Palaeoecology and palaeoclimatic context of Romanian Carpathian MIS 3 cave bears using stable isotopes (δ13C and δ18O)

Millimeter-scale growth rings in canine dentine of MIS 3 cave bears have been interpreted as annual growth bands produced, in part, by seasonal variation in growth rate. We present new intra-tooth stable carbon (δ13C) and oxygen (δ18O) isotope profiles in dentine hydroxylapatite of early forming permanent teeth, from three famous Late Pleistocene cave bear sites from Romanian Carpathians. We measured δ13C and δ18O of the CO3 fraction of dentine hydroxylapatite from samples covering a profile across the root, representing a general line from juvenile period to adulthood. Carbon isotopes measured in dentine samples – from the first to the last to be deposited – of the same individual, record an increase in δ13C values throughout immature life of bears as has been shown previously, with lower precision, using age categories. For the first time, based on δ13C data analysis, the weaning process in cave bears was identified. The δ18O values show substantial variations related, most probably, to seasonal growth of the dentine. Finally, the CO3 of dentine apatite extracted from cave bear canines proves to be reliable for geochemical analyses, reflecting physiology, behavior and palaeoclimatic conditions.