If you ever wanted proof that ancient giant turtles really were giant, this is it.
Venezuelan palaeontologist Rodolfo Sánchez is dwarfed by the carapace of a male Stupendemys geographicus, which was found in eight-million-year-old deposits near the desert town of Urumaco.
The carapace is nearly three metres long, and the turtle itself was almost 1145 kilograms – around one hundred times the weight of its closest living relative, the big-headed Amazon river turtle (Peltocephalus dumerilianus).
Researchers from Switzerland, Venezuela, Colombia and Brazil, led by Marcelo Sánchez from the University of Zurich, have been studying some “exceptional specimens” of the extinct turtle recently found in new locations in tropical South America – and they have made some interesting discoveries.
Of particular note is that in some cases the complete carapace shows 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,” says Sánchez, adding that this is the first time 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 worldwide.
The research is described in a paper in the journal Science Advances.