New fossil specimens of the largest land turtle to have ever lived are giving up more of its secrets, revealing brand new insights into these giants that roamed Earth 8 million years ago.

The new specimens found in northern Venezuela and, for the first time, Colombia expands its range across South America, suggests a form of sexual dimorphism not seen before in any side-necked turtle, and include the largest carapace (upper shell) discovered yet.

First described in the 1970s, Stupendemys geographicus was one of the many behemoths found in tropical South America 5-10 million years ago. The region would have been warm, humid, and swampy; perfect for a range of megafauna that included giant crocodiles, alligators, caimans, and gavialis. Though it was likely preyed on by these, its own size is not to be sniffed at.

Reporting in Science Advances, researchers have analyzed several new shells – as well as the first-ever lower jaw – including the largest S. geographicus carapace ever found at 2.4 meters long (7.8 feet). Based on this, the researchers think the hefty turtle weighed around 1,145 kilograms (2,520 pounds), 100 times that of its closest living relative, the big-headed Amazon river turtle. This makes it the largest land turtle we know of, and rivals the famous Late Cretacious marine turtle Archelon in size.

“Stupendemys is for sure the largest recorded side-necked turtle, one of the two kinds of turtles there are,” Professor Marcelo Sánchez, director of the Paleontological Institute and Museum of UZH and head of the study, told IFLScience. “In the other group, the Cryptodira, Archelon is the biggest, a marine turtle. Archelon is the largest turtle there has been based on available specimens, but Stupendemys was very close.”