Fossil Jaws Show Giant Octopuses in Cretaceous Seas

Scientists from Hokkaido University in Japan have identified evidence of colossal octopuses that roamed the ancient oceans about 100 million years ago during the Cretaceous period, potentially ranking among the largest invertebrates ever known. Based on an analysis of fossilized jaws, the researchers describe two species, Nanaimoteuthis jeletzkyi and the larger N. haggarti, that measured up to 19 meters long, including their extended arms, challenging long-held assumptions about marine predator dynamics in an era dominated by dinosaurs on land.

The study, published in the journal Science, examined 27 fossil jaws collected from Cretaceous sediments in Japan and Canada's Vancouver Island. Fifteen of these were previously known, while the team uncovered 12 additional specimens using a technique called digital fossil mining, which involves scanning rock cross-sections layer by layer with artificial intelligence to reveal hidden fossils without physical extraction. By comparing the ancient jaws to those of modern octopuses and cuttlefish, the researchers estimated body sizes ranging from 7 to 19 meters for the largest individuals. The biggest jaw, from N. haggarti, was about 50...