Infrared mapping resolves soft tissue preservation in 50 million year-old reptile skin

N. P. Edwards, H. E. Barden, B. E. van Dongen, P. L. Manning, P. L. Larson, U. Bergmann, W. I. Sellers, R. A. Wogelius

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Non-destructive Fourier Transform InfraRed (FTIR) mapping of Eocene aged fossil reptile skin shows that biological control on the distribution of endogenous organic components within fossilized soft tissue can be resolved. Mapped organic functional units within this approximately 50 Myr old specimen from the Green RiverFormation(USA) includeamide and sulphur compounds.These compounds aremost probably derived from the original beta keratin present in the skin because fossil leaf-and other non-skin-derived organic matter from the same geological formation do not show intense amide or thiol absorption bands. Maps and spectra from the fossil are directly comparable to extant reptile skin. Furthermore, infrared results are corroborated by several additional quantitative methods including Synchrotron Rapid Scanning X-Ray Fluorescence (SRS-XRF) and Pyrolysis-Gas Chromatography/Mass Spectrometry (Py-GC/MS). All results combine to clearly showthat the organic compound inventory of the fossil skin is different fromtheembedding sedimentary matrix and fossil plant material. A new taphonomic model involving ternary complexation between keratin-derived organic molecules, divalent trace metals and silicate surfaces is presented to explain the survival of the observed compounds. X-ray diffraction shows that suitable minerals for complex formation are present. Previously, this study would only have been possible with major destructive sampling. Nondestructive FTIR imaging methods are thus shown to be a valuable tool for understanding the taphonomy of high-fidelity preservation, and furthermore,may provide insight into the biochemistry of extinct organisms. © 2011 The Royal Society.
    Original languageEnglish
    Pages (from-to)3209-3218
    Number of pages9
    JournalProceedings of the Royal Society B: Biological Sciences
    Volume278
    Issue number1722
    DOIs
    Publication statusPublished - 7 Nov 2011

    Keywords

    • Amide
    • Green river
    • Keratin
    • Pyrolysis-gas chromatography/mass spectrometry
    • Synchrotron rapid scanning x-ray fluorescence
    • Taphonomy

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