. 2019 Sep 19;95(1):22–50. doi: 10.1111/brv.12552

Table 1.

Current lines of evidence for palaeocolour reconstruction

Observational evidence	Examples	Considerations
Macroscopic carbonaceous stains (Vinther et al., 2008; Zhang et al., 2010; Smithwick et al., 2017)	Colour patterns (e.g., stripes, mottling, bars, 'bandit masks', countershading).	Absence of stains may be due to: (i) early taphonomic processes (e.g. scavenging, decay, physical perturbation); (ii) non‐pigmented integument; (iii) structurally coloured integument that lacks fossilisation potential through diagenesis; (iv) non‐melanin‐based pigmentation; (v) late taphonomic processes (e.g. oxidative weathering of organics).
Melanosome morphology and organisation (Vinther et al., 2008, Li et al., 2010, 2012, Zhang et al., 2010)	Aspect ratio, shape, and size from organic preservation or mouldic impression in sediment (e.g. oblong, oblate, platelet). Internal structure (e.g. solid/hollow). Arrangement of melanosomes relative to each other can reveal structural colouration (e.g. melanosome lattices).	Melanosome organic structure can be lost through oxidative weathering or through aqueous conditions during thermal maturation/diagenesis.Thermal maturation/diagenesis results in some minor (<10%) shrinkage of melanosomes. Many structural colour arrays involve proteinaceous components that likely do not fossilise.
Organic chemistry (Colleary et al., 2015)	Chemical signatures consistent with fossil pigment – precise signature dependent on the pigment and analytical technique used (e.g. secondary ions, pyrolysates, infrared absorption spectra, etc.).	Some sulphur moieties can be derived from phaeomelanin or from taphonomic incorporation of sulphur into eumelanin. Chemical makeup of biomolecules can alter during diagenesis.

Observational evidence

Examples

Considerations

Macroscopic carbonaceous stains (Vinther et al., 2008; Zhang et al., 2010; Smithwick et al., 2017)

Colour patterns (e.g., stripes, mottling, bars, 'bandit masks', countershading).

Absence of stains may be due to: (i) early taphonomic processes (e.g. scavenging, decay, physical perturbation); (ii) non‐pigmented integument; (iii) structurally coloured integument that lacks fossilisation potential through diagenesis; (iv) non‐melanin‐based pigmentation; (v) late taphonomic processes (e.g. oxidative weathering of organics).

Melanosome morphology and organisation (Vinther et al., 2008, Li et al., 2010, 2012, Zhang et al., 2010)

Aspect ratio, shape, and size from organic preservation or mouldic impression in sediment (e.g. oblong, oblate, platelet). Internal structure (e.g. solid/hollow).

Arrangement of melanosomes relative to each other can reveal structural colouration (e.g. melanosome lattices).

Melanosome organic structure can be lost through oxidative weathering or through aqueous conditions during thermal maturation/diagenesis.Thermal maturation/diagenesis results in some minor (<10%) shrinkage of melanosomes.

Many structural colour arrays involve proteinaceous components that likely do not fossilise.

Organic chemistry (Colleary et al., 2015)

Chemical signatures consistent with fossil pigment – precise signature dependent on the pigment and analytical technique used (e.g. secondary ions, pyrolysates, infrared absorption spectra, etc.).

Some sulphur moieties can be derived from phaeomelanin or from taphonomic incorporation of sulphur into eumelanin. Chemical makeup of biomolecules can alter during diagenesis.