VANCOUVER ISLAND — A finned octopus species that lived during the Cretaceous Period reached an estimated length of up to 18.6 meters (61.02 feet), making it one of the largest invertebrates on record, according to a study published Thursday in the journal Science. The species, Nanaimoteuthis haggarti, lived about 86 to 72 million years ago.

Researchers examined the jaws of 15 ancient octopus fossils previously found in Japan and on Canada's Vancouver Island, and identified 12 additional octopus jaws from Japan using a technique called digital fossil mining, which scans rock cross-sections to reveal hidden fossils. The study, conducted by researchers affiliated with Hokkaido University, identified two main species of finned octopuses: Nanaimoteuthis jeletzkyi and Nanaimoteuthis haggarti.

Analysis comparing ancient octopus jaws to modern-day octopus jaws determined that the ancient octopuses ranged from 23 to 62 feet in length. The largest ancient octopus jaw was substantially larger than that of any modern octopus.

"The predator is one of the largest invertebrates on record," said co-author and paleontologist Yasuhiro Iba. Until now, the largest known invertebrate has been the modern giant squid, which can reach about 12 meters (39 feet) in total length. The finned octopuses described in the study were nearly 20 feet longer than the largest specimens of modern giant squid, the longest cephalopod living today. The ancient finned octopuses had among the largest body sizes of all organisms in the Cretaceous oceans.

Researchers examined patterns of wear on the fossilized jaws of dozens of octopus specimens from the Cretaceous epoch. The largest ancient octopus jaws showed scratches, chips and rounded edges, indicating repeated crushing of hard prey such as shells and bones. Octopus beaks are made of stiffened chitin, which are tough enough to crush shelled and bony organisms.

"Our findings show that powerful jaws, and the loss of superficial skeletons, convergently transformed cephalopods and marine vertebrates into huge, intelligent predators," the researchers said. Invertebrates with soft bodies generally do not preserve well in the fossil record, making it difficult to determine their size from fossils.

"It's a big old planet. So we have lots to look at to piece together the marine ecosystem through time," said paleontologist Neil Landman.