Hundreds of fossils have been discovered at what's being called an underwater lemur graveyard in flooded caves off the west coast of Madagascar—the single largest fossil collection of extinct giant lemurs. Today’s lemurs are much smaller, and these Madagascan primates are some of the most threatened mammal species on Earth.
Brooklyn College’s Alfred Rosenberger and Laurie Godfrey from the University of Massachusetts led an international team of divers on an expedition through a series of three inland caves within Tsimanampesotse National Park at the center of the island nation. Among their prized findings is the enormous skull of Megaladapis (pictured above), also known as the koala lemur. As one of the largest of the recently extinct giant lemurs, Megaladapis skulls measured up to a foot or about a third of a meter long. They also found fossils belonging to Archaeoindris or sloth lemurs, which may have weighed as much as gorillas.
In addition to lemurs both giant and small, the team also found many other extinct Madagascar natives that died out about a thousand years ago or so: elephant birds, horned crocodiles (pictured right), giant fossa (a carnivorous mongoose relative), as well as extinct hippos, bats, and rodents. "We have a real cross-section," Rosenberger tells National Geographic, of both "tiny things and big things."
Entire skeletons showing hardly any damage over the centuries (millennia even) provide an unprecedented look at their anatomy and perhaps even the cause of their species’ disappearance. In fact, some of the lemurs appeared to have been “defleshed in place,” Rosenberger adds, with decomposition slowly revealing their bones over time. And thanks to the seclusion and preservation offered by their deep, watery graves, many of these skeletons stayed intact and in good condition—a rare thing in mammal paleontology. “Nothing’s bothering them, nothing’s disturbing them,” Godfrey tells The Washington Post. “A huge cache of fossils like this has never been explored before.”
And how did all these lemurs end up there? It’s possible they washed into the caves over many, many years, and or maybe a predator (like the giant fossa) dragged them in.
"This is the success of just phase one," Rosenberger says in a statement, adding that it’s just "the beginning of a complex international project that has a lot of long, hard work in store." The team should be able to extract DNA from the fossils and carbon date them. Not to mention, all of these specimens were visible on the surface of the cavern floor: They haven’t explored below the sediment. Furthermore, the stalactites and stalagmites in the caves could provide a record of climatic changes, which could help them understand how the environment impacted past fauna, the team explains in a news release. They're now submitting their initial findings for publication. Here’s an awesome National Science Foundation video of the discoveries:
Images: screenshot/National Science Foundation (top), Brooklyn College (middle)