Coracoid

A coracoid[a] is a paired bone which is part of the shoulder assembly in all vertebrates except therian mammals (marsupials and placentals).

[2] In other tetrapods, it joins the scapula to the front end of the sternum and has a notch on the dorsal surface which, along with a similar notch on the ventral surface of the scapula, forms the socket in which the proximal end of the humerus (upper arm bone) is located.

The acrocoracoid process is an expansion adjacent to this contact surface, to which the shoulderward end of the biceps brachii muscle attaches in these animals.

In birds (and generally theropods and related animals), the entire unit is rigid and called scapulocoracoid.

In other dinosaurs, the main bones of the pectoral girdle were the scapula (shoulder blade) and the coracoid, both of which directly articulated with the clavicle.

Diagram of skeletal structure and musculature of a bird's wing