The Thick-Boned Lemur
Pachylemur was a genus of giant lemur closely related to modern ruffed lemurs (Varecia), but it was a much more robust animal. There were two known species, Pachylemur insignis and Pachylemur jullyi, which weighed around 10 kilograms (22 pounds) and 13 kilograms (29 pounds) respectively. This makes them three to four times larger than their living relatives. The name Pachylemur translates to "thick lemur," a fitting description for its powerful and heavily built skeleton. Its forelimbs and hindlimbs were nearly the same length, suggesting it was not a leaper like modern ruffed lemurs. Instead, analysis of its bones indicates it was a slow, deliberate arboreal quadruped. It likely moved through the upper canopy with caution, using hindlimb suspension to hang and reach fruits, similar to its modern cousins.
Subfossil remains of Pachylemur have been discovered in caves, marshes, and other sites across most of Madagascar, with notable finds in locations like Ankilitelo Cave and Tsimanampesotse National Park. These bones paint a picture of an animal that was a fruit specialist. Dental analysis, including wear patterns and the presence of caries, shows a diet heavy on fruit, possibly supplemented with some leaves. The massive jaws and large molars of Pachylemur suggest it could process harder and more fibrous fruits than any lemur alive today.
An Ecological Disappearance
The extinction of Pachylemur is a loss to Madagascar's ecosystems. As a large frugivore, it dispersed seeds. Certain tree species with large seeds may have depended almost entirely on this giant lemur to spread their offspring. In the spiny thickets of the southwest, it may have also dispersed plants whose seeds evolved to be carried by attaching to fur. Its disappearance likely created a void in the forest that no other living species could fill, contributing to changes in forest composition and the decline of specific plant populations.
The timeline for Pachylemur's extinction coincides with the increasing presence of humans on the island. The first people arrived in Madagascar around 350 BCE, and the giant lemur's population began to decline within 500 years of their arrival. Most radiocarbon-dated remains place its extinction between 680 and 960 CE. However, some subfossil remains found in a pit cave in southwestern Madagascar might be as recent as 500 years old. The extinction was not a single event but a gradual process driven by human-related pressures. Factors such as widespread habitat loss from agriculture, forest fragmentation, and hunting for bushmeat are considered the primary causes of its demise.