Research from Hokkaido University reveals that ancient octopus relatives were massive predators that coexisted with dinosaurs, challenging previous beliefs about their evolutionary history.
Octopuses’ earliest relatives, which lived approximately 100 million years ago, may have been formidable predators that roamed the oceans alongside dinosaurs, according to new research from Hokkaido University.
Previously, scientists believed that the earliest finned octopuses emerged around 15 million years ago. However, the recent study, published in the journal Science, presents fossilized jaws discovered in Late Cretaceous rock samples as evidence of these ancient creatures. The fossils were unearthed from rock layers preserved in seafloor sediments located in Japan and Vancouver Island, dating back between 100 and 72 million years.
Due to their soft-bodied nature, octopuses do not fossilize well, making it challenging to trace their evolutionary history. The researchers utilized high-resolution grinding tomography and an artificial intelligence model to locate the fossils, which are critical to understanding the biology of these ancient animals.
The Late Cretaceous period, the final epoch of the Mesozoic Era, was characterized by the dominance of dinosaurs, including iconic species such as Tyrannosaurus rex and Triceratops. The fossils examined in this study belonged to a group of extinct finned octopuses known as Cirrata, which researchers believe possessed powerful jaws capable of crushing their prey.
Professor Yasuhiro Iba of Hokkaido University stated, “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 creatures could reach lengths of nearly 20 meters, potentially surpassing the size of large marine reptiles from the same era.
One of the most striking discoveries was the extent of wear on the jaws, which exhibited significant chipping, scratching, and cracking. “In well-grown specimens, up to 10% of the jaw tip relative to the total jaw length had been worn away, which is larger than that seen in modern cephalopods that feed on hard-shelled prey,” Iba explained. This wear suggests that these ancient octopuses engaged in repeated, forceful interactions with their prey, indicating a surprisingly aggressive feeding strategy.
The implications of this research challenge previous assumptions about the dynamics of predator-prey relationships during the Late Cretaceous. Traditionally, scientists believed that vertebrate predators dominated this period, relegating invertebrates to the lower tiers of the food chain. Iba emphasized, “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.”
The findings underscore the significance of powerful jaws and the loss of superficial skeletons—traits common to both octopuses and marine vertebrates—in the evolution of large, intelligent marine predators.
As researchers continue to explore the evolutionary history of cephalopods, these revelations may reshape our understanding of marine ecosystems during the age of dinosaurs, highlighting the complexity and diversity of life that existed in prehistoric oceans.
According to Hokkaido University, this groundbreaking study opens new avenues for research into the evolutionary adaptations that allowed ancient octopuses to thrive as apex predators in their environments.