he alligator snapping turtle (Macrochelys temminckii) is the largest freshwater turtle in the world based on weight. It is often associated with, but not closely related to, the common snapping turtle, which are in the genus Chelydra.
Deinosuchus - A crocodile so large that it hunted down dinosaurs. At 12 meters in length ft), it rivalled a T. rex in size and ferocity! Like saltwater crocodiles today, it would have lived both in fresh and salt water.