October 3, 2016:

An international team of scientists led by the University of Manchester is uncovering the true colours of extinct birds and dinosaurs.

The team is using state-of-the-art x-ray methods to analyse the chemistry of bird feathers in order to get a clearer idea of what they looked like in life. The pioneering research at The University’s Interdisciplinary Centre for Ancient Life has studied the feathers of modern birds in order to find long-lived chemical markers for different pigments present in living birds' feathers, so that traces may be reconstructed in good quality fossil specimens.

Melanin is the dominant pigment in mammals and birds that gives them either a black or dark brown colour such as in Raven, or a reddish or yellow hue, as in Fox. This black pigment is more specifically called eumelanin, while the reddish type is pheomelanin.

In collaboration with the UK’s Diamond Light Source x-ray laboratories and Stanford University in the USA, the scientists analysed feathers shed by birds housed in animal sanctuaries. Their research has been able to show that the trace metal zinc is a reliable and sensitive indicator for the presence of pheomelanin within the distinct feathers of birds of prey, when it is bonded to sulphur compounds in a specific way.

This discovery means that scientists are getting closer to portraying true colours based upon chemical evidence, building on work by palaeontologists at China's Institute for Vertebrate Paleontology, who first published evidence that they had identified melanosomes (melanin-bearing cells) in fossil bird feathers in 2010.

“A fundamental rule in geology is that the present is the key to the past” said Roy Wogelius, Professor of Geochemistry at The University of Manchester and senior author of the study. “This work on modern animals now provides another chemical ‘key’ for helping us to accurately reconstruct the appearance of long extinct animals.”

“Melanin is a very important component in biology, but its exact chemistry is still not precisely known, especially as to how metals such as calcium, copper and zinc interact with it,” said Nick Edwards, Post Doctoral Research Associate and lead author of the study. “Here we have used a new approach to probe these components of melanin and have found that there are subtle but measurable differences between the different types of melanin with regards to certain elements.”

”The avian descendants of dinosaurs have kept the chemical key to unlocking colour precisely locked in their feather chemistry.” added co-author Professor Phil Manning.

References
Edwards, N P, van Veelen, A, Anné, J, Manning, P L, Bergmann, U, Sellers, W I, Egerton, V M, Sokaras, D, Mori, R A , Wakamatsu, K, Ito, S, and Wogelius, R A. 2016. Elemental characterisation of melanin in feathers via synchrotron X-ray imaging and absorption spectroscopy. Nature Scientific Reports, in press.
Zhang, F, Kearns, S L, Orr, P J, Benton, M J, Zhou, Z, Johnson, D, Xu, X, and Wang, X. 2010. Fossilized melanosomes and the colour of Cretaceous dinosaurs and birds. Nature 463: 1075-1078.