Giant Octopuses Were Once Top Predators of the Prehistoric Seas

追加: 2026-05-05

[00:00:00]The human fascination with our planet's vast oceans is ancient. Our species has long looked out across these expanses of water and marveled at the wonders and dangers that swim unseen beneath the waves. One of the mythological dangers that has long haunted the minds of sailors is the legend of the Kraken, a gigantic kelopod lurking in the depths of the sea, preying on unfortunate vessels passing above. It's now thought that the concept of the Kraken may, at least in part, have been inspired by rare sightings of giant and colossal squid, which can reach up to 10 m in total length, nearly 33 ft, including their elongate feeding tentacles. Well, in a phenomenal new paper published this week, paleontologists have reported evidence for the existence of real life prehistoric krakens, truly giant prehistoric octopuses from the Cretaceous period that may have grown up to 19 m in length, nearly 62 feet, and preyed on plesiosaurs and mosasaurs. Not only that, but this new research also presents evidence that these octopuses possessed advanced intelligence. It seems that the oceanic food chains of our planet's deep past may not have been as completely dominated by large marine reptiles as we previously thought.

[00:01:20]Instead, there were 60 foot long, highly intelligent octopuses at the top of the food web as well. And many of those marine reptiles would have met their ends as they found themselves grasped by the arms of these enormous Keopods and felt their bones being crushed by their hard beaks. And the scariest thing is that we just haven't really been finding evidence of these animals since they are almost entirely composed of soft tissues that do not fossilize very well. Just thinking about how many giant octopuses might once have existed yet never left a trace in the fossil record is mindblowing. So what evidence for prehistoric krakens do we actually have?

[00:01:59]Although octopuses are mostly softbodied, they do possess beaks composed of kitonous jaws. These beaks sometimes end up being fossilized, and previous papers have reported more than a dozen instances of very large octopus jaws found in Cretaceous aged rocks in Japan and on Vancouver Island in Canada, which date to between 172 million years ago. In this new research, a team of paleontologists has revisited 15 of these large octopus jaws and reported another 12 jaws from the Cretaceous of Japan and analyzed how the beaks had worn down as the animals fed. These beak fossils belong to two species of extinct octopuses called Namothis Gilletki and Naomotus Hagati which are members of the octopus suborder serata known as the fininned octopuses. Finned octopuses today tend to inhabit the deep sea while the other octopus suborder in Sarata known as the finless octopuses generally inhabit more coastal regions. Amazingly, one of the specimens of Namothus Gilletki reported in this study is now the oldest known fossil of a true octopus, extending the known range of these animals back by about 5 million years and extending the range of the finned octopuses in particular back by 15 million years. When the researchers examined the wear patterns of these nonatuous jaws, they found that in the larger adult individuals, the jaws were blunter and their edges were more rounded than in the smaller juvenile specimens. Chips, scratches, and areas of polishing were present, the result of intensive wear. Interestingly, the right edges of the jaws were also more worn than the left edges in both species.

[00:03:44]These wear patterns provide strong evidence that these large prehistoric octopuses were duropagus. That is, they fed on hard prey items. Like modern octopuses and cuttlefish, frequent consumption of prey such as crustations, mollisks, other kelopods, and bony fishes results in the gradual wearing down of their beaks. The researchers therefore hypothesize that given the large sizes of these Cretaceous octopuses and the abundance of marine reptiles they would have shared the oceans with, it's not unreasonable to hypothesize that their diets could have included plesiosaurs and mosasaurs, as they were clearly capable of crunching down through bone. Keopods jaw muscles increase in size as the overall jaw size gets bigger, meaning that these very large namotus individuals would have had strong bite forces. The long lateral walls in these jaws also indicate that their muscles were large and powerful.

[00:04:40]The asymmetry of the wear patterns is the authors suggest also an indication of advanced intelligence in these octopuses. The asymmetric loss of the jaw edges shows that these animals were engaging in lateralized behavior, meaning they were favoring one side of the beak more than the other.

[00:04:59]lateralized behavior has been linked to a highly developed brain and cognition in various animals, including humans and modern octopuses. And so this signal from the fossils could be evidence that even this early in their evolution, octopuses were remarkably bright creatures. As a quick side note, I've read quite a bit on octopus cognition over the past few years, and the way their decentralized intelligence seems to work is seriously fascinating. I might one day do an entire video about it on the Benji Thomas channel, but I was originally inspired to look more into it by the fantastic book Children of Ruin, the second novel in the Children of Time series by AdrienChaikovski. If you're into speculative evolution and want to read one of the most mind-blowing imaginative stories I've ever come across, featuring a civilization of space fairing octopuses and also space fairing spiders and crows and mantis shrimps, then I cannot recommend this series enough.

[00:05:54]Anyway, as if the idea that there were once giant octopuses capable of taking on mosasaurs wasn't awesome enough, the idea that they might have been exceedingly intelligent problem solvers is just so intriguing. So, how big could these octopuses have grown? I already mentioned the 19 m value or about 62 ft, but this is the extreme upper end of the size estimates and some paleontologists have cautioned that this might be a little too extreme. Within the modern representatives of the octopus suborder serata, there are forms with elongate bodies and forms with short bodies. A correlation between body form and jaw anatomy has been observed in modern fininned octopuses, suggesting that based on the anatomy of the naotus jaws, these prehistoric species were likely long-bodied. Using data on the sizes of various modern long-bodied forms, the authors then estimated a range of mantle sizes for the two nanomotus species.

[00:06:52]Since there's a pretty consistent ratio between the mantle length and the total length, including the arms, in modern long-bodied finned octopuses, this then allowed the researchers to produce a range of possible total lengths. For the smaller species, Namotus Gilletki, this range came out at between about 2.8 and 7.7 m or 9.2 to 25.3 ft. Namotus Hagatai, on the other hand, had a range of between about 6.6 6 and a whopping 18.6 m in length, which is about 21.7 to 61 ft. Now, that is quite a range and so it's not absolutely confirmed that over 60 ft long octopuses really did exist.

[00:07:36]But even at the lower to medium estimates, these are some absolutely enormous predators, rivaling the dimensions of many of the other prehistoric animals it would have shared the Cretaceous oceans with. Plus, the jaw of the biggest nanoasis haggatai specimen is already larger in absolute size than the jaw of the giant squid, which has the largest jaw of any living teopod. I'm really looking forward to seeing all the comments about how I pronounce teflopod. By the way, I used to say sephopod and then I heard Electra sayopod and I I just thought it was cooler that way. Anyway, the paper also highlights an interesting case of convergent evolution between these huge krakens of the Cretaceous and marine vertebrate top predators. Both kelopods and vertebrates evolved jaws between 423 and 47 million years ago. Marine vertebrate top predators used to be armorplated fishes, but then they became replaced by fish with scales. And then secondarily aquatic reptiles with smooth skin filled the top predator roles during the messoic. In parallel with this loss of armor invertebrates, various lineages of kelopods evolved from external shellbearing ancestors developed internal shells and then others lost their shells entirely to become softbodied. Eventually, some of these softbodied kelopods rivaled the smooth skinned marine reptiles as apex marine predators. The authors therefore conclude that the evolution of robust jaws and a reduction of superficial skeletons is essential for becoming a large intelligent marine top predator.

[00:09:10]Certainly an intriguing hypothesis.

[00:09:13]This study really could be heralding somewhat of a revolution in how we view the prehistoric oceans of the messoic era. Vertebrates have been top predators at the apex of marine food webs for the past 370 million years. And yet during the Cretaceous, colossal octopuses managed to invade these top tier positions. An increase in durapagus predation during the late Mesazoics spurred a radiation of marine predators better adapted to feed on hardshelled prey. And in turn, species at risk of predation evolved to better protect themselves. But while it had been thought that this arms race was driven mostly by durophagus top predators such as sharks and mosasaurs, it now turns out that early octopuses were probably part of the arms race as well, achieving enormous body sizes and becoming well suited to crushing tough exo and endoskeletons. This is a very exciting new study and I hope you've enjoyed the 7 Days of Science special feature all about it. Let us know what you think of this new research in the comments below.

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