<P> In dinosaurs the main bones of the pectoral girdle were the scapula (shoulder blade) and the coracoid, both of which directly articulated with the clavicle . The clavicle was present in saurischian dinosaurs but largely absent in ornithischian dinosaurs . The place on the scapula where it articulated with the humerus (upper bone of the forelimb) is the called the glenoid . The scapula served as the attachment site for a dinosaur's back and forelimb muscles . </P> <P> Chimpanzees are far better adapted to brachiation than modern humans . Their clavicles possess a cranially oriented twist on the acromial end, conducive to better force transfer through it - a very important function in arboreal locomotion . Chimpanzee scapulas also possess a considerably larger supraspinous fossa, allowing for a larger supraspinatus muscle . Through the process of evolution, humans have lost the Atlantoclavicularis muscle, originating on the atlas of the vertebral column, and inserting onto the acromial clavicle . This muscle acts to elevate the clavicle . </P>

What region of the body is best described as the tip of the shoulder