As Pangea continued to break apart, Madagascar split from Africa, some 160 million years ago. Drifting to the south, it merged with the remnants of Gondwanaland, the combined mass of Antarctica, India and Australia. There, its African flora and fauna mingled with the plants and animals of that tropical land mass. About 95 million years ago, the India-Madagascar segment broke from Antarctica-Australia, moving to the northeast; within another 15 million years, Madagascar began to rift from India, presumably triggered by an underlying hotspot that also produced the massive Deccan Traps basalt flow at the end of the Mesozoic. By 70 million years ago, Madagascar was moving into prolonged isolation and now rests 350 miles off the southeast coast of Africa.
While the earliest mammals arose during the Triassic, more than 200 million years ago, primates first appeared late in the Cretaceous, after Madagascar had become an isolated land mass. About 60 million years ago, these ancestral primates split into the prosimian line (which led to lemurs, lorises, galagos and pottos) and the anthrapoid line (leading to monkeys, apes and hominids). Spreading across the globe these two groups shared similar habitats and, over time, the anthrapoids were more successful, pushing the prosimians toward extinction.
According to current scientific theory, ancestral lemurs reached Madagascar on rafts of vegetation, torn from the African coast by seasonal storms. There, free from anthrapoid competition, they have flourished and, today, are represented by more than 100 species and subspecies. A second primate, humans, reached Madagascar by boat, colonizing the Earth's fourth largest island about 2000 years ago. Unfortunately, the Malagasy and their descendents have since destroyed much of the natural habitat; lemurs and other Madagascar animals, 80% of which are endemic to the island, are increasingly threatened by deforestation and other human activity.