shoulder girdle of birds - Shoulder Girdle of birds; shoulder girdle of birds - This series of bones serves as the intermediary between the fore limb and the vertebral column. It consists of three distinct elements. There is, first of all, a sword-blade-like bone with sharp edges, which lies along the vertebral column - the scapula. To the end of this is firmly attached a somewhat shorter bone, which approaches its fellow as it joins the sternum below; this bone is known as the coracoid (52. fig.). The angle between these two bones is, in flying birds, a considerable one, but in the ostrich tribe they are almost in the same straight line; this is really connected with the power of flight, for it has been shown by careful measurements that, in birds which still have wings that bear every appearance of being functional, and yet are not used for their legitimate purpose, the angle tends to approach the obtusity of the scapula and coracoid of the Ostrich. Birds have, besides these two bones, the merry-thought, or clavicle (58, fig.), which corresponds to our collar-bone. Its two halves are generally closely united to form one U-shaped or V-shaped bone; but sometimes they are separate, and then more or less rudimentary.