Fig 1 - available from: Nature Communications
This content is subject to copyright. Terms and conditions apply.
Optical and X-ray images of Apodemus atavus "lateral" fossil. a Optical image of "lateral" fossil A. atavus (GZG.W.20027b) with the inset of extant A. sylvaticus in the upper right for comparison (scale bars = 1 cm). b False-color SRS-XRF image reveals exceptional preservation of integument as well as bone. This image is a combination of three maps, two standard single-element maps (blue = P, green = Zn), plus a third map which has been produced to especially emphasize the distribution of a specific oxidation state of organic sulfur (red = S in thiol) in order to highlight the clear correlation between the distribution of Zn and organic sulfur which together appear as bright yellow. (Optical photograph by P.L.M.)

Optical and X-ray images of Apodemus atavus "lateral" fossil. a Optical image of "lateral" fossil A. atavus (GZG.W.20027b) with the inset of extant A. sylvaticus in the upper right for comparison (scale bars = 1 cm). b False-color SRS-XRF image reveals exceptional preservation of integument as well as bone. This image is a combination of three maps, two standard single-element maps (blue = P, green = Zn), plus a third map which has been produced to especially emphasize the distribution of a specific oxidation state of organic sulfur (red = S in thiol) in order to highlight the clear correlation between the distribution of Zn and organic sulfur which together appear as bright yellow. (Optical photograph by P.L.M.)

Source publication
Article
Full-text available
Recent progress has been made in paleontology with respect to resolving pigmentation in fossil material. Morphological identification of fossilized melanosomes has been one approach, while a second methodology using chemical imaging and spectroscopy has also provided critical information particularly concerning eumelanin (black pigment) residue. In...

Contexts in source publication

Context 1
... phylogenetically well-constrained and taphonomically well-preserved fossil specimens of Apodemus atavus 27 from Willershausen (Germany) were selected, the holotype GZG. W.20027b (Figs. 1a, b and 2a-c) and a second specimen GZG. W.17393a (Fig. 2d-g). This Pliocene species of field mouse is closely related to the extant wide-ranging species Apodemus sylvaticus and Apodemus flavicollis 28 . Extant members of this genus are reddish colored and thus the phylogeny would imply that the related extinct species would also have ...
Context 2
... XRD. Grazing-incidence X-ray diffraction (XRD) analysis identified the minerals gypsum, calcite, quartz, ankerite, and muscovite in the sedimentary matrix plus hydroxyapatite in the fossil bone ( Supplementary Fig. 1). ...
Context 3
... imaging. The holotype of A. atavus (GZG.W.20027b) is preserved as an intact laterally compressed fossil (Fig. 1a, inset photograph of extant A. sylvaticus for comparison) and will hence be referred to as the lateral fossil. Figure 1b shows the corresponding false color Zn, P, and organic S composite SRS-XRF image. The organic S part of this three-component image was produced by tuning the monochromatic incident X-ray beam to a specific reduced sulfur ...
Context 4
... holotype of A. atavus (GZG.W.20027b) is preserved as an intact laterally compressed fossil (Fig. 1a, inset photograph of extant A. sylvaticus for comparison) and will hence be referred to as the lateral fossil. Figure 1b shows the corresponding false color Zn, P, and organic S composite SRS-XRF image. The organic S part of this three-component image was produced by tuning the monochromatic incident X-ray beam to a specific reduced sulfur oxidation state resonance (2472.5 eV), thereby excluding any contribution from oxidized inorganic sulfate to the image. ...
Context 5
... and Zn are concentrated and correlated within the skin and parts of the fur: high correlation is indicated by the bright yellow regions. Supplementary Fig. 2 presents computed correlation maps of Zn with organic S and Zn with Cu in both of the A. atavus specimens used in this study. The clear correlation of zinc with organic sulfur highlighted in Fig. 1b and Supplementary Fig. 2 robustly shows that the bulk of the Zn imaged is bound within the integument and is associated with organic S. (See the "Methods" section for details. Additional elemental maps are shown in Supplementary Fig. 3.) Figure 2 provides further details of the S oxidation state mapping of the lateral fossil, and ...
Context 6
... above the critical excitation energy for all oxidation states of sulfur, including fully oxidized sulfate (~2.482 keV). High-sulfur concentrations in the surrounding matrix are due to the presence of sulfate contributed from the mineral gypsum (CaSO 4 ·2H 2 O: identified by grazingincidence XRD on this specimen's bedding plane, see Supplementary Fig. 1). Figure 2b was obtained by mapping with the incident beam energy set below the sulfate absorption edge, at the energy equivalent to the absorption edge for an organic thiol sulfur species (2472.5 eV, calibrated using Zn-cysteine). Here, the inorganic bedding plane sulfate salts disappear, resulting in a higher contrast image of the ...
Context 7
... oxidation state to each fossil spectrum (Supplementary Table 1). The sedimentary matrix, as expected, contains pure sulfate, a result corroborated by imaging and XRD analyses. Sulfur within the fossil bone is 97% sulfate, consistent with previous results for fossil bone 2,3,6,9,15 . The graminoid fragment (purple region at the top center of Fig. 1b) is mostly disulfide (24%) and sulfate (71%). In contrast, spectra obtained from two different locations within the integument on the lateral mouse fossil exhibit a significant quantity of a heterocyclic organic sulfur component, with benzothiazole-type groups contributing as much as 24% to the fit of the topmost spectrum. From these ...
Context 8
... is thus clear from the XRF point analysis that the Zn, Cu, and S concentrations in the fossil do not require postmortem enrichment. Indeed, XRF analyses of light elements (Supplementary Table 1) show that the sulfur concentration in the fossil is nearly identical to sulfur concentrations in extant fur, and therefore complete geochemical replacement of the original fossil is extremely unlikely; much more likely is hydrolysis and oxidation of the original biomaterial in situ, as the sulfur spectroscopy indicates. ...
Context 9
... transform-infrared (FTIR) spectroscopy (Supplementary Fig. 10) was also completed in order to further test the endogeneity of the chemistry of the fossil soft tissue. The fossil soft tissue FTIR spectra are completely different from the background matrix (see Supplementary Fig. 10), containing clear strong organic absorption bands including amide I-III, hydrocarbon, and C = O. The matrix is ...
Context 10
... transform-infrared (FTIR) spectroscopy (Supplementary Fig. 10) was also completed in order to further test the endogeneity of the chemistry of the fossil soft tissue. The fossil soft tissue FTIR spectra are completely different from the background matrix (see Supplementary Fig. 10), containing clear strong organic absorption bands including amide I-III, hydrocarbon, and C = O. The matrix is however dominated by carbonate and silicate absorption bands and includes only a single weak absorption band for trace organics (C = O). ...
Context 11
... revealed the presence of numerous spheroidal bodies (0.8-2 μm; see Supplementary Fig. 11), calcite rhombs, phyllosilicate platelets, abraded sediment grains (quartz and feldspar), and Ti-rich aquatic microbodies (chrysophyte cysts: ~30 µm diameter). ESEM energy-dispersive spectrometry (EDS) revealed high Ca concentrations in the matrix, consistent with the XRF analyses, the XRD results, and the presence of calcite rhombs. ...
Context 12
... energy-dispersive spectrometry (EDS) revealed high Ca concentrations in the matrix, consistent with the XRF analyses, the XRD results, and the presence of calcite rhombs. The abundant micron-sized spheroidal bodies blanket much of the fur and skin regions of the fossil A. atavus (see Supplementary Table 3 and Supplementary Fig. 11). The corrugated surfaces, shapes, and size range of these are consistent with fossilized melanosomes. ...
Context 13
... any surface film of microbodies would contribute far less than 5% of the fluoresced Zn X-rays and most likely would not significantly contribute to the signal from the underlying mouse fossil. In any case, the presence of these micron-sized spheroidal bodies which dominate the exposed fur and skin regions of the fossil A. atavus (see Supplementary Fig. 11a-d) suggests that fossil pheomelanosomes may be present, which further supports the chemical evidence for the presence of pheomelanin residue. ...
Context 14
... in order to improve the spatial resolution of our X-ray imaging so that we could be certain that the distribution of residual chemistry displayed biological structural control, we completed microfocus XRF mapping ( Supplementary Fig. 11e-g). This showed that the Zn distribution resolved hair-like filaments within the A. atavus specimens and that lineations on the periphery grade into masses of higher Zn concentration from distal to proximate locations, as would be expected if this metal pattern has been derived from original fur. ...
Context 15
... our results indicate that for these specimens, this is unlikely, given that Zn and organosulfur compounds map discretely within the fur and any postulated geochemical process would have to deposit organosulfur compounds of Zn in such a way as to mimic the original organism's structure. All of the sulfur concentration measurements via synchrotron XRF and ESEM-EDS ( Supplementary Fig. 8, Supplementary Tables 1 and 3) have an average of 5.2% (range: 1.14-7.75, n = 9) comparable with the sulfur content measured for extant mouse fur (5.51%, Supplementary Table 1) and therefore there is no requirement for mass transfer of sulfur into this system to account for the observed sulfur content. ...
Context 16
... is a lack of organically bound Zn in the extremities (i.e., tail and feet) of both A. atavus specimens as shown in the XRF images. Optical photographs show clearly that this is not due to preferential separation between part and counterpart, because the optical images show comparable quantities of soft tissue residue on each side of the bedding plane fossils (see Supplementary Fig. 12). The lower quantities of organosulfur-Zn complexes in these regions compared with the corpus could reasonably be caused by lower in vivo quantities of pigment in these parts of the organism. ...

Similar publications

Article
Full-text available
Background Although the impact of the microphthalamia-associated transcription factor (Mitf) signaling pathway on melanocytes progression has been extensively studied, the specific molecular mechanisms behind MITF-M-enhanced melanin production in melanocytes still need to be clarified. Methods In this study, we analyzed the levels of Mitf-M in sk...
Article
Full-text available
Fossil melanosomes, micron-sized granules rich in melanin in vivo, provide key information for investigations of the original coloration, taxonomy and internal anatomy of fossil vertebrates. Such studies rely, in part, on analysis of the inorganic chemistry of preserved melanosomes and an understanding of melanosome chemical taphonomy. The extent t...
Article
Full-text available
Terahertz imaging has been proposed for burns and skin cancer identification. However, the role of melanocytes, melanosomes, melanin content and distribution in determining the terahertz optical properties of human skin has not been investigated. We use terahertz time domain spectroscopy to measure the optical properties of in vitro pigmented human...
Article
Full-text available
Skin forms a physical barrier that protects the body against outside agents. The deepest layer of the skin, the stratum basale, contains two cell types: agent-sensing keratinocytes, and melanin-producing melanocytes. Keratinocytes can sense both harmless commensal organisms and harmful pathogens via Toll-like receptors (TLRs), and keratinocytes sub...
Article
Full-text available
The relationship between skin color and skin cancer is well established: the less melanin in one's skin the greater the risk for developing skin cancer. This review is in two parts. First, we summarize the current understanding of the cutaneous pigmentary system and trace melanin from its synthesis in the pigment cell melanosomes through its transf...

Citations

... The theoretical background can be found in reviews by Ritchie et al. (2012) and Newbury and Ritchie ( , 2015. Two materials were used for this investigation: (1) tooth-like remains of conodonts and (2) Durango apatite, commonly used as reference material for fission-track microprobe analysis (Jarosewich et al. 1980), oxygen isotope analyses (Sun et al. 2016) and synchrotron X-ray fluorescence of hard tissues (Anné et al. 2014(Anné et al. , 2019 and preserved soft tissues (Manning et al. 2019). The comparison between these abiotic and biotic materials was selected owing to their similar composition, Ca 5 (PO 4 ) 3 (F,Cl,OH), as well as their importance and broad use in Earth sciences. ...
Article
Full-text available
Energy dispersive X-ray microscopy (EDX) is a widely available, inexpensive method of characterizing the in-situ elemental composition of samples in Earth and life sciences. Common protocols and textbooks focussing on material sciences address EDX analysis of metallic samples that can be polished perfectly, whereas geoscientists often investigate specimens with prominent topography and composed of light, difficult to resolve elements. This is further compounded by the scarcity of literature surrounding the methodology of SEM–EDX in the field of palaeontology, leading to common misinterpretations and artefacts during data acquisition. Here, the common errors in elemental composition obtained with EDX arising from surface topography and from parameters subject to user decisions are quantified. As a model, fossil bioapatite (conodonts) and abiotic Durango apatite are used. It is shown that even microscale topography can distort measured composition by up to 34%, whereas topographic features such as tilt with respect to the electron beam lead to differences of up to 85%. Working distance was not the most important parameter affecting the results and led to differences in composition of up to 13%, whereas the choice of standard and its levelling with the sample surface led to inaccuracy reaching 33%. EDX results can be also affected by beam damage and the effects of acceleration voltage on sample acquisition and resolution are quantified. An estimate is provided of the severity of errors associated with samples which cannot satisfy preparation requirements for EDX fully, such as holotypes, and with user decisions. Using a palaeontological example, recommendations are offered for the best parameters and the relative importance of error sources are assessed.
... Previous studies have provided clues regarding melanogenesis regulation by specific amino acids and have revealed that supplementation with glutathione or cysteine provokes intermediate production, which imparts a range of yellowish to reddish colors to skin 45,46 . The addition of cysteine or glutathione to DOPA quinone leads to the intermediates formation, followed by subsequent transformations and polymerization to the final product, pheomelanin 47,48 . ...
Article
Full-text available
Background The regulation of melanogenesis has been investigated as a long-held aim for pharmaceutical manipulations with denotations for malignancy of melanoma. Mucins have protective function in epithelial organs however, the most outer organ, skin, the role of mucins has not studied enough. Objectives Our initial hypothesis developed from the identification of correlations between pigmentation and expressions of skin mucins, particularly those exists in skin tissue. We try to investigate the action of mucins in human melanocytic cells. Methods The expression of mucin proteins in human skin was investigated using microarray data from Human Protein Atlas consortium and genome-based tissue expression consortium database. Mucin expression was measured at RNA and protein level in melanoma cells. Findings were further validated and confirmed by analysis of independent experiments. Results We found out that the several mucin proteins showed expressions in human skin cells and among these, mucin-like protein 1 (MUCL1) showed highest expression and also clear negative correlation with melanogenesis in epidermal melanocytes. We confirmed the correlations between melanogenesis and MUCL1 by revealing negative correlations in melanocytes with different melanin production, resulting from increased composition of threonine, mucin-conforming amino acid, and increased autophagy-related forkhead-box O signaling. Furthermore, threonine itself affects melanogenesis and metastatic activity in melanoma cells. Conclusions We identified a significant association between MUCL1/Threonine with melanogenesis and metastasis-related genes in melanoma cells. Our results define a novel mechanism of mucin regulation, suggesting a diagnostic role and preventive actions of MUCL1 in cutaneous melanoma.
... The present study deals with the analysis of typical extracellular bone matrix proteins taken from cortical bone of the femur of a late Pliocene gomphothere proboscidean (Anancus arvernensis; Elephantidae; Klähn 1932;Göhlich 2012;Karl et al. 2013). The exceptional preservation of these proteins (cf. also Buckley and Wadsworth 2014;Wadsworth and Buckley 2014) and other biomolecules and chemical compounds (e.g., Keely et al. 1994;Manning et al. 2019;Wolkenstein and Arp 2021) was caused by special taphonomic features, well known from the limnic Konservat Lagerstätte Willershausen (e.g., Briggs et al. 1998;Briggs 1999). ...
Article
Full-text available
In an exceptional preservation state, bones conserve the entire pattern of extracellular bone matrix proteins over thousands or sometimes even millions of years. Here we present typical extracellular bone matrix proteins, which were extracted from a 3.0-million-year-old gomphothere proboscidean, and identified with special antibodies. For the first time, osteonectin, osteopontin and BMP-2 were confidently identified from the extinct Anancus arvernensis , based on late Pliocene material from Willershausen, Lower Saxony, Germany. Our study has value in demonstrating that the longevity of original extracellular bone matrix proteins is much greater than formerly expected, and that such materials may be stabilised for distinct geological periods of time, especially in Fossil Lagerstätten.
... Hair keratin can be preserved for thousands of years after its accumulation only under special natural conditions in other sedimentary environments, such as ice, permafrost, waterlogged and anaerobic acid bogs, and arid environments, sometimes in combination with elevated salinity or as inclusion in amber (Tridico et al., 2014;Chernova et al., 2016;Manning et al., 2019). ...
Article
Full-text available
The Bàsura Cave (Toirano, Savona, NW Italy) hosts important cave bear bone assemblages and a numerous and varied, tracks and traces record left by humans and other producers. An outstanding element of the analysed material is represented by fossil bear fur fragments, which were found in the inner deposits of the cave, and that, to date, are virtually unknown in the cave global record. After analysing and discussing micromorphological features of the inedited material, we integrate and interpret new radiocarbon data, along with taphonomic, sedimentological, geochemical and mineralogical evidences, with the aim of improving our understanding about the nature and chronology of the bear fur-bearing deposit. The bear fur fragments are included in a stratigraphic succession corresponding to a secondary deposit, formed after the dismantling, reworking and redeposition of a former bear-bearing deposit, as a result of short but intensive flooding events that most probably took place at the end of the Last Glacial Maximum. After sediments redeposition, important diagenetic changes have occurred and probably driven by guano deposits, whose pre-existence, in absence of record, is inferred from corrosion features, nutrient concentrations, mineral species identified (REE bearing hydroxyapatite), and claw traces left by bats on the cave ceiling and walls. Diagenetic imprint derived by guano deposits caused mineralization of bear fur fragments by replacement with apatite, which faithfully copied the form and structure of hairs but also of vegetal tissues, phytoliths and pollen found within them. Our study demonstrates for the first time that the bear fur is one of the main vectors in introducing botanical microremains into the interior of the “Old World” caves.
... Fossil color is a major focus of paleobiological research (Roy et al., 2019). Melanosomes, micron-sized organelles rich in melanin in vivo, are preserved in diverse fossil taxa and tissues (Vinther et al., 2008;Lindgren et al., 2012;Manning et al., 2019;Rogers et al., 2019;Rossi et al., 2019) and provide information about the evolution of color (Li et al., 2014;Gabbott et al., 2016;Lindgren et al., 2018;Manning et al., 2019) and the internal anatomy (Rossi et al., 2019) and phylogenetic affinities (Clements et al., 2016;Rogers et al., 2019) of ancient animals. ...
... Fossil color is a major focus of paleobiological research (Roy et al., 2019). Melanosomes, micron-sized organelles rich in melanin in vivo, are preserved in diverse fossil taxa and tissues (Vinther et al., 2008;Lindgren et al., 2012;Manning et al., 2019;Rogers et al., 2019;Rossi et al., 2019) and provide information about the evolution of color (Li et al., 2014;Gabbott et al., 2016;Lindgren et al., 2018;Manning et al., 2019) and the internal anatomy (Rossi et al., 2019) and phylogenetic affinities (Clements et al., 2016;Rogers et al., 2019) of ancient animals. ...
... Melanosomes typically show tissue-specific metal associations in extant (Edwards et al., 2016;Rossi et al., 2019) and some fossil vertebrates (Wogelius et al., 2011;Manning et al., 2019;Rossi et al., 2019). Other fossil vertebrates, however, show widespread Cu enrichment in melanosomes from all tissues (Rossi et al., 2020). ...
Article
Full-text available
Fossil melanosomes are a major focus of paleobiological research because they can inform on the original coloration, phylogenetic affinities, and internal anatomy of ancient animals. Recent studies of vertebrate melanosomes revealed tissue-specific trends in melanosome-metal associations that can persist in fossils. In some fossil vertebrates, however, melanosomes from all body regions are enriched only in Cu, suggesting diagenetic overprinting of original chemistry. We tested this hypothesis using laboratory experiments on melanosomes from skin and liver of the African clawed frog Xenopus laevis. After maturation in Cu-rich media, the metal chemistry of melanosomes from these tissues converged toward a common composition, and original differences in Cu oxidation state were lost. Elevated Cu concentrations and a pervasive Cu(II) signal are likely indicators of diagenetically altered melanosomes. These results provide a robust experimental basis for interpretating the chemistry of fossil melanosomes.
... Integumentary coloration in fossils has been inferred from the visual tone of fossil tissues, melanosome geometry, distributions of melanin-associated metals and/or potential molecular fragments of melanin [3,4]. In the bird Confuciusornis [19], clusters of melanosomes of different morphologies (resembling eumelanosomes and pheomelanosomes of extant birds) and within-feather variations in Table S1 in the supplemental information online) [7,9,23,24,27,28,53,56,57,126,127]. Internal melanosomes are less common in extant birds and mammals than other vertebrate groups. ...
... Spatial distributions of Zn, S, and organo-S and organo-Zn species in the fossil mouse Apodemus are consistent with pheomelanin-based fur [27]. Chemical evidence for eumelanin and uniform visible tones in fossil marine reptiles may represent homogeneous dark coloration consistent with background matching, especially in ichthyosaurs (with inferred deep-diving behavior [28]). ...
... Certain metals preferentially associate with specific functional groups of eumelanin (Ca 2+ and Zn 2+ : COOH -; Fe 2+/3+ and Cu 2+ : OH -; Fe 2+/3+ : NH 4 + ; these associations can alter with pH [10]). In pheomelanin, Zn 2+ coordinates with OHand with organic sulfur [27] and Cu 2+ , with COOHand quinine-imine (but SHand catechol groups at higher pH [105]). The inherent affinity and binding capacity of melanins for different metals underpins proposed functions of melanin in metal regulation and detoxification. ...
Article
Full-text available
Melanins are widespread pigments in vertebrates, with important roles in visual signaling, UV protection, and homeostasis. Fossil evidence of melanin and melanin-bearing organelles-melanosomes-in ancient vertebrates may illuminate the evolution of melanin and its functions, but macroevolutionary trends are poorly resolved. Here, we integrate fossil data with current understanding of melanin function, biochemistry, and genetics. Mapping key genes onto phenotypic attributes of fossil vertebrates identifies potential genomic controls on melanin evolution. Taxonomic trends in the anatomical location, geometry, and chemistry of vertebrate melanosomes are linked to the evolution of endo-thermy. These shifts in melanin biology suggest fundamental links between melanization and vertebrate ecology. Tissue-specific and taxonomic trends in melanin chemistry support evidence for evolutionary tradeoffs between function and cytotoxicity. Melanin in Vertebrates Melanins (see Glossary) are dark to rufous pigments that are widespread in vertebrates and underpin critical functions in physiology and behavior [1]. Fossil evidence of melanin extending to over 300 million years ago has triggered a paradigm shift in paleobiology, prompting remarkable reconstructions of the coloration and behavior of extinct vertebrates [2-6]. New discoveries of internal melanins in vertebrate fossils have broadened our understanding of the functional diversity of ancient melanins [7-9] and invite a re-evaluation of the macroevolu-tionary history of melanin and its functions. Here, we synthesize trends in the fossil record of melanin and explore fossil evidence for the evolution of melanin function and the genetic basis of melanization. This highlights the value of the fossil record as a resource for tracking melanin evolution through deep time.
... [2][3][4] Recent works started to look beneath the surface and into the ultrastructure and chemistry of fossil feathers and bones, and bring our understanding of this major transition to a new level. 1,[5][6][7][8][9][10][11][12] The chemistry of exquisitely preserved fossil animals, including several iconic flying/gliding theropods, have been investigated to reveal information on their paleobiology and the fossilization process. 1,6,9,10,[12][13][14] Various chemical imaging techniques, e.g. ...
... Fourier-transform infrared (FTIR) spectroscopy, Raman spectroscopy, X-ray spectroscopy, and secondary-ion mass spectroscopy (SIMS), have been employed to track the molecular, elemental and isotopic information. 1,5,6,[8][9][10][11][12][13][15][16][17][18] Unfortunately, previous studies all focused on non-destructive chemical imaging of small-sized specimens (e.g. Archaeopteryx, Confuciusornis), limited by the analytical instruments 6,8,11,12 or the chemical analyses of small samples destructively taken from fossils. ...
... 1,5,6,[8][9][10][11][12][13][15][16][17][18] Unfortunately, previous studies all focused on non-destructive chemical imaging of small-sized specimens (e.g. Archaeopteryx, Confuciusornis), limited by the analytical instruments 6,8,11,12 or the chemical analyses of small samples destructively taken from fossils. 9,10,13,16,17 Up to now, systematic non-destructive chemical imaging on meter-sized specimens of non-avialan dinosaurs has not been carried out. ...
Article
Full-text available
Jianianhualong tengi is a key taxon for understanding the evolution of pennaceous feathers as well as of troodontid theropods. It is known by only the holotype, which was recovered from the Lower Cretaceous Yixian Formation of western Liaoning, China. In this study, we carried out a large-area micro-X-Ray fluorescence (micro-XRF) analysis of the holotype of Jianianhualong tengi via a Brucker M6 Jetstream mobile XRF scanner. The elemental distribution measurements of the specimen show an enrichment of typical bone-associated elements, such as S, P and Ca, which allows to visualize the fossil structure. Additionally, the bones are enriched with several heavier elements, such as Sr, Th, Y and Ce relative to the surrounding rocks. The enrichment is most likely associated to secondary mineralization and the phosphates from the bones. Interestingly, the plumage shape correlates with an enrichment in elements, such as Cu, Ni and Ti, consistent with the findings of a previous study 1 on Archaeopteryx using synchrotron imaging. Elemental variations among the skeleton, the unguis and the sheath blade further indicate their possible compositional or ultrastructural differences, providing new biological and taphonomic information on the fossilized keratinous structures. An in-situ and nondestructive micro-XRF analysis is currently the most ideal way to map the chemistry of meter-sized fossils and has so far been mainly restricted to small samples. Micro-spatial chemical analysis of larger samples usually required a synchrotron facility. Our study demonstrated that a laboratory-based large-area micro-XRF scanner can provide a practical tool for the study of large specimens, thus allowing to collect full chemical data in order to obtain a better understanding of evolutionary and taphonomic processes.
... In vertebrates, the most common types of melanins are eumelanin and pheomelanin, which are associated with black-brown and red-yellow colors, respectively. Interestingly, eumelanin (and possibly also pheomelanin) has been found to persist across geological time, providing biomolecular data from multimillionyear-old fossils [4][5][6][7][8][9][10]. This information can be used to infer novel biological, ecological, and evolutionary aspects of now long-extinct animals, including traits associated with crypsis, thermoregulation, and social interactions [4][5][6][7][8]. ...
Article
Residual melanins have been detected in multimillion-year-old animal body fossils; however, confident identification and characterization of these natural pigments remain challenging due to loss of chemical signatures during diagenesis. Here, we simulate this post-burial process through artificial maturation experiments using three synthetic and one natural eumelanin exposed to mild (100 °C/100 bar) and harsh (250 °C/200 bar) environmental conditions, followed by chemical analysis employing alkaline hydrogen peroxide oxidation (AHPO) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). Our results show that AHPO is sensitive to changes in the melanin molecular structure already during mild heat and pressure treatment (resulting, e.g., in increased C-C cross-linking), whereas harsh maturation leads to extensive loss of eumelanin-specific chemical markers. In contrast, negative-ion ToF-SIMS spectra are considerably less affected by mild maturation conditions, and eumelanin-specific features remain even after harsh treatment. Detailed analysis of ToF-SIMS spectra acquired prior to experimental treatment revealed significant differences between the investigated eumelanins. However, systematic spectral changes upon maturation reduced these dissimilarities, indicating that intense heat and pressure treatment leads to the formation of a common, partially degraded, eumelanin molecular structure. Our findings elucidate the complementary nature of AHPO and ToF-SIMS during chemical characterization of eumelanin traces in fossilized organismal remains.
... [2][3][4] Recent works started to look beneath the surface and into the ultrastructure and chemistry in fossil feathers and bones and bring our understanding of this major transition to another new level. 1,[5][6][7][8][9][10][11][12] Chemistry of exquisitely preserved fossil animals including several iconic flying/gliding capable theropods www.at-spectrosc.com/as/article/pdf/202101001 ...
... At. Spectrosc. 2021, 42(1), [1][2][3][4][5][6][7][8][9][10][11] have been investigated to reveal information of their paleobiology and the fossilization process. 1,6,9,10,[12][13][14] Various chemical imaging techniques, e.g., Fourier-transform infrared (FTIR) spectroscopy, Raman spectroscopy, X-ray spectroscopy, and secondary-ion mass spectroscopy (SIMS), have been employed to track the molecular, elemental and isotopic information. ...
... 1,6,9,10,[12][13][14] Various chemical imaging techniques, e.g., Fourier-transform infrared (FTIR) spectroscopy, Raman spectroscopy, X-ray spectroscopy, and secondary-ion mass spectroscopy (SIMS), have been employed to track the molecular, elemental and isotopic information. 1,5,6,[8][9][10][11][12][13][15][16][17][18] Unfortunately, previous studies all focused on non-destructive chemical imaging on small-sized specimens (e.g., Archaeopteryx, Confuciusornis) as limited by the analyzing instruments, 6,8,11,12 or chemical analyses on small samples destructively taken from fossils. 9,10,13,16,17 So far systematic non-destructive chemical imaging on meter-sized specimens of non-avialan dinosaurs have not been done. ...
... In the search to identify what makes fungi so impervious to radiation, the pigment melanin has been identified as an interesting candidate. Melanin has been detected in ancient fossils dating back to the Cretaceous and Jurassic periods, and is present in most kingdoms, suggesting strong evolutionary preservation [55,31,16]. The presence of melanin, moreover, is associated with enhanced survival and improved fitness in extremely radioactive environments, as indicated by the prevalence of melanized fungal strains isolated from these locations [28]. ...
Article
Full-text available
Melanized fungi have been isolated from some of the harshest radioactive environments, and their ability to thrive in these locations is in part due to the pigment melanin. Melanin imparts a selective advantage to fungi by providing a physical shield, a chemical shield, and possibly a signaling mechanism. In previous work we demonstrated that protracted exposure of the melanized yeast Exophiala dermatitidis to mixed alpha-, beta-, and gamma-emitting radiation resulted in an adapted strain able to mount a unique response to ionizing radiation in the environment in a melanin-dependent fashion. By exploring the genome and transcriptome of this adapted melanized strain relative to a non-irradiated control we determined the altered response was transcriptomic in nature, as whole genome sequencing revealed limited variation. Transcriptomic analysis indicated that of the adapted isolates analyzed, two lineages existed: one like the naïve, non-adapted strain, and one with a unique transcriptomic signature that exhibited downregulation of metabolic processes, and upregulation of translation-associated genes. Analysis of differential gene expression in the adapted strain showed an overlap in response between the control conditions and reactive oxygen species conditions, whereas exposure to an alpha particle source resulted in a robust downregulation of metabolic processes and upregulation of DNA replication and repair genes, and RNA metabolic processes. This suggest previous exposure to radiation primes the fungus to respond to subsequent exposures in a unique way. By exploring this unique response, we have expanded our knowledge of how melanized fungi interact with and respond to ionizing radiation in their environment.