Age of the Vastan Lignite in Context of Some Oldest Cenozoic Fossil Mammals from India

A highly diverse assemblage of mammal and other continental vertebrate fossils is reported in recent years from Vastan lignite mine (21°25'47" N; 73°07'30" E). Its importance in testing palaeobiogeographic hypothesis of mammalian dispersal in to or out of India has necessitated a definite age of the sequence. Nummulites burdigalensis is the only age diagnostic foraminifer in the section. This species is widespread in the Indian sedimentary basins and used to mark Early Eocene strata. In the present study two subspecies of Nummulites burdigalensis, viz., Nummulites burdigalensis burdigalensis and Nummulites burdigalensis kuepperi, are distinguished which led to further biostratigraphic refinement. Their concurrence in the section implies basal Cuisian age and shallow benthic zone SBZ 10 (most likely the lower part). The examination of this species from Kutch indicates the occurrence of evolutionarily advanced subspecies Nummulites burdigalensis cantabricus of middle Cuisian age (SBZ 11). Contrary to some recent reports, the study rules out the occurrence of N. globulus or any other Ilerdian foraminifer from the mine section.