Extended Data Fig. 4: Pyrolysis data collected at 560 °C for 10 s, from the soft tissues of MH 432. | Nature

Extended Data Fig. 4: Pyrolysis data collected at 560 °C for 10 s, from the soft tissues of MH 432.

From: Soft-tissue evidence for homeothermy and crypsis in a Jurassic ichthyosaur

Extended Data Fig. 4

a, Py-GC/MS chromatograms obtained from MH 432 (TIC, total ion currents). The prominent peak series in each sample represents homologous n-alkenes and n-alkanes; chromatograms are normalized to the highest of these peaks. Inset ion chromatograms (m/z 217) illustrate the distribution of eukaryote-derived steranes, with 27 and 29 denoting carbon numbers. S and R denote (20S)-5α,14α,17α(H) and (20R)-5α,14α,17α(H) isomers, respectively. Abundant C27-steranes (cholestanes) in the integument constitute diagenetic products of ichthyosaur cholesterol. The predominant 20R isomer is also indicated in the TICs to illustrate its abundance among the total pyrolysates. C29-steranes (stigmastanes) reflect background sedimentation from algae and/or terrestrial plants. Note the high amount of cholestanes in the integument and greater abundance of stigmastanes in the host rock. Also note the higher intensities of aromatics (relative to aliphatics), diasteranes (relative to regular steranes) and a stronger unresolved complex mixture in the liver, reflecting original compositional differences and/or enhanced biodegradation. b, Py-GC/MS ion chromatograms (m/z 250, normalized to sample weight) showing a compound tentatively identified as n-octadecadiene (arrowheads, n-C18:2). This molecule is interpreted as a pyrolysis product of kerogen-bound n-octadecenyl (n-C18:1) moieties potentially originating from oleic acid (C18:1ω9c), the most abundant monoenoic fatty acid in extant vertebrates. Note the localized occurrence within the flank integument (where the blubber is best preserved). Replicate sample measurements (denoted by i and ii) are provided to demonstrate reproducibility.

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