有机壁微体化石 Tappania，最初发现和描述自我国山西永济地区约17—14亿年前古老的古元古代晚期—中元古代早期汝阳群北大尖组。随后，该形态属标本相继从印度、澳大利亚、西伯利亚、美洲等地的同期地层被发现和报道。无疑，它成为该地质时期生物地层对比的重要微体化石证据。由于它是自前寒武纪早期微体化石记录以来，被认定为最初具有动态细胞支架和膜系统的复杂有机壁真核微体化石，它成为干群真核生物在该古老地质时期演化趋异的见证。本文旨在认识 Tappania的形态特征及其生物亲缘，并探讨它的生活、繁衍生态环境和地质背景。结合已知古地理和地球化学研究资料，可推测Tappania 的出现与该地质时期的重大地质事件相关联。在古元古代晚期至新元古代早期的海水盆地中，尽管占主导地位的仍然是蓝菌和单细胞藻类，但是，具有渗析营养功能的多细胞真核生物在适宜生态环境已繁衍。

Organic-walled microfossil-Tappania was firstly described and reported from the Beidajian Formation of the Ruyang Group in the Yongji area,Shanxi Province,North China,which was deposited during the period of late Paleoproterozoic-early Mesoproterozoic in the period from about 1 700—1 400 Ma.So far,Tappania has been widely found in roughly coeval sediments distributed in India,Australia,Siberia,America,etc.Certainly,it becomes significant microfossil evidence of stratigraphic correlation in the geological time.Furthermore,it is recognized as a complex eukaryotic microfossil by possessing features like dynamic cytoskeleton and membrane system,and forms the evidence of indicating the divergence of stem group eukaryotes during the geological period. The paper is aimed to understand morphological features and biological affinity of Tappania and to discuss its ecological environment and relative geological background.In combination with paleogeographic and geochemical research data,it could be suggested that the appearance of Tappania was relevant with important geological events that happened in the geological interval. Though cyanobacteria and unicellular algae dominated in late Paleoproterozoic-early Neoproterozoic marine basins,some multicellular organisms with function of osmotrophy were already actively reproductive in the suitable ecological niche.

现代古生物学和地层学国家重点实验室(中国科学院南京地质古生物研究所)(No．173114)资助