How and when the Lemur separated from the evolutionary line that later led to monkeys is unclear. Separated from the mainland of Africa for millions of years, the Lemur had to adapt to the many terrains and habitats of Madagascar. The Lemur came to the island as one species of primate descent and soon spread into fifty. When Europeansfirst came to Madagascar in the mid-1600's, 15 species had become extinct. From studying "subfossil," fossil and current remains of the lemurs on Madagascar, scientist have tried to discover how these animals came to be the way they are. It is difficult because there are so many differing varieties. There are those Lemurs that adapted to a life in the trees, and Lemurs who live on the ground. There are nocturnal and diurnal Lemurs and there are smaller Lemurs and larger Lemurs. Each Lemur, living in its own distinct habitat, developed its own system for surviving and living comfortably.