Fig. 4. (A) Lateral view of the right medial carpal in articulation with the distal carpal of the Cretaceous pterosaur Coloborhynchus robustus. Scale bar, 25 mm. (B) Traditionally recognised articular surfaces of the right carpal-pteroid joint of Coloborhynchus, the medial carpal in distal (anterior) view showing the fovea (fov), and the head of the pteroid in proximal view. Specimen details can be found in Wilkinson et al. (Wilkinson et al., 2006). Scale as in A. (C) Reconstruction of the right wrist of Coloborhynchus in dorsal view according to descriptions provided by Bennett (Bennett, 2001; Bennett, 2006), with a sesamoid bone (ses) within the fovea, and the pteroid articulating on the side of the medial carpal. Note that the medial carpal has been rotated about its long axis by 180° with respect to A and B. The postulated trajectory of the wing-finger metacarpal extensor tendon (ten), in which the sesamoid is embedded, is also shown. Scale bar, 50 mm. (D) Reconstruction of the right wrist in dorsal view according to Wilkinson et al. (Wilkinson et al., 2006), with the pteroid at maximum elevation, and an alternative reconstruction of the sesamoid, which is shown in close association with the carpal-pteroid joint, embedded within a putative pteroid extensor tendon (origin and insertion points unknown). Scale as in C. Abbreviations as in Fig. 1. Broken line indicates a continuation of the extent of the tendon.