FIGURE 2.

Left forelimbs of Palorchestes (a, b) and Vombatus (c, d) in lateral view demonstrating poses resulting from maximum elbow rotation about the Z axis (flexion–extension, FE) when modelled with a fixed joint centre and three rotational degrees of freedom (XYZ). Palorchestes (a) minimum flexion (0°, −12°, 69°) and (b) maximum extension (1°, 1°, 125°); Vombatus (c) minimum flexion (−8°, −26°, 12°) and (d) maximum extension (−2°, 3°, 151°). The 3D points representing these minimum (a, c) and maximum (b, d) FE poses are plotted on the ROM map along with the complete ROM envelopes as examples to show how the degrees of freedom interact and how this differs between species. Achieving the full range of FE requires different combinations of abduction–adduction and long–axis rotation in Palorchestes compared to Vombatus. Points on 2D projections represent all sampled poses to show density of our manual sampling method. Bone models are scaled to same humeral length