One-billion-year-old epibionts highlight symbiotic ecological interactions in early eukaryote evolution

Raman spectroscopy is a powerful tool in molecular paleobiology: An analytical response to Alleon et al. (https://doi.org/10.1002/bies.202000295)

“…They did not consider a number of other examples of the application of Raman spectroscopy to carbonaceous fossil material that yielded similar, if not identical spectra. [5,[7][8][9][10][13][14]17,[20][21][22][23] Alleon et al [28] criticized the presence of wide spectral bands even though they are also present in other studies on carbonaceous fossil, conserved modern museum, and fresh tissue spectra. [7,[13][14]17,[20][21][22][23][24][25][26] Their case for instrumental artefacts was based on a freely available 532 nm RazorEdge ultrasteep long pass edge filter transmission spectrum (Fig- ure 2A in [28] ), which resembles a periodic, sinusoidal wave function, obtained from the commercial website "Semrock" (www.semrock.com/ FilterDetails.aspx?id = LP03-532RE-25).…”

“…[1,2] Applications of non-destructive, in situ Raman microspectroscopy have resulted in rapid progress in understanding biomolecule fossilization and the detection of biosignatures based on comparative statistical analyses of fossil organic matter. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] The in situ approach facilitates rapid non-destructive analysis of surface-cleaned samples without requiring time-consuming extractions of the organic matter that may alter fossil molecular compounds. Raman spectroscopy not only characterizes molecular functional groups (small molecular units with distinct chemical properties), but also provides insights into higher-level structural organization by detecting intermolecular and organo-mineral interactions.…”

“…[3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][20][21][22][23] A diversity of studies conducted by different laboratories have recovered similar patterns in the molecular makeup of fossil organic matter in independently acquired in situ Raman spectra. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][20][21][22][23] However, a recent Perspective by Alleon et al [28] concluded that the biological results of a selected subset of these studies [3,4,6,11,12,15] are compromised, based on their detection of sinusoidal edge filter ripples, i.e., instrumental artefacts, in the Raman data. [28] The results in the disputed studies are b...…”

“…Patterns revealed by multivariate statistical analyses of relative intensities extracted at informative band positions, primarily by ordination methods such as the Chemospace Principal Component Analysis (PCA), were consistently biologically and geologically meaningful, accurately predicting biological traits assessed for large data sets. [11] Although the studies disputed by Alleon et al [28] were based on Phanerozoic samples, the same Raman spectroscopy protocols have since been used in independent studies to identify biosignatures in Neoproterozoic carbonaceous fossils [17] and in biological samples that yielded partially artefactual spectra (etaloning effects). [18] The claim [28] that biomolecular composition cannot be characterized with a conventional Raman setup combined with the statistical approach used in our studies, [3,4,6,11,12,15] and the suggestion that only thermal maturation signals can be detected [28] and references therein], throw doubt on conventional Raman-based results in other disciplines.…”

Evolution of Holdfast Diversity and Attachment Strategies of Ediacaran Benthic Macroalgae

“…Moreover, the redox interface migrated downwards to a deeper depth (Figure 7). Although benthic macroalgae (represented by the Chuaria-Tawuia assemblage) are not rare in pre-Ediacaran strata, the fossil record of erect benthic macroalgae, such as Longfengshania and Protoarenicola/Pararenicola (Tang et al, 2021) remains scarce. Macroalgae in the early Ediacaran, despite various shapes of the thalli, e.g., simple dichotomously branching, bush-like, or conical, were adapted to sticking on the surface of microbial mats while mats were still somewhat developed on the seafloor.…”