Fossilized jaws (beaks) from Cretaceous-era rocks in Japan and Canada suggest that extinct octopus species reached lengths of up to 19 meters (about 62 feet), according to a study published in the journal Science. The study provides new evidence regarding the size, diet, and ecological role of these ancient invertebrates.
Discovery and Methodology
Researchers from Hokkaido University and Ruhr University Bochum analyzed fossilized beaks preserved in sedimentary rock samples from northern Japan and Vancouver Island, Canada. The fossils date to the Late Cretaceous period, approximately 100 to 72 million years ago.
The team examined 15 previously identified specimens and discovered 12 additional fossils. They used high-resolution grinding tomography and artificial intelligence to create three-dimensional models of the jaws embedded in solid rock, a technique described as "digital fossil mining."
"Digital fossil mining" allowed researchers to create 3D models of jaws embedded in solid rock.
Species Identification
The fossils were reclassified from their original attribution to vampire squids and assigned to the extinct genus Nanaimoteuthis, belonging to the finned octopus suborder Cirrata. Two species were identified:
- Nanaimoteuthis jeletzkyi: Estimated total length of 2.8 to 7.7 meters (9 to 25 feet).
- Nanaimoteuthis haggarti: Estimated total length of 6.6 to 18.6 meters (22 to 61 feet), with a jaw approximately 150% larger than that of a modern giant squid.
The size estimates were derived by comparing jaw dimensions to body proportions in living finned octopuses. The upper size range of N. haggarti would make it among the largest known invertebrates.
Physical Evidence of Diet and Behavior
Analysis of the beaks revealed wear patterns including chips, scratches, and rounded edges. In the largest specimens, up to 10% of the jaw tip length had worn away. Researchers stated these patterns indicate repeated, forceful interactions with hard materials such as shells and bones. The wear resembled but exceeded that observed in modern octopuses that feed on hard-shelled prey.
The jaws showed more wear on one side than the other, suggesting lateralized behavior, which in modern animals is associated with advanced neural processing.
Wear patterns suggest these octopuses repeatedly interacted with hard materials like shells and bones, exceeding the wear seen in modern octopuses.
Ecological Context
The study proposes that these octopuses were active carnivores that preyed on hard-shelled organisms, large fish, and potentially marine reptiles. This suggests they may have competed with vertebrate predators such as mosasaurs, plesiosaurs, and large sharks for ecological niches.
The findings challenge the longstanding view that Late Cretaceous marine ecosystems were dominated exclusively by large vertebrate predators. One co-author stated the research provides evidence that invertebrates could evolve into large, intelligent predators in ecosystems typically dominated by vertebrates.
Expert Commentary
- Dr. Thomas Clements (University of Reading, not involved in the research): Noted the size of the beak was impressive and suggested the animal was massive.
- Professor Tim Coulson (University of Oxford, not involved): Called the work "compelling and exciting," noting the octopuses likely fed on large fish, marine reptiles, and shellfish.
- Dr. Jakob Vinther (University of Bristol, not involved): Cautioned that while Nanaimoteuthis was a formidable predator, smaller prey could have met its energy needs; it may not have exclusively preyed on large marine reptiles.
- Dr. Adiel Klompmaker (University of Alabama, not involved): Commented that the animals "must have been a fearsome sight to behold."
- Dr. Neil Landman (American Museum of Natural History, not involved): Noted there are many fossils yet to be found to piece together the marine ecosystem through time.
- Dr. Fernando Ángel Fernández-Álvarez (Spanish Institute of Oceanography, not involved): Stated he was not expecting an octopus of that magnitude.
- Other paleontologists (not involved in the study): Noted that size estimation methods may be error-prone and that large size does not necessarily equate to apex predator status.
Significance
The research extends the known fossil record of finned octopuses by approximately 15 million years. Because octopuses are soft-bodied, their fossils are rare, and their hard chitin beaks provide the primary evidence for size and diet. The study demonstrates the utility of combining digital fossil analysis with AI for reconstructing ancient ecosystems.