only the jaw bones tend to survive in the fossil record, which complicates our understanding of these ancient animals.
To uncover these fossils, the research team employed high-resolution grinding tomography and an artificial intelligence model. The fossils were found in rock samples preserved in seafloor sediments located in Japan and Vancouver Island, dating back between 100 and 72 million years.
The Late Cretaceous epoch marked the final chapter of the Mesozoic Era, a period dominated by dinosaurs such as Tyrannosaurus rex and Triceratops. The fossils in question belonged to a group of extinct finned octopuses known as Cirrata, which researchers believe used their powerful jaws to crush prey.
Professor Yasuhiro Iba of Hokkaido University commented on the findings, stating, “Our findings suggest that the earliest octopuses were gigantic predators that occupied the top of the marine food chain in the Cretaceous.” He noted that the exceptionally well-preserved fossil jaws indicate these ancient octopuses could reach lengths of nearly 20 meters, potentially surpassing the size of large marine reptiles from the same era.
One of the most surprising aspects of the study was the extent of wear observed on the jaws. The researchers found significant chipping, scratching, and cracking on the fossils. “In well-grown specimens, up to 10% of the jaw tip relative to the total jaw length had been worn away,” Iba explained. “This is larger than what is seen in modern cephalopods that feed on hard-shelled prey, indicating repeated, forceful interactions with their prey and revealing an unexpectedly aggressive feeding strategy.”
These findings challenge the long-held belief that vertebrate predators dominated the Late Cretaceous period, relegating invertebrates to the bottom of the food chain. “This study provides the first direct evidence that invertebrates could evolve into giant, intelligent apex predators in ecosystems that have been dominated by vertebrates for about 400 million years,” Iba added.
The research highlights the significance of powerful jaws and the loss of superficial skeletons—characteristics common to both octopuses and marine vertebrates—as essential traits for evolving into large, intelligent marine predators.
As scientists continue to uncover the mysteries of ancient marine life, this study opens new avenues for understanding the evolutionary history of cephalopods and their role in prehistoric ecosystems, according to Hokkaido University.