The largest octopus alive today, in comparison, is the giant Pacific octopus. Per National Geographic, it tends to reach up to 16 feet in size, and though it has been known to eat larger animals like sharks and birds, it usually eats shrimp, clams, lobsters and fish.

The finned octopus lived alongside T. rex and may have been one of the top predators in the ancient ocean food chain.

The discovery challenges a 370-million-year-old assumption that only vertebrates could be top ocean predators.

Giant octopus fossil: A new study published in Science reveals that giant octopus-like creatures up to 19 metres long lived as apex predators in the ancient oceans 100 million years ago. Fossilised beaks show they crushed bones and rivalled mosasaurs.

Scientists have uncovered evidence of enormous, intelligent, octopus-like predators that dominated Earth's ancient oceans. These creatures, some up to 19 meters long, possessed bone-crushing beaks and rivalled top predators like mosasaurs.

New research suggests giant octopuses up to 19 metres long may have ruled ancient oceans 100 million years ago, challenging beliefs about prehistoric marine predators.