Theropod dinosaurs offer an excellent opportunity for the study of the evolution of locomotion. Since theropods are the other major group of striding bipeds besides humans, understanding their locomotion and morphology presents a chance to both broaden understanding of general locomotor principles, and also compare and contrast evolutionary adaptations for bipedality. The research presented here focuses on understanding joint function in a living theropod, the Helmeted Guineafowl. Biplanar X-rays of hind limb joints in motion are analyzed using the marker-based X-ray Reconstruction of Moving Morphology (XROMM) workflow. When combined with explicit joint coordinate systems, these reconstructions and kinematic data offer the most accurate and complete descriptions of joint motion in ground-dwelling birds to date. Chapter one investigates the kinematics that underlie common maneuvers, such as sidestepping, yawing to face a new direction, and turning while progressing forwards. Results demonstrate that non-sagittal rotations play a critical role in all of these behaviors. Long-axis rotation at the hips is used to move the feet mediolaterally, and shift the body to the left and right. Long-axis rotation of the tibia at the knees is used to reorient the foot compared to the body, and to yaw the body over a planted limb. Chapter two investigates steady locomotion. Results demonstrate that long-axis rotation at the knee and hip is used during walking and grounded running as well. Importantly, we find that individuals on treadmills routinely yaw away from their direction of travel. These yaws require asymmetric joint kinematics and induce hip long-axis rotation patterns that resemble those of sidesteps. Chapter three focuses on range of motion at the major hind limb joints. The data show that degrees of freedom at a joint can interact in significant and complex ways. 3-dimensional (3-D) volumes of limb pose data are effective tools to visualize these relationships. The range of motion envelopes may overestimate the motions used in vivo in some dimensions, but some degrees of freedom appear to be fully utilized by the individual in life.
Kambic, Robert Emmett,
"Hind limb joint function in the Helmeted Guineafowl"
Ecological and Evolutionary Biology Theses and Dissertations.
Brown Digital Repository. Brown University Library.