我国西南地区震旦系陡山沱组微体遗迹化石的发现

目前世界上发现的最古老并得到普遍承认的动物化石是澳大利亚南部的伊迪卡拉动物群^15,16]。伊迪卡拉山的晚先寒武纪砂岩中发现有大型的相当进化的水母和蠕虫化石,其中含有直径数十公分的狄更逊虫(Dickinsonin costata)、体长3公分的枝沙蚕(Spriggina floundersi)以及遗迹化石等。其所在地层为寒武纪灰岩之下160米的庞德砂岩^1]。

THE DISCOVERY OF THE TRACE FOSSILS OF MICROBES IN THE ROCKS OF SINIAN DOUSHANTOU FORMATION SOUTHWEST CHINA

In the course of research on the phosphorites in southwest China, from 1980 to 1981, the author first discovered the trace fossils of microbes which, after being identified, is preliminarily named as Microptychoites fuquanensis Dong. It is well preserved in the rocks of Sinian Doushantou Formation aged 693?66 m.y., a little older than the trace fossils of Bdiacaran fauna in South Australia. The Ediacaran fauna, preserved in the rocks of Precambrian, aged about 579 to 700 m.y., has been universally accepted as the oldest one found in the world.The Microptychoites fuquanensis was also found in the phosphorite of Meishucun Formation, the lowest horizon of Lower Cambrian. Its discovery not only offeres the valuable materials for the study of the evolution of the Precambrian fauna but also facilitate the study of the depositional environment of the phosphorite.