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Abstract

Dental microwear texture analysis (DMTA) is widely used for dietinferences in extant and extinct vertebrates. Often, a reference toothposition is analysed in extant specimens, while isolated teeth arelumped together in fossil datasets. It is therefore important to testwhether dentalmicrowear texture (DMT) istooth position specificand,ifso, what causes the differences in wear. Here, we present results fromcontrolled feeding experiments with 72 guinea pigs, which receivedeither fresh or dried natural plant diets of different phytolith content(lucerne, grass, bamboo) or pelleted diets with and without mineralabrasives (frequently encountered by herbivorous mammals in naturalhabitats). We tested for gradients in dental microwear texture along theupper cheek tooth row. Regardless of abrasive content, guinea pigs onpelleted diets displayed an increase in surface roughness along thetooth row, indicating that posterior tooth positions experience morewear compared with anterior teeth. Guinea pigs feedings on plants oflow phytolith content and low abrasiveness (fresh and dry lucerne,fresh grass) showed almost no DMT differences between toothpositions, while individuals feeding on more abrasive plants (drygrass, fresh and dry bamboo) showed a gradient of decreasing surfaceroughness along the tooth row. We suggest that plant feeding involvescontinuous intake and comminution by grinding, resulting in posteriortooth positions mainly processing food already partly comminuted andmoistened. Pelleted diets require crushing, which exerts higher loads,especially on posterior tooth positions, where bite forces are highest.These differences in chewing behaviour result in opposing weargradients for plant versus pelleted diets.