Fossilized Cephalopod Jaws from 72 Million Years Ago Suggest Some Large Predatory Squid-Like Species Inhabited Late Cretaceous Seas

Fossilized jawbones belonging to a previously unknown octopus species were uncovered in geological formations on Hokkaido Island in Japan and on Vancouver Island in Canada. The creatures lived about 72 million years ago during the Late Cretaceous period. A study describing the finds was published in the journal Science.

Researchers identified 12 additional fossil jaws from rocks in Japan and examined 15 previously found jaws. The specimens were assigned to two species, N. jeletzkyi and N. haggarti, based on differences in size and form.

N. jeletzkyi reached estimated lengths of 10 to 26 feet. N. haggarti measured between 23 and 62 feet, making it potentially the largest invertebrate ever discovered. All size estimates were derived from measurements of the largest jaw in each species.

The jaws were recovered from the Yezo Group formation on Hokkaido and the Nanaimo Group formation on Vancouver Island. Yasuhiro Iba, a paleontologist at Hokkaido University in Japan and study co-author, told Live Science that the findings revise the view of the Cretaceous ocean as a world dominated only by large vertebrate predators.

He said the fossils show that giant invertebrates also occupied the top of the food web.

Before these discoveries, all known top marine predators from the period were thought to be vertebrates such as plesiosaurs and mosasaurs. The new evidence indicates that prehistoric marine ecosystems contained a greater variety of predators and were more complex than previously understood.