Sexual dimorphism in skull morphology of the brown bear (Ursus arctos Linnaeus, 1758) in Iran using geometric morphometric technique

Sexual dimorphism is a common phenomenon in many animal species. This study was conducted to investigate the patterns of sexual dimorphism in skull of Iranian brown bears (Ursus arctos) using geometric morphometric technique. The ventral، dorsal and lateral faces of 79 collected skulls were photographed using digital camera and seventeen، thirteen and sixteen landmarkd points were defined and digitized on images، respectively. Landmark data after generalised procrustes analysis (GPA) were analyzed using CVA (Canonical Variate Analysis) and MANOVA (Multivariate Analysis of Variance). Results showed significant difference between skull shape of male and female (P<0. 05) and adults and youngs as well. Observed differences in the shape of skull could confirm sexual shape dimorphism in the cranium of brown bears. According to the results، sexual dimorphism of bear’ skull was more pronounced in occipital crest، zygomatic arc، parietal bones and teeth row. These differences could display the allometric growth pattern in both genders’ skull as a result of different functional morphology.