Artist’s impression of an extinct Nanaimoteuthis species, often called krakens, which could have rivalled large marine reptiles in terms of size. Credit: Masato Hattori/Science Photo Library In the age of the dinosaurs, while Tyrannosaurus rex terrorized the land, gargantuan octopuses might have been among the top predators in the sea. Scientists have identified extinct octopuses — sometimes named krakens after the mythological monsters — that might have grown to nearly 19 metres in length. The estimate is based on fossilized jaws, which the researchers say show patterns of wear that came from devouring animals that had hard shells and skeletons. Their study, published on 23 April in Science 1 , challenges the idea that giant marine reptiles such as mosasaurs and other vertebrates exclusively dominated marine ecosystems in the Cretaceous period 143 million to 66 million years ago.…