The earliest known fossil of a gliding mammal dates to more than 125 million years ago. Today there are about 60 different species of mammals capable of sustained gliding. These species are spread among six groups: three marsupials, one dermopteran and two rodent families. Rocky, the squirrel of Rocky and Bullwinkle fame and probably the most well known of these animals, introduced generations of children to gliding mammals.
The marsupial species of gliding mammals include sugar gliders, the greater glider and feather-tailed possums. The flying possums have long flat tails that in some species have feather-like hairs that help the animal use its tail like a rudder.
Colugos, or flying lemurs, from Southeast Asia are members of the order Dermoptera. Dermopterans have a membrane of skin, called a patagium, extending from their bodies to their limbs, which enable them to glide. The colugo has the largest patagium possible for its body size. It extends from its shoulder to its hands, from its hands to its feet, and from its feet to the tip of its tail. There is even webbing between its toes and fingers.
The two gliding rodent groups are the flying squirrels and the scaly-tailed flying squirrels. There are more species of flying squirrels than in any of the other gliding mammal groups. These squirrels use their fluffy tails like a brake when they land from a glide.
Scaly-tailed flying squirrels are found in central Africa and are named for the rows of pointed scales on the underside of their tails.