. Bulletin. Natural history. 142 PEABODY MUSEUM BULLETIN 36. fig. 39. Diagrammatic reconstruction of the scapulocoracoid and forelimb of a walking pelycosaur viewed from the posterolateral aspect. A, the beginning of the propulsive phase, with the ante- brachium directed forward; B, the completion of the propulsive phase, with the humerus rotated (arrows) on its longitudinal axis to permit elevation of the antebrachium. Long axis, longitudinal axis of the body. The remainder of the glenoid and humeral head facets are constructed to facilitate the humeral movements described above. The posterio
. Bulletin. Natural history. 142 PEABODY MUSEUM BULLETIN 36. fig. 39. Diagrammatic reconstruction of the scapulocoracoid and forelimb of a walking pelycosaur viewed from the posterolateral aspect. A, the beginning of the propulsive phase, with the ante- brachium directed forward; B, the completion of the propulsive phase, with the humerus rotated (arrows) on its longitudinal axis to permit elevation of the antebrachium. Long axis, longitudinal axis of the body. The remainder of the glenoid and humeral head facets are constructed to facilitate the humeral movements described above. The posterior half of the glenoid is a broad shelf which faces dorsolaterally and slightly anteriorly (Fig. 38). This half merges with the anterior half of the glenoid across a surface which is nearly vertical and faces later- ally and, more anteriorly, posterolaterally. The posterior half of the humeral head is a strap-shaped surface, convex both dorsoventrally and anteroposteriorly (Fig. 38). This surface, facing medially and slightly ventrally, contacts the posterior half of the gle- noid at the beginning of the stroke. Since the humeral surface does not face so much ventrally as does the glenoid surface dorsally, the humerus must be slightly elevated for the two surfaces to make even contact. At the completion of the stroke the posterior sector of the strap-shaped humeral facet is rotated dorsally out of contact with the glenoid. Simultaneously the anterior sector of the strap-shaped surface (X, Fig. 38) is brought into contact with the center sector of the glenoid (F). This brings the. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Peabody Museum of Natural History. New Haven, Peabody Museum of Natural History, Yale University
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