FOSSIL COLOUR · THE TAPHONOMY OF COLOUR IN FOSSIL INSECTS AND FEATHERS

THE TAPHONOMY OF COLOUR IN FOSSIL INSECTS AND FEATHERS

Objectives. This project aims to resolve important aspects of the fossil record of animal coloration, thereby enhancing our ability to infer original coloration and its evolution and functions in fossil insects and theropods. The research will employ 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. Work performed. A new research laboratory, including key links with administrative and technical support staff, as well as collaborators in other institutes, has been established and equipped with state-of-the-art facilities for experimental decay, disarticulation and maturation. A comprehensive series of taphonomic experiments has investigated the degradation of pigmented and structurally coloured insect cuticle during decay, transport and maturation, and of feathers during maturation. Experimental data, plus data on untreated extant specimens and fossils, have been analysed using various imaging and chemical techniques, include FESEM-EDS, TEM, microspectrophotometry, LC-MS, GC-MS, ToF-SIMS and synchrotron-XRF, -XANES and –EXAFS. The results of the research have been disseminated extensively. A total of 12 papers have already been published (including two in Science, one in Current Biology, two in Nature Communications and one in Science Advances); five papers are in review, three papers are in preparation. The work has resulted in a total of 22 conference presentations. Results. Published results include the reports of the oldest structural colours in fossil lepidopterans, the first descriptions of 3D photonic crystals in the fossil record, of non-integumentary melanosomes in fossils, of skin in feathered dinosaurs, of carotenoid-based coloration in fossil integument and of complex feathers in non-theropod dinosaurs. Three major manuscripts in preparation will treat the taphonomy of pigmentary colours in insect cuticle, and the taphonomy of feathers. Research career development. The CIG has been critical to the development and evolution of the PI’s research career. It has provided a platform for the acquisition of additional research grants facilitating expansion of the research group (currently 9 members; 12 in October 2018), acquisition of key laboratory equipment (maturation rig, SEM, FTIR) and over €2.5M in research funding. The PI is now a recognised leader in the field of fossil colour research. She has secured a permanent position, been promoted, and leads a vibrant and dynamic programme of undergraduate teaching and public outreach, much of which can be accessed at her website (http://mariamcnamara.ucc.ie).

Data: CORDIS, © European Union