Octopuses that crushed their prey with violence and persistence
Long before fish and reptile claimed the ocean's highest throne, something stranger and softer held it — giant octopuses, some nearly twenty meters long, ruled Cretaceous seas between 72 and 100 million years ago. New research from Hokkaido University, drawing on fossilized jaws recovered from Japan and Canada, reconstructs these creatures as apex predators whose intelligence and ferocity rivaled the mosasaurs swimming beside them. Their disappearance, whether by competition or catastrophe, marks the moment invertebrate life surrendered the summit of the sea — a summit it has never reclaimed.
- Fossil jaws, the only durable remnant of otherwise boneless bodies, have been reconstructed through AI-assisted tomography to reveal octopuses that grew as large as 19 meters — among the biggest invertebrates ever to have lived.
- These were not passive filter-feeders: up to ten percent of the jaw's working edge had been ground away by the repeated, forceful crushing of hard-shelled prey, evidence of a predator that hunted with violence and persistence.
- Uneven wear patterns on the jaws suggest these ancient giants favored one side of their mouth — a trait called lateralization, linked in modern octopuses to advanced cognition and the capacity for learning.
- Their existence upends a long-held assumption that only vertebrates — sharks, reptiles — could occupy the ocean's apex, revealing a window of invertebrate dominance science had not previously imagined.
- Why they vanished remains unresolved: competition, environmental upheaval, or both may have ended their reign, leaving researchers to piece together the extinction of an evolutionary experiment that would never be repeated.
Between 72 and 100 million years ago, the Cretaceous seas were home to predators that science is only now beginning to fully reckon with — giant octopuses, some stretching to nearly 20 meters, that rivaled the great marine reptiles of their age. A study published in Science and led by researchers at Hokkaido University reconstructs these creatures from their fossilized jaws, recovered from sediments in Japan and Canada.
Soft-bodied animals almost never fossilize, but octopus jaws — hard and resistant to decay — do. Using high-resolution grinding tomography and artificial intelligence, the team rebuilt the jaws in three dimensions from impossibly thin rock slices, then extrapolated body sizes ranging from seven to nineteen meters. The largest would have dwarfed today's giant squid and matched the mosasaurs and plesiosaurs swimming alongside them.
The jaws carry the marks of lives lived at the top of the food chain. In the largest specimens, up to ten percent of the jaw's working edge had been worn away by repeated, forceful contact with hard prey. The damage was uneven — heavier on one side — suggesting these animals favored one jaw over the other, a behavior called lateralization that, in modern octopuses, correlates with advanced cognition. These were not merely enormous hunters; they appear to have been intelligent ones.
What ended them remains unknown. Competition from other predators, or some broader environmental upheaval in the late Cretaceous, may have sealed their fate. Their extinction marks a turning point — the moment vertebrate dominance in the ocean became absolute, and invertebrate life, no matter how vast or clever, surrendered the apex for good.
Between 72 and 100 million years ago, the Cretaceous seas may have harbored predators as formidable as any dinosaur—but they were octopuses, some stretching to nearly 20 meters long. A study published in Science in April, led by researchers at Hokkaido University in Tokyo, reconstructs these creatures from fragments that rarely survive the geological record: their chitinous jaws, preserved in sediments across Japan and Canada.
Soft-bodied animals almost never fossilize. Octopuses, lacking bones, should be among the most ephemeral of fossils. But their jaws—hard, resistant to decay—persist. Using high-resolution grinding tomography, the research team sliced rock samples into impossibly thin layers, imaged each one, and fed the data into artificial intelligence to rebuild the jaws in three dimensions. From jaw size alone, they extrapolated body lengths ranging from seven to nineteen meters. The largest specimens would have dwarfed the giant squid alive today and matched the mosasaurs and plesiosaurs that swam alongside them.
Dr. Yasuhiro Iba, the paleontologist leading the work, described the findings as a rare window into marine dominance before the age of fish. For hundreds of millions of years, vertebrate predators—sharks chief among them—have ruled the oceans. These octopuses represent an exception so striking it reshapes how we think about invertebrate potential. They were apex hunters, occupying the top of the food chain in an era when most scientists assumed only reptiles could claim that position.
But the jaws tell a more intimate story than size alone. The fossil specimens bear the scars of their lives: chips, scratches, cracks concentrated at the jaw tips. In the largest individuals, up to ten percent of the jaw's working edge had been worn away by repeated, forceful contact with hard prey. These octopuses were not delicate hunters. They crushed their food with violence and persistence, their jaws bearing the cumulative damage of countless meals. The wear pattern was uneven—heavier on one side than the other—suggesting these animals favored one side of their mouth, a behavior called lateralization. In modern octopuses, this trait correlates with advanced cognition and brain development. The ancient giants, it seems, were not just large but intelligent, capable of learning and preference.
What remains unknown is why they vanished. Competition from other predators, or some large-scale environmental upheaval during the late Cretaceous, may have sealed their fate. Dr. Iba acknowledged the question remains open, a puzzle for future research. The extinction of these creatures marks a turning point in ocean history—the moment when vertebrate dominance became absolute, when invertebrates, no matter how massive or clever, ceded the apex to fish and reptile. The jaws in the rock are all that remain of an experiment in predation that evolution would not repeat.
Citas Notables
The earliest octopuses were gigantic predators that occupied the top of the marine food chain in the Cretaceous period.— Dr. Yasuhiro Iba, Hokkaido University
Up to 10 percent of the jaw tip had been worn away, indicating repeated, forceful interactions with prey and an unexpectedly aggressive feeding strategy.— Dr. Yasuhiro Iba
La Conversación del Hearth Otra perspectiva de la historia
How do scientists even know these octopuses existed if soft bodies don't fossilize?
The jaws survive. Octopuses have hard, chitinous beaks—like a parrot's beak but made of different material. Those resist decay far better than muscle or skin. A few jaws, preserved in the right sediment, are enough to work backward from.
And they can really estimate the whole body from just the jaw?
They use the proportions of modern octopuses as a template. If a living octopus's jaw is a certain fraction of its total length, you can apply that ratio to a fossil jaw. It's not perfect, but it's grounded in biology.
The wear on the jaws—that's the part that surprised me. What does that actually tell you?
It tells you how they hunted. Ten percent of the jaw worn away means they were crushing hard things repeatedly. Shells, armor, bone. Not gentle feeders. And the uneven wear—favoring one side—that's a behavioral signature. Modern octopuses do this too. It suggests a brain sophisticated enough to develop a preference, a habit.
So they were smart predators, not just big ones.
Exactly. Size alone doesn't make you apex. You need strategy, learning, the ability to adapt. These creatures had all of that.
Why did they disappear?
That's the honest answer: nobody knows yet. Something changed in the late Cretaceous—climate, competition, food availability. But these octopuses couldn't adapt to it, or couldn't compete. After they were gone, vertebrates owned the ocean completely.