Pleistocene habitats for proboscideans from five sites in the Japanese archipelago: Insights from isotopic composition of tooth enamel and dentin collagen

Megafauna became extinct during the late Quaternary, with climate changes and human activities the two main proposed extinction drivers. Palaeoloxodon naumanni (Naumann's elephant) and Mammuthus primigenius roamed the Japanese archipelago during the Pleistocene. In contrast to the increasing amount of chronological information regarding extinct elephants, stable isotopic composition of these animals is less well studied, despite its potential to reveal foraging ecologies and surrounding paleoenvironments. The isotopic compositions were measured for tooth enamel and dentin collagen of fifteen P. naumanni and five Mammuthus sp. specimens from Lake Nojiri in Honshu and four sites in Hokkaido, Japan. Statistical differences were observed between the carbon isotopic composition of tooth enamel of the Lake Nojiri elephants and those of the two elephant species in Hokkaido, suggesting more open grassland for the former. In Hokkaido, no overlap was observed in the isotopic compositions of the two species, suggesting a separation in foraging behaviors. The specimens had relatively low nitrogen isotopic composition for Late Pleistocene elephants possibly reflecting an environmental stress at the edge of their distributions. The large isotopic variations of Naumann's elephants suggest that their demise was not triggered by inflexibility in their feeding strategies.