98.2 Saturday, Jan. 7 A new look at the avian wishbone BAIER, D.B.*; GATESY, S.M.; DIAL, K.P.; JENKINS, F.A. Jr.; Providence College; Brown University; University of Montana; Harvard University firstname.lastname@example.org
The V-shaped avian furcula (fused clavicles) spans between the shoulders and is known to be capable of considerable bending in most species. Earlier studies of European starlings suggested that the furcula might act as a spring, because the ends of the furcula expand laterally during downstroke and then recoil during upstroke at their attachment to the distal coracoids. Thus, energy put into the spring during downstroke might be recaptured during upstroke. Herein, we present the first subsequent in vivo measurement of the furcula during flight in two species, pigeons (multiple speeds; windtunnel; single-fluoroscope) and chukar partridges (ascending; free-flight; biplanar fluoroscopy). We employ markerless XROMM (X-ray Reconstruction of Moving Morphology) to reconstruct 3-D skeletal motions using high-speed cinefluoroscopy. Consistent among all three species is pronounced lateral bending during the wingbeat cycle, however the phasic pattern in chukars and pigeons is opposite that of observed in starlings. Since bending of the furcula is driven by movements of the robust coracoid that articulates at the coracosternal joint, there is clearly need for further exploration of the complex forces affecting the shoulder girdle during flight.