One could guess from this difference that smell plays a greater role in prosimian behavior than it does in that of monkeys who tend to be more visually oriented. Today, lemurs survive only on the island of Madagascar off the southeast coast of Africa in the Indian Ocean, and on the neighboring Comores Islands. Lemurs spend most of their time in trees or large bushes, although the ringtail lemur, the most terrestrial species, may spend as much as half of its day on the ground. Various species of lemurs can be found in habitats as different as the lush, wet, rainforest of eastern Madagascar and the very dry spiny desert in the southwest. The smaller species tend to be nocturnal, but most of the larger species are active during the day.
Lemurs feed primarily on leaves and fruits, and most are arboreal .
For some of nocturnal lemurs, insects form a large part of their diet. They use these tails for balance when leaping through the forest canopy, but unlike New World monkeys, these tails are not prehensile , and lemurs cannot hang from them. How and when lemurs diverged from the lineage that led to monkeys is unclear. Although it was once thought that lemurs were on Madagascar when the island separated from Africa, recent advances in geological science have shown that Madagascar was separated from Africa by hundreds of kilometers before primates evolved. Accordingly, the ancestors of Madagascar's lemurs must have crossed over from Africa on floating vegetation.