Spatio-temporal variation in the preservation of ancient faunal remains.

Palaeodemographic studies of animals using frequency distributions of radiocarbon dates are increasingly used in studies of Quaternary extinction but are complicated by taphonomic bias, or the loss of material through time. Current taphonomic models are based on the temporal frequency distributions of sediments, but bone is potentially lost at greater rates because not all sedimentary contexts preserve bone. We test the hypotheses that (i) the loss of bone over time is greater than that of sediment and (ii) this rate of loss varies geographically at large scales. We compiled radiocarbon dates on Pleistocene-aged bone from eastern Beringia (EB), the contiguous United States (CUSA) and South America (SA), from which we developed models of taphonomic loss. We find that bone is lost at greater rates than terrestrial sediment in general, but only for CUSA and SA. Bone in EB is lost at approximately the same rate as terrestrial sediments, which demonstrates the excellent preservation environments of arctic regions, presumably due to preservative effects of permafrost. These differences between bone and sediment preservation as well as between arctic and non-arctic regions should be taken into account by any research addressing past faunal population dynamics based on temporal frequency distributions.