Colugo

Neither. The old name "flying lemur" is doubly wrong. It is not a lemur — lemurs are primates from Madagascar — and it does not fly. The colugo belongs to its own small mammal order, Dermoptera, with just two living species (the Sunda colugo and the Philippine colugo). And it glides rather than flies — it has no ability to generate lift by flapping and cannot gain height, only slow its fall while moving forward. What is true is that its closest living relatives really are the primates — genetic studies consistently place Dermoptera as the sister group to primates, making the colugo one of our nearer relatives among mammals.

Very far. A colugo's gliding membrane, the patagium, is the most extensive of any gliding mammal — it connects the neck, all four limbs right to the fingertips and toe tips, and the entire tail, and even the spaces between the fingers and toes are webbed. Spread out, the animal becomes a large, nearly rectangular kite. Typical glides between trees are 50 to 100 metres, and glides of over 130 metres have been recorded, with the animal losing only around 10 metres of height over 100 metres travelled — a very shallow, efficient glide. A mother can glide the full distance with a dependent young clinging to her belly.

The trade-off is built into its body. To make the glide membrane as large as possible, the colugo's limbs are relatively long and slender and the skin between and around them is stretched taut, and its hands and feet are adapted for gripping bark with strong claws rather than for powerful climbing. The result is an animal that cannot bound up a trunk the way a squirrel does; instead it moves up in a series of slow, ungainly hops, gripping and sliding the membrane along. On the ground it is nearly helpless — it cannot walk properly or stand, and would be very vulnerable to predators — so it essentially never comes down, gliding from tree to tree instead.

Colugos are strict herbivores, feeding mainly on young leaves, along with buds, shoots, flowers, and some fruit, from a wide variety of forest trees. They have comb-like lower front teeth, unique among mammals, which may be used to scrape sap, groom, or strain food. They are nocturnal, spending the day hidden — pressed flat against a trunk with their camouflaged fur, curled in a tree hollow, or hanging under a branch — and becoming active at dusk to feed and glide between feeding trees. They are solitary and largely silent, and females carry a single tiny, undeveloped young in a fold of the tail membrane that works like a pouch until it is old enough to glide on its own.