A combined-mesowear analysis of late Miocene giraffids from North Chinese and Greek localities of the Pikermian Biome

Abstract

The family Giraffidae is represented by two extant taxa (Giraffa camelopardalis and Okapia johnstoni), both of which are committed browsers. During the late Miocene, however, the Pikermian Biome included more than 15 giraffid species with a wider range of dietary ecologies. To examine the diet of these taxa, we apply a novel combined approach using four variables from two methods of dental mesowear. We score the traditional outer mesowear, which evaluates the sharpness and relief of the labial-most paracone enamel band. We also apply inner mesowear, which evaluates the surface morphology of the lingual band of paracone enamel on the mesial and distal ends, as well as the junction point between the two. Using a database of 8 extant species (N=98) of browsing, grazing, and mixed feeding ruminants, we predict the diets 190 extinct giraffid specimens. The discriminant function analysis (DFA) of the extant taxa using all four mesowear variables predicted diet with greater accuracy than any single mesowear variable. We compare the dietary profiles of species found in four Pikermian Biome regions: Samos, Pikermi, North China, and Linxia Basin. We find differences in the giraffid diet throughout the Pikermian Biome: in the localities from Greece, a larger number of giraffids were predicted as browsers, whereas both Chinese regions included a larger number of mixed feeding individuals. Our inner and outer mesowear dietary predictions agree with previously studied ecomorphological paleodietary proxies. Our data supports the hypothesis that the late Miocene giraffids comprised a wider range of dietary habits than the living giraffe and okapi.