Colossochelys atlas

Colossochelys atlas, formerly known as Testudo atlas, and originally described as Geochelone atlas, is an extinct species of cryptodire turtle from the Pleistocene period, about 2 million years ago. During the dry glacial periods it ranged from western India and Pakistan (possibly even as far west as southern and eastern Europe) to as far east as Sulawesi and Timor in Indonesia.

Other members of the family Testudinidae are generally small (7–35 centimetres (2.8–14 in) long). C. atlas is the largest known member of the family, with a shell length of about 2.1 metres (6.9 ft), an estimated total length of 2.5 to 2.7 metres (8.2 to 8.9 ft) and an approximate total height of 1.8 metres (5.9 ft). Weight estimates vary greatly: some go as high as 3 to 4 metric tonnes (= 3000 to 4000 kilograms), but a weight of around 1 metric tonne (1000 kilograms) is probably more realistic (Paul and Leahy, 1994). The only bigger turtles were the oceanic Archelon and Protostega from the Cretaceous period. Colossochelys atlas probably looked similar to a giant Galápagos tortoise.

Like the modern Galápagos tortoise, Colossochelys atlas's weight was supported by four elephantine feet. Since most members of the related genus Testudo are herbivores, paleontologists presume C. atlas had the same diet. When a predator threatened it, C. atlas could probably retract its limbs and head into its shell, just like its modern relatives.

References

Paul, G.S., and Leahy, G.D. (1994). Terramegathermy in the time of the titans: Restoring the metabolics of colossal dinosaurs. Paleontol. Soc. Spec. Publ. 7, 177-198

Bakker, Robert. The Dinosaur Heresies. 1. New York: Zebra, 1996.