Thermal stress on the biosphere during the extreme warmth of the Paleocene–Eocene Thermal Maximum (PETM) was most severe at low latitudes, with sea surface temperatures at some localities exceeding the 35 ^∘C at which marine organisms experience heat stress. Relatively few equivalent terrestrial sections have been identified, and the response of land plants to this extreme heat is still poorly understood. Here, we present a new record of the PETM from the peak ring of the Chicxulub impact crater that has been identified based on nannofossil biostratigraphy, an acme of the dinoflagellate genus Apectodinium, and a negative carbon isotope excursion. Geochemical and microfossil proxies show that the PETM is marked by elevated TEX${}_{\mathrm{86}}^{\mathrm{H}}$-based sea surface temperatures (SSTs) averaging ∼37.8 ^∘C, an increase in terrestrial input and surface productivity, salinity stratification, and bottom water anoxia, with biomarkers for green and purple sulfur bacteria indicative of photic zone euxinia in the early part of the event. Pollen and plants spores in this core provide the first PETM floral assemblage described from Mexico, Central America, and the northern Caribbean. The source area was a diverse coastal shrubby tropical forest with a remarkably high abundance of fungal spores, indicating humid conditions. Thus, while seafloor anoxia devastated the benthic marine biota and dinoflagellate assemblages were heat-stressed, the terrestrial plant ecosystem thrived.

中文翻译：

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Chicxulub撞击坑的生与死：古新世-始新世最高温度的记录

在古新始新世热最大（PETM）的极端温暖在生物圈热应力最严重在低纬度地区，与海表面温度在一些地方超过35  ^∘ Ç在该海洋生物经历热应力。相对较少的陆地被发现，陆地植物对这种极端高温的反应仍然知之甚少。在这里，我们提供了基于Chicxulub撞击坑的峰环的PETM的新记录，该记录是根据纳米化石生物地层学，鞭毛鞭毛属Apectodinium的顶峰以及负碳同位素偏移确定的。地球化学和微化石代理显示，PETM具有高TEX的特征${}_{\mathrm{86}}^{\mathrm{H}}$基于海洋表面温度（海面温度）平均~37.8  ^∘ Ç，增加在陆地输入和表面生产率，盐度分层，底水缺氧，使用生物标志物为绿色和紫色硫细菌指示的早期部分透光区euxinia的事件。花粉和植物孢子在该核心中提供了从墨西哥，中美洲和北加勒比海地区描述的第一个PETM花卉组合。来源地区是多样化的沿海灌木热带森林，其中真菌孢子的丰度非常高，表明潮湿。因此，当海底缺氧破坏了底栖海洋生物区系，并鞭毛了鞭毛藻时，陆生植物生态系统蓬勃发展。