Large theropod dinosaurs like tyrannosaurs were the biggest land-living predators in earth history. Because of this, there has been considerable interest in reconstructing the paleobiology of these immense carnivores (Bakker, 1986; Bakker et al., 1988; Paul, 1988; Molnar and Farlow, 1990; Farlow et al., 1991; Abler, 1992; Farlow, 1993, in press; Horner and Lessem, 1993). In the present paper we consider a topic relevant to interpretations of how tyrannosaurs used their teeth during feeding: the incidence of wear surfaces on tyrannosaur teeth.