Extended Data Fig. 9: Muscle moment arm data from the nine modelled strands from the deep part of the pectoralis muscle in five hawks.

a–i, Comparisons of real muscle paths (orange bars) that are guided across the interface between the deepest part of the pectoralis, the SPD and hypothetical straight-line paths (blue bars) that deliberately ignore the contribution of the SPD to pectoralis geometry. Eurydice (a), Lysimachus with the shoulder joint axis defined as described in the main text (b), Lysimachus with alternative shoulder joint axis of rotation (c), Polyperchon with the shoulder joint axis defined as described in the main text (d), Polyperchon with alternative shoulder joint axis of rotation (e), Ptolemy with the shoulder joint axis defined as described in the main text (f), Ptolemy with alternative shoulder joint axis of rotation (g), Roxana based on the right side (h) and Roxana based on the left side (i). Comparison of moment arms in Lysimachus (b,c), Polyperchon (d,e) and Ptolemy (f,g) calculated about different joint axis angles illustrates that the qualitative comparisons and conclusions presented here are not sensitive to the precise angle of shoulder rotation prescribed in the models. j, Comparison of pectoralis moment arms in Seleucus in the nine deep muscle strands wrapping across the surface of the SPD when the SPD is inflated versus deflated.