Editing Tetrapod (section)

=== Girdles ===
The shoulder girdle was disconnected from the skull, resulting in improved terrestrial locomotion. The early sarcopterygians' [[cleithrum]] was retained as the [[clavicle]], and the [[interclavicle]] was well-developed, lying on the underside of the chest. In primitive forms, the two clavicles and the interclavical could have grown ventrally in such a way as to form a broad chest plate. The upper portion of the girdle had a flat, [[Scapula|scapular blade (shoulder bone)]], with the [[glenoid cavity]] situated below performing as the [[Joint|articulation]] surface for the humerus, while ventrally there was a large, flat coracoid plate turning in toward the midline.

The [[pelvis|pelvic]] girdle also was much larger than the simple plate found in fishes, accommodating more muscles. It extended far dorsally and was joined to the backbone by one or more specialized sacral [[rib]]s. The hind legs were somewhat specialized in that they not only supported weight, but also provided propulsion. The dorsal extension of the pelvis was the [[ilium (bone)|ilium]], while the broad ventral plate was composed of the [[pubis (bone)|pubis]] in front and the [[ischium]] in behind. The three bones met at a single point in the center of the pelvic triangle called the [[acetabulum]], providing a surface of articulation for the femur.