Non-functional sexually dimorphic mandibular differences in the African rodent Thryonomys swinderianus(Temminck, 1827)

Abstract

This study aimed to compare mandibular parameters in adult males and females of Greater cane rat or African cane rat (Thryonomys swinderianus). For this purpose,9lateral mandibular landmarks were analysed by means of geometric morphometrics. Based on data, and exclusion of the size related component of shape variation, males and females can be clearly discriminated according to mandible shape.In males the ventral point of first incisor alveolus tends to be more cranial, whereas the mental foramen presented a more caudal displacement in females, which moreover demonstrated a more slender mandible. Main biomechanical points (mandibular ramus flexure) showed no differences between genders. It may be concluded that morphological differences the in the mandible of both sexes of T. swinderianus are not due to a functional reasons, as masticatory behaviour would be. This is the first time to the best of our knowledge that geometric morphometric comparison of mandibles in this African rodent is reported, which has enabled the inference of identical biomechanical forces in males and females.