Recent advances in amniote palaeocolour reconstruction and a framework for future research

Arindam Roy, Michael Pittman, Evan T. Saitta, Thomas G. Kaye, Xing Xu
  • Biological Reviews, September 2019, Wiley
  • DOI: 10.1111/brv.12552

Palaeocolour reconstruction in fossil amniotes

Photo by Amber Flowers on Unsplash

Photo by Amber Flowers on Unsplash

What is it about?

Colour and patterns are critical to understanding the life, ecology and behaviour of animals. Animals routinely use colour patterns while looking for potential mates, as warning signals to defend their territories and camouflage for hunting or for escaping. Different colours in vertebrates range from blacks, greys and reds to yellows and greens produced by pigments like melanin, carotenoids, pterins, flavins, psittacofulvins, and porphyrins. These are found all across the vertebrate evolutionary tree.

Why is it important?

In the last ten years, melanin-based colour patterns have been reconstructed in over 30 fossil animals including birds, non-avialan dinosaurs and mammals. Unfortunately, our knowledge of other pigments is scarce in the fossil record as these non-melanin pigments are more difficult to fossilise. This incomplete knowledge and the lack of a standard study approach have been prevailing challenges to the reconstruction of colour in fossil animals.In our new paper, Dr. Michael Pittman and I at the Vertebrate Palaeontology Laboratory, University of Hong Kong with our international collaborators, propose a framework that overcomes past challenges by incorporating the chemical signatures of different pigments, large and small-scale anatomical details visible in fossils as well as the potential for non-melanic pigments to fossilise. This comprises four main steps: (1) Map the known or suspected extent of preserved colour and patterns in the specimen; (2) Search for pigment-bearing microstructures using electron microscopy e.g. microstructure shape can be used to identify melanin-based colours like black, grey, brown and iridescence and non-iridescent blue; (3) If melanin-based colours are not detected, use high-end chemical analysis techniques to detect biomarkers of other pigments (4) Use reconstructed colours and patterns to test fundamental hypotheses related to animal physiology, ecology and behaviour.

Perspectives

Arindam Roy
University of Hong Kong

People are fascinated by the colour and pattern of dinosaurs and other extinct animals because these aspects can tell you so much about an animal. Just think of a zebra and a peacock. We evaluated everything we know about fossil and modern animal colour and used that knowledge to propose a framework to improve how we reconstruct fossil colour in the future. This is the first comprehensive study that not only critically evaluates the currently available methods, but also provides a reliable and repeatable framework that covers all vertebrate pigment systems not just melanin alone.

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http://dx.doi.org/10.1111/brv.12552

The following have contributed to this page: Arindam Roy and Dr. Evan Thomas Saitta