It is established that green algae and land plants progressively colonized freshwater and terrestrial habitats throughout the Paleozoic Era, but little is known about the ecology of Paleozoic saline lakes. Here, we report lipid biomarker and petrographic evidence for the occurrence of a green alga as a major primary producer in a late Paleozoic alkaline lake (Fengcheng Formation; 309–292 Ma). A persistently saline and alkaline lacustrine setting is supported by mineralogical and lipid biomarker evidence alongside extremely enriched δ¹⁵N_bulk values (+16 to +24‰) for the lake depocenter. The prominence of C₂₈ and C₂₉ steroids, co‐occurring with abundant carotene‐derived accessory pigment markers in these ancient rocks, is suggestive of prolific primary production and elevated source inputs from haloalkaliphilic green algae. The high C₂₈/C₂₉‐sterane ratios (0.78–1.29) are significantly higher than the typical marine value reported for late Paleozoic rocks (<0.5) and thus are associated with certain groups of chlorophytes. Adaptation to such extreme lacustrine environments, aided by enhanced biosynthesis of certain cell membrane lipids, likely played an important role in the evolution and physiological development of ancient green algae.

中文翻译：

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一个新的限制对古代卤代碱绿色藻类的兴旺在约。300 Ma古生代湖

可以确定的是，藻类和陆生植物逐渐在整个古生代定居在淡水和陆地生境中，但是对古生代盐湖的生态学知之甚少。在这里，我们报告了脂质生物标志物和岩石学证据，表明在晚古生代碱性湖泊（凤城组； 309-292 Ma）中，绿藻是主要的主要生产者。甲持续盐碱湖泊设置由矿物学和脂质生物标记证据的支持一起非常富集δ ^15个Ñ_散装为湖沉积中心值（16到+ 24‰）。C ₂₈和C ₂₉的突出之处在这些古老的岩石中，类固醇与丰富的胡萝卜素衍生的辅助色素标记同时出现，表明卤代嗜盐绿藻的初级产量较高，而来源的投入则较高。高C ₂₈ / C ₂₉甾烷比（0.78-1.29）显着高于晚古生代岩石的典型海洋值（<0.5），因此与某些类绿藻有关。在某些细胞膜脂质的增强生物合成的辅助下，对这种极端湖相环境的适应可能在古代绿藻的进化和生理发育中起重要作用。