Biggest Turtle to Ever Walk the Earth Was Hunted by 40 Foot Crocodiles 13 Million Years Ago

The shell of an enormous prehistoric turtle that would have been eight feet long has been discovered in Colombia's Tatacoa Desert. Analysis of the shell showed several bite marks indicating this animal was hunted by enormous crocodiles that lived at the same time, some of which could have been over 40 feet in length.

The turtle, Stupendemys geographicus, lived during the mid to late Miocene, 13 to 7 million years ago. It represents the biggest complete turtle shell ever discovered.

S. geographicus was first discovered in the 1970s and is believed to be the largest land turtle ever to have walked Earth. However, the species is not well understood, with key details about it are lacking.

Edwin Cadena, a Geologist and Vertebrate Paleontologist from Colombia's Universidad del Rosario, and colleagues were searching for specimens to see if they could find out more about their lifestyles and biology. Findings are published in Science Advances.

S. geographicus was previously known to have lived in Brazil, Colombia and Venezuela. The discovery of the new specimen expands this range significantly. It also provides an insight into the life of these turtles, showing males had huge horns on their shells that aided fighting.

Their analysis also revealed bite marks and punctured bones that indicates they were preyed on by the enormous, extinct crocodiles Gryposuchus and Purussaurus, the latter of which could reach over 40 feet in length.

In an email to Newsweek, Cadena said he and the team were surprised at the size of the new specimens, and even more so when they identified the "massive horns" the males had. The team propose these horns would have helped protect their skulls during combat.

Stupendemys geographicus
Artist impression of Stupendemys geographicus. The biggest complete specimen of the extinct turtle has been discovered in Colombia. Jaime Chirinos

Researchers say these turtles were able to grow to huge sizes because of their warm, wet habitat. Several other species in South America are known to have been extremely large, such as Titanoboa, the largest snake ever.

Cadena said S. geographicus may have gone extinct around 5 million years ago. "Although there is not last word on the causes of its extinction we attribute it to a combination of factors including the habitat segmentation due to geological and hydrological events that occurred in northern South America for that time including intense uplift of the Andes, and the reconfiguration of the major rivers: Amazon, Orinoco and Magdalena," he said. "This reduction in habitat size could have created ecological disruptions for the giant turtles and crocodiles inhabiting this region and favoring their extinction."

Cadena said they now plant to continue to explore South America in search of new fossils: "Not only of this giant Stupendemys, but also other extinct species that could shed light on the origin and history of current biodiversity, fossils that could even make a small contribution to conservation plans of their living descendants."

Stupendemys geographicus
Edwin Cadena with a male specimens of Stupendemys geographicus. Rodolfo Sanchez

James Parham, Associate Professor of Geological Sciences from the California State University, Fullerton, who was not involved in the research, said the findings were important as they give a more complete picture of a turtle celebrated by paleontologists: "They show that Stupendemys was not only bigger than we thought, but also more widespread. Is also nice to know what the skull of these turtles looks like," he told Newsweek.

Adán Pérez García, from the Evolutionary Biology Group of Spain's UNED, who was also not involved told Newsweek the research has several implications and markedly increases our knowledge of the anatomy of the biggest turtle to ever live. "The new study not only allows to know new anatomical information, but also helps to distinguish between males and females, and to better understand the way of life of this unique large form," he said.