Guineafowl hind limb function. I: Cineradiographic analysis and speed effects

Area of Science:

• Biomechanics
• Paleontology
• Zoology

Background:

• Understanding avian bipedalism is crucial for inferring theropod dinosaur locomotion.
• The helmeted guineafowl (Numida meleagris) serves as a model for studying avian striding bipedalism.

Purpose of the Study:

• To quantify hind limb kinematic changes in helmeted guineafowl across various speeds.
• To investigate the evolution of theropod locomotion through avian bipedalism analysis.

Main Methods:

• High-speed cineradiography, light films, and video recordings captured hind limb movements.
• X-ray imaging provided accurate, direct visualization of skeletal changes.
• Stride parameters were quantified and analyzed in relation to locomotion speed.

Main Results:

• Most stride parameters, including pelvic and femoral positioning, are speed-dependent.
• Gait transitions were observed, with a notable change near 0.9 m/sec.
• Knee flexion dominates at low speeds, while hip and knee extension increase with higher speeds.

Conclusions:

• Avian bipedalism exhibits speed-dependent kinematic adjustments in the hind limb.
• Guineafowl locomotion data offers insights into extinct theropod movement.
• Specific avian bipedal traits evolved within subsets of Theropoda, limiting direct extrapolation to all members.