THE FIRST RECORD OF VENDIAN MEDUSOIDS AND TRACE FOSSIL-BEARING ALGAL MATGROUNDS FROM THE BASAL PART OF THE MARWAR SUPERGROUP OF RAJASTHAN, INDIA

摘要

A new biostratigraphically significant medusoidal Ediacaran fossil Marsonia artiyansis gen. et sp. nov. has been reported from the Sonia Formation of the Jodhpur Group of Rajasthan. This is the first record of Vendian (600-546 Ma) medusoids from the Marwar Neoproterozoic Basin. The medusoids have been attributed to the Class Scyphozoa on morphological basis. They are associated with trace fossils Planolites sp. and Skolithos sp. and patchy algal mats. The biotic association has definite Ediacaran affinity and is suggestive of Vendian age for the host lithounit. This palaeontological age assignment is congruent with the known radioactive ages for the underlying Malani volcanics. These fossils also suggest biogeographic extension of the Ediacaran biota to the western India and endorse possible stratigraphic correlation of the Jodhpur Group of the Marwar Supergroup of Rajasthan with the Ediacarabearing Bhander Group of the Vindhyan Supergroup of the central India. The Jodhpur metazoan and metaphytic association is also congruent with the Vendian ecological scenario of the world.