A sketch of the giant octopus. Yohei Utsuki/Department of Earth and Planetary Sciences, Hokkaido University hide caption toggle caption Yohei Utsuki/Department of Earth and Planetary Sciences, Hokkaido University A hundred million years ago during the late Cretaceous period, the oceans were filled with giant predators, prowling for their next meal. There was the mosasaur — a giant toothy marine reptile (and a surprise hero in Jurassic World). There were large sharks. And now, in the journal Science , researchers present evidence for ancient colossal octopuses — what they believe are the largest invertebrates ever described. Using innovative fossil reconstruction techniques, the researchers revealed remnants of two extinct species locked inside large rocks. They appear to have been up to 60-feet long — longer than a school bus — rivaling other apex predators of the time, and calling to mind the Kraken of legend .…