Colugos, often called “flying lemurs,” are gliding mammals found exclusively in Southeast Asia. While their common nickname suggests a connection to the primate family, the direct answer is no. Colugos are not members of the order Primates, which includes lemurs, monkeys, and apes. They belong to their own distinct mammalian group, yet they maintain a close evolutionary relationship with primates that modern science has recently clarified.
Defining the Dermoptera Order
Colugos are classified within the mammalian order Dermoptera, a name that literally means “skin wing” in Greek. This order contains only one family, Cynocephalidae, represented by just two living species: the Sunda colugo and the Philippine colugo. This isolation in the mammalian tree makes them a specialized lineage.
The defining characteristic of the Dermoptera is the patagium, an extensive fur-covered membrane of skin that stretches almost the entire length of the body. This gliding membrane is the most developed of any gliding mammal, extending from the neck to the forelimbs, back to the hindlimbs, and even to the tip of the tail. This specialization allows the colugo to glide long distances between trees, with some recorded glides covering over 100 meters.
Physical Traits and Misclassification History
Colugos possess several physical traits that superficially resemble those of primates. They have large, forward-facing eyes, which provide the binocular and stereoscopic vision useful for judging distance in an arboreal environment. Their small, broad heads and faces led early naturalists to find them similar to some strepsirrhine primates, resulting in the confusing common name “flying lemur.”
These shared characteristics led to a long history of taxonomic confusion, linking colugos to insectivores, bats, and primates. Another element is their specialized dentition: procumbent, comb-like lower incisors that are deeply grooved. While some lemurs also have a dental comb, the colugo’s structure is far more specialized, with each incisor divided into multiple tines. This feature is thought to be used for scraping plant matter or possibly for grooming.
Evolutionary Relationship to Primates
Despite the historical confusion based on morphology, modern science has definitively established the colugo’s precise placement in the mammalian family tree using genetic evidence. Molecular and genomic studies, including DNA sequencing, have shown that colugos are the closest living non-primate relatives to primates. This means the order Dermoptera is the sister group to the order Primates.
This close genetic bond places both groups within a larger superorder of placental mammals called Euarchonta. The Euarchonta clade is overwhelmingly supported by molecular data, including the analysis of specific genetic changes. Specifically, the group Primatomorpha unites Primates and Dermoptera, placing colugos closer to primates than to the third major order in the supergroup.
The three modern mammalian orders that make up the Euarchonta are Primates (lemurs, monkeys, apes), Scandentia (tree shrews), and Dermoptera (colugos). Genetic analysis suggests that the Dermoptera and Primates lineages diverged from a common ancestor approximately 79.6 million years ago.