Confirming the identity of early animals The first complex organisms emerged during the Ediacaran period, around 600 million years ago. The taxonomic affiliation of many of these organisms has been difficult to discern. Fossils of Dickinsonia, bilaterally symmetrical oval organisms, have been particularly difficult to classify. Bobrovskiy et al. conducted an analysis using lipid biomarkers obtained from Dickinsonia fossils and found that the fossils contained almost exclusively cholesteroids, a marker found only in animals (see the Perspective by Summons and Erwin). Thus, Dickinsonia were basal animals. This supports the idea that the Ediacaran biota may have been a precursor to the explosion of animal forms later observed in the Cambrian, about 500 million years ago. Science, this issue p. 1246; see also p. 1198 Lipid biomarkers extracted from organically preserved Ediacaran macrofossils unambiguously clarify their phylogeny. The enigmatic Ediacara biota (571 million to 541 million years ago) represents the first macroscopic complex organisms in the geological record and may hold the key to our understanding of the origin of animals. Ediacaran macrofossils are as “strange as life on another planet” and have evaded taxonomic classification, with interpretations ranging from marine animals or giant single-celled protists to terrestrial lichens. Here, we show that lipid biomarkers extracted from organically preserved Ediacaran macrofossils unambiguously clarify their phylogeny. Dickinsonia and its relatives solely produced cholesteroids, a hallmark of animals. Our results make these iconic members of the Ediacara biota the oldest confirmed macroscopic animals in the rock record, indicating that the appearance of the Ediacara biota was indeed a prelude to the Cambrian explosion of animal life.

中文翻译：

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古老的类固醇使埃迪卡拉纪化石狄更逊鱼成为最早的动物之一

确认早期动物的身份 第一个复杂的生物出现在大约 6 亿年前的埃迪卡拉纪时期。许多这些生物的分类隶属关系很难辨别。Dickinsonia 的化石，双边对称的椭圆形生物，特别难以分类。博布罗夫斯基等人。使用从 Dickinsonia 化石中获得的脂质生物标志物进行了分析，发现这些化石几乎只含有胆甾醇，这是一种仅在动物中发现的标志物（参见 Summons 和 Erwin 的观点）。因此，狄更逊是基础动物。这支持了埃迪卡拉纪生物群可能是后来在大约 5 亿年前在寒武纪观察到的动物形态爆炸的先兆的观点。科学，这个问题 p。1246; 另见第。1198 从有机保存的埃迪卡拉纪巨化石中提取的脂质生物标志物明确阐明了它们的系统发育。神秘的埃迪卡拉生物群（5.71 亿至 5.41 亿年前）代表了地质记录中第一个宏观复杂的生物，可能是我们了解动物起源的关键。埃迪卡拉纪的大型化石“就像另一个星球上的生命一样奇怪”，并且逃避了分类学分类，解释范围从海洋动物或巨型单细胞原生生物到陆地地衣。在这里，我们表明从有机保存的埃迪卡拉纪巨化石中提取的脂质生物标志物明确阐明了它们的系统发育。Dickinsonia 及其亲属只生产胆甾醇，这是动物的标志。