FIGURE 3. Comparison of archosaur scapulocoracoids.
From the following article:
A critical ligamentous mechanism in the evolution of avian flight
David B. Baier, Stephen M. Gatesy and Farish A. Jenkins
Nature 445, 307-310(18 January 2007)
doi:10.1038/nature05435
Lateral view of right scapulocoracoids of Alligator mississippiensis (a), Sinornithoides youngi (b), Sinornithosaurus millenii (c), Archaeopteryx lithographica (d), Confuciusornis sanctus (e) and Columba livia (f) on a simplified phylogeny23. The changing orientation of the CHL/AHL (dashed lines) and the reduction of the scapulocoracoid plate anterior to the glenoid for muscle attachment (orange surfaces) record the transition to a novel, ligament-based force balance mechanism in modern birds. The dashed lines do not represent ligament length.