Order Chiroptera

The order Chiroptera includes all bats that are characterized by their forelimbs modified into wings with a naked and double-layered membrane stretched over greatly elongated phalanges and metacarpals; this membrane can extend to the hind limbs and enclose the tail in many species. Other flight-ready features include thumb free of the wing membrane and usually clawed; knee joint directed outward and posteriorly; ears well developed, often of large size; very small eyes in most species; a reduced ulna with limited functionality; a large radius; an usually keeled sternum and greatly developed pectoral musculature; a well-developed clavicle; a dorsally directed glenoid fossa of the scapula; generally tubular limb bones; thoracic and cervical vertebrae that lack neural spines; a dome-shaped skull with an usually inflated braincase and a frontal region both inflated and concave. The distribution is nearly cosmopolitan. Bats are divided into two suborders: Megachiroptera (often diurnal bats limited to the Old World) and Microchiroptera (strictly nocturnal bats with worldwide distribution). Eight families occur in North America.