Sexual dimorphism in auricular surface projection and postauricular sulcus morphology.

The presence of an elevated auricular surface and a postauricular sulcus is presented in numerous reference books as osteological indicators of sex, but the validity of these traits has not been adequately evaluated. The ilia of 322 (181 male, 141 female) adults were examined, the auricular surface was scored as completely, partially, or nonelevated, and the postauricular sulcus was scored as present or absent. Complete elevation occurred almost exclusively in females (67% of females and 0.6% of males). The postauricular sulcus was present in 27% of males and 85% of females. When present, an elevated auricular surface is a reliable indicator that the individual is female. However, the absence of the trait is a less reliable indicator of sex. The postauricular sulcus is a moderately accurate estimator of sex.