Form and function of the selenodont molar in southern African ruminants in relation to their feeding habits

Abstract

The general aim of the present study was to test whether there are differences in the occlusal design of the ruminant selenodont molar, and by examining correlations between tooth form and diet, improve our understanding of the function of the selenodont molar within the Bovidae. Twenty-six species of bovid ruminants were grouped into the three feeding types established by Hofmann (1968) – i.e. browsers, grazers and intermediate feeders. The characteristics of the shape, number, width and length of the enamel ridges were found to correlate with the hypothesized function of the molar occlusal surface. These follow the principles applied to non-bovid species where adaptation of the occlusal surface has been investigated in some detail. Thirteen characteristics of the occlusal surface were scored. ANOSIM results reject the null hypothesis that there are no differences in the selenodont molar occlusal surface. SIMPER results showed that all the characteristics scored contributed to the differences between groups, and crown height was not explaining the major dissimilarity between feeding groups. Differences in enamel ridge characteristics between feeding types suggest that food is being processed in essentially different ways by the browsers and grazers. Intermediate feeding species cluster within the other feeding types, depending on what the major component of the diet is. The grouping produced by the MDS, based on dental characters, closely agrees with Hofmann's classification based on gut structure.