Lemurs of Madagascar: Surviving on an Island of Change
Lemurs in Madagascar: Then
The lemurs of Madagascar, the most diverse group of primates in the world, had even more members in their ranks before humans first arrived to the island two millennia ago. There was Palaeopropithecus ingens, a lemur that hung from branches like a sloth. There was Daubentonia robusta, or an oversize version of the current-day aye-aye—a lemur with long, skeletal fingers, large eyes, and rodentlike teeth. The lumbering Archaeoindris fontoynontii weighed in at 160 kg, the size of a male gorilla. The 45–85 kg Megaladapis edwardsi had a prehensile upper lip to pluck leaves while slowly ascending trees like a koala.
An eastern lesser bamboo lemur eating its favorite food in Ranomafana National Park, Madagascar.
These four species, all larger than current-day lemurs, are now extinct. In fact, about 16 of the perhaps 70 species of wildly diverse lemurs that existed upon human arrival aren’t around anymore. Of the species still living, four top Conservation International’s “World’s 25 Most Endangered Primates” list.
Despite the disappearances of plants and animals on Madagascar, the country remains incredibly rich biologically. Its environments vary from desert to rain forest to shrubby highlands. The country still boasts a huge variety of species, 90 percent of which are found nowhere else. How did Madagascar develop such a range of wildlife? The reasons can be traced back to when Madagascar began to be decidedly its own place, some 160 million years ago.
A Fateful Split
At that time, Madagascar (then attached to India, Australia, and Antarctica) began to split from the supercontinent Gondwanaland. Just before the start of the Late Cretaceous period, 124 million years ago, Madagascar arrived at its present position, separated from Africa by the 770 km wide Gulf of Mozambique. Now the fourth-largest island in the world, it straddles many latitudes. This helps foster its myriad climates and habitats.
Paleontologist Laurie Godfrey, left, examines lemur bones with graduate student Emilienne Rasoazanabary at the University of Antananarivo.
This geographic seclusion from other land is one reason why Madagascar is considered a “laboratory of evolution” by researchers like University of Massachusetts paleontologist Laurie Godfrey. The country’s flora and fauna have evolved independently, with little influence from species migrating from adjacent areas. As evidenced by Charles Darwin's discovery of a unique finch for each unique island of the Galapagos chain, physical barriers to interbreeding are key to the development of new species in an area. Such evolutionary isolation of the island of Madagascar would have telling consequences for its lemur populations.
