The discovery and significance of the fossils from the Early Precambrian strata in the Yimen region, central Yunnan

The Palaeoproterozoic Yimen Group including six formations was established during the 1:50 000 regional geological survey in the last years in the Yimen region, central Yunnan. The abundant well-preserved macroscopic multicellular fossils were successively found in the greyish dark carbonaceous-muddy slates in the Liangshan Formation and the dark grey muddy limestones in the Yongjingshao Formation in the Yimen Group. The macroscopic multicellular fossils 20 cm in length were also found in the grayish purple muddy slates in the Meidang Formation in the Mesoproterozoic Kunyang Group. The microprobe and scanning electron microscopy analysis indicates that the compositions of the fossils collected from the above-mentioned Formations consist dominantly of the elements carbon, oxygen and phosphorus. The discovery will fill the fossil-free gaps in the Early Precambrian strata in Yunnan, and also will be important to the study of the early history of the Earth and lift evolution.