Effects of ontogeny and sexual dimorphism on scapula morphology in the mountain gorilla (Gorilla gorilla beringei).

Scapular measurements were obtained from growth series of the sexually dimorphic mountain gorilla (Gorilla gorilla beringei). Juveniles, subadults, and adults were compared to determine if scapula morphology varies with age. Analyses reveal significant (P < 0.05) differences in scapula form for shape ratios of length vs. breadth, length vs. infraspinous fossa length, and length vs. spine length. Males and females were also compared to determine if sexual dimorphism in scapula morphology is a consequence of differential extension of common patterns of relative growth. Analyses reveal that scapula proportions are ontogenetically scaled. Data indicate that male scapulae grow at a faster rate and for a longer duration than females. Results of comparisons of males and females suggest that unique adaptations to different ecological niches have not evolved between the sexes despite sexual differences in frequency of patterns of locomotor behavior. By contrast, age-related variation in scapula morphology may be linked to differences in locomotor behavior during ontogeny.