We view octopuses as silent, elusive creatures with odd behavior. They hide by nature and never top the food chain.
Yet geologists found fossil evidence that something similar but much larger once roamed the oceans.
Far removed from today’s species, it was an intimidating, massive hunter.
This discovery challenges everything we know about marine history. What were those 65-foot-long ancient octopuses?
Were there perhaps times in the past when they were among the most fearsome hunters on earth?
Shadows below ancient seas
Geologists know very little about the evolution of animals without bony skeletons.
The fossil record is also sparse regarding soft-bodied species, including octopuses.
Because these creatures tend to leave few clues about their former presence, their histories get erased.
Now and then, a rare surviving structure provides some evidence. Such discoveries remain uncommon in the fossil record, though. This latest discovery provides significantly more insight than all others.
Octopus jaws can fossilize while the rest of their fleshy bodies cannot. These are the only hardened sections that can endure millions of years.
For many years, fragmented evidence hinted that something unique existed.
No single piece of evidence explained what these animals looked like. But now we have clues.
A multi-legged puzzle immortalized inside a rock
Researchers went to work with innovative imaging techniques to gather deep data.
Their rock samples dating back around 100 million years appeared standard at first glance. But they actually contained fossils of octopus jaws preserved in relatively slow sedimentation environments.
The jaw forms were so well-preserved that researchers were able to make thorough analyses and note minute patterns and markings on their surface.
We now know so much more about how these body parts were used and how the animals interacted with their environment.
The evidence still did not immediately allow researchers to visualize the type of creature that produced them. If something larger than today’s octopuses created these traces, what exactly were researchers viewing?
The study “Earliest octopuses were giant top predators in Cretaceous oceans,” published in Science, delivered fascinating insight. Supporting facts are available from Hokkaido University.
A hidden world revealed through a set of jaws
Before a definitive explanation was found, the data was unclear. The jaws clearly indicated energetic usage by the creatures they belonged to.
But essentially, size comparisons of these bones suggest the creature was abnormal in several ways.
Researchers lacked the detail needed to form a complete understanding of their activities or biological characteristics.
As researchers continued analyzing additional samples, a clearer image began to take shape.
The 65-foot terror of the Cretaceous period
What length would those 65-foot ancient octopuses have achieved if they had evolved until today?
The fossils were derived from an extinct branch of octopuses referred to as Cirrata. But these had fins.
Comparing the size of the jaws and their wear patterns allowed researchers to recreate images of the original animals.
Although they appear similar to the somewhat goofy eight-legged versions we know today, they were so, so much larger and more battle-hardened.
Some species may have reached nearly 65 feet in total body length. That would place them among the largest invertebrates to ever exist.
Their jaws show repetitive contact with hard prey surfaces, indicating that they actively hunted.
It is likely that they were dominant predators in their ecosystems and occupied the uppermost tier of the marine food web.
This is a major challenge to our existing perception of ancient oceans where vertebrates dominated for millions of years.
Now we believe that large octopuses coexisted with vertebrates at the same level of their respective ancient marine food webs.
Perhaps these massive predators in ancient oceans represent an overlooked and previously unknown part of octopus evolutionary history.
If these behemoths once roamed ancient oceans, what other colossal creatures remain hidden in stone?