Gnathomandibular Morphology and Character Displacement in the Bat-Eared Fox

Abstract

Relations in mandibulo-dental size were evaluated in a sample of 74 (42 male) bat-eared foxes ( Otocyon megalotis ). Mesiodistal and buccolingual dental measurements, together with eight mandibular measurements (intercondylar distance, intercarnassial breadth, mandibular length, condylar height, canine-condylar length, mandibular width, mandibular height) were allometrically scaled to total length of the skull. These results were then compared with those on domestic dogs and on three small southern-African canids: Vulpes chama , Canis adustus , and Canis mesomelas . I suggest that canine dimorphism in size may not be related to body-size dimorphism. In contrast to previous studies, I show that the specialized soft diet of the bat-eared fox is not reflected in an increase of shearing facets of the molars. Indeed, the species is characterized by robust dentinal development, blunted pulp-horns, and multicuspal molars. Finally, I provide cautious evidence of character displacement in the trophic apparatus within this southern-African guild of canids.