Graduation Year

2024

Document Type

Dissertation

Degree

Ph.D.

Degree Name

Doctor of Philosophy (Ph.D.)

Degree Granting Department

Biology (Integrative Biology)

Major Professor

Ryan M. Carney, Ph.D., M.P.H., M.B.A.

Committee Member

Stephen Deban, Ph.D.

Committee Member

Bradford Gemmell, Ph.D.

Committee Member

Diego Sustaita, Ph.D.

Keywords

alligator, chukar, Deinonychus, guineafowl, joints, XROMM

Abstract

Research on the evolution of dinosaur flight has long been dominated by the wing, often overlooking the foot. The foot of Archaeopteryx, the “icon of evolution”, thus offers a unique opportunity to investigate this critical evolutionary stage. Chapter I of this dissertation integrates advanced 3D reconstruction techniques, combining photogrammetry with X-ray data, to create a high-resolution model of the foot of the Thermopolis specimen of Archaeopteryx for visualization and analysis. Driven by 3D coordinate axes derived from joint surface topology, the analyses in Chapter II reveal terrestrial adaptations -- such as a medially oriented hallux (81°), serially shorter phalanges on digits III and IV, and a relatively short metatarsus to tibia ratio (0.54) -- contrasting with one of the traditional views of Archaeopteryx as a perching bird. Expanding from intraspecific to interspecific, Chapter III introduces a comparative framework by reconstructing and analyzing the feet of various archosaurs such as Deinonychus along with extant birds (chukar, emu, guineafowl) and the alligator, to calculate phalangeal proportions as well as ranges of articulation and motion of the metatarsophalangeal and interphalangeal joints. The hyperextensibility of the proximal interphalangeal joint in digit II of Archaeopteryx is quantified here for the first time (72°) and found to have a similar range of motion as that of Deinonychus (96°), but with a less hypertrophied “killer claw”, which together suggest terrestrial predation on small prey. Lastly, Chapter IV analyzes in vivo pedal kinematics of three of the aformentioned extant animals, measured through X-ray Reconstruction of Moving Morphology (XROMM), to scientifically transfer motion data to Archaeopteryx, resulting in hypotheticalstrides of this extinct dinosaur. This reconstruction suggests a terrestrial locomotor repertoire that was likely capable of wing-assisted incline running (WAIR). Together, these results provide an unprecedented, 3D data-driven perspective on the locomotion of this key transitional taxon in early avian evolution.

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