中国科学院南京地质古生物研究所研究员袁训来等合作发现一种埃迪卡拉纪晚期冠群海绵动物。2024年6月5日，《自然》杂志在线发表了该研究论文。

研究人员描述了华南地区灯影组（约5.51-5.39亿年前）的埃迪卡拉纪晚期化石Helicolocellus cantori。该化石被重建为一种大型茎基底栖生物，身体呈高脚杯状，高度超过0.4米，体壁由至少三阶嵌套网格组成，网格由四边形场定义，类似于康托尔尘埃分形图案。由此形成的网格被解释为一种有机骨架，由正交排列的十字形元素组成，在结构上与一些六放海绵纲海绵相似，尽管后者是用生物矿化的棘刺构建的。

通过贝叶斯系统发生学分析，H. cantori被认为是与六放海绵纲有关的冠群海绵。H.cantori证实了海绵在前寒武纪是作为具有有机骨架的非生物矿化动物而分化和存在的。考虑到硅质生物矿化可能在不同的海绵类别中独立演化，研究人员质疑将生物矿化的海绵作为鉴定前寒武纪海绵化石的必要标准的有效性。

研究人员表示，海绵是最底层的新元古代动物，可能在调节新近纪海洋的氧化还原结构方面发挥了重要作用。尽管分子钟预测海绵是在新元古代分化的，但它们的化石在寒武纪之前还没有明确的证据，这可能是因为前寒武纪的海绵是无刺、非生物矿化的。

附：英文原文

Title: A late-Ediacaran crown-group sponge animal

Author: Wang, Xiaopeng, Liu, Alexander G., Chen, Zhe, Wu, Chengxi, Liu, Yarong, Wan, Bin, Pang, Ke, Zhou, Chuanming, Yuan, Xunlai, Xiao, Shuhai

Issue&Volume: 2024-06-05

Abstract: Sponges are the most basal metazoan phylum1 and may have played important roles in modulating the redox architecture of Neoproterozoic oceans2. Although molecular clocks predict that sponges diverged in the Neoproterozoic era3,4, their fossils have not been unequivocally demonstrated before the Cambrian period5,6,7,8, possibly because Precambrian sponges were aspiculate and non-biomineralized9. Here we describe a late-Ediacaran fossil, Helicolocellus cantori gen. et sp. nov., from the Dengying Formation (around 551–539million years ago) of South China. This fossil is reconstructed as a large, stemmed benthic organism with a goblet-shaped body more than 0.4m in height, with a body wall consisting of at least three orders of nested grids defined by quadrate fields, resembling a Cantor dust fractal pattern. The resulting lattice is interpreted as an organic skeleton comprising orthogonally arranged cruciform elements, architecturally similar to some hexactinellid sponges, although the latter are built with biomineralized spicules. A Bayesian phylogenetic analysis resolves H. cantori as a crown-group sponge related to the Hexactinellida. H. cantori confirms that sponges diverged and existed in the Precambrian as non-biomineralizing animals with an organic skeleton. Considering that siliceous biomineralization may have evolved independently among sponge classes10,11,12,13, we question the validity of biomineralized spicules as a necessary criter

DOI: 10.1038/s41586-024-07520-y

Source: https://www.nature.com/articles/s41586-024-07520-y