Tripp Madison, Wiemann Jasmina, Brosnan Luke, Rickard William D A, Vajda Vivi, Böttcher Michael Ernst, Greenwood Paul F, Grice Kliti
Western Australian Organic and Isotope Geochemistry Centre, School of Earth and Planetary Sciences, Curtin University, Bentley, WA, Australia.
Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, Maryland, USA.
Geobiology. 2025 Sep-Oct;23(5):e70030. doi: 10.1111/gbi.70030.
Diagenetically mineralized fossil tissues represent invaluable paleobiological evidence of past life. Lipid biomarkers may be identified alongside fossils, yet the relationship between localized, diagenetic mineral precipitation, and lipid preservation remains underexplored. Coprolites (fossilized feces) attract a unique diversity of early diagenetic minerals including carbonates and phosphates, within individual samples, mediating molecular preservation of soluble lipid biomarkers alongside exceptional morphological preservation. Analysis of a well-preserved coprolite from the Carboniferous (307 ± 0.1 Ma) Mazon Creek assemblage, USA via time of flight-secondary ion mass spectrometry (ToF-SIMS) spatial compound mapping demonstrated the association of 5α,14α,17α(H) 20R cholestane, a C dietary sterane, with iron carbonate (and some pyrite) rather than phosphate minerals. Furthermore, Raman spectroscopic fingerprinting of a suite of organic-rich fossils spanning a number of biological species and preserved across the Mazon Creek site and other depositional settings was utilized to explore whether the localized preservation of steroids in carbonate phases represents a lagerstätten-specific or generalizable pattern. Our spectroscopic analyses demonstrate a significant positive correlation between signatures of lipid biomarkers and carbonates rather than phosphates across all soft-part samples at the Mazon Creek site and throughout Phanerozoic time and space. Early diagenetic carbonate measurably immobilizes otherwise labile lipid biomarkers and shields them against diagenetic stressors. Localized preservation identifies carbonate phases as a preferential resource for lipid-based biological information and reveals organomineral associations as a new frontier in understanding the survival of molecules in deep time.
成岩矿化的化石组织代表了过去生命中极其宝贵的古生物学证据。脂质生物标志物可能与化石一同被识别出来，但局部成岩矿物沉淀与脂质保存之间的关系仍未得到充分探索。粪化石（化石粪便）在单个样本中吸引了包括碳酸盐和磷酸盐在内的独特多样的早期成岩矿物，这些矿物在介导可溶性脂质生物标志物的分子保存的同时，还能实现异常的形态保存。通过飞行时间二次离子质谱（ToF-SIMS）空间化合物映射对来自美国石炭纪（3.07±0.1百万年）马宗溪组合的一块保存完好的粪化石进行分析，结果表明，5α,14α,17α(H) 20R胆甾烷（一种C类膳食甾烷）与碳酸铁（以及一些黄铁矿）有关，而非与磷酸盐矿物有关。此外，利用拉曼光谱指纹技术对一系列跨越多个生物物种、保存在马宗溪遗址及其他沉积环境中的富含有机质化石进行分析，以探究碳酸盐相中类固醇的局部保存是代表了特异埋藏型还是普遍存在的模式。我们的光谱分析表明，在马宗溪遗址以及整个显生宙的时间和空间范围内，所有软质部分样本中脂质生物标志物的特征与碳酸盐而非磷酸盐之间存在显著的正相关。早期成岩碳酸盐能够显著固定原本不稳定的脂质生物标志物，并保护它们免受成岩应激源的影响。局部保存将碳酸盐相确定为基于脂质的生物信息的优先来源，并揭示了有机矿物关联是理解深层时间中分子存活情况的一个新前沿领域。
