Shape of the Lateral Mandibular Outline in Lemuridae: A Quantitative Analysis of Variability Using Elliptical Fourier Analysis

Abstract

While several morphometric analyses in lemurids have focused on the craniofacial complex, the characterization of their mandibular morphology has received less attention. The mandibular outline, in lateral perspective, was quantified using elliptical Fourier analysis, in an osteological sample encompassing 189 lemurid mandibles (66 Eulemur, 51 Hapalemur, 22 Lemur and 50 Varecia), and compared using multivariate statistical techniques. The taxonomic value of this outline in Lemuridae was demonstrated by the existence of significant separations between the four genera studied. In particular, the mandibular morphology of Hapalemur was markedly different from that in the group Eulemur-Lemur-Varecia. Excluding Hapalemur from analysis, the distinctions between Eulemur, Lemur and Varecia were enhanced suggesting the existence of more subtle intergeneric differences in mandibular morphology. Variation in mandibular form was greatest in Hapalemur and smallest in Eulemur and Varecia (as demonstrated by the mean values of interindividual distances); variation was higher in Lemur than in Eulemur and Varecia, but not higher than in Hapalemur. This morphological diversity may be related to functional adaptation in response to particular dietary habits. The patterns of intergeneric and intrageneric shape variations of the mandible in Lemuridae presented here provide a valuable resource for the analysis of variation among living and fossil lemurids.