Fig 1.
Messel fish Atractosteus ganoid scales and bones where porphyrins were detected.
A) Ganoid scale 1 with gray-brown film. White arrows indicate presence of gray-brown film on parts of ganoid layer and exposed laminar bone. Red arrow shows aperture penetrating ganoid layer. B) Zoom-in of white box in A. C) Ganoid scale 2. Red arrows indicate presence of apertures in ganoid layer. D) Zoom-in of white box in C. E) Fish bone fragment. Red arrow indicates foramen in bone while blue arrow indicate area with whitish non-bony structure. F) Zoom-in of white box in E. Green dotted squares in B, D, F indicates precise area of ToF-SIMS analysis in Figs 2 and 3 and S3–S5.
Fig 2.
Molecular characterization of gray-brown film on Messel fossil fish scale by ToF-SIMS indicating porphyrins.
Positive ToF-SIMS spectra (m/z 380–650) of A) area indicated by green dotted box on ganoid scale 1 in Fig 1B, B) heme b standard, C) sediment attached to scale (S1 Fig) and D) shale sample collected nearby (S1 Fig). E-H) Zoom-in of green dotted box in spectra in A-D showing m/z 448–461. I) Micrograph of area in green dotted box in Fig 1B. High spatial resolution ToF-SIMS ion images of J) sum of porphyrin peaks (m/z 434–447, 449–461, 462–473 and 474–485), K) Fe+, L) FeC2N2-, M) Ni+, N) NiC2N2-, O) sum of PAH:s (m/z 77, 91, 139, 141 and 165), P) Al+, Q) Si+, R) Mg+ and S) sum of AlSiO4- and AlSi2O6-.
Fig 3.
Molecular characterization of gray-brown film on Messel fossil scale by ToF-SIMS indicating diagenetically altered porphyrins.
Positive ToF-SIMS spectra (m/z 410–530) of A) area indicated by green dotted box on ganoid scale 1 in Fig 1B, B) mosquito, C) heme b standard and D) chlorophyll a standard. E-H) Zoom-in of green dotted box in spectra in A-D showing m/z 448–461. ToF-SIMS spectra of fish scale with gray-brown film (I, M, Q, U), sediment attached to scale (J, N, R, V), shale sample collected nearby (K, O, S, W) and mosquito (L, P, T, X) showing Ni+ (m/z 57.94), FeC2N2- (m/z 107.94), NiC2N2- (m/z 109.94) and 60NiC2N2- (m/z 111.94).
Fig 4.
Chemical and mineralogical characterization of Messel fossil scale and bone fragment by Raman.
A) Micrograph of ToF-SIMS area on ganoid scale 1 with gray-brown film (Fig 1A and 1B). B) Blue laser Raman spectrum from blue circle in area of film on fish scale in A. C) Micrograph of area in green square in A where green laser Raman scan was performed. Note that scale is rotated compared with A. D) Raman map of D1 peak of red area in C. E) Summed Raman spectrum of scan in red square in C) indicating refractory carbon. F) Micrograph of ToF-SIMS area on bone fragment (Fig 1E and 1F). Blue circle indicates area of Raman analysis on porphyrin-rich area identified by ToF-SIMS. G) Blue laser Raman spectrum of blue circle on bone fragment in F.
Fig 5.
Chemical and mineralogical characterization of gray-brown film on Messel fossil scale by EDX and Raman.
A) SEM of gray-brown film on ganoid scale 1. Note that the ganoid scale is rotated compared with Figs 1, 2 and 4A. B-I) EDX maps of white square in A. Green square in D-I show area of ToF-SIMS analysis. Red dots in D indicate area of point spectra in S2 Table. J-M) Micrographs of ganoid scale 1. Yellow square in J indicates area of overlapping Fe and O signals and of micrograph in K. White squares in J indicate areas of Fe and S overlapping signals and of micrographs in L and M. N) SEM image of white square in M. White arrows show pyrite crystals intermixed with gray-brown film. O) Blue laser Raman spectrum obtained from blue circle in L, showing presence of pyrite in highly reflective phase infilling pore in fossil.
Fig 6.
Ultrastructure of gray-brown film on Messel fossil fish scale.
A) Low-vacuum SEM image showing gray-brown film on ganoid scale 1. The film appears darker than the rest of scale. Note that the ganoid scale is rotated compared with Figs 1, 2 and 4A. B) Zoom-in of white square in A. C) Same area as in B but in high-vacuum mode. D) Zoom-in of right white square in C. E) Zoom-in of left white square in C. F) Zoom-in of white square in D.
Table 1.
Ratios of porphyrin peaks.
Table 2.
Ratios of peaks assigned to nickel and organically bound nickel.