Megalochelys ("great turtle") is an extinct genus of
tortoises that lived from the
Miocene to
Pleistocene. They are noted for their giant size, which is among the largest of any known testudine, with a maximum carapace length over 2 m (6.5 ft) in M. atlas. 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, though the island specimens likely represent distinct species.[4]
Description
One species of Megalochelys,M. atlas, is the largest known
tortoise, with a shell length of 2 m (6 ft 7 in) and even 2.7 m (8 ft 10 in), and an approximate total height of 1.8 m (5 ft 11 in).[5] Popular weight estimates for this taxon have varied greatly with the highest estimates reaching up to 4,000 kg (8,800 lb) in some instances.[6] However, weights based on volumetric displacement of the skeleton,[7] or inferences based on two-dimensional skeletal drawings,[8] indicate that M. atlas was probably closer to 1,000 to 2,000 kg (2,200 to 4,400 lb) in mass. M. atlas is thus the largest known tortoise. The only larger turtles were the
marineArchelon and Protostega from the
Cretaceous Period, and the aquatic, freshwater Stupendemys of the
South AmericanLate Miocene. A similarly gigantic tortoise, Titanochelon, is known from the Miocene to Pleistocene of Europe, which had shell lengths of up to 2 m (6 ft 7 in).
Like the modern Galápagos tortoise, M. atlas' weight was supported by four elephantine feet. Like other tortoises, it is thought to have been herbivorous.
Taxonomy
Megalochelys is the original and valid name for what has been called Colossochelys. It contains three named species with several unnamed taxa.[1]
Megalochelys atlas Falconer and Cautley, 1844[1][3] Late Miocene to Early Pleistocene, India (
Sivalik Hills), Myanmar, ?Thailand
Megalochelys cautleyiLydekker, 1889[1][9] Late Pliocene to Early Pleistocene, India (Sivalik Hills) probable nomen dubium.[1]
Megalochelys margae[1] Early Pleistocene,
Sulawesi, Indonesia. Size estimation between 1,4-1,9 m long.[1]
Megalochelys sondaari Karl and Staesche, 2007 [1] Early Pleistocene (until 1.7 ma)
Luzon, Philippines
The genus is suspected to have gone extinct due to the arrival of Homo erectus, due to staggered extinctions on islands coinciding with the arrival of H. erectus in these regions, as well as evidence of exploitation by H. erectus. The genus was largely extinct by the end of the
Early Pleistocene, but persisted on
Timor into the
Middle Pleistocene.[1]
^Falconer, H. and Cautley, P.T. 1837. On additional fossil species of the order Quadrumana from the Siwalik Hills. Journal of the Asiatic Society of Bengal 6:354–360.
^
abFalconer, 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.
^
abcdRhodin, Anders; Pritchard, Peter; van Dijk, Peter Paul; Saumure, Raymond; Buhlmann, Kurt; Iverson, John; Mittermeier, Russell, eds. (2015-04-16). "Turtles and Tortoises of the World During the Rise and Global Spread of Humanity: First Checklist and Review of Extinct Pleistocene and Holocene Chelonians".
Conservation Biology of Freshwater Turtles and Tortoises. Chelonian Research Monographs. Vol. 5 (First ed.). Chelonian Research Foundation.
doi:
10.3854/crm.5.000e.fossil.checklist.v1.2015.
ISBN978-0-9653540-9-7.
^Hirayama R, Sonoda T, Takai M, Htike T, Maung Thein ZM, Takahashi A. 2015. Megalochelys: gigantic tortoise from the Neogene of Myanmar. PeerJ PrePrints 3:e961v1
https://doi.org/10.7287/peerj.preprints.961v1
^Orenstein, R. 2001. Survivors in Armor: Turtles, Tortoises, and Terrapins. Key Porter Books Ltd.
^Brown, B. 1931. The Largest Known Land Tortoise. Nat. Hist. Vol. 31:184–187.
^Lydekker, R. 1889. Catalogue of the Fossil Reptilia and Amphibia in the British Museum. Part III. Chelonia. London: British Museum of Natural History, 239 pp.