Meeting Abstract

P1.104  Wednesday, Jan. 4  Morphology and histology of avian quill knobs: The fine structure of remigial feather attachments HIERONYMUS, TL*; SIMONS, ELR; Northeast Ohio Medical University; Midwestern University

The primary and secondary flight feathers (remiges) of bird wing are attached to the appendicular skeleton by a series of short ligaments. These ligaments form a link that assists in transmitting the aerodynamic forces generated by the wing to the remaining body mass of the bird. All bird species examined to date have similar arrangements of remigial ligaments. However, the presence and size of the bony exostoses (“quill knobs”) associated with the ligaments of the secondary remiges is variable among avian taxa, and there are no prominent bony landmarks associated with the attachments of the primary remiges. Variability in quill knob size has been tentatively linked to flight performance, but the relationship between quill knob morphology, remigial ligament morphology, and wing shape is still largely unexplored. We examined the osteohistology and soft tissue histology of remigial attachments to the ulna, carpometacarpus, and major digit in a number of species exhibiting a range of body size and flight behaviors. Preliminary results indicate that even in the absence of grossly visible bony quill knobs (as in some galliform birds), ossified portions of the remigial ligament on the dorsal surface of the ulna mark sites of secondary remex attachment. Ossified ligament remnants appear in histological sections as shallow patches of extrinsic (Sharpey’s) fiber bone overlying fibrolamellar bone. Primary remigial ligament attachments in the manus, which typically lack bony exostoses, also show similar patches of extrinsic fibers. Further exploration of the relationships between remigial ligament attachment histology, quill knob morphology, wing shape, and flight behavior may provide a means of documenting the evolution of avian wings from bony features preserved in fossil specimens.