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The Permian-Triassic (P/T) mass extinction qualifies as the severest biotic perturbation in the history of our planet. Biomarkers, stable isotopes and palynomorphs are excellent proxies offering glimpses into palaeobiota and past ecosystems. These were investigated from coal-bearing upper Permian (Raniganj Formation) and Lower Triassic (Panchet Formation) Gondwana sediments recovered from the Raniganj Sub-basin, eastern India. The geochemical and palaeobotanical data suggest a shift in the terrestrial vegetation during the Early Triassic. A distinct change occurs from high abundance of n -C 23 and n -C 25 alkanes and higher CPI values in the upper Permian sediments to predominantly n -C 27 and n -C 29 alkanes along with relatively lower CPI values in the Lower Triassic. A sharp decline of the diterpenoid compounds and Glossopteridales pollens with a concomitant rise in lycopsid spores in the Lower Triassic sediments reflects the waning of a gymnosperm-dominated mire and onset of a stressed environment. Unlike the Glossopteridales, the Coniferales appear to be a resilient floral group with several new genera adapting to the growing arid conditions in the Early Triassic. The microbial community also responded to the contemporaneous ecosystem shift, with higher concentration of C 27 sterane relative to C 29 sterane in Lower Triassic sediments indicating proliferation of algal phytoplankton. The decreasing moretane/hopane (M/H) suggests that the soil bacteria were adversely affected plausibly due to enhanced soil erosion at the early part of the Triassic. A marked shift in the bulk isotopic composition (δ13C org) from higher values in the upper Permian sediments (˗21.0 to ˗24.1‰) to lower values in the Lower Triassic sediments (˗21.2 to ˗32.5‰) is diagnostic of a vegetation changeover as a result of environmental deterioration. This is the first integrated study using molecular organic geochemical proxies and palynology from terrestrial Gondwana sediments in the Indian subcontinent, designed to investigate the pattern of floral and microbial restructuring as a result of an environmental shift during the Permian-Triassic transition. • Biomarkers, δ13C org and palynomorphs reported from Gondwana sediments, India. • Molecular and palaeobotanical proxies suggest a declining palaeomire. • Changeover of vegetation as a response to environmental shift could be discerned. [ABSTRACT FROM AUTHOR]

The late Cretaceous Corsinipollenites from central India and its nearest living fossil pollen Ludwigia from Pleistocene Karewa sediments in Kashmir shows morphometrical affinities with pollen of seven extant Ludwigia species (L. octovalvis (Jacq) P.H. Raven , L. octovalvis subsp. sessiliflora (M.Micheli) Raven , L. adscendens (L.) H. Hara , L. perennis (L.), L. hyssopifolia (G.Don) Exell , L. peruviana (L.) H. Hara and L. decurrens Walt.) commonly growing in swampy ecosystems of India. The Field Emission Scanning Electron Microscope (FESEM) and Light Microscope (LM) study draws plausible lineage of extant Ludwigia species with that of fossil specimens recovered at two different time frames based on similarities in pollen morphometry. The pollen aperture and its character along with the sexine pattern were main identifiable features to distinguish different species of extant/fossil Ludwigia pollen. The aspidote aperture varies from brevi-colporate to slit-like colpi (colporate). The sexine is stenopalynous type characterized by rugulate to reti-rugulate pattern. The multivariate principal component analysis (PCA) was applied on the numerical data obtained from pollen morphometry of living and fossil Ludwigia spp. The Pleistocene Ludwigia morphotype with slit-like colpi shows close proximity to L. octovalvis, L. octovalvis subsp. sessiliflora and L. adscendens. However, Late Cretaceous, Corsinipollenitis characterized by brevicolpi is closer to L. perennis and L. hyssopifolia with respect to primary pollen characters and inferred as primitive species having lineage to the "Old World" (paleotropical) species. A short pollen key of Ludwigia spp., is presented here to enable the identification of living/fossil pollen. • Morphometry and morphology of seven extant species of Ludwigia from India. • A plausible lineage of living Ludwigia with their fossil pollen records. • Pleistocene Ludwigia and L. octovalvis subsp. sessiliflora shares similar pollen characters. • Late Cretaceous, Corsinipollenitis is similar to L. perennis and L. hyssopifolia. • Ludwigia perennis and L. hyssopifolia are primitive species having lineage to the "Old World." [ABSTRACT FROM AUTHOR]

We report studies of petrography, palynofacies, charcoal and adpressed plant fossils for the coal-bearing Jagannath section in the Talcher Coalfield, Mahanadi Basin, India, to improve understanding of the age, palaeoecology and depositional setting of this palaeo-mire. Palynology is indicative of the Scheuringipollenites barakarensis assemblage, suggesting an Early Permian (Artinskian) age for the studied section. The age of the studied section is inferred based on correlation with coeval assemblages across Gondwana. Palynoassemblages have more similarity with those of Africa than South America. Petrographic indices suggest that peat-forming vegetation accumulated mainly in telmatic settings under ombrotrophic-mesotrophic (intermittent fluctuating) hydrological conditions. Palynofacies suggest that the deposition of organic matter (by high energy fluvio-deltaic agents) took place in an oxic to occasionally dysoxic setting. Megaflora comprise a low diversity assemblage dominated by Equisetales (Schizoneura and Paracalamites), with less common Glossopteridales (Glossopteris , Gangamopteris) and Filicales (Dichotomopteris) indicative of dense arborescent vegetation. Numerous fossil macrocharcoal fragments indicate the repeated occurrence of wildfires in the catchment area. The high abundance of pyrogenic inertinites in Permian coals of Gondwana may indicate a high-fire phase of Earth history linked to elevated atmosphere oxygen level, and our current study further substantiates this idea demonstrating the occurrence of fire, not only in seasonally dry ecosystems but also in peat forming ecosystems under humid conditions. Our multiproxy study is significant for understanding Permian peat-forming ecosystems and environments and provides a robust age assessment based on inter and intra-basinal correlations of coeval sequences across the Gondwana. • An integrated approach depicting the palaeovegetation and depositional environment • Study resolves the ambiguity regarding the age of studied sediments in this basin • Accumulation of organic matter occurred under dysoxic-oxic conditions • Fossil charcoal indicate occurrence of palaeowildfires in the source area • Macerals group indicate significant contribution of higher plants for peat formation [ABSTRACT FROM AUTHOR]