Pleurodira

The Pleurodira are one of the two living suborders of turtles (the other being the Cryptodira) more known commonly as the side-necked turtles. The name "Pleurodira" translates to "side neck", whereas the Cryptodira are known as hidden-necked turtles; these names reflect the distinct neck retraction mechanisms between the two suborders, which are the product of diverging evolutionary histories. Within the Pleurodira, three living families are represented: Chelidae, the Austro-South American side-necked turtles, the Pelomedusidae, the African mud terrapins, and the Podocnemididae, the American side-neck river turtles.

Pleurodiran turtles are currently restricted to the freshwater ecosystems of former Gondwanan landmasses, including in Australia, South America, Arabia, Madagascar and Africa. Prehistorically, they were a cosmopolitan clade during the Cretaceous and most of the Cenozoic, and even occurred in marine environments around the world.