Bioapatite 87Sr/86Sr of the last woolly mammoths-Implications for the isolation of Wrangel Island

The movements of terminal Pleistocene and Holocene mammoths on Wrangel Island, off northeastern Siberia, were investigated using the isotopic composition of Sr in skeletal remains. A significant shift toward more radiogenic Sr-87/Sr-86 ratios, from 0.71218 +/- 0.00103 to 0.71491 +/- 0.00138 in bioapatite, marks the beginning of the Holocene. The higher Sr isotope values in mid-Holocene mammoth remains are interpreted as an influence of radiogenic Sr derived from the Neoproterozoic rocks in the central part of Wrangel Island. The shift implies a change in the ranging and feeding areas of the animals, ultimately reflecting the inundation of the mainland connection and isolation of the population. The shift indicates also that the late Pleistocene animals were not permanent occupants in the territory that makes up present-day Wrangel Island.