Background: Accurate sex estimation from skeletal remains is essential in forensic identification, yet population-specific reference data for cervical vertebrae, particularly the first cervical vertebra (C1), are limited. This lack of data compromises the accuracy of sex estimation in forensic contexts where primary skeletal elements such as skull and pelvis are unavailable. Geometric morphometric (GM) analysis offers a robust alternative by quantifying shape variation independent of size, enabling precise assessment of morphological differences that conventional linear measurements may overlook. Objective: This study aimed to investigate the utility of C1 vertebra morphology for sex estimation among Omani adults using two-dimensional geometric morphometrics. Methods: A total of 320 lateral cervical radiographs (160 males, 160 females) were retrospectively collected from Sultan Qaboos University Hospital. Six anatomical landmarks on the atlas were digitized using TPSDig2, and shape analyses were performed using MorphoJ software. Statistical methods included Principal Component Analysis (PCA), Procrustes ANOVA, Canonical Variate Analysis (CVA), and Discriminant Function Analysis (DFA). Intra- and inter-observer reliability was also assessed. Results: While centroid size did not significantly differ between sexes (p = 0.2432), shape analysis revealed statistically significant sexual dimorphism (p = 0.0457). DFA correctly classified 77.19% of individuals by sex, with a cross-validated accuracy of 73.44%. Shape variation was most pronounced in the posterior tubercle and superior facets of the atlas. Conclusions: Two-dimensional geometric morphometric analysis of the first cervical vertebra (C1) reliably captures sexual dimorphism in the Omani population, providing a population-specific reference that enhances the accuracy and objectivity of forensic sex estimation.
Al-Mojahed et al. (2026) studied this question.