Temporal range: Miocene-Pleistocene
|Skeleton at the American Museum of Natural History|
|Species:||† M. atlas|
(Falconer & Cautley, 1844)
Megalochelys atlas is an extinct species of cryptodiran turtle from the Miocene through to the Pleistocene periods. 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 cm (2.8–13.8 in) long). M. atlas is the largest known member of the family, with a shell length of about 2.1 m (6.9 ft), an estimated total length of 2.5 to 2.7 m (8.2 to 8.9 ft), and an approximate total height of 1.8 m (5.9 ft). Weight estimates vary greatly: some go as high as 3 to 4 metric tonnes (3000 to 4000 kg), but a weight of around 1 mt (1000 kg) is probably more realistic. The only larger turtles were the oceanic Archelon and Protostega from the Cretaceous period, and the freshwater Stupendemys of the South American late Miocene. In life, M. atlas would have resembled a giant Galápagos tortoise.
Like the modern Galápagos tortoise, M. atlas's weight was supported by four elephantine feet. Since most members of the related genus Testudo are herbivores, paleontologists presume M. atlas had the same diet. When a predator threatened it, M. atlas could probably retract its limbs and head into its shell, like its modern relatives.
Megalochelys atlas has a complicated nomenclatural history. It has previously been placed in the genus Colossochelys, however this name is in fact a junior synonym of Megalochelys, the statement of withdrawn by Auffenberg (1974). Hence the correct genus is Megalochelys and the correct species is M. atlas.
- Falconer, H. and Cautley, P.T. 1844. Communication on the Colossochelys atlas, a fossil tortoise of enormous size from the Tertiary strata of the Siwalk Hills in the north of India. Proceedings of the Zoological Society of London 1844(12):54–84.
- "Colossochelys atlas". Paleobiology Database. Retrieved 2012-03-02.
- Hansen, D. M.; Donlan, C. J.; Griffiths, C. J.; Campbell, K. J. (April 2010). "Ecological history and latent conservation potential: large and giant tortoises as a model for taxon substitutions". Ecography (Wiley) 33 (2): 272–284. doi:10.1111/j.1600-0587.2010.06305.x. Retrieved 2011-02-26.
- 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
- Auffenberg, Walter (1974). Checklist of fossil land tortoises (Testudinidae). Bulletin of the Florida State Museum, Biological sciences. 18, no. 3. University of Florida. p. 173. OCLC 1532640. Retrieved 2012-03-02.
Bakker, Robert. The Dinosaur Heresies. 1. New York: Zebra, 1996.
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