[dinosaur] Shuvuuia feathers do not preserve protein + fossil dinosaur bone microbiome

Ben Creisler

New papers about claims of preserved proteins and soft tissue associated with dinosaur fossils::

Evan T. Saitta, Ian Fletcher, Peter Martin,Â Michael Pittman, Thomas G.Kaye, Lawrence D. True, Mark A. Norell, Geoffrey D. Abbott, Roger E. Summons, Kirsty Penkman &Â Jakob Vinther (2018)

Preservation of feather fibers from the Late Cretaceous dinosaur Shuvuuia deserti raises concern about immunohistochemical analyses on fossils.

Organic Geochemistry (advance online publication)

doi: https://doi.org/10.1016/j.orggeochem.2018.09.008Â

https://www.sciencedirect.com/science/article/pii/S0146638018302195

Highlights

Immunohistochemistry has been used to claim fossil protein preservation.

Reanalysis of a fossil feather reveals that it is inorganic, not proteinaceous.

The fossil feather was also covered in cyanoacrylate consolidant.

Antibody cross-reactivity might lead to false positive results in fossils.

Claims for ancient proteins require multiple lines of corroborating evidence.

Abstract

White fibers from a Late Cretaceous dinosaur Shuvuuia deserti stained positive for Î-keratin antibodies in a 1999 paper, followed by many similar immunological claims for Mesozoic protein in bones and integument. Antibodies recognize protein epitopes derived from its tertiary and quaternary structure, so such results would suggest long polypeptide preservation allowing for sequencing with palaeobiological implications. However, proteins are relatively unstable biomacromolecules that readily hydrolyze and amino acids exhibit predictable instability under diagenetic heat and pressure. Furthermore, antibodies can yield false positives. We reanalyzed a Shuvuuia fiber using focused ion beam scanning electron microscopy, energy-dispersive X-ray spectroscopy, time-of-flight secondary ion mass spectrometry, and laser-stimulated fluorescence imaging, finding it to be inorganic and composed mainly of calcium phosphate. Our findings are inconsistent with any protein or other original organic substance preservation in the Shuvuuia fiber, suggesting that immunohistochemistry may be inappropriate for analyzing fossils due to issues with false positives and a lack of controls.

Free pdf:

Evan Thomas Saitta, Renxing Liang, Chui Y. Lau, Caleb M. Brown, Nicholas R. Longrich, Thomas G. Kaye, Ben J. Novak, Steven Salzberg, Paul Donohoe, Marc Dickinson, Jakob Vinther, Ian D. Bull, Richard A. Brooker, Peter Martin, Geoffrey D. Abbott, Timothy D.J. Knowles, Kirsty Penkman & Tullis C. Onstott (2018)

Life Inside A Dinosaur Bone: A Thriving Microbiome.

BioRxiv 400176

doi: https://doi.org/10.1101/400176

https://www.biorxiv.org/content/early/2018/09/07/400176

This article is a preprint and has not been peer-reviewedÂ

Fossils were long thought to lack original organic material, but the discovery of organic molecules in fossils and sub-fossils, thousands to millions of years old, has demonstrated the potential of fossil organics to provide radical new insights into the fossil record. How long different organics can persist remains unclear, however. Non-avian dinosaur bone has been hypothesised to preserve endogenous organics including collagen, osteocytes, and blood vessels, but proteins and labile lipids are unstable during diagenesis or over long periods of time. Furthermore, bone is porous and an open system, allowing microbial and organic flux. Some of these organics within fossil bone have therefore been identified as either contamination or microbial biofilm, rather than original organics. Here, we use biological and chemical analyses of Late Cretaceous dinosaur bones and sediment matrix to show that dinosaur bone hosts a diverse microbiome. Fossils and matrix were freshly-excavated, aseptically-acquired, and then analysed using microscopy, spectroscopy, chromatography, spectrometry, DNA extraction, and 16S rRNA amplicon sequencing. The fossil organics differ from modern bone collagen chemically and structurally. A key finding is that 16S rRNA amplicon sequencing reveals that the subterranean fossil bones host a unique, living microbiome distinct from that of the surrounding sediment. Even in the subsurface, dinosaur bone is biologically active and behaves as an open system, attracting microbes that might alter original organics or complicate the identification of original organics. These results suggest caution regarding claims of dinosaur bone soft tissue preservation and illustrate a potential role for microbial communities in post-burial taphonomy.

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