Meet the 19 metre octopus that may have prowled ancient seas - BBC

Fossil evidence suggests a giant octopus up to 19 metres long may have prowled the seas about 100 million years ago, with a crushing beak, powerful arms, and a comparatively large brain. That research implies such cephalopods could have competed with other large marine predators during the late Cretaceous. The recent study naming a 43-foot mosasaur Tylosaurus rex highlights that these oceans supported diverse, large predators, increasing the likelihood of ecological interactions and competition among top predators.