; infraclass Eutheria, cohort Unguiculata)
An order that comprises the only true flying mammals, possessing features parallel to those of birds (e.g. active metabolism and economy of weight). Insectivores possibly ancestral to the bats are known from the Paleocene. The first undoubted bats are preserved in middle Eocene deposits in both Europe and N. America. Differentiation of the modern lineages was far advanced by the Eocene–Oligocene transition. The wing is a patagium supported by four, or in some species all five, elongated digits of the fore limb, and attached along the sides of the body, the legs (leaving the feet free), and in most species the tail. The pelvis is weak but adapted to enable the legs to rotate to the rear so that the bat can hang head-down. The orbit is rarely closed behind. The incisors are often specialized or reduced. There are two suborders: Megachiroptera and Microchiroptera.
Subjects: Zoology and Animal Sciences.