A smart car sized turtle roamed what is now Colombia some 60 million years ago, according to paleontologists who have discovered its fossilized remains.
Part of a group of side-necked turtles known as pelomedusoides, the fossil was discovered in 2005 in a coal mine in northern Colombia. Researchers aptly named it Carbonemys cofrinii, meaning “coal turtle.”
The skull of the newly discovered specimen measures about 10 inches (24 centimeters), while the shell which was recovered nearby — and is believed to belong to the same species — measures about 5 feet 7 inches (172 centimeters) long.
That’s the same height as Edwin Cadena, the NC State doctoral student who discovered the fossil.
“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,” Cadena said.
Smaller relatives of Carbonemys existed alongside dinosaurs. However, the giant variety showed up five million years after the dinosaurs vanished, during a time when giant reptiles – including Titanoboa cerrejonensis, the largest snake ever discovered – lived in this part of South America.
Researchers believe that these giant species survived thanks to a combination of changes in the ecosystem, including fewer predators, a larger habitat area, plentiful food supply and climate changes. Carbonemys’ habitat would have resembled a much warmer modern-day Orinoco or Amazon River delta.
Besides the turtle’s huge size, the fossil also revealed that this particular turtle had massive, powerful jaws.The creature would have been able to eat anything nearby – from mollusks to smaller turtles or even crocodiles.
Thus far, only one specimen of this size has been recovered. Paleontologist Dan Ksepka, 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.
“It’s like having one big snapping turtle living in the middle of a lake,” says Ksepka, co-author of the paper describing the find.
“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,” he said.
Edwin Cadena, Dan Ksepka, Carlos Jaramillo, Jonathan Bloch. New pelomedusoid turtles from the late Palaeocene Cerrejon Formation of Colombia and their implications for phylogeny and body size evolution. Journal of Systematic Palaeontology, 2012; in press.