Here we review published molar wear rates, measured in terms of tooth height loss per year (mm yr -1 ) published on natural populations of ungulates (25 species), rodents and lagomorphs (Glires; 14 species) and macropodid marsupials (seven species). Although the data are limited, they nevertheless reveal consistent patterns, and raise new questions. Among ungulates, wear rates are uncorrelated with body mass but are positively correlated with hypsodonty. Browsers show lower wear rates than do mixed feeders or grazers. Percentage of grass in the diet shows a non-linear relationship with wear rates suggesting that levels of dietary abrasives result from a complex interaction among forages, habitat characteristics and feeding behaviours (whether or not grass itself is a significant abrasive agent). Rodents exhibit higher wear rates, and kangaroos lower wear rates, than do ungulates feeding on similar diets. Hypselodont rodents and lagomorphs show rates of molar wear an order of magnitude higher than do grazing ungulates.
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