Archaeolemur has a lower dental formula of 1-1-3-3. Therefore, the tooth comb, a key feature of strepsirrhines, consists of four teeth rather than the characteristic six teeth of most taxa. This dental reduction is also observed in indriids and palaeopropithecids, suggesting this is a potential synapomorphy among these groups. Microwear analysis of the lower incisors shows no evidence that the tooth comb of
Archaeolemur was used for grooming. Rather, the lower incisors are thought to have served a dietary function, such as the procurement and processing of food. The upper incisors are large and spatulate, the premolars form a cutting edge, with the anterior lower premolar adopting a caniniform shape, and the molars are bilophodont and low-crowned. This bilophodont molar morphology converges on that of cercopithecine molars. These features have frequently been attributed to a frugivorous diet. The enamel of
Archaeolemur teeth is very thick and highly
decussated, which might have played a role in processing hard-objects.
Archaeolemur also has a fused
mandibular symphysis, an adaptation for resisting chewing stress. A biomechanical analysis of the jaw showed that
Archaeolemur was well suited for breaking apart large food items and dental microwear analysis of
A. edwardsi and
A. majori molars shows pitting that indicates
Archaeolemur processed harder foods, supporting a generalist diet. Furthermore, the most similar microwear pattern among modern primates is found in
Cebus apella, a hard-object feeder. Stable isotope analysis of
A. majori indicates
Archaeolemur was a consumer of C3 plants and coprolites associated with
Archaeolemur indicate an omnivorous diet that included fruit, seeds, and even small animals. Overall, the evidence suggests
Archaeolemur had a generalist diet that mainly consisted of fruit, seeds, and hard-objects. The postcranial skeletal morphology reveals important aspects of
Archaeolemur’s lifestyle. As the name "monkey lemur" suggests,
Archaeolemur has often been compared to the
Old World monkeys due to convergences in morphological and locomotory features, such as limb proportions. While there are certainly similarities between the two, the convergences are sometimes overstated. A comprehensive analysis of the hands and feet of
Archaeolemur shows that its limbs are relatively short for its body size, as are the hands and feet. The pollex and hallux are reduced, along with the other digits, and were likely not prehensile; nevertheless, the ability to grasp when climbing was probably retained.
Archaeolemur has broad apical tufts on the distal phalanges of both the hands and feet, which some have suggested might be related to grooming in the absence of a functioning tooth comb. Unlike the Paleopropithecidae, or "sloth lemurs," who had highly curved proximal phalanges for suspensory behavior, the proximal phalanges of
Archaeolemur are straighter than those of all extinct Malagasy primates, although still more curved than those of baboons. This morphological data, along with a previous study of the pelvis and scapula, support the conclusion that
Archaeolemur’s locomotory habits most likely consisted of both terrestrial and arboreal quadrupedalism. It was probably neither cursorial, nor a leaper. ==Geographic range==