Report
Teaser, summary, work performed and final results
Periodic Reporting for period 2 - ANICOLEVO (Animal coloration through deep time: evolutionary novelty, homology and taphonomy)
Teaser
Evidence of colour in fossils can inform on the visual signalling strategies used by ancient animals. Research to date often has a narrow focus, lacks a broad phylogenetic and temporal context, and rarely incorporates information on taphonomy. This proposal represents a bold...
Summary
Evidence of colour in fossils can inform on the visual signalling strategies used by ancient animals. Research to date often has a narrow focus, lacks a broad phylogenetic and temporal context, and rarely incorporates information on taphonomy. This proposal represents a bold new holistic approach to the study of fossil colour: it will couple powerful imaging- and chemical analytical techniques with a rigorous programme of fossilisation experiments simulating decay, burial, and transport, and analysis of fossils and their sedimentary context, to construct the first robust models for the evolution of colour in animals through deep time. The research will resolve the original integumentary colours of fossil higher vertebrates, and the original colours of fossil hair; the fossil record of non-melanin pigments in feathers and insects; the biological significance of monotonal patterning in fossil insects; and the evolutionary history of scales and 3D photonic crystals in insects. Critically, the research will test, for the first time, whether evidence of fossil colour can solve broader evolutionary questions, e.g. the true affinities of enigmatic Cambrian chordate-like metazoans, and feather-like integumentary filaments in dinosaurs. The proposal entails construction of a dedicated experimental maturation laboratory for simulating the impact of burial on tissues. This laboratory will form the core of the world’s first integrated ‘experimental fossilisation facility’, consolidating the PI’s team as the global hub for fossil colour research. The project will reach out to diverse scientists and will inspire a positive attitude to science among the general public and policymakers alike.
The project has the following ultimate goals:
To resolve (1) the original integumentary colours of fossil higher vertebrates, and the original colours of fossil hair; (2) the feasibility of preserving non-melanin pigments in fossils (and the nature of the fossil record of such colours), (3) the original pigmentary colours of fossil insects, (4) the biological significance of monotonal colour patterning in fossil insects; (5) the evolutionary history of cuticular scales and 3D photonic crystals in insects; the true affinities of (6) enigmatic Cambrian chordate-like metazoans, and (7) of disputed feather-like integumentary filaments in dinosaurs, (8) the origins of the vertebrate neural crest and of the dermal chromatophore unit, (9) the functional evolution of melanin in vertebrates, (10) the role of homology in driving innovation in insect colour patterning, (11) whether patterning in fossils can be used to predict palaeoenvironment and burial history.
Work performed
The project has the following ultimate goals:
To resolve (1) the original integumentary colours of fossil higher vertebrates, and the original colours of fossil hair; (2) the feasibility of preserving non-melanin pigments in fossils (and the nature of the fossil record of such colours), (3) the original pigmentary colours of fossil insects, (4) the biological significance of monotonal colour patterning in fossil insects; (5) the evolutionary history of cuticular scales and 3D photonic crystals in insects; the true affinities of (6) enigmatic Cambrian chordate-like metazoans, and (7) of disputed feather-like integumentary filaments in dinosaurs, (8) the origins of the vertebrate neural crest and of the dermal chromatophore unit, (9) the functional evolution of melanin in vertebrates, (10) the role of homology in driving innovation in insect colour patterning, (11) whether patterning in fossils can be used to predict palaeoenvironment and burial history.
More specifically, the project aims to determine the following:
WP (a) (i) the anatomical distribution of melanin in extant vertebrates
WP (a) (ii) how to recognise melanin from different tissue sources
WP (a) (iii) the taphonomy of melanin from different tissue sources
WP (a) (iv) tissue-specific signatures for melanin in higher vertebrate fossils
WP (a) (v) the feasibility of preserving non-melanin colours in fossil skin
WP (b) (i) the anatomical distribution of melanin in extant basal chordates and vertebrates
WP (b) (ii) taphonomy of melanin in basal chordates and vertebrates
WP (b) (iii) the affinities of enigmatic Cambrian metazoans
WP (c) (i) taphonomy of feather pigments
WP (c) (ii) the feasibility of preserving non-melanin pigments in fossil feathers
WP (c) (iii) how to discriminate between melanin in fossil hair, feathers, skin
WP (c) (iv) the taphonomy of melanin in hair
WP (c) (v) how to reconstruct the original coloration of the hair of diverse fossil mammals
WP (d) (i) how to quantify variation in colour patterning in fossil insects
WP (d) (ii) the fidelity of preservation of colour patterns in fossil insects
WP (d) (iii) phylogenetic trends in colour patterning
WP (d) (iv) links between colour patterning in fossil insects and short-term fluctuations in environmental conditions
WP (d) (v) variations in patterning through time
WP (e) (i) the inorganic chemistry of diverse cuticular pigments
WP (e) (ii) the taphonomy of insect cuticular pigments
WP (e) (iii) the feasibility of preserving pigments in fossil insects
WP (f) (i) the fossil record of insect scales
WP (f) (ii) the taphonomy of insect scales
Achievements.
All research areas are proceeding well.
WP (a). The colour of vertebrate skin. All tasks are ahead of schedule. Tasks a(i), a(ii) and a(iv) are complete. Two papers have been published (McNamara et al. 2016, Current Biology; McNamara et al. 2018, Nature Communications), one has been submitted (Rossi et al. Science Advances, in review) and a fourth paper is in preparation.
Early in the project the PI analysed phosphatized soft tissues from a 10 million year old snake from the Libros biota in Spain. The preserved skin retains cellular and subcellular details of all three types of pigment cell (chromatophore). The relative abundance of the different chromatophore types varies across the body. Comparison with chromatophore abundance in extant reptiles allowed the team to reconstruct the original coloration of the fossil snake in ‘full’ colour (i.e. not just the melanin component, as was the only method used previously). The results were published in Current Biology.
The PI analysed a limited number of tissues from three extant frog species and discovered that all the internal tissues contain melanin. Building on this work, the PhD student for WP (a) has analysed 14 extant vertebrate species (amphibians, reptiles, birds and mammals) for the presence of melanin using tissue histology coupled with the melanin-specific Warthin-Starry stain, SEM, sync
Final results
Early results from the project have resulted in eight publications, including a number of high-impact publications, most notably two papers in Nature Communications (McNamara et al. 2018a,b), one in Science Advances (Zhang et al., 2018) and one in Current Biology (McNamara et al., 2016). The research is also the subject of three papers in review with high-impact journals, i.e., one with Science, one with Science Advances, one with Nature Ecology and Evolution. The high impact of the research exceeds expectations for a regular research project and emphasizes the cutting-edge nature of the PI\'s work.
The PI anticipates the following publications during the remainder of the project:
- Experimental taphonomy of melanosomes - chemical changes during diagenesis (2-3 papers)
- Taphonomy of eyes in non-vertebrate chordates (1-2 papers)
- Taphonomy of feather keratin - testing immunohistochemistry and experimental approaches (2-3 papers)
- Evolution of wing patterning in fossil insects from Daohuguo, China (2 papers)
- Evolution of wing patterning in fossil insects through deep time (1 paper)
- Diagenesis and fossilization of insect pigments (1-2 papers)
- Evolution of 3D photonic structures: fossil evidence (1-2 papers)
Website & more info
More info: http://mariamcnamara.ucc.ie.