A recent discovery in Spain, we know they also would have had to contend with sea turtles the size of a fairly big modern mammal.
Called Leviathanochelys aenigmatica after a biblical sea monster, the animal’s pelvis indicates it could have been over 13 feet long. It lived an estimated 83.6-72.1 million years ago.
Until now, the largest documented marine turtle was Archelon, which lived during the late Cretaceous (66 million years ago).
Though its size is impressive, scientists are equally excited to solve the mystery of novel anatomical features on its pelvis and carapace that suggest the turtle is an entirely new species or even a new group of turtles, then we’ve seen before.