This is a study of the functional morphology and behavioral 

dynamics underlying locomotor ontogeny in a free-ranging group of rhesus monkeys (Macaca mulatta) at Cayo Santiago, Puerto Rico. It tests the hypothesis that developmental modifications of morphology in the shoulder gird le and forelimb of Macaca mulatta are associated with changes in the frequencies of locomotor and postural behavior, and it demonstrates systematic study of the morphological and behavioral development of primates can be used to assess the validity of predicting habitual locomotor pat terns from anatomical evidence.Eight osteometric features of the scapula, clavicle and humerus, which reflect myological ada ptations to locomotor function, are statistically combined through discriminant function analysis and indicate differential modification of shoulder

gird le locomotor morphology occurs in the Cayo Santiago population with age and by sex. Hypothetical shifts in positional behavior, derived from analysis of the skeletal data, are checked against actual behavioral frequencies observed in a free-ranging troop of macaques over a period of 13 months. The effects of seasonal changes in rainfall and flora, the annual reproductive cycle and an animal's sex, dominance rank, and genealogical affiliation are also considered as additional factors that can pattern frequencies of positional behavior.