Lemurs represent the most primitive type of primate. Isolated to the island of Madagascar about 55 million years ago, they retain features that differ from the other primates. First, they have wet, shiny noses; the noses of other primates are dry. Second, their feet have a mixture of toenails (on the large digit) and claws on the other four digits. The types of lemurs include: the true lemurs, the dwarf or mouse lemurs, the indris or sifakas, the sportive lemurs, and the very unique aye-aye. The group includes about 101 species. Most are nocturnal, and hence the name “lemur” means “ghost”.