March 4, 2015

Underwater Lemur Graveyard

Primate paleontologists strike the mother lode

Imagine diving the murky depths of a cave in Madagascar and happening upon a cache of thousands of perfectly preserved skeletons of species no longer found on Earth: giant lemurs, elephant birds, horned crocodiles, and Malagasy hippos. What do you do next?

If you are Ryan Dart, the Australian diver who discovered this paleontological treasure trove, you go to your connections: namely Phillip Lehman, a diver for the Dominican Republic Speleological Society. Lehman then contacted Alfred Rosenberger, a primate paleontologist at Brooklyn College, who enlisted the career expertise of Laurie Godfrey, professor of anthropology emerita and a specialist on lemurs, to collaborate on proposals and join in an expedition.

The team’s proposals won funding from the National Geographic Society and the National Science Foundation, which helped them assemble an international team of researchers and divers to explore the floors of three flooded freshwater caves—Malaza Manga, Aven, and Mitoho—in Tsimanampesotse National Park in southwest Madagascar, where the remains had lain undisturbed, researchers suspect, maybe for millennia.

“Caves are wonderful places for the collection of subfossils [bones that have not yet turned to stone _ Ed.],” says Godfrey. The researchers do not know why such a high number of skeletons accumulated there: cave openings, often associated with water, attract animals. A flood may have washed many animals into the cave. “We want to retrieve the story,” says Godfrey.

As astounding as its findings were, this expedition was just “a reconnaissance mission”—the first phase of a multiyear project, explains Godfrey. Because of the team’s agreement with Madagascar National Parks, every bone had to be carefully replaced. So far only a small percentage of the bones to be found in the cave have been documented by the team.

As an island with limited migration options for animals, Madagascar is a vulnerable ecosystem. Deforestation may have played a role in the giant lemurs’ demise, by forcing the primates into an ever-narrower hem of forests around the island’s coast. Godfrey and the rest of the research team hope the subfossils will yield clues to this story, or reveal yet another.

As all lemurs are endangered, this rich discovery could generate important insight not only into the primates’ past, but also their possible future.

 

Professor Godfrey also wishes to credit collaborator Haingoson Andriamialison at the Department of Paleontology and Biological Anthropology at the University of Antanananarivo, and the Madagascar National Parks.

All photographs by Pietro Donaggio Bittner.