Preserved melanin pigments have been discovered in fossilised integumentary appendages of several amniote lineages (fishes, frogs, snakes, marine reptiles, non‐avialan dinosaurs, birds, and mammals) excavated from lagerstätten across the globe. Melanisation is a leading factor in organic integument preservation in these fossils. Melanin in extant vertebrates is typically stored in rod‐ to sphere‐shaped, lysosome‐derived, membrane‐bound vesicles called melanosomes. Black, dark brown, and grey colours are produced by eumelanin, and reddish‐brown colours are produced by phaeomelanin. Specific morphotypes and nanostructural arrangements of melanosomes and their relation to the keratin matrix in integumentary appendages create the so‐called 'structural colours'. Reconstruction of colour patterns in ancient animals has opened an exciting new avenue for studying their life, behaviour and ecology. Modern relationships between the shape, arrangement, and size of avian melanosomes, melanin chemistry, and feather colour have been applied to reconstruct the hues and colour patterns of isolated feathers and plumages of the dinosaurs Anchiornis, Sinosauropteryx, and Microraptor in seminal papers that initiated the field of palaeocolour reconstruction. Since then, further research has identified countershading camouflage patterns, and informed subsequent predictions on the ecology and behaviour of these extinct animals. However, palaeocolour reconstruction remains a nascent field, and current approaches have considerable potential for further refinement, standardisation, and expansion. This includes detailed study of non‐melanic pigments that might be preserved in fossilised integuments. A common issue among existing palaeocolour studies is the lack of contextualisation of different lines of evidence and the wide variety of techniques currently employed. To that end, this review focused on fossil amniotes: (i) produces an overarching framework that appropriately reconstructs palaeocolour by accounting for the chemical signatures of various pigments, morphology and local arrangement of pigment‐bearing vesicles, pigment concentration, macroscopic colour patterns, and taphonomy; (ii) provides background context for the evolution of colour‐producing mechanisms; and (iii) encourages future efforts in palaeocolour reconstructions particularly of less‐studied groups such as non‐dinosaur archosaurs and non‐archosaur amniotes.

The bizarre scansoriopterygid theropods Yi and Ambopteryx had skin stretched between elongate fingers that form a potential membranous wing. This wing is thought to have been used in aerial locomotion, but this has never been tested. Using laser-stimulated fluorescence imaging, we re-evaluate their anatomy and perform aerodynamic calculations covering flight potential, other wing-based behaviors, and gliding capabilities. We find that Yi and Ambopteryx were likely arboreal, highly unlikely to have any form of powered flight, and had significant deficiencies in flapping-based locomotion and limited gliding abilities. Our results show that Scansoriopterygidae are not models for the early evolution of bird flight, and their structurally distinct wings differed greatly from contemporaneous paravians, supporting multiple independent origins of flight. We propose that Scansoriopterygidae represents a unique but failed flight architecture of non-avialan theropods and that the evolutionary race to capture vertebrate aerial morphospace in the Middle to Late Jurassic was dynamic and complex.

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Melanin pigments are central to colors and patterns in modern vertebrate integuments, which inform upon ecological and behavioral strategies like crypsis, aposematism, and sociosexual selection. Over the last decade, melanin has emerged as a valuable tool for predicting color in exceptionally preserved fossil feathers and subsequent testing of paleobiological hypotheses in long-extinct dinosaurs and birds. Yet much remains to be learned about melanin stability, diagenetic alterations to melanin chemistry, and their implications for “paleocolor reconstruction.” Pressure–temperature maturation experiments with modern feathers offer a way to examine these topics but have mostly been conducted in closed-system capsules or open-system aluminum foil. Both methods have operational limitations and do not consider the filtering effect of porous sediment matrices on thermally labile chemical groups versus stable ones during natural fossilization. We use sediment-encased maturation to resolve this issue and demonstrate replication of organic preservation of melanin highly comparable to compression fossils. Our experiments, coupled with time-of-flight secondary ion mass spectrometry, show predictable volatilization of N/S-bearing molecules and increased melanin cross-linking with elevated temperatures. We also suggest that eumelanin is more stable compared with pheomelanin at higher temperatures, explaining why eumelanic colors (black, dark brown, iridescent) are better preserved in fossils than pheomelanic ones (reddish brown). Furthermore, we propose that proteins preferentially undergo hydrolysis more so than forming N-heterocycles in selectively open systems analogous to natural matrices. Thus, we conclude that melanin pigments and not diagenetically altered protein remnants are the key players in promoting fossilization of soft tissues like feathers.