Recent advances on Phanerozoic Biodiversity, bioevents and climate in India

Abstract

In the present write up, a synthesis of the research done in the last four years in vertebrate palaeontology, palynology, ammonoid biostratigraphy and stable isotope geochemistry is presented. SB and GVR discuss the issues relating to Cretaceous-Palaeogene (K-Pg) boundary bioevents in India and their linkage to Deccan volcanism, Jurassic and Cretaceous diversity of dinosaurs and elasmobranchs-origin and evolution of archaic mammals of Cretaceous - Early Eocene age during the northward flight of India, their biogeographic relationships, evolution of whales and Neogene mammals. In a related discussion, VP discusses on the time of origin of grass family Poaceae and rice tribe Oryzeae based on the analysis of late Cretaceous dinosaur coprolites and sediments bioevents at the K-Pg boundary in Um Sohryngkew River section in Meghalaya, NE India and the effects of environmental stress from Deccan volcanism on Palaeogene flora presently restricted to Western Ghats, the role of dinoflagellates in dating the highly diversified mammal-bearing levels within the Vastan lignite mine, and the presence of dipterocarp angiosperm trees in the Early Eocene of India and thus supporting the "out of India Dispersal" hypothesis for this group of plants. JK presents a comprehensive picture on the refined Triassic and Jurassic ammonoid biozonation in the Himalayan and western Indian regions, respectively, sequence stratigraphic framework of Mesozoic marine sequences of India, and the relationship between major tectonic events of the Indian ocean and sea level changes. AS discusses the relevance of isotopic studies across Permo-Triassic boundary and Eocene/Oligocene boundary in understanding the extinction of plants and the role of silicate weathering in the Himalaya, respectively, forced regressive event in the Palaeogene of the Himalayan foreland basin linked to the early phases of Himalayan uplift, development of palaeosols with the expansion of C4 vegetation in Ganga-Brahmaputra delta plain during the last glacial maximum (LGM), and different episodes of monsoon intensification that coincide with major pulses in the Himalayan uplift based on hydrogen isotopic studies of Quaternary Siwalik palaeosols.