Morphodiversity, complexity and macroevolution: revealed by the megascopic life of the Palaeo-Neoproterozoic Vindhyan Supergroup, India
Purnima Srivastava, 2012. "Morphodiversity, complexity and macroevolution: revealed by the megascopic life of the Palaeo-Neoproterozoic Vindhyan Supergroup, India", Palaeoproterozoic of India, R. Mazumder, D. Saha
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Evidence of past life found in the Vindhyan Supergroup exhibits extensive diversity and taxonomically unresolved morphological complexities indicating varied biological affinities, advanced life and macroevolutionary dynamics of evolving clades. The megascopic life of the supergroup documents possibly two macroevolutionary modes, demarcated as: (i) the Palaeo-Mesoproterozoic transitional period, which is represented by the fossil assemblages of the Semri and Rewa groups, and exhibits the domination of a diversified prokaryotic cyanobacterial community and moderately diversified megascopic life; (ii) the Neoproterozoic (Bhander groups, Uppermost Vindhyans), represented by the diversified and morphologically complex megascopic eukaryotes, and the emergence of multicellularity among plant and animal clades, viz. structures resembling bryophytes, sporophyte and Ediacara fauna. The overall Vindhyan fossils exhibit episodes of adaptive innovations and the emergence of complex morphologies in separate lineages of evolutionary history, resulting in extensive morphodiversity.
The present assemblage can be represented by that of prokaryotes, eukaryotes, possibly a symbiotic association, a Jacutianema-like Neoproterozoic form, specimens possibly of vaucheriacean affinity, mesoscopic intermediate forms inferred as transitional forms of microscopic–megascopic evolution, discs with process-like structures, the emergence of animal life (Ediacaran fauna) and a number of other complex morphologies that have no parallels in time and space. Traditionally and conventionally, the age of the Vindhyan Supergroup is considered to be that of Palaeoproterozoic–Neoproterozoic.
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Palaeoproterozoic of India
The Indian shield represents a vast repository of the Palaeoproterozoic geological record. Built over the four large amalgamated Archaean nuclei (Dharwar, Bastar, Singhbhum and Aravalli–Bundelkhand) the major and minor Palaeoproterozoic sedimentary basins and supracrustal sequences in India are comparable in scale, and perhaps also in development, to those of North America, Africa, Australia and Brazil. The deformation of these supracrustal sequences, attendant metamorphism and emplacement of plutonic bodies hold important clues to their connection with major orogenies. Research in these areas has led to investigations into global correlation, which in turn has had a direct bearing on refining models of Palaeoproterozoic supercontinent assembly and break-up. This book covers various aspects of regional geology as well as broader issues of the Indian Palaeoproterozoic geology and its global context. It is an outcome of the UNESCO-IGCP 509 Palaeoproterozoic Supercontinents and Global Evolution research project.