PDF(Pubmed)
Abstract：
The Ediacaran-Cambrian transition documents a critical stage in the diversification of animals. The global fossil record documents the appearance of cloudinomorphs and other shelled tubular organisms followed by non-biomineralized small carbonaceous fossils and by the highly diversified small shelly fossils between ~ 550 and 530 Ma. Here, we report diverse microfossils in thin sections and hand samples from the Ediacaran Bocaina Formation, Brazil, separated into five descriptive categories: elongate solid structures (ES); elongate filled structures (EF); two types of equidimensional structures (EQ 1 and 2) and elongate hollow structures with coiled ends (CE). These specimens, interpreted as diversified candidate metazoans, predate the latest Ediacaran biomineralized index macrofossils of the Cloudina-Corumbella-Namacalathus biozone in the overlying Tamengo Formation. Our new carbonate U-Pb ages for the Bocaina Formation, position this novel fossil record at 571 ± 9 Ma (weighted mean age). Thus, our data point to diversification of metazoans, including biomineralized specimens reminiscent of sections of cloudinids, protoconodonts, anabaritids, and hyolithids, in addition to organo-phosphatic surficial coverings of animals, demonstrably earlier than the record of the earliest known skeletonized metazoan fossils.
摘要：
埃迪卡拉-寒武纪过渡记录了动物多样化的关键阶段。全球化石记录记录了cloudinomorphs和其他带壳的管状生物的出现，其次是非生物矿化的小型碳质化石以及〜550至530Ma之间的高度多样化的小型架子化石。这里,我们报告了EdiacaranBocaina组的薄片和手样本中的各种微化石，巴西,分为五个描述性类别：细长实心结构（ES）；细长填充结构（EF）；两种类型的等维结构（EQ1和2）和带有盘绕末端的细长空心结构（CE）。这些标本,被解释为多样化的候选后生动物，早于上覆的Tamengo地层中Cloudina-Corumbella-Namacalathus生物区的最新Ediacaran生物矿化指数大化石。我们新的碳酸盐U-Pb年龄为Bocaina组，将这一新颖的化石记录定位在571±9Ma(加权平均年龄)。因此，我们的数据指向后生动物的多样化，包括生物矿化标本，让人联想到云纹切片，原牙,anabaritids,和hyolithids，除了动物的有机磷酸盐表面覆盖物，明显早于已知最早的骨骼化后生化石的记录。
