Trophic Structure and Climatic Information From Isotopic Signatures in Pleistocene Cave Fauna of Southern England

Abstract

The preservation of trophic structure and climatic information in Kent's Cavern Upper Pleistocene mammal bones and teeth was assessed by comparing the isotopic composition of modern and fossil equivalents. Yields of collagen from both bone ( N=19) and tooth ( N=49) were extremely variable, with values relative to modern bone ranging from 0% to 100%. No evidence of preferential preservation of tooth collagen was detected. The carbon and nitrogen isotopic differences in the herbivore versus carnivore collagen from Kent's Cavern fauna were consistent with those observed in modern faunas. Moreover, an enrichment of 0·4-1·7‰ in 15N was observed in tooth collagen of both deer and hyena as compared to bone collagen. This enrichment presumably reflects a trophic shift from the consumption of milk during infancy. Herbivores and carnivores had distinct differences in the carbon isotopic composition of enamel carbonate hydroxylapatite, similar to those measured in modern specimens from similar climatic environments. The spacing between the Δ 13C values (difference between isotopic composition in collagen and carbonate hydroxylapatite) of Kent's Cavern herbivores and carnivores is similar to that measured in modern mammals from a single locality. The preservation of primary oxygen isotopic composition of enamel carbonate hydroxylapatite was more difficult to assess, however. Oxygen isotopic compositions of Kent's Cavern enamel are systematically lower than those of contemporaneous faunas from Southern France, which is consistent with a latitudinal effect on rainfall oxygen isotopic compositions. Although the Kent's Cavern specimens have been subjected to extensive diagenetic alteration, the biological isotopic signals seem to have utility for paleoecological reconstructions.