Fossilized Jaws Show Giant Octopuses Up to 19 Meters Long Dominated Cretaceous Oceans

Fossilized jaws reveal that enormous octopuses growing up to 19 meters long were top predators in the oceans during the Cretaceous Period. Researchers reported these findings in Science on April 23. Yasuhiro Iba, a paleontologist at Hokkaido University in Sapporo, Japan, noted that most soft bodies of octopuses decompose before fossilization, leaving few hard parts like beaklike jaws to fossilize.

Some particularly large fossil jaws were found by researchers in Japan and on Canada’s Vancouver Island. The fossil jaws date back to the Late Cretaceous Period, about 72 million to 100 million years ago. The jaws appeared to belong to octopus-like creatures.

Iba and colleagues examined 15 fossil cephalopod jaws. They used a technique to discover and document 12 more jaw fossils embedded in rocks found in Japan. The rocks containing the 12 jaw fossils were ground down layer by layer and photographed at each step.

With artificial intelligence, the team created a detailed digital model of fossils too fragile to mine out using traditional methods. The 27 cephalopod jaws were initially thought to be from five different extinct species. The researchers reassigned the 27 cephalopod jaws as just two species: Nanaimoteuthis jeletzkyi and N.

Haggarti. Based on comparisons with other cephalopod jaws, the creatures appear to be early finned octopuses. Today’s finned octopuses, such as the dumbo octopus, are deep-sea animals with webbing between their arms and flapping fins.

The largest lower jaw belonging to N. haggarti was about 50 percent bigger than that of the 12-meter-long modern giant squid. Iba and colleagues estimate N. haggarti could have been between about seven and 19 meters long including its arms.