Fossilization of melanosomes via sulfurization

• DOI: 10.1111/pala.12238
• Publication Date: 2016-04-02T17:20:25Z
• Authors: Maria E. McNamara; Bart E. van Dongen; Nick P. Lockyer; Ian D. Bull; Patrick J. Orr
• Keywords: Melanosome; Taphonomy; Organosulfur compounds

Abstract Fossil melanin granules (melanosomes) are an important resource for inferring the evolutionary history of colour and its functions in animals. The taphonomy melanosomes, however, is incompletely understood. In particular, chemical processes responsible melanosome preservation have not been investigated. As a result, origins sulfur‐bearing compounds fossil melanosomes difficult to resolve. This has implications interpretations original fossils based on potential sulfur‐rich phaeomelanosomes. Here we use pyrolysis gas chromatography mass spectrometry (Py‐GCMS), fourier transform infrared spectroscopy (FTIR) time flight secondary ion (ToF‐SIMS) assess mode microstructures, confirmed as presence melanin, preserved frogs from Late Miocene Libros biota ( NE Spain). Our results reveal high abundance organosulfur non‐sulfurized fatty acid methyl esters both tissues host sediment; signatures inconsistent with phaeomelanin. reflect via diagenetic incorporation sulfur, i.e. sulfurization (natural vulcanization), other polymerization processes. Organosulfur and/or elevated concentrations sulfur reported various invertebrate vertebrate depositional settings, suggesting that through likely be widespread. Future studies require geochemistry sediment tested evidence order constrain phaeomelanosomes thus integumentary fossils.