A lemur that moved like a sloth
In the limestone caves of northern Madagascar's Ankarana Massif, paleontologists in 1988 found the nearly complete skeleton of Babakotia radofilai, an extinct, medium-sized lemur. This creature was a member of the Palaeopropithecidae family, a group commonly known as sloth lemurs due to their remarkable convergent evolution with modern tree sloths. Babakotia weighed between 16 and 20 kilograms and was built for a life of slow, deliberate climbing and suspension. Its anatomy shows a fascinating mix of features: long forearms, curved fingers, and mobile hip and ankle joints, all adaptations for hanging and moving through trees.
The discovery of Babakotia helped clarify the evolutionary relationships among Madagascar's extinct primates. It represents an intermediate form between the smaller, more agile sloth lemurs like Mesopropithecus and the larger, more suspensory ones like Palaeopropithecus. Analysis of its skeleton suggests it was a slow climber, similar to a loris, but also engaged in sloth-like hanging behaviors. This evidence indicates that the ancestors of modern indriids—the leaping lemurs we see today—were likely slow climbers and hanging feeders, and that the high-speed leaping of their descendants evolved much later. Its diet consisted mainly of leaves, supplemented with fruits and hard seeds.
Bones too young to be fossils
The remains of Babakotia are technically "subfossils," not true fossils. This means they are not fully mineralized because they are geologically very young, dating from the Holocene epoch. The cave environments where they were found preserved them so well that organic molecules, such as collagen, still exist within the bones. This exceptional preservation is a scientific benefit. Collagen is an excellent source for extracting ancient DNA (aDNA).
The ability to sequence high-quality aDNA from Babakotia allows researchers to precisely map its genetic relationship to its closest living relatives, the indriids (Indri, Propithecus, and Avahi). This genetic information provides a clear picture of its place in the lemur family tree. While the extinction of the sloth lemurs is tied to the arrival of humans in Madagascar around 2,000 years ago, Babakotia may have vanished within the last 1,000 years. The high quality of its remaining genetic material makes it a theoretical candidate for future "de-extinction" projects, a concept demonstrated as possible with the brief revival of a Pyrenean ibex in 2003.