There are 64 species of extant gliding mammals that are currently recognized, which are divided into six different families. These comprise eight species of gliding marsupials that live within Australasia and include six species of lesser gliding possums of Petaurus (family Petauridae), one species of greater glider of Petauroides (family Pseudocheiridae), and one species of feathertail glider of Acrobates (family Acrobatidae). The flying squirrels of the tribe Pteromyini within the rodent family Sciuridae represent the greatest diversity of gliding mammals, with a total of 48 species in 15 genera currently recognized, and occur throughout Asia, Europe, and North America. A second group of gliding rodents, known as the scaly-tailed flying squirrels, comprises six species from the family Anomaluridae that live in central and western Africa. The most specialized and unique of the extant gliding mammals are the enigmatic colugos, or flying lemurs, of the order Dermoptera that comprise two species and occur throughout Southeast Asia and the Philippines. In addition to the extant species there are various fossils of extinct species that are thought to have had an ability to glide, although there has been a lot of debate over most of these taxa. These fossil taxa include 3 marsupials, 18 dermopterans, 51 flying squirrels, 7 species of scaly-tailed flying squirrels, and 1 extinct species in each of the families Myoxidae, Eomyidae, and Volaticotheriidae. The taxonomic status of many living and extinct gliding mammals is still in a state of flux, and significant further revision of the taxonomic status of many groups still needs to be resolved.