Fig. 1 in Quadrupedal dinosaurs did not evolve fully pronated forearms: New evidence from the ulna

Fig. 1. An example of the stylized tetrapod skeleton and terminologies that are traditionally used to demonstrate the grades of forearm pronation. A. The three anatomical planes. B. Simplified tetrapod limbs with uniplanar joint alignments in the transverse plane, showing general limb terminology, including the directions required to pronate/supinate the limb segments, and thereby joint planes of action distal to these segments. Note that, like the hindlimb in this traditional characterization, the three major tetrapod forelimb bones are assumed to plesiomorphically lack any diaphyseal torsion or oblique planes of joint flexion/extension.