Morphometric Variability in the Calcaneus of Sheep (Ovis aries) and Goats (Capra hircus)

Distinguishing between sheep (Ovis aries) and goat (Capra hircus) calcanei is challenging due to their close taxonomic relationship and skeletal similarities, which complicates species identification in veterinary, comparative anatomy, and zooarchaeological contexts. The calcaneus is a robust and functionally significant bone in small ruminants, providing valuable insights into their biomechanical adaptations. This study conducted a comprehensive morphometric analysis of the calcaneus in sheep (n = 163, including Akkaraman, Hamdani, Morkaraman, and Dağlıç breeds) and goats (n = 61, Hair Goats), using a digital caliper to measure 10 standardized linear parameters focused on critical calcaneal tuber and articular surface dimensions, capturing functional weight-bearing and joint articulation aspects. Notably, the maximum width of the sustentaculum tali, which supports the talus and enhances tarsal joint stability, consistently showed larger values in sheep than in goats. Overall, sheep exhibited larger measurements, reflecting adaptations to distinct locomotor and ecological roles. A simplified linear discriminant analysis, based on key functional measurements, achieved a classification accuracy of 87.1%, highlighting the utility of these morphological features in species differentiation. Correlation analysis further revealed strong interrelationships among measurements, indicating coordinated growth patterns in the calcaneus. These findings establish a robust reference framework for future comparative anatomy, veterinary science, and zooarchaeology studies, underscoring the diagnostic and functional importance of the calcaneus in small ruminants.