Oxygen isotope variation in the tusks of extinct proboscideans: a measure of season of death and seasonality

Abstract

Centimetre-scale laminae in tusk and molar dentine of late Pleistocene mastodonts and mammoths have been interpreted as annual growth bands produced, in part, by seasonal variation in growth rate. To test this interpretation, we measured the oxygen isotope composition (δ 18 O) of the CO 3 fraction of dentinal hydroxyapatite from samples covering consecutive inferred years of growth in tusks. We demonstrate that there are substantial variations in the oxygen isotope composition of proboscidean dentinal apatite, and that isotopic identifications of winter (ie low δ 18 O values) coincide with those based on growth rate (ie slow-growth zones). Finally, the potential of oxygen isotope analyses of terrestrial mammals for assessing the seasonality of paleoclimates is considered. -from Authors