Mammals

Koala lemur (Megaladapis edwardsi) EX
The koala lemur is one of the best known of the giant lemurs, and had a skull the size of a gorilla’s. It was a squat-bodied vertical clinger and climber with a mobile proboscis, and may have superficially resembled a giant koala in the way it moved. The most recent remains of Megaladapis edwardsi, from Manamby Plateau north of Toliara in southwest Madagascar, have been dated to 630±50 years BP, strongly suggesting that koala lemurs survived until the European colonisation of Madagascar.
Why did this species go extinct?
The koala lemur went extinct as a result of over-hunting and habitat destruction by the people who first colonised Madagascar from the mainland.
Distribution
Southern Madagascar.
 
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Evolutionary Distinctiveness
Order: Primates
Family: Megaladapidae
The Malagasy lemurs represent an incredible radiation of over 50 living species and many additional recently extinct species, that are believed to have evolved from a common ancestor that colonized Madagascar from Africa during the early Tertiary Period (60-50 mya). Three species of Megaladapis, M. edwardsi, M. grandidieri and M. madagascariensis, have been described from subfossil remains. M. edwardsi is now placed in the separate subgenus Peloriadapis as it is morphologically quite distinct from the other two species, which are often considered to be conspecific. Megaladapis is usually thought to be most closely related to the tiny living sportive lemurs (Lepilemur), which are often placed together in the same family. However, genetic analysis of subfossil material has revealed that Megaladapis does not show a sister-group relationship with Lepilemur.
Description, ecology and habitat
Megaladapis edwardsi was the largest of the three Megaladapis species, with an estimated body weight of more than 75 kg, making it one of the biggest prosimians ever to have evolved – only the giant terrestrial Archaeoindris (c. 200 kg) was larger. Megaladapis species were all folivorous. M. edwardsi had an extremely long, narrow skull (277-317 mm cranial length), possibly because of its huge molar teeth, which were far larger than expected for its body size. Both the upper and lower jaws had a long diastema, and the upper incisors were replaced by a bony ridge, suggesting the presence of a horny ‘cropping pad’ against which to grind food. It is likely that all three Megaladapis species also possessed a mobile proboscis, like a tapir. The body was rather short and stocky in relation to the size of the head. The forelimbs were longer than the hind limbs, and the feet and hands elongated and curved for powerful grasping. It is likely that M. edwardsi was a vertical climber, clinging to trees and branches with all four limbs. It had reduced suspensory capabilities compared with the two smaller Megaladapis species, and its large size would have prohibited leaping; it was presumably also more terrestrial, probably moving mainly quadrupedally on the ground like an orang-utan. Studies of dental formation time suggest a minimum gestation length of approximately 6 months for this species.
Factors leading to extinction
All of Madagascar’s Quaternary large vertebrate fauna are believed to have survived until humans first colonised Madagascar slightly over 2,000 years ago. As the three species of Megaladapis were all dependent on forested environments, and would have been tempting targets for hunters due to their large size and slow movements, it is likely that they were all driven to extinction by a combination of hunting and forest destruction for agriculture.
Links
Seal Specialist Group (1996). Monachus tropicalis. In: IUCN (2006). 2006 IUCN Red List of Threatened Species. IUCN Red List of Threatened Species.Accessed 08 May 2006.
References
Godfrey, L. R., Semprebon, G. M., Jungers, W. L., Sutherland, M. R., Simons, E. L. and Solounias, N. 2004. Dental use wear in extinct lemurs: evidence of diet and niche differentiation. Journal of Human Evolution 47 (3): 145-169.

Karanth, K. P., Delefosse, T., Rakotosamimanana, B., Parsons, T. J. and Yoder, A. D. 2005. Ancient DNA from giant extinct lemurs confirms single origin of Malagasy Primates. Proceedings of the National Academy of Sciences of the United States of America 102 (14): 5090-5095.

Mittermeier, R. A., Tattersall, I., Constant, W. R., Meyers, D. M. and Mast, R. B. 1994. Lemurs of Madagascar. Conservation International, Washington, D.C.

Montagnon, D., Ravaoarimanana, B,. Rakotosamimanana, B. and Rumpler, Y. 2001 Ancient DNA from Megaladapis edwardsi (Malagasy Subfossil): Preliminary Results Using Partial Cytochrome b Sequence. Folia Primatol (Basel), 72(1):30-2.

Nowak, R.M. (ed.) 1999.Walkers Mammals of the World. Sixth edition. The Johns Hopkins University Press, Baltimore and London.

Schwartz, G. T., Mahoney, P., Godfrey, L. R., Cuozzo, F. P., Jungers, W. L. and Randria, G. F. N. 2005. Dental development in Megaladapis edwardsi (Primates, Lemuriformes): Implications for understanding life history variation in subfossil lemurs. Journal of Human Evolution 49 (6): 702-721

Vuillaume-Randriamanantena, M., Godfrey, L. R., Jungers, W. L. Jr. and Simons, E. L. 1992. Morphology, taxonomy and distribution of Megaladapis - giant subfossil lemur from Madagascar. Comptes Rendus de l'Academie des Sciences Serie II Mecanique-Physique-Chimie Sciences de l'Univers Sciences de la Terre 315 (13): 1835-1842.

Yoder, A.D., Ruvolo, M. and Vilgalys, R. 1996. Molecular evolutionary dynamics of cytochrome b in strepsirrhine primates: the phylogenetic significance of third position transversions. Molecular Biology and Evolution, 13(10):1339-1350.

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