UNC emeritus professor Alan Fedducia has long argued that supposed “proto” precursors to these structures are simply collagen fibers or ossified tendons. They aren’t teeth, (15[1])but pulp caps are gradually reabsorbed into the rachis during the formation of these structures. (-5[1])The disintegration of the “powder down” variety of these structures produces copious amounts of fine keratin dust. Hooklets and cilia branch from the (*) barbules of these structures. (10[1])Rectrices and remiges (10[1])are specialized types of the contour variety of these structures which possess an expansive vane. These structures develop in bloody white sheaths (10[1])as pins. (10[1])Raised “knobs'' on the ulna are indicative of these structures in fossils, which likely evolved to provide (10[1])insulation. (-5[1])For 10 points, (10[1]-5[1])preening is the (10[1])rearrangement (10[1]-5[2])of what (10[3])bristled, water-proof structures (10[1])whose aerodynamic qualities help birds to fly? ■END■ (10[3])