Mesowear represents a lifetime signal in sheep (Ovis aries) within a long-term feeding experiment

A herbivore's diet can affect its teeth by causing different types of wear. Browsers typically have sharper, higher cusps, while grazers show lower, blunter cusps, presumably due to the more abrasive nature of their diet. On the macroscopic scale, this allows the reconstruction of herbivore diets based on the shape of the tooth's profile, using the mesowear method. However, the timeframe involved in constituting a stable dietary signal represented by mesowear has not been precisely defined. To obtain a more precise delimitation of this timeframe, sheep (Ovis cries, n = 39) were fed pelleted diets containing external abrasives of different sizes (phi 4 mu m, phi 50 mu m, and phi 130 mu m), and concentrations (4%, or 8%) for 17 months. Mesowear was scored on the skulls at the end of the experiment, as well as on computer-tomographic scans and on resin casts of the teeth taken at different time-points along the experiment. These datasets were compared, and changes in score were calculated using the CT and cast data from the beginning and end of the experiment. Overall, even though a visual trend appeared of more wear on higher abrasion diets, it was of an extremely small magnitude, and the dietary effect on the mesowear scores or the change of the mesowear scores in these animals was never significant. This leads us to conclude that, at least in small ruminants, mesowear is more of a general signal than a seasonal one, and needs to be considered as such for tooth wear-based palaeodietary reconstructions. Experiments with natural forages are required to corroborate this conclusion.