Examination of Shape Variation of the Calcaneus, Navicular, and Talus in Homo sapiens, Gorilla gorilla, and Pan troglodytes

Analyses of morphological integration among primates commonly focus on relationships between the face, braincase and base of the skull, as well as the upper and lower dentition, and the within portions of the post-cranial skeleton. Despite the prominence of these studies, the associations between the bones of the foot and their articular surfaces have largely been ignored among primates, even though the foot demonstrates high degrees of variation and modification. This variation offers an ideal opportunity to study the relationship between morphology and locomotion. Because the talus, calcaneus and navicular act together to stabilize the foot in locomotion and form a direct interface with the substrate, they comprise a complex structural unit, and the matching articular surfaces should be tightly integrated. However, preliminary results suggest there is no difference in the magnitude or pattern of integration within and between bones. While there is no systematic difference in the magnitude of correlations distinguishing articular surfaces from non-articular parts of the bones, the pattern of covariation is itself correlated across species for each bone, with correlations among measurements of articular surfaces consistently positive. This suggests at the least that there are shared patterns of integration across species