Table 2.

Predictions of palaeocolour in fossil amniotes with gaps in current knowledge

Specimens	Colour patterns predicted	Gaps in knowledge
theropod dinosaurs
Inkayacu (Clarke et al., 2010)	Secondary remiges and an isolated body contour feather were brown, whereas preserved covert and tertials were grey.	Remaining body colour unknown. No chemical data available.
Eocypselus (Ksepka et al., 2013)	Feathers on the top of the head were glossy black.	Melanosomes were also found in the wing feathers but have not been analysed or interpreted as any specific colour. No chemical data available.
Messelornis (Colleary et al., 2015)	A single feather was found to be iridescent.	Unclear exactly where the sample was taken but appears to have been a wing feather. No chemical data available.
Primotrogon (Nordén et al., 2018)	Black, iridescent, and grey colours detected.	Incomplete preservation. Differentiating between covert and body feathers is difficult on both specimens. No chemical data available.
Eocoracias (Babarović et al., 2019)	First instance of a fossil bird showing non‐iridescent structural blue colour.	Colour reconstructed using ancestral state reconstruction of non‐iridescent structural blue in Coraciidae. However, the morphology of melanosomes producing this colour overlaps significantly with grey colour producing ones.
Scaniacypselsus (Nordén et al., 2018)	Black and grey wings with grey body.	Reconstruction based on combined data from three different individuals. Incomplete preservation in all three fossils leaves gaps in reconstruction. In two sampling points, statistical predictions offer equal probability for black/iridescent and grey/brown colours. No chemical data available.
Changzuiornis (Huang et al., 2016)	Preserved wing and tail feathers were black.	Remaining body colour unknown. No chemical data available.
Unnamed enantiornithine CUGB P1202 (Peteya et al., 2017)	Feathers of nape, head, and body were iridescent.	Melanosomes were also found in a wing feather but had degraded too much to determine colour based on morphology. No chemical data available.
Confuciusornis (Li et al., 2018; Zheng, 2009)	Contour feathers were black all over the body with lighter wings. One specimen (CUGB P1401) had small spots on the wings, coverts, crest, and throat. Cryptic colouration in wing coverts, crest, and throat.	Sexual dimorphism in pair of long tail feathers unclear. No chemical data available.
Eoconfuciusornis (Zheng et al., 2017)	Feathers making up the wing coverts, nape, and tail were black. A dark spotted pattern is visible on the secondary remiges. Feathers on the hindlimb and top of the head were grey. Feathers on the throat were brown.	Colour not predicted beyond identifying melanosome morphology. No chemical data available.
Archaeopteryx (Carney et al., 2012)	The isolated holotype feather (possibly a covert wing feather) was black.	Remaining body colour unknown. Uncertain if feather belongs to Archaeopteryx (Kaye, Pittman, Mayr et al., 2019b).
Anchiornis (Li et al., 2010)	Body contour feathers were dark grey. Forelimb and hindlimb coverts and remiges were white with black tips. Feathers on the top of the head were reddish brown. Flecks of reddish brown were also present on the face.	Colouration of tail feathers unknown, as the specimen examined did not preserve a tail, but other specimens' tails show similar spotting as in the wings. No chemical data available.
Caihong (Hu et al., 2018)	Iridescent feathers as in hummingbirds.	Precise hue created by light scattering from the platelet‐like melanosomes cannot be reconstructed because it is determined by the spacing of the photonic nanostructures in vivo as well as the distribution of keratin.
Microraptor (Li et al., 2012)	Feathers sampled across the body were iridescent. Most conservative possibility is that they were glossy black.
Sinornithosaurus (Zhang et al., 2010)	Rod and spherical melanosomes detected in different samples, interpreted as black and rufous feather colouration.	Feathers are from pieces of the counterpart with uncertain location. No chemical data available.
Caudipteryx (Zhang et al., 2010; Li et al., 2014)	Feathers sampled across the body were black. Tail feathers preserve a visible banding pattern.	Colour not predicted beyond identifying melanosome morphology. No chemical data available.
Yi (Xu et al., 2015)	Feathers near the skull contain both oblong (as do feathers near neck, tibia and ulna) and oblate (as do membranous tissue) melanosomes.	Colour not predicted beyond identifying melanosome morphology. No chemical data available.
Beipiaosaurus (Li et al., 2014)	Feathers sampled from the neck were brown.	Remaining body colour unknown. No chemical data available.
Sinosauropteryx (Smithwick et al., 2010)	Feathers sampled from the tail were reddish brown with intervening non‐melanised bands. More detailed examination of preserved feather distribution across several specimens suggests a counter shaded pattern on the body and a "bandit mask" on the face.	Reconstruction based on combined data from different individuals of different sizes. No chemical data analysed for a taxon that is suggested by some (Eliason, Shawkey & Clarke, 2016; Li et al., 2014) to lack the correlation between melanosome morphology and colour.
ornithischian dinosaurs
Psittacosaurus (Vinther et al., 2016)	Scales sampled across the body were melanised. The face, ankle, ischial region, cloacal region, and some large scales on the shoulder were particularly heavily pigmented. Countershading present.	Colour reconstruction purely based on melanosome morphology. No chemical data available.
Borealopelta (Brown et al., 2017)	No melanosomes with preserved structure were found, but chemical signatures suggest high concentrations of phaeomelanin based on benzothiazole detected from TOF‐SIMS interpreted to give a reddish‐brown colouration. Countershading present.	No melanosomes preserved, so the colour predictions are based purely on chemistry.
marine reptiles
Stenopterygius (Lindgren et al., 2018)	Abundant branched melanophores and melanosomes across the flank but conspicuously absent in belly ‐ evidence of dark dorsum and a light ventrum (i.e., countershading).	Skeleton and soft tissue preservation not complete. Parts of snout and regions beyond the pelvis missing. Incomplete model for melanophore preservation mechanism.
Platecarpus (Lindgren et al., 2010)	Melanosomes preserved in the eye. Macroscopic colour patterns in preserved scales.	Colour not reconstructed.
pterosaurs
Pterorhynchus (Czerkas & Ji, 2002)	Macroscopic colour patterns noted in the head crest.	Colour not reconstructed.
Tupandactylus (Pinheiro et al., 2012)	Swaths of melanosomes preserved in large head crest misinterpreted as fossilised microbial consortia.	Colour not reconstructed.
Anurognathid pterosaurs NJU‐57003, CAGS‐Z070 (Yang et al., 2019)	Most likely covered in pycnofibres with various degrees of branching. Melanosomes of diverse morphologies reported.	Brown and black colour in filaments. Colour patterns not reconstructed.
mammals
Palaeochiropteryx (Colleary et al., 2015)	Phaeomelanin signature identified using TOF‐SIMS. Spherical to oblate melanosomes observed in hair filaments. Brown pelage.	Entire body colour not reconstructed.
Hassianycteris (Colleary et al., 2015)	Phaeomelanin signature identified using TOF‐SIMS. Spherical to oblate melanosomes observed in hair filaments. Brown pelage.	Entire body colour not reconstructed.
Apodemus (Manning et al., 2019)	Phaeomelanin pigment remnants reportedly mapped using Cu2+/Zn2+ ions bound to organosulphur residues through a combination of SRS‐XRF and XAS. Brown pelage.	The use of chelating metal ions is not a reliable method of colour reconstruction.