Exceptional three-dimensional preservation and coloration of an originally iridescent fossil feather from the Middle Eoc
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RESEARCH PAPER
Exceptional three-dimensional preservation and coloration of an originally iridescent fossil feather from the Middle Eocene Messel Oil Shale Natasha S. Vitek • Jakob Vinther • James D. Schiffbauer Derek E. G. Briggs • Richard O. Prum
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Received: 3 September 2012 / Accepted: 12 February 2013 Ó Springer-Verlag Berlin Heidelberg 2013
generated by incoherent light diffraction between this sediment layer and melanosomes and, although related to the original iridescence of the feather, is not a feature of the feather itself. The reddish and greenish hues frequently exhibited by fossil feathers from the Messel Formation appear to be due to precipitates on the surface of individual melanosomes.
Abstract A feather from the Eocene Messel Formation, Germany, has been demonstrated to have been originally structurally colored by densely packed sheets of melanosomes similar to modern iridescent feathers exhibiting thinfilm diffraction. The fossil itself currently exhibits a silvery sheen, but the mechanism for generating this optical effect was not fully understood. Here we use scanning electron microscopy, electron probe microanalysis, and dual-beam focused ion beam scanning electron microscopy to investigate the source of the silvery sheen that occurs in the apical feather barbules. Focused ion beam scanning electron microscopy provides a powerful tool for studying three-dimensionality of nanostructures in fossils. Use of the method reveals that the flattened apical barbules are preserved almost perfectly, including smooth structural melanosome sheets on the obverse surface of the fossil feather that are identical to those that cause iridescence in modern bird feathers. Most of each apical barbule is preserved beneath a thin layer of sediment. The silvery sheen is
Kurzfassung Bei einer Feder aus der eoza¨nen Messel Formation von Deutschland wurde eine originale strukturelle Fa¨rbung aus dicht gepackten Melanosomen nachgewiesen, die modernen irridisierenden Federn a¨hnlich ist, die Du¨nnschichtdiffraktion zeigen. Das Fossil selbst zeigt in seinem derzeitigen Zustand einen silbrigen Glanz, aber es ist unklar, durch welchen Mechanismus dieser entsteht. Mit Hilfe von Rasterelektronenmikroskopie, Elektronenstrahlmikroanalyse
N. S. Vitek (&) J. Vinther D. E. G. Briggs Department of Geology and Geophysics, Yale University, 210 Whitney Avenue, New Haven, CT 06520, USA e-mail: [email protected]
D. E. G. Briggs R. O. Prum Peabody Museum of Natural History, Yale University, 170 Whitney Avenue, New Haven, CT 06511, USA e-mail: [email protected]
N. S. Vitek J. Vinther Jackson School of Geosciences, The University of Texas at Austin, Austin, TX 78712, USA
R. O. Prum Department of Ecology and Evolutionary Biology, Yale University, 21 Sachem Street, New Haven, CT 06520, USA e-mail: [email protected]
J. Vinther Department of Earth Sciences and Biological Sciences, University of Bristol, Bristol BS8 1UG, UK e-mail: [email protected]
Keywords Exceptional preservation Color Melanin Irides
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