Archelon was the largest marine Chelonian of all time. With a 23-26 foot flipper span, and a weight likely to be over 3 tonnes, Archelon was a monster of a reptile. It lived 80-65.5 Million Years Ago, in the seas of the Northern Hemisphere. It fed on jelly fish and other soft bodied prey, with the sting proof beak and thickened skin mouth. It would have been a docile, peaceful wonder of nature, yet it in spite of being at least twice the size of even the greatest Leatherback and Loggerhead turtles, it was far from invulnerable. It is said to have lived in 'the single most dangerous seas of all time - hell's aquarium'. Giant Mosasaurs over 17 metres long, giant sharks 6-7 metres long, killer fish such as the 6 metre long Xiphactinus, and an array of other marine killers would have come into contact with Archelon. Mosasaurs would have been the most frequent and persistant predators of Archelon, capable of biting them in two and tearing their flippers.