R script for performing 2D geometric morphometrics on 100 landmarks of primate proximal phalanges to assess longitudinal curvature shape used in this study is available in the Supporting Information. Morphologika data files for all specimens (n = 378) used in this study is also available in the Supporting Information. 3D surface models illustrated in Figure 1 are available on MorphoSource.org as part of project “Anthropoid Primate Hands”, the details of which are provided in Table A1.