NASSAR, P.N.*; JENKINS, F.A., Jr.; Univ. of Pennsylvania; Harvard Univ.: Kinematic analysis of the thoracic cage in guinea fowl (Numida meleagris) during terrestrial locomotion

Running guinea fowl (Numida meleagris) entrain their ventilation with their stride using a variety of breaths : stride ratios. The kinematics of the thoracoabdominal skeleton during locomotion are still mostly unknown, and there is evidence to suggest that the motions of the ribcage may conflict with the movements of the respiratory system during exercise. To examine this further, guinea fowl were filmed via cineradiography to determine the absolute and relative motions of the thoracoabdominal skeleton during rest and exercise (N = 3 birds). Data obtained from two birds show that during exercise: i) the vertical motion of the sternum is in phase with that of the vertebral column, ii) the thoracic cavity collapses each time the hindlimb strikes the ground and expands again as the limb pushes off, and iii) the caudal sternum undergoes further vertical excursions than the cranial sternum, the opposite of what is seen in flight. Thus, the motion of the sternum changes depending upon the center of rotation � the hip joint in running, the glenohumeral joint during flight � and, as such, its motions can be considered �bifulcral� depending on the point of reference. These results are consistent with kinematic predictions based on previous ventilatory studies, and support the idea that the kinematics of the thoracoabdominal skeleton aid in ventilation when the bird is exercising and entrained at 0.5:1 (strides:breaths).