“江南古陆”东北端上溪群中，发现了虫牙类化石和疑源类化石组合，为这套地层的准确定时，提供了直接证据。经鉴定，这一化石及化石组合的时代为寒武－奥陶纪，而不是以往所认为的中元古代。这些化石的发现说明依据岩体同位素年龄确定围岩年龄具有不确定性，另外，这一发现对研究该区的构造演化史具有重要意义。 In the Shangxi Group at the northeastern tip of “Jiangnan Old Land,” pest-type fossils and suspected fossil assemblages were found, providing direct evidence for the accurate timing of this formation. It has been identified that the age of this fossil and fossil assemblage is Cambrian-Ordovician instead of Mesoproterozoic as previously thought. The discovery of these fossils shows that it is uncertain to determine the rock age based on the age of the rock mass. In addition, the discovery is of great significance for studying the tectonic evolution history of the area.