Artist impression of a male Stupendemys geographicus with horns on its carapace and a female individual (left) swimming in freshwater.
One of the largest turtles ever to roam the Earth was as big as a sedan, built like a tank and equipped with two lance-like horns on its shell, new fossils recovered from South America show.
Colombian paleontologist Edwin Cadena is seen taking notes on one of the male specimens of Stupendemys geographicus during fieldwork in 2016.
Lead author Professor Edwin Cadena said "The now-extinct animal is the largest land turtle of all time".
Paleobiologists from the University of Zurich (UZH) have discovered the fossils of an extinct giant freshwater turtle that weighed a ton and had a shell almost three metres long in northern South America. Its carapace was nearly three meters long, making it one of the largest, if not the largest turtle that ever existed.
The huge extinct freshwater turtle Stupendemys geographicus, which lived in lakes and rivers in northern South America during the Miocene Epoch, is seen in an illustration released February 12, 2020.
Venezuelan Palaeontologist Rodolfo Sánchez and a male carapace of the giant turtle Stupendemys geographicus, from Urumaco, Venezuela.
Researchers suggest the unique horn-like shells at the front of the hard upper shells, may have served to protect their massive skulls when engaged in combat with other males.
"Based on studies of the turtle anatomy, we now know that some living turtles from the Amazon region are the closest living relatives", Sánchez said. This is the first time that sexual dimorphism in the form of horned shells has been reported in any side-necked turtle (any species of turtle belonging to the families Chelidae, Pelomedusidae, and Podocnemididae).
Through analysis of the ancient turtle fossils, scientists determined mature Stupendemys geographicus specimens weighed upwards of 2,500 pounds. Among those prehistoric predators was the caiman Purussaurus, which measured 11 metres (36 feet) long, and the slightly smaller Gryposuchus, which was 10 metres (33 feet) long.
The new research provided scientists an improved understanding of the species' position within the turtle family tree.