Archelon lived during in the oceans of the Late Cretaceous period from 80-65 Million Years Ago.
Archelon was unlike any turtle in the 21st Century, that largest turtle of all time. Measuring 4.5 meters long. Despite its' size, it was no more aggressive than the modern sea turtles are, and actually lacked a hard bony shell, just as the modern leatherback turtle does. That made it vulnerable to attacks by such monstrous sea carnivores.