Aye-Aye

FAMILY DAUBENTONIIDAE

This monotypic family is composed of one living species, the aye-aye, Daubentonia madagascariensis. This animal is separated from the other lemurs because it is highly specialized in many different ways, among them its unique dental formula (distinct from all other primates), its continuously growing incisor teeth (which led to its being considered a rodent during part of the 19th century), its large ears almost certainly used in locating insect larvae in dead wood, and its long skeleton-like middle finger used to extract larvae from holes. So unique is it among the lemurs that it has proven extremely difficult to determine which other lemurs are its closest relatives, although there is some suggestion that its affinities may lie with the indriids (Schwartz and Tattersall, 1985). The aye-aye is so unusual that it is not only strange within the context of the Order Primates, it is one of the most distinct mammals on Earth.

Illustration by Stephen D. Nash, Conservation International

Although only one living species of aye-aye is currently recognized, remains of a second, extinct species, Daubentonia robusta, are known from a few sites in the south of Madagascar. No skull has yet been found, but postcranial bones are larger and much more robust than those of the living form, suggesting that it was at least 2.5 times, and possibly as much as 5 times heavier. Teeth of D. robusta perforated for stringing provide one of the few direct evidences that any extinct lemur was hunted by humans, and it is virtually certain that this species was driven to extinction by human action (E. Simons, pers. comm.).

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

Schwartz, J.H. and I. Tattersall 1985. Evolutionary relationships of living lemurs and lorises (Mammalia, Primates) and their potential affinities with European Eocene Adapidae. Anthropological Papers of the American Museum of Natural History, 60 (1). New York, 100 pp.