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This work documents for the first time a palynological assemblage in the Rajmahal Basin, tentatively considered probable youngest Late Pennsylvanian assemblage, which was hitherto considered early Permian. The palynocomposition consists of 39 species (5 spores, 25 monosaccate, 5 bisaccate- 3 non striate and 2 striate grains, scarce Navifusa sp., scolecodont, algae and fungal hyphae). Two assemblages are described based on the first appearance of taxa, Assemblage I (608.90–599.00 m) dominated by monosaccates and absence of bisaccates and spores. Assemblage II (592.0–590.80 m) also dominated by monosaccates but with the inception of spores, bisaccates and marine palynomorphs. The Assemblage I is correlated to the oldest Potonieisporites neglectus Assemblage Zone of Tiwari and Tripathi based on their similarities and the absence of species recorded in the Assemblage II which is correlated to their overlying Plicatipollenites gondwanensis Assemblage Zone. Palynoassemblages similar to the Assemblage I, radiometrically constrained to the Late Pennsylvanian across Gondwana, along with the lack of diagnostic Permian pollen grains as well as marine Eurydesma fauna and terrestrial glossopterids, tentatively support an older age at least for the lower interval of the Talchir Formation. The latter fossils associated to Assemblage II confirm an early Permian age. [ABSTRACT FROM AUTHOR]

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]