Supplemental Information for Sediment-encased pressure–temperature maturation experiments elucidate the impact of diagenesis on melanin-based fossil color and its paleobiological implications. Arindam Roy* (https://orcid.org/0000-0002-4890-6851) Michael Pittman* (https://orcid.org/0000-0002-6149-3078) Thomas G. Kaye (https://orcid.org/0000-0001-7996-618X) Evan T. Saitta (https://orcid.org/0000-0002-9306-9060) *Corresponding author(s) Email: ar15313@bristol.ac.uk ; mpittman@cuhk.edu.hk The Dataset contains two files, (1) Supporting Information and (2) Supporting Data PCA worksheet. The first contains Supplementary tables and figures (.docx file) while the structural organisation of the second (.xlsx file) is provided below: We received ToF-SIMS data (Samples 1–30, 36–51) pertaining to purified melanosome extracts of modern bird feathers (both fresh and capsule-matured) from Caitlin Colleary (Associate Curator of Vertebrate Paleontology, Cleveland Museum of Natural History), based on their previous work (Colleary et al. 2015). Citation below: Colleary, C., A. Dolocan, J. Gardner, S. Singh, M. Wuttke, R. Rabenstein, J. Habersetzer, S. Schaal, M. Feseha, M. Clemens, B. F. Jacobs, E. D. Currano, L. L. Jacobs, R. L. Sylvestersen, S. E. Gabbott, and J. Vinther. 2015. Chemical, experimental, and morphological evidence for diagenetically altered melanin in exceptionally preserved fossils. Proceedings of the National Academy of Sciences USA 112(41):12592-7. doi: https://doi.org/10.1073/pnas.1509831112 We further augmented this data set by adding ToF-SIMS spectra from our own samples (31-34, 52-79) pertaining to sediment encased maturation experiments (190ºC to 300ºC) and fossilised feathers of paravian dinosaurs housed at the Shandong Tianyu Museum of Natural History, Linyi Shi, Shandong, China. We conducted Principal Components Analysis with this Data and this dataset effectively serves as a PCA worksheet. The file can be opened/edited using Microsoft 365 Excel (.xlsx) with the following organisation of sheets. Sheets: |----- PCA All : contains Sample ID, treatment categories, mass by charge (m/z) ratios of 55 peaks, peak identity and raw intensity counts |-----PCA All Normalised : same data as PCA All but peak raw intensity counts normalised. |-----PCA All Mean Centered: same data as PCA Normalised but with peak raw intensity mean centered. |-----PCA All Loading Matrix: Loading matrix for PCA All using all 55 peaks. |-----PCA All Eigen Vectors: Eigen vectors for PCA All. |-----PCA All Scores: PCA scores for all 55 peaks. |-----PCA No Lipids RAW: same data as PCA All but without peaks suspected to arise from lipids (e.g., CxH-). |-----PCA No Lipids Normalised: same data as PCA without Lipids RAW but with peak raw intensity counts normalised. |-----PCA No Lipids MeanCentred: same data as PCA without Lipids Norm but with peak raw intensity counts mean centered. |-----PCA No Lipids Loading Matrix: Loading matrix for PCA All excluding peaks of lipid origin (CxH-). |-----PCA No Lipids Eigen Vectors: Eigen vectors for PCA No Lipids Eigen Vectors. |-----PCA No Lipids Scores: PCA scores for all peaks excluding those of lipid origin (CxH-). The dataset has been created in Microsoft Office 365 (Excel: .xlsx file). The file can also be also be opened and edited using the following softwares. 1. Google Sheets 2. Apache Open Office 3. Libre Office 4. PAST 4 (free software for scientific data analysis, with functions for data manipulation, plotting, univariate and multivariate statistics, ecological analysis, time series and spatial analysis, morphometrics and stratigraphy)."