Hogs, hippos or bears? Paleodiet of European Oligocene anthracotheres and entelodonts

Abstract

Anthracotheres and entelodonts are large mammals with peculiar morphological characteristics that combine plesiomorphic and derived features. The unusual anatomy of anthracotheres shows a morphological resemblance to pigs and hippos and their bunoselenodont low-crowned molars have been interpreted as an adaptation to frugivorous/folivorous diets. Entelodonts share cranial and dental similarities to pigs and carnivores, and this has been interpreted as an adaption to opportunistic omnivore diets, hunting/scavenging, or bone-crushing (cf. hyenas). The objective of the present study is to use dental microwear analysis to test these assumptions and to infer the diet of anthracotheres and entelodonts. Dental microwear was quantified on the upper and lower molars using a stereomicroscope. To assess the dietary traits of the fossil samples, the results were compared to a dataset of extant large mammals covering ten dietary categories. The microwear features indicate different diets for Anthracotherium sp. and Entelodon magnus. Our sample of entelodonts shows an omnivorous diet similar to that of the wild boar, and it probably varied considerably between seasons. The anthracotheres we analysed were opportunistic browsing, frugivore, and grazing herbivores. During the Oligocene, these two taxa occupied ecological niches characterised by a large diversity of food resources. The results of the study offer further insights into the characteristics of the digestive system in fossil artiodactyls. The large dataset used in this research opens new perspectives for the dietary reconstruction of poorly known mammal taxa by considering a wide range of diets.