黔东北伊迪卡拉纪陡山沱组的宏体藻类

宏体生物广泛地生活于扬子地区伊迪卡拉纪陡山沱期的海洋中,它们为后生动物的快速发展和演化奠定了一个崭新的环境和一个新生态链的基础.产自于黔东北伊迪卡拉系陡山沱组的瓮会生物群生活环境应在贫氧的、透光性良好的浅海低能环境,以宏体藻类为主,共描述15属18种(其中包括3个新属、5个新种、2个修定属和4个修定种)和1个未命名藻以及不明藻类固着器,另包含有宏体后生动物,可能的后生动物以及遗迹化石.瓮会生物群不但含有鄂西庙河生物群和皖南蓝田植物群的分子,也有南澳大利亚Ediacara生物群和俄罗斯WhiteSea生物群的分子,而且具有自已的特征而有别于其他伊迪卡拉期的生物群.其宏体藻类形态变化较大,组织器官和功能已出现明显的分化,并与高等植物之间存在一定的演化关系.宏体藻类多为直立固着于海底,提高了光合作用的效率,增加了水体中的含氧量.同时,宏体藻类作为生态系统中的初级生产者成为一种新的食物,改变了后生动物的食谱.因此,陡山沱期的宏体植物不仅改善了环境,为依赖一定氧而生活、生长和繁殖的后生动物给予了必要的支持,而且作为生态系统中的必要基础,为宏体后生动物的快速发展和演化提供了一个新的食物源.另外,宏体生物群的繁盛不仅提高了有机质的生产率,而且促进了富有机碳的沉积和保存.

Macroscopic Algae from the Ediacaran Doushantuo Formation in Northeast Guizhon,Sonth China

Macroscopic algae widely lived in the Doushantuo-period sea of the Ediacaran in the Yangtze region, South China. They have successfully laid down an essential basis in a new environment and an ecosystem chain for the evolution and the development of the metazoan. The Wenghui biota, which is found in the Ediacaran Doushantuo Formation in Northeast Guizhou, is composed mainly of macroalgae (18 species of 15 genera, one unnamed macroalgae, and macroalgal holdfast forms described herein), and contains macroscopic metazoan, putative metazoan and trace fossils. This biota not only contains some elements of the Miaohe biota from West Hubei, the Lantian flora from South Anhui, the Ediacara fauna in Australia, and the White Sea biota in Russia, but also has its own characters to distinguish other Ediacaran biota. The diverse macroalgae of the Wenghui biota clearly show organic and functional differentiations with some exhibiting a relationship with higher plants. The Wenghui biota lived in the euphotic zone of shallow sea with lower-energy and poor oxygen. Numerous macroalgae settled on the deposits by their holdfasts, and their semi-floating bodies erected on sea floors. They advanced the photosynthetic efficiency and increased oxygen in water. In addition, the macroalgae served as a primary producer in the paleoecosystem to provide an alternative food for the metazoan. Therefore, the appearance of macroscopic algae not only improved the environment and played an essential support for the growth and propagation of the metazoan which depended on oxygen, but also provided a new food source that served as a new basis in the ecosystem for metazoan's evolution and development. Moreover, prosperous macrobiota not only increased the productivity of organic matter but also favored the sedimentation and the preservation of organic carbon.