Figure 1.

Principal component analysis. (A) PCA of chemical signature of 86 organic and inorganic peaks. HQ femur, HQ tooth and HQ coprolite are all thin sections from H2, and HQ bone is an untreated bone fragment from H4. The HQ matrix is from H4. The modern bones (alligator and elephant) and the 100 °C are more similar chemically to one another than the other samples. The HQ fossils show little variation between one another, but there is a greater amount of variation with the associated matrix. Therefore, there are amino acids present in the fossils that are not present in the associated matrix. (B) PCA Loadings show how each one of the 86 peaks influences the specimen placement in the PCA.