Conventional magnetofossils represent magnetic mineral remains of magnetotactic bacteria. Giant magnetofossils have no known modern analog. Both conventional and giant magnetofossil assemblages can record paleoenvironmental information through changes in magnetotactic bacteria diversity driven by nutrient supply and oxygenation. We use marine sediments that record a rapid global warming event, the Paleocene‐Eocene Thermal Maximum (∼56 Ma), to assess how abundant well‐preserved magnetofossils with high morphological disparity record paleoenvironmental information. We find that conventional magnetofossils can be distinguished from giant, needle‐shaped magnetofossils using principal component analysis of first‐order reversal curves (FORC‐PCA); moreover, FORC‐PCA may be able to distinguish between well‐preserved magnetically soft and magnetically hard magnetofossils. FORC‐PCA is a robust, nondestructive technique that can be applied to other marine archives to understand how these ecosystems respond to rapid environmental change. We hypothesize that the sudden appearance of giant magnetofossils represents a natural response to niche expansion within the water column (a thicker oxic‐anoxic interface) and eutrophication (via iron supply) by protists that biomineralize giant magnetofossils. This application has potential as a proxy for changes in marine oxygen and iron concentrations stimulated by rapid planetary change.

中文翻译：

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新世-始新世热最大值期间铁生物矿化生物的多样化：传统和巨型磁化石的磁性特征的定量分解证据

常规的磁化石代表趋磁细菌的磁性矿物残留物。巨型磁化石没有已知的现代类似物。常规和巨型磁化石组合体都可以通过营养供应和氧合驱动的趋磁细菌多样性变化来记录古环境信息。我们使用记录了快速全球变暖事件的海洋沉积物，即古新世-始新世热最大值（〜56 Ma），来评估保存有高度形态差异的保存良好的磁化石，记录古环境信息的程度。我们发现，通过一阶反转曲线的主成分分析（FORC-PCA），可以将常规的化石与巨型的针状化石区分开来；而且，FORC‐PCA可能能够区分保存良好的软磁性和硬磁性磁石。FORC-PCA是一种强大的无损技术，可以应用于其他海洋档案馆，以了解这些生态系统如何响应快速的环境变化。我们假设，突然出现的巨型化石代表对水柱（较厚的有氧-缺氧界面）内的生态位扩张和富营养化的自然反应（通过铁供应）由生物矿化巨大的化石的原生生物。该应用有可能替代由于行星快速变化而刺激的海洋氧气和铁浓度的变化。