Morphometric analysis of the supraorbital region for sexual dimorphism: A study on Brazilian adult dry skulls.

Introduction: Pelvis, long bones, and skull are good indicators of sexual dimorphism. In the skull, the supraorbital region is considered a highly sexually dimorphic part. Thus, the present study aimed to analyze the sexual dimorphism of Brazilian adult dry skulls using conventional and geometric morphometry.

Materials and methods: Conventional morphometry was performed on 179 skulls, through the analysis of six linear measurements. For geometric morphometry, 89 skulls (right side) were selected and seven landmarks were considered. Generalized procrustes analysis, principal component analysis, and linear discriminant analysis were then carried out.

Results: All linear measurements presented differences between both sexes. Geometric morphometry showed that 77.05% of the sample variation could be explained by the first three principal components. Moreover, considering the centroid size, there was a difference in shape between the sexes. Geometric morphometry classified sex correctly in 77.32% of the skulls and conventional morphometry from 60.89% to 73.74%.

Conclusions: According to the analyses, the supraorbital region presents significant sexual dimorphism in Brazilian adult dry skulls. Moreover, it can be analyzed efficiently by both conventional and geometric morphometry, although the latter seems to be slightly more accurate.