Fourier transform infrared characterization of the Middle Devonian non‐vascular plant Spongiophyton

Abstract

Spectroscopy information (functional groups and semiquantitative data) by Fourier transform infrared (FTIR) spectroscopy of Spongiophyton Kr€ ausel emend. Chaloner et al. is reported for the first time, in an attempt to identify spectroscopic patterns that would differentiate species of these taxa. A total of 33 specimens identified as S. lenticularis, S. nanum and S. minutissimum and preserved as compressions were analysed. They come from the same fossiliferous horizon of one outcrop situated in the uppermost Middle Devonian São Domingos Formation of the Paran a Basin in southern Brazil. The results reveal that functional groups in the 3000-2800 and 1800-700 cm À1wavenumber regions are present in all specimens. Infraredderived ratios (CH 2 /CH 3 , Al/Ox, Ox1/Ox2, C=O cont., C=C cont., Al2 and Ar/Al) and types of kerogen led to a comparison of the morphological characteristics of the studied material and indicate that compressions of S. lenticularis, S. nanum and S. minutissimum contain different organic compounds. S. nanum and S. minutissimum show higher oxidation and lower aromaticity of its organic matter than S. lenticularis. Additionally, S. lenticularis shows low A-factor values, suggesting a composition similar to type III kerogen, while S. nanum and S. minutissimum showed intermediate to high A-factor values, suggesting a composition similar to type II kerogen. In conclusion, the chemical-analytical techniques and statistical analysis (using PCA technique) reveal a closer taxonomic relationship between S. nanum and S. minutissimum than either has with S. lenticularis, supporting their taxonomic separation, previously proposed in the literature on the basis of morphological features. Lastly, the chemical signatures support the hypothesis that links these enigmatic fossils to a type of lichen or other early inland plant.

Analysis of fossil plant cuticles using vibrational spectroscopy: A new preparation protocol

“…Recent studies showed that biomolecules may be very well preserved in fossil leaves (Pšenička et al, 2005;Matsumura et al, 2016;Vajda et al, 2017Vajda et al, , 2021Lafuente Diaz et al, 2020. This preservation has proven true for plant cuticles as old as 360 Ma: these extremely wellpreserved cuticles were analyzed for their chemical composition and stability under the fossilization process (Lyons et al, 1995;Vajda et al, 2017), being also used for extensive phylogenetic studies using Fourier-transform infrared spectroscopy (FTIR) (Zodrow and Mastalerz, 2001;D'angelo, 2006;D'Angelo and Zodrow, 2015;Vajda et al, 2017Vajda et al, , 2021.…”

“…The most widely used palynological and palaeobotanical processing methods include cleaning steps using: HCl and/or HF (e.g., Steemans et al, 2010;Matsumura et al, 2016;Lafuente Diaz et al, 2020;Jardine et al, 2021) for inorganics removal; and for cuticle or coal maceration, Schulze's solution (Zodrow and Mastalerz, 2009;D'Angelo et al, 2011;Zodrow et al, 2012;Jardine et al, 2021), followed by KOH (Pšenička et al, 2005;Slodownik et al, 2021). Yet, potential alterations of the fossil chemical composition caused by the different cleaning reagents used are not fully understood, as these protocols were developed and became standard practice before chemical spectroscopic studies of fossil cuticles and pollen became popular.…”

Fourier Transform Infrared Spectroscopy Studies of Cretaceous Gymnosperms from the Santa Cruz Province, Patagonia, Argentina

“…Among them, the preservation types and paleochemotaxonomy of plant fossil remains as well as paleoenvironmental, diagenetic, and postdiagenetic conditions involved in fossilization processes have been mainly analyzed (e.g., D'Angelo and Zodrow, 2015;Zodrow et al, 2016;Lafuente Diaz et al, 2018a, 2019a, 2020aZodrow and Mastalerz, 2019, among others). These investigations have been predominantly carried out on Pennsylvanian gymnosperms, vegetative and reproductive organs from the Sydney Coalfield, Canada and, to a lesser extent, on plant remains from the Devonian, Carboniferous, and Triassic of Canada, the Czech Republic, Spain, and Brazil, among others (e.g., Pšenicka et al, 2005;D'Angelo and Zodrow, 2015;Matsumura et al, 2016). Among the latest analyzes, a chemical representation of the fertile structures of Trigonocarpus grandis in organic connection to vegetative organs has been obtained (Zodrow et al, 2013).…”