Size and Weight:
Dinosaurs weren't the only creatures that grew to jumbo sizes in the late Cretaceous period. Archelon was the largest prehistoric turtle that ever lived (the second largest was its close contemporary Protostega), about the size (and shape, and weight) of a classic Volkswagen Beetle. By comparison with this two-ton behemoth, the biggest Galapagos tortoises of today weigh a little over a quarter of a ton and measure about four feet long!
Archelon differed significantly from modern turtles in two ways. First, its shell wasn't hard, but leathery in texture, and supported by a skeletal framework underneath; and second, this turtle had unusually wide, flipperlike arms and legs. Today, Archelon's closest living relative is the sea turtle known as the Leatherback. (By the way, the fossils of Archelon were discovered in South Dakota and Wyoming, which were mostly covered by the Western Interior Sea 75 million years ago.)