STABLE CARBON AND OXYGEN-ISOTOPE RATIOS IN UNGULATE TEETH FROM FRENCHEOCENE AND OLIGOCENE LOCALITIES

The oxygen (delta(18)O) and carbon (delta(13)C) isotope values from ma rine foraminifera indicate a global climatic cooling and significant c hanges in oceanic circulation from the]ate Eocene to the early Oligoce ne. The carbon and oxygen isotope composition of ungulate tooth dentin e and enamel carbonate hydroxylapatite from French Eocene and Oligocen e localities was measured in order to use the isotopic analyses to bet ter understand the palaeoenvironmental changes at the Eocene/Oligocene boundary and to tentatively establish a correlation with curves estab lished from marine delta(13)C and delta(18)O values. The variations of delta(13)C and delta(18)O values are important between the different species, as among modern mammalian species, but a 1 to 2 parts per tho usand difference exists between fossil and modern forms. The tooth ena mel carbonate hydroxylapatite from Palaeogene ungulates seems to have suffered some degree of diagenesis. Part of the biological isotopic si gnal may be diagenetically altered. The degree of resolution in the st udied Palaeogene mammals is not sufficient to interpret palaeodiets in C-3-plant palaeoenvironments or to establish correlations with marine carbon and oxygen isotopic curves. However, carbon and oxygen isotopi c fluctuations from ungulate tooth enamel seem to follow the same dire ction as marine curves.