Oxygen isotopic determination of climatic variation using phosphate from beaver bone, tooth enamel, and dentine

The δ18O of Canadian beaver (Castor canadensis) teeth should reflect variations in the isotopic composition of the water in which the beavers live, as their incisors grow rapidly and continuously. We observe seasonal variations in phosphate δ18O using samples of enamel taken along the length of single teeth. In the spring the δ18O of the enamel being deposited gradually declines, reflecting a retarded input of δ18O depleted winter water. After …