Named By: R. C. Wood - 1970.
Classification: Chordata, Reptilia, Anapsida, Testudines, Pleurodira, Pelomedusoidea, Podocnemididae.
Species: S. geographicus (type), S. souzai.
Diet: Probable omnivore. Current thinking is that Stupendemys would eat plants, animals, almost anything organic that would fit in its mouth.
Size: Preserved length of carapace of largest individual 1.8 meters long. Estimated length of shell up to 3.3 meters long.
Known locations: Venezeula - Urumaco Formation and Brazil - Solimões Formation.
Time period: Messinian of the Miocene to Zanclean of the Pliocene.
Fossil representation: Remains of two species, including the carapace.
was a genus of pleurodiran turtle, a type better known as a
side-necked turtle. Side necked turtles acquired their name because
their necks are so long that the only way they could fit under the
shell was to fold their necks into one side. The preserved length of
the largest known Stupendemys carapace (the upper
shell) is one
hundred and eighty centimetres long, and has been estimated to be as
much as three hundred and thirty centimetres long in the living
animal. With the addition of the long neck Stupendemys
been even longer than the famously huge Archelon,
a giant sea
turtle that lived earlier in the late Cretaceous period.
Unlike Archelon, Stupendemys was a freshwater turtle, and one that inhabited the river systems and lakes of Northern South America around the boundary of the late Miocene and early Pliocene. The huge size of Stupendemys might be a response to the predatory threats living in South America which included giant crocodiles such as Mourasuchus, Gryposuchus and particularly the caiman-like Purussaurus.
Additional remains of Stupendemys shells now found have revealed that male Stupendemys grew two enlarged spikes from the front of the shell that pointed forwards alongside each side of the neck. These spikes have wear patterns on them that seem to indicate that they were used in combat between rival males. The larger the spikes grew, the more advantage they would have in combat, and may have also served as display for impressing females.
Large pleurodiran turtles seemed to have been very common in the river systems of South America during the Cenozoic, with another example being Carbonemys, a pleurodiran with a shell one hundred and seventy-two centimetres long that lived in South America not long after the dinosaurs went extinct.
- Stupendemys geographicus, the world's largest turtle. - Breviora 436:1-31. - R. C. Wood. - 1976.
- A cintura pélvica do quelônio Stupendemys (Podocnemididae, Podocnemidinae) proveniente do Mioceno superior-Plioceno do Estado do Acre, Brasil [The pelvic girdle of quelônio Stupendemys (Podocnemididae, Podocnemidinae) coming from the upper Miocene-Pliocene of the State of Acre, Brazil]. - Acta Geologica Leopoldensia, 20(45):47-50. - J. Bocquentin & E. Guilherme - 1997.
- Stupendemys souzai sp. nov. (Pleurodira, Podocnemididae) from the Miocene-Pliocene of the Solimões Formation, Brazil. - Revista Brasileira de Paleontologia 9(2): 187-192. - Jean Bocquentin & Janira Melo - 2006.