T02_P28

The impact of micro-CT scanning on radiocarbon dating of fossil material: a cautionary note

Wood R¹,  Martín-Francés L², Duval M³

¹University Of Oxford, Oxford, United Kingdom, ²Centro de Evolución y Comportamiento Humanos (UCM-ISCIII), Madrid, Spain, ³Centro Nacional de Investigación sobre la Evolución Humana, Burgos, Spain

It is imperative that damage to rare and valuable remains is minimised in palaeoanthropological research. Micro-computerized tomography (mCT) scanning of fossils is now routinely used to record a high resolution three-dimensional reconstruction of samples prior to destructive analyses such as radiocarbon dating. It is therefore crucial to establish whether the method has a negative impact on the associated analysis, and to determine how this impact can be reduced. We examine whether a range of mCT acquisition parameters could influence collagen yield of a well preserved woolly rhino bone. Whilst mCT had no significant impact on the radiocarbon age obtained, we find that collagen yield is reduced from around 7% to 4.5%, suggesting protein is damaged during the scanning process. This does not seem to be strongly correlated to the x-ray intensity. In this bone, collagen yield remained well above the minimum cut-offs of 0.5 or 1%  typically used in radiocarbon laboratories. However, it does imply that a larger sample may be required from bones that have undergone previous scanning. This might become an issue for highly valuable fossils like in palaeoanthropology. Additionally, samples with low collagen yield might also result unsuitable for ¹⁴C dating after mCT. This is the second study showing that mCT scanning of fossils may have a non-negligible impact on dating results, after a similar work focused on Electron Spin Resonance (ESR) dating. It might be worth reconsidering the systematic and unlimited use of mCT scanning in palaeoanthropology in the light of these results.