Chemical preservation of tail feathers fromAnchiornis huxleyi, a theropod dinosaur from the Tiaojishan Formation (Upper Jurassic, China)

Abstract

A panel of geochemical techniques is used here to investigate the taphonomy of fossil feathers preserved in association with the skeleton of the Jurassic theropod Anchiornis huxleyi. Extant feathers were analysed in parallel to test whether the soft tissues morphologically preserved in the fossil also exhibit a high degree of chemical preservation. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) indicate that clays and iron oxide pseudomorphs occur in the surrounding sediment and also reveal the preservation of melanosome‐like microbodies in the fossil. Carbon gradient along a depth profile and co‐occurrence of carbon and sulphur are shown in the fossil by elastic backscattering (EBS) and particle‐induced x‐ray emission (PIXE), which are promising techniques for the elemental analysis of fossil soft tissues. The molecular composition of modern and fossil soft tissues was assessed from micro‐attenuated total reflectance fourier transform infrared spectroscopy (micro‐ATR FTIR), solid‐state 13C nuclear magnetic resonance (CP‐MAS 13C NMR) and pyrolysis gas chromatography mass spectrometry in the presence of TMAH (TMAH‐Py‐GC‐MS). Results indicate that the proteinaceous material that comprises the modern feathers is not present in the fossil feathers. The fossil feathers and the embedding sediment exhibit a highly aliphatic character. However, substantial differences exist between these samples, revealing that the organic matter of the fossil feathers is, at least partially, derived from original constituents of the feathers. Our results suggest that, despite the morphological preservation of Anchiornis feathers, original proteins, that is keratin, were probably not preserved in the 160‐myr‐old feathers.

Forged soft tissues revealed in the oldest fossil reptile from the early Permian of the Alps

“…Overall, the pattern of peaks in the spectrum of the sample from the abdomen is not comparable with these and with those reported from organically preserved vertebrate soft tissues (i.e. fossilized melanin; Lindgren et al 2012;Barden et al 2015;McNamara et al 2016b;Yang et al 2019;Cincotta et al 2020); instead, our data closely resemble that of the manufactured bone black pigment reported by Van Loon & Boon (2004).…”

“…2019; Cincotta et al . 2020); instead, our data closely resemble that of the manufactured bone black pigment reported by Van Loon & Boon (2004).…”

Sediment-encased pressure-temperature maturation experiments chemically simulate natural diagenesis of melanin

“…Therefore, if proteins were to survive (relatively intact or cross-linked with sugars or lipids) organic mass in the feather tissue would not be signi cantly lost and melanosomes would be obscured by these polymers 54 . Total ion pyrochromatograms by both Saitta, Rogers 29 and Cincotta, Nguyen Tu 55 showed a lack of enriched peaks resulting from the pyrolysis of modern feather protein in both P/T-matured and fossil samples. ToF-SIMS spectra of experimental samples and fossils are quite different from α/β-keratin controls from Schweitzer, Zheng 56 ( Supplementary Fig.…”

“…Non-polar organic solvents 55 can be used to selectively recover recalcitrant molecules of low solubility but are unrealistic of natural conditions and might lead to dissolution and loss of many geochemically relevant compounds (e.g., small aliphatic lipids and sterols).…”

Sediment-encased pressure–temperature maturation experiments elucidate the impact of diagenesis on melanin-based fossil color and its paleobiological implications

“…If proteins were to survive (relatively intact or cross-linked with sugars or lipids), then presumably, organic mass in the feather tissue would not be significantly lost, and melanosomes would be obscured by these polymers (Vinther 2020). Total ion pyrochromatograms by both Saitta et al (2017) and Cincotta et al (2020) showed a lack of enriched peaks resulting from the pyrolysis of modern feather protein in P-T-matured and fossil samples. ToF-SIMS spectra of our experimental samples and fossils are quite different from αand β-keratin controls from Schweitzer et al (2018) (see Supporting Information, Fig.…”