1) Muséum national d’Histoire naturelle, Département Ecologie et Gestion de la Biodiversité, USM 303/UMR 7209 du CNRS, “Archéozoologie, Archéobotanique: Sociétés, Pratiques et Environnements”, case postale 56, 55 rue Buffon, F-75231 Paris cedex 05, France, 2) Department of Earth and Planetary Sciences, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA, 3) Teagasc, Grange Beef Research Centre, Dunsany, Co. Meath, Ireland, 4) UCD School of Agriculture, Food Science and Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland, 5) UCD School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland Geochimica et Cosmochimica Acta (2010), V74 (12), pp3571–3586, doi:10.1016/j.gca.2010.03.017 The isotope record of short- and long-term dietary changes in sheep tooth enamel: Implications for quantitative reconstruction of paleodiets A. Zazzo (1), M. Balasse (1), B.H. Passey (2), A.P. Moloney (3), F.J. Monahan (4) and O. Schmidt (5) Shorted text: Quantitative reconstruction of paleodiet carbon isotope analysis in hypsodont tooth enamel requires a precise knowledge of the isotopic enrichment between dietary carbon and carbon from enamel apatite (εD–E), as well as timing and duration of the mineralization process. High resolution sampling and stable carbon isotope analysis of breath CO2 following a diet-switch showed that 70–90% of dietary carbon had turned over in < 24 h.The changes in diet were recorded in all molars. Portions of enamel in equilibrium with dietary carbon were used to calculate εD–E values. Animals on grass silage diets had values similar to previous observations, whereas animal switched to pelleted corn diets had values ca. 4‰ lower, a pattern consistent with lower methane production observed for animals fed concentrate diets. Our results demonstrate that they can provide useful information about dietary variability if the mineralization process is taken into account.