Microbiota from the early precambrian of south India: Evolutionary significance and perspectives of biostratigraphy

Paleobiological study of the Dodguni chert and quartzite-like sandstone from the Dharvar Sedimentary Complex has shown the presence of numerous microorganisms of bacterial appearance. The possibility of contamination is doubtful as the rocks are characterized by great compactness without any joints. The microbiota is syngenetic. Morphologically they are represented by two varieties-coccoidal and filamentous forms which are found as typical colonial groupings. In some of the microorganisms the stages of development from reproductive cells to mature colony are seen. The symbiosis of filamentous forms of life with the colonies of coccoidal organisms is observed. Microfossils are reported from the light-coloured cherts and grey quartzite-sandstones. They are represented by 3 new genera which include 4 new species. Besides 3 new species referred to the genera Gunflintia Barghoorn, Eoastrion Barghoorn and Veteronostocale Schopf et Blacic are described. One species is identified with Gunflintia minuta Barghoorn. In the light coloured cherts the alga-like microfossils represented by one new genus Dodgunia are prevailing. In grey quartzite-sandstone microfossils are more diverse and are represented by two new genera hypothetically of bacterial nature. The complex of Dodguni microflora is of great interest for Precambrian palaeonthology since it occupies more ancient position when compared to Gunflint microbiota. The existence of representatives of genus Gunflintia in the Dodguni microbiota indicates certain evolutionary succession between these microbiotas. © 1983 Indian Academy of Sciences