Age, stable isotopes, and redescription of the first mammoth tooth from the Labrador Peninsula

A mammoth (Mammuthus) molar was discovered on Long Island, Nunavut in 1878, making it the first mammoth fossil from the Labrador Peninsula and most northeastern mammoth in eastern North America. On the basis of morphology, we cautiously identify the tooth as the worn stump of the third left upper molar of a woolly mammoth (Mammuthus primigenius) although it was originally identified as the premolar of a Columbian mammoth (Mammuthus columbi). The Long Island tooth yielded an infinite calibrated radiocarbon age of >39 800 years. However, bulk-sampled stable oxygen isotopes in the tooth’s enamel structural carbonate suggest a local climate with a mean air temperature of around 2.1 °C. This roughly corresponds to the predicted temperatures in the Long Island area during climatic optima. The tooth’s age can further be constrained by the presence of glaciers in the Long Island area and the appearance of M. primigenius-type mammoths in North America. Thus, we estimate the Long Island tooth to be between 500 ka and 55 ka years old, but more likely from an interglacial period, and most likely from MIS5e. The Long Island tooth has a collagen δ15N value of 10.7‰, higher than expected for comparable North American mammoths and possibly indicative of nutritional stress. The tooth’s collagen δ13C value of -21.6‰ falls within the range of values for comparable mammoths, and the calculated dietary δ13C value of -26.0‰ suggests a diet rich in C3 plants.