Chelidae

The Chelidae are a family of freshwater turtles. They are "side-necked turtles". The family is distributed in Australia, New Guinea, parts of Indonesia, and throughout most of South America. It is a large family of turtles, and its fossil history goes back to the Cretaceous. 
The family Chelidae has about 60 living species in about twenty genera. The family is entirely Gondwanan in origin, with no members found outside Gondwana, either now or as a fossil.
They are called side-necked turtles because they withdraw their heads by moving the head sideways (see Pleurodira). Other turtles, if they withdraw their heads, pull them back in the vertical plane. 
The subfamilies within Chelidae show that most of the South American species and all the Australian species are a clade, that is, evolved from the same ancestor (monophyly. The far more ancient turtle genus "Hydromedusa" is their sister taxon.
Nowadays, all these species live in fresh water, but we know from the fossil record that many of their forebears lived in seas around the world.