Functional implications of skeletal diversity in two South American tamarins

This study examines the relationship between positional behavior and morphology for two closely related South American tamarin species, Saguinus fuscicollis illigeri and Saguinus oedipus oedipus. Although never systematically documented, the two species are suspected of exhibiting highly similar yet subtly different locomotor behaviors with a greater propensity for climbing, springing, and more powerful leaping in S. oedipus. Fourteen measurements reflecting biomechanical structuring were taken from the postcranial skeleton of 28 individuals of each species. The data were reduced to principal component scores and subjected to a multiple analysis of variance to determine the extent of intergroup skeletal variation. Areas of significant skeletal diversity were interpreted functionally. The results suggest that the differences in functional patterning among the two species is consistent with the behavioral hypothesis. It is concluded that subtle changes in positional behavior may be capable of altering skeletal morphology.