Most differences in anatomy of limbs & trunk of living primates clearly related to differences in locomotor & postural abilities. Locomotion and posture also effect orientation of head on trunk, shape of thorax, & positioning of abdominal viscera. Posture correlated with diet e. g. foraging. Modifications of musculoskeletal system related to locomotor differences influenced by ancestry of group being considered. Primates often evolved different solutions to the same problem. Thus quadrupedal lemurs, quadrupedal monkeys, and quadrupedal apes show similarities related to their quadrupedal habits, but they show affinities to other lemurs, monkeys, and apes as well. Bones can provide information about both phylogeny & adaptation if two can be accurately distinguished. Best approach is to examine mechanical problems that different types of locomotion present. Consider how living primate species have evolved musculoskeletal differences to meet these mechanical demands. Phylogeny has a large effect on morphology. Concentrate on features of skeleton that can be related to different postures and methods of progression.