Podocnemididae

Podocnemididae is a family of side-necked turtles that was once far more diverse, with most of its forty one known genera and fifty seven species now extinct. Of the eight surviving species, seven are found in South America and one, in the genus Erymnochelys, is native to Madagascar; the two other living genera are Peltocephalus and Podocnemis. Fossil evidence shows the family was once also present in Europe, Asia, North America and Africa. Podocnemidids defend themselves by turning the head sideways beneath the shell rather than retracting it, and the family includes Stupendemys, the largest freshwater turtle known to have existed, with a shell measuring roughly 2.4 meters across.