Biggest Turtle That Ever Lived Had 10 Foot Shell With Horns The huge extinct freshwater turtle Stupendemys geographicus,  Palaeontologist Rodolfo Sanchez lies alongside a carapace of the giant turtle Stupendemys geographicus, from Urumaco, Venezuela. Photograph: University of Zurich/Edwin Cadena/PA Car-sized Turtle Fossils UnearthedScientists have unearthed new fossils of one of the largest turtles that ever […]

Biggest Turtle That Ever Lived Had 10 Foot Shell With Horns The huge extinct freshwater turtle Stupendemys geographicus,  Palaeontologist Rodolfo Sanchez lies alongside a carapace of the giant turtle Stupendemys geographicus, from Urumaco, Venezuela. Photograph: University of Zurich/Edwin Cadena/PA

Car-sized Turtle Fossils UnearthedScientists have unearthed new fossils of one of the largest turtles that ever lived: a car-sized reptile which prowled the lakes and rivers of what is now northern South America from about 13m years ago to 7m years ago.

The tropical region of South America is one of the world’s hot spots when it comes to animal diversity. The region’s extinct fauna is unique, as documented by fossils of giant rodents and crocodylians -including crocodiles, alligators, caimans and gavials — that inhabited what is today a desert area in Venezuela. Five to ten million years ago, this was a humid swampy region teeming with life. One of its inhabitants was Stupendemys geographicus, a turtle species first described in the mid-1970s.

Giant turtle 100 times heavier than its closest relativeResearchers of the University of Zurich (UZH) and fellow researchers from Colombia, Venezuela, and Brazil have now reported exceptional specimens of the extinct turtle recently found in new locations across Venezuela and Colombia.

“The carapace of some Stupendemys individuals reached almost three meters, making it one of the largest, if not the largest turtle that ever existed,” says Marcelo Sánchez, director of the Paleontological Institute and Museum of UZH and head of the study. The turtle had an estimated body mass of 1,145 kg — almost one hundred times that of its closest living relative, the big-headed Amazon river turtle.Males carried horns on their carapaceIn some individuals, the complete carapace showed a peculiar and unexpected feature: horns. “The two shell types indicate that two 𝓈ℯ𝓍es of Stupendemys existed — males with horned shells, and females with hornless shells,” concludes Sánchez. According to the paleobiologist, this is the first time that 𝓈ℯ𝓍ual dimorphism in the form of horned shells has been reported for any of the side-necked turtles, one of the two major groups of turtles world-wide.

Despite its tremendous size, the turtle had natural enemies. In many areas, the occurrence of Stupendemys coincides with Purussaurus, the largest caimans. This was most likely a predator of the giant turtle, given not only its size and dietary preferences, but also as inferred by bite marks and punctured bones in fossil carapaces of Stupendemys.Turtle phylogeny thoroughly revisedSince the scientists also discovered jaws and other skeleton parts of Stupendemys, they were able to thoroughly revise the evolutionary relationships of this species within the turtle tree of life. “Based on studies of the turtle anatomy, we now know that some living turtles from the Amazon region are the closest living relatives,” says Sánchez. Furthermore, the new discoveries and the investigation of existing fossils from Brazil, Colombia and Venezuela indicate a much wider geographic distribution of Stupendemys than previously assumed. The animal lived across the whole of the northern part of South America.