What is "stupendemys"

Stupendemys is a prehistoric genus of freshwater turtle. Its fossils have been found in northern South America, in rocks dating from the late Miocene to the very start of the Pliocene, about 6 to 5 million years ago.

Stupendemys's carapace measured over in length and was also very wide. With an estimated total carapace length of more than , it was the largest turtle that ever existed, surpassing even Archelon. The largest freshwater turtle living in the Neotropics today is the Arrau turtle (Podocnemis expansa), a pleurodire closely related to Stupendemys, but the Arrau turtle measures only .

Two species have been described to date. Stupendemys geographicus was more robust; its remains have been found in the Urumaco Formation of Venezuela. Stupendemys souzai, marginally smaller and more slender, was recovered from the Solimões Formation in Acre State, Brazil.