A ring-tailed lemur (Lemur catta) pausing on a prickly-pear cactus which they eat. This lemur is easily recognisable by its banded tail. Lemurs belong to a group of primates called the prosimians, meaning before monkeys . Everywhere in the world except Madagascar, monkeys replaced them 35 million years ago. Madagascar has outstanding biodiversity; most of its flora and fauna is unique to the island and can be found nowhere else.