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Re: black and white Archaeopteryx
From: Ben Creisler
Here's the citation for the paper:
Phillip. L. Manning, Nicholas P. Edwards, Roy A. Wogelius, Uwe
Bergmann, Holly E. Barden, Peter L. Larson, Daniela Schwarz-Wings,
Victoria M. Egerton, Dimosthenis Sokaras, Roberto A. Mori and
William I. Sellers (2013)
Synchrotron-based chemical imaging reveals plumage patterns in a 150
million year old early bird.
Journal of Analytical Atomic Spectrometry (advance online article)
Charles Darwin acknowledged the importance of colour in the natural
selection of bird plumage. Colour can indicate age, sex, and diet, as
well as play roles in camouflage, mating and establishing territories.
Feather and integument colour depend on both chemical and structural
characteristics and so melanosome structure and trace metal biomarkers
can be used to infer colour and pigment patterns in a range of extant
and fossil organisms. In this study, three key specimens of
Archaeopteryx were subjected to non-destructive chemical analysis in
order to investigate the potential preservation of original
pigmentation in early fossil feathers. Synchrotron Rapid Scanning
X-ray Fluorescence (SRS-XRF) maps are combined with sulphur X-ray
Absorption Near Edge Structure (XANES) spectroscopy to provide the
first map of organic sulphur distribution within whole fossils, and
demonstrate that organically derived endogenous compounds are present.
The distribution of trace-metals and organic sulphur in Archaeopteryx
strongly suggests that remnants of endogenous eumelanin pigment have
been preserved in the feathers of this iconic fossil. These
distributions are used here to predict the complete feather pigment
pattern and show that the distal tips and outer vanes of feathers were
more heavily pigmented than inner vanes, contrary to recent studies.
This pigment adaptation might have impacted upon the structural and
mechanical properties of early feathers, steering plumage evolution in
Archaeopteryx and other feathered theropod dinosaurs.