Silicified and Phosphatized Tianzhushania , Spheroidal Microfossils of Possible Animal Origin from the Neoproterozoic Doushantuo Phosphorites of Guizhou,South China
Silicified and Phosphatized Tianzhushania , Spheroidal Microfossils of Possible Animal Origin from the Neoproterozoic Doushantuo Phosphorites of Guizhou,South China
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作者：
Yue Zhao
对中国贵州省瓮安地区上新元古代陡山沱磷岩两种沉积物：燧石夹层（薄片研究）和磷矿/磷酸盐碳酸盐（薄片和浸渍）微化石的比较研究表明，磷化的Megasphaera ornata Shaw和Knoll，2000和燧石保存的天柱山石化石tuberifera Yin、Gao 和 Xing，2001，应被视为代表不同矿化过程保存的同一类群。在磷化样品中，外壁经常剥落，露出装饰的中壁。从岩石基质中分离出来的一些磷化样本和在磷矿薄片中看到的样本显示出部分保存的带有刺的外壁，这可以与来自燧石床的薄片样本进行比较。磷化标本装饰中壁表面常见的小凹坑与外壁刺的附着点相对应。多刺的外壁的存在是天柱山虫的一个特征 Yin and Li, 1978。Tianzhushania ornata (Xiao and Knoll, 2000) 梳子。十一月此处建议作为该物种的有效名称。不能排除所提出的T. ornata 的静卵性质，主要基于中壁的装饰类型。然而，多刺外壁的存在表明它是一种中上层生物而不是底栖生物。
Comparative study of microfossils from two kindsof sediments: chert intercalations (studied in thin section) and phospho-rite/phosphatic carbonate (in thin section and maceration), from the upper Neoproterozoic Doushantuo phosphorites in the Weng'an area, Guizhou Province, South China, shows that the phosphatized Megasphaera ornata Xiao and Knoll, 2000, and the chert-preserved Tianzhushania tuberifera Yin, Gao and Xing, 2001, should be regarded as representing the same taxon preserved by different mineralization processes. In phosphatized specimens the outer wall is often peeled off, exposing the ornamented middle wall. Some phosphatized specimens isolated from the rock matrix and specimens seen in thin sections of phosphorites show a partly preserved outer wall with spines, which can be compared to the thin-sectioned specimens from the chert beds. The small pits usually seen on the surface of the ornamented middle wall of phosphatized specimens correspond to the attachment spots of the spines in the outer wall. The presence of a spiny outer wall is a characteristic of Tianzhushania Yin and Li, 1978. Tianzhushania ornata (Xiao and Knoll, 2000) comb. nov. is here proposed as the valid name for the species. The proposed resting-egg nature of T. ornata, mainly based on the ornament type of the middle wall, cannot be excluded. The presence of a spiny outer wall, however, suggests that it is a pelagic rather than a benthic form.