Taxonomy and evolution

Sea Turtles, along with other turtles and tortoises, are part of the Order Testudines. The seven living species of sea turtles are: flatback, green sea turtle, Hawksbill, Kemp’s Ridley, Leatherback, Loggerhead and Olive Ridley. All species except the leatherback are in the family Cheloniidae. The leatherback belongs to the family Dermochelyidae and is its only member. The species are primarily distinguished by their anatomy: for instance, the prefrontal scales on the head, the number of and shape of scutes on the carapace, and the type of inframarginal scutes on the plastron. The leatherback is the only sea turtle that does not have a hard shell; instead it bears a mosaic of bony plates beneath its leathery skin.