Ancient Giant Turtle Fossil Discovered

Posted on May 17, 2012

Carbonemys cofrinii


Paleontologists from North Carolina State University have discovered the fossilized remains of a 60-million-year-old South American giant turtle that lived in what is now Colombia. The researchers say the turtle would have been the size of a Smart car with a shell that could have doubled as a kiddie pool. The turtle also had massive, powerful jaws that would have enabled the omnivore to eat anything nearby, including crocodiles.

The ancient giant turtle, Carbonemys cofrinii, which means "coal turtle," is part of a group of side-necked turtles known as pelomedusoides. The fossil was named Carbonemys because it was discovered in 2005 in a coal mine that was part of northern Colombia's Cerrejon formation. The specimen's skull measures 24 centimeters. The shell, recovered nearby, measures 172 centimeters - about 5 feet 7 inches, long.

Edwin Cadena, the NC State doctoral student who discovered the fossil, says, "We had recovered smaller turtle specimens from the site. But after spending about four days working on uncovering the shell, I realized that this particular turtle was the biggest anyone had found in this area for this time period - and it gave us the first evidence of giantism in freshwater turtles."

Smaller relatives of Carbonemys existed alongside dinosaurs. But the giant version appeared five million years after the dinosaurs vanished, during a period when giant varieties of many different reptiles - including Titanoboa cerrejonensis, the largest snake ever discovered - lived in this part of South America. Researchers believe that a combination of changes in the ecosystem, including fewer predators, a larger habitat area, plentiful food supply and climate changes, worked together to enable these giant species to thrive.

Only one specimen of this size has been recovered so far. Dr. Dan Ksepka, NC State paleontologist and research associate at the North Carolina Museum of Natural Sciences, believes that this is because a turtle of this size would need a large territory in order to obtain enough food to survive.

Ksepka, a co-author of the paper, says, "It's like having one big snapping turtle living in the middle of a lake. That turtle survives because it has eaten all of the major competitors for resources. We found many bite-marked shells at this site that show crocodilians preyed on side-necked turtles. None would have bothered an adult Carbonemys, though - in fact smaller crocs would have been easy prey for this behemoth."

The paleontologists' findings appear in the Journal of Systematic Palaeontology. Dr. Carlos Jaramillo from the Smithsonian Tropical Research Institute in Panama and Dr. Jonathan Bloch from the Florida Museum of Natural History contributed to the work. The research was funded by grants from the Smithsonian Institute and the National Science Foundation.

Image: Artwork by Liz Bradford