The component structures of the outer covering and flight surfaces of all modern birds and some dinosaurs, apparently having evolved from the scales of reptilian ancestors. The many different types of feathers are variously specialized for insulation, flight, formation of body contours, display, and sensory reception. The typical feather consists of a central shaft (rachis), with serial paired branches (barbs) forming a flattened, usually curved surface (the vane). The barbs possess further branches, the barbules.