Coloration is a multifunctional attribute of modern animals but its evolutionary history is poorly resolved, in part due to our limited ability to recognize and interpret fossil evidence of colour. Indeed, original coloration was considered one of the most enigmatic aspects of the biology of ancient organisms, but recent studies on fossil feathers and the cuticles of fossil insects have led to advances in the field. Research to date, however, has focussed on very specific aspects of colour, i.e. fossil melanosomes in feathers and structural colours in fossil insects. As a result, key aspects of the fossil record of colour in insects and feathers are unknown, and the evolutionary histories of the diverse colours and colour patterns deployed by modern insects and birds are poorly resolved. The innovative and multidisciplinary research proposed herein will resolve these issues by employing a powerful three-fold approach combining decay experiments, maturation experiments and fossil analysis to the study of the taphonomy of key pigments (melanins, carotenoids and pterins) and colour-producing structures in insects and feathers. Experiments will simulate the processes of autolytic decay and deep burial, and will elucidate, for the first time, the chemical steps involved in the alteration of key pigments in insects and feathers during decay and diagenesis, and the extent to which this process, and alteration of structural colours, is impacted by sedimentological and taxonomic factors. The experimental results will ground truth data obtained from comprehensive analysis of diverse fossil insects and feathers from the Cenozoic and Mesozoic, facilitating the first systematic attempt to map preservation of colour in fossil insects and feathers through deep time. In doing so the research will resolve outstanding questions regarding the taphonomy of colour and will enhance our ability to infer original coloration and its evolution and functions in fossil insects and theropods.