Abstract: Abundant and preserved chain algal microfossils have been discovered in cherty stromatolitic mats from the second member of Gaoyuzhuang Formation (about 1,500 Ma old), Ling-qiu county of Shanxi province, China. They are described as Veteronostocale moniliforme Xu et Gao sp. nov.. The small diametral trichomes resemble the Family Nostocaceae in possessing specilized cells resembling the classic heterocysts and akinetes. This paper gives emphasis to the following remark: (1) The Gaoyuzhuang stromatolitic mats were products of microbial (Veteronostocale moniliforme) activity and the plant Nostocaceae was one of the main stromatolitic builders as both modern and Precambrian stromatolite-forming microorganisms; (2) Based on the fact that the chain fossils are preserved perpendicularly to the laminations the rates of sedimentation and algal growth were probably equal and each small sedimentary rhythm could be completed in about one or two months; (3) According to the environment and habits of living Nostoc Precambrian hydrosphere might be of a fresh water type.

Key words: Veteronostocale moniliforme Xu et Gao sp. nov., Algal mats, Late Preca-Mbrian