Fossilized melanosomes and melanin in Chordates

The recognition, by Jakob Vinther of melanosomes, organelles which manufacture the pigment melanin, in the fossil record has attracted a lot of recent research attention. Melanosomes are typically spherical to elliptical-shaped bodies 1-2µm in diameter. Their shape and distribution in fossil groups, especially in bird feathers, and non-avian dinosaurs has been used to reconstruct colour and colour-based patterns which have in turn, provided insight into ecological aspects of extinct animals. Recognizing melanosomes in fossils is not straight forward because they are approximately the same size and shape as bacteria; indeed many records of putative fossilized bacteria are now being reinterpreted as melanosomes.

I have recently investigated pigmentation, as recorded by melansomes and chemical biomarkers for melanin, in fossil early Chordates; principally in agnatha and gnathostome fish. I have discovered the world’s oldest melansomes from the 307Ma Carboniferous Mazon Creek deposit in fossil lamprey and hagfish. The distribution and type of pigmentation is providing us with details on integument colour patterning and the visual sophistication of these animals. I am expanding this work more broadly to include more fish taxa from a range of deposits and environments to investigate in particular, ecological signals, eye evolution and evolutionary developmental aspects of pigmentation. In the lab I will run experiments to constrain exactly how pigmentation across taxa is modified through the decay process. See this PhD opportunity:

I work principally with Dr Jakob Vinther (University of Bristol) and Andrei Dolocan (University of Texas at Austin).

Lamprey with pigmentation
A Carboniferous lamprey with pigmentation

Publications

Colleary, C., Dolocan, A.,  Gardner, J., Singh, S., Wuttke, M.,  Rabenstein, R., Habersetzer, J., Schaal, S., Feseha, M., Cle­ments, M.,  Jacobs, B.,  Jacobs, L., Sylvestersen, L.,, Gabbott, S. E. & Vinther, J. In press. Chemical and morphological evidence for melanin in exceptionally preserved fossils. Proceedings of the National Academy of Sciences, USA.

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