华南滇东地区震旦(Ediacaran)系顶部Longfengshaniaceae藻类化石的发现及意义

Discoveries of Longfengshaniaceans from the Uppermost Ediacaran (Sinian)in Eastern Yunnan,South China and Significances

本文报道了在中国云南东部晋宁、江川地区的震旦(Ediacaran)系顶部渔户村组旧城段新发现的龙凤山藻科(Longfengshaniaceae)化石,与华北燕山地区新元古代青白口系长龙山组及北美中元古代小达尔群产出的Longf engshania化石明显不同,叶状体形态更为多样,呈梭形、枣核形、铲形、长条带形或球囊形等,拟茎较粗壮,与叶状体的接合很平缓,部分可见盘状、短茎状、披针状固着构造和叶状体萌生现象。依据形态记述了2属6种,包括1新属2新种3相似种,讨论和修订了龙凤山藻的科、属特征。华南滇东地区这些宏体藻类化石的发现进一步表明震旦(Ediacaran)纪末期也存在后生植物的多样化发展,可能为早寒武世“澄江生物群”的爆发性演化奠定了生态基础。

A morphologically more diverse assemblage of Longfengshaniaceae is found in the uppermost Ediacaran （Sinian） Jiucheng Member, Yuhucun Formation in Jinning and Jiangchuan County, eastern Yunnan, South China. A majority of them are different from Longfengshania in the Neoproterozoic Changlongshan Formation, Yanshan Mountain Area, North China and the Little Dal Group, North America. They are mainly characterized by a more varied, often thallus-like appearance, lack of branches, such as oval, pyriform, spindle, shovel, heart, ribbon, and balloon shapes, and more sturdy stalk-like projection （stipe）, with a smooth connection on the basal part of the thallus. In addition, they appear to have a remarkable attaching organ of lanceolate, shuttle-like or short stem-like structure at the base of the stipe. Six distinct morphological taxa are recognized, including one new genus, two new species and three conformis species. The characters of the family and the genus Longfengshania are further discussed and amended in this paper. The new discoveries of these carbonaceous macrofossils identified as Longfengshaniaceae algae on the basis of the diagnostic forms and anastomosis patterns of their thalli and stipes, demonstrate that an important evolutionary radiation of metaphytes took place in the last Ediacaran stage. Moreover this flourishing of benthonic thallophytes attached on the substrate from the eastern Yunnan, considered to be photosynthetic alga, probably provided continuous nutritional habitats for the explosion and diversification of the early Cambrian ＂Chengjiang Biota＂.