Palaeoclimatic information from isotopic signatures of Late Pleistocene Ursus ingressus bone and teeth apatite (Loutra Arideas Cave, Macedonia, Greece)

摘要

Bones and teeth samples of Ursus ingressus from Loutra Arideas Cave (Greece) were used to determine the diet of this extinct species and to reconstruct the palaeoclimatic conditions. The age range of the fossil layers is from 32 ka BP to a maximum of 38 ka BP (radiocarbon dating). The method used was the isotopic analysis of carbonate bioapatite of fossil cave bear (U. ingressus) and brown bear (Ursus arctos) bone and tooth fragments, as well as water samples from springs of the Pindos area, the modern bear habitat. Several possible effects that may affect the isotopic composition of apatite were investigated, including age, sex, tooth type and diagenesis. The comparison of isotopic values of Greek U. ingressus to other Pleistocene Ursidae species in Europe, exhibit more positive and more variable δ13C values. These positive values are attributed mainly to diet, to bear physiology (differences among species) and to climate conditions. The diet of U. ingressus apparently was based mainly on vegetable matter, however with a variable component of animal protein. The variation observed in the δ18O values of U. arctos tooth enamel samples were attributed to environmental conditions, and through the spring waters isotopic gradient for the region of Northeastern Pindos, to differences in the bear's habitat elevation. Assuming similarity of the metabolism of modern and fossil bear species and incorporating only the effect of drinking water on the isotopic composition of body water, an equation has been derived that could be used to provide palaeoclimatic information.