Figure 6. X in Mechanisms of soft tissue and protein preservation in Tyrannosaurus rex

Figure 6. X-ray microprobe analysis of iron in the T. rex vascular tissues. (a,b,e) Optical microscope images of vessel tissues and (c,d,f) corresponding iron µ-XRF distribution maps recorded at 10 keV. Brighter pixels correspond to higher Fe content. All scale bars are 50 µm. Additional elemental maps of regions (a) and (b) can be found in Fig. S5. In (b,d) the vessel structure is not an organic tissue but a mineralised cast rich in Ba and S (see Fig. S5). Such fine-scale variation in preservation underscores the notion that preservation depends on the microenvironment. Numbered white circles indicate locations of Fe µ-XANES analysis. (g) Stacked normalised Fe K-edge extended XANES spectra of spots 0–6. Fits are shown in red dashed lines, with corresponding residuals plotted at the bottom. All spectra match to goethite (α-FeO(OH)) with normalised sum-square values ranging from 0.59 to 1.93·10−4. For comparison, an example set of the iron bearing reference spectra used are displayed in Fig. S7.