Herein, we present a diverse record of dinoflagellate cysts from the lignite-associated sedimentary succession (belonging to the Akli Formation) at Sonari Lignite Mine, Barmer Basin, Rajasthan State, western India. The dinoflagellate cyst assemblage implies a Danian to Ypresian age for the investigated succession and argues that the deposition of lignitic sequences along India's western margin is not coeval. We also identify two vertebrate (dominantly fish-yielding) units within the studied Akli Formation succession. The Ypresian fish genera (mainly represented by dental remains) include Ginglymostoma, Jaekelotodus, Brachycarcharias, Pycnodus and Myliobatis while the Selandian-Thanetian fish dental remains include Dasyatis. A discontinuous distribution of fish fauna during the early Paleogene (based on the temporal and spatial data) within the lignite-associated sedimentary successions of western and north India allows us to infer the prevalence of separated realms with variably restricted palaeoenvironmental conditions. Overall, the faunal evidence is indicative of dominantly estuarine to shallow marine conditions with enhanced freshwater influence during the Thanetian as compared to the Danian. Our study also argues in favour of the earliest appearance of dinoflagellate cyst Apectodinium in the near-equatorial region of the Tethys Ocean during the early Paleocene. (within Danian).

The Deccan-associated sediments (Lameta and intertrappean deposits) hold great potential for understanding the role of Deccan Volcanism in the late Maastrichtian ecological upheaval. However, it is challenging to ascertain Deccan Volcanism driven floral changes on the Indian Plate due to unresolvedstratigraphyic and lack of well-dated terrestrial sequences. We provide a thorough palaeobotanical, palaeoclimatic and palaeobiogeographic review of the pre-Deccan (Lameta deposits) and syn-Deccan (intertrappean deposits) sequences. We present a detailed palynological analysis of C29R magnetochron intertrappean section from Yeotmal, central India, depicting episodic regional floral responses to volcanism. We have critically reviewed the Indian Maastrichtian palaeofloral and palaeoclimatic records within the best-resolved chronologies to clarify the spatiotemporal changes in palaeovegetation and palaeoclimate pertaining to the Deccan Volcanism. Furthermore, we evaluated the global fossil records of all the nearest living relatives of the studied assemblage to enhance our understanding of the genesis of the late Maastrichtian flora of the Deccan Volcanic Province. Our study showcases three stages of the Maastrichtian floral succession, corresponding to a quiescent phase between two secondary magmatic pulses of the C29R Magnetochron. Palaeowildfires and massive magmatic outflow caused by the active volcanism severely damaged the pre-existing flora. Progressively, confined and diminished volcanism at Stage-I allowed few aquatic and herbaceous species to flourish within the accessible lacustrine habitats. The dormant volcanic activity at Stage-II, in conjunction with the warm (MAT- similar to 26 degrees C) and moist (MAP- similar to 2270 mm) conditions due to latitudinal shifting of the Indian Plate within the Inter Tropical Convergence Zone, facilitated rapid expansion and diversification of the low-lying megathermal angiosperm forest within various habitats along shallow embayments. The gradual resurgence of volcanic activity at Stage-III resulted in widespread wildfires and forest knockdowns. The swift revival of the hyper-diverse tropical flora during the quiescent phase (Stage-II) does not show long-term (millennial scale) adverse impact of the Deccan Volcanism on the Indian Maastrichtian flora. The palaeobotanical and palaeoclimatic review suggests a consistent subtropical to tropical climate on the Indian Plate during the late Maastrichtian. However, a shift in seasonality from a seasonally dry climate supporting gymnosperm-angiosperm flora during the pre-Deccan phase to a seasonally wet climate and angiosperm-dominated flora during the syn-Deccan phase is noticeable. Furthermore, the palaeobiogeographic analysis suggests that much of the Maastrichtian biodiversity on the Indian Plate is a consequence of floral influx from South America and Africa via the Kohistan-Ladakh Island arc. Nonetheless, 41.2 % of the palaeoendemic taxa in the studied palynoassemblage signify substantial in-situ evolution and diversification of tropical angiosperms on the Indian Plate. Consequently, the observed floral and climatic changes during the Maastrichtian period should not solely be attributed to the Deccan Volcanism but to a combination of variables. These include the shifting of the Indian Plate within the Inter Tropical Convergence Zone, enhanced warm and humid climate due to high CO2 emissions, episodic nature of the Deccan Volcanism, persistence of rich spore and seed stock in legacy flora, better physiological adaptibility of angiosperms for wet climate regimes and tropical floral influx from contiguous biotic corridor.

Arecaceae (palms) is a pantropical plant family with an ancient origin. It shows distinct spatial patterns of species richness in tropical regions having greatest diversity within the Neotropical regions and Southeast Asia. The wider palaeobiogeographic records of palms in relation to current distribution requires a re–examination of their palaeobiogeographic history. The present study reports eleven fossil pollen form–species from the early Palaeogene of India, enhancing our understanding of the evolution of four palm subfamilies: Arecoideae, Calamoideae, Coryphoideae and Nypoideae, on the Indian Plate prior to the India–Asia collision. We suggest the dispersal of diverse palms from Africa to India via the Kohistan– Ladakh Island Arc during Maastrichtian–Palaeocene as part of the Africa–India Floristic Interchange. Subsequently, with wet and humid climates across much of the Indian Plate during the Palaeocene–early Eocene, they underwent a phase of diversification and adaptation leading to habitat expansion. Thus, Indian Plate served as an evolutionary hotspot for the diversification of palms during the early Palaeogene. An in–depth investigation of Palaeogene palm fossils revealed that many palms, currently endemic to Southeast Asia, initially evolved and diversified on the Indian Plate and later dispersed to Southeast Asia following India–Asia collision. The present study thus favours the “Out–of–India” dispersal hypothesis for the Asian palms. The expansion of seasonal climates, and aridification during Neogene and Quaternary led extinction in numerous palm lineages on the Indian subcontinent. This study proposes that deep time climate change and plate tectonism have highly influenced the heterogeneity in spatial and temporal distribution of Asian palms.

Meliaceae is an important angiosperm family having floristic and ecological significance in major biomes, especially in tropical rainforests. Well preserved leaflet and pollen comparable to the extant genus Swietenia of the Meliaceae from the late Paleocene-early Eocene sedimentary horizon of the Gurha lignite mine, Rajasthan (western India) are described. The genus Swietenia (usually called mahogany) has scarce and fragmentary fossil records, and its evolutionary and paleobiogeographic history is partly understood. The fossil leaflet is characterized by an asymmetrical microphyll-sized lamina with an entire margin, festooned brochidodromous venation, mainly mixed percurrent tertiary and freely ramified quaternary veins, whereas the fossil pollen grains have a tetra-colporate aperture, relatively short colpi, alolongate pore, and a thick and laevigate exine with pitted to psilate ornamentation. These early Paleogene fossils are the oldest known fossil records of the genus Swietenia and add a new perspective to its paleobiogeographic distribution in Southeast Asia during the early Paleogene and this study would encourage future research endeavors to elucidate the evolution and diversification of the economically important group encompassing the genus Swietenia.

Around 37% of the Mediterranean territory is covered with polyploid angiosperms, of which the genus Linum occupies a considerable region. Linum is the most diversified genus of the plant family Linaceae that comprises a “family pair” of Hugonioideae distributed in tropical regions and Linoideae mainly distributed in temperate to subtropical regions. We provide the oldest fossils of Linaceae, comparable to the living genera Linum and Reinwardtia, from the Late Cretaceous Infratrappean Deccan volcano sedimentary sequences of Maharashtra, India. The phylogenetic analysis conducted by combining the morphological characters of the pollen fossils recovered and the pollen morphological as well as molecular characters of extant species of Linaceae reveals that the family originated in the wet and warm tropical zones of South America in the Late Cretaceous. Thereafter, the family dispersed to Africa giving rise to the lineage of Linoideae that further diverged into two main clades, one of which evolved either on seasonally wet areas of Kohistan-Ladakh Island arc (KLIA) or on the Indian Plate in Maastrichtian-Paleocene. The second clade encompassing the genus Linum originated on seasonally wet areas of Africa and later dispersed to Mediterranean region via Boreotropical route in Paleocene where it adapted to seasonally dry climatic conditions that prevailed during late Eocene. The family further expanded its geographical range and spread to Eurasia, and to North America via Bering land bridge. We also propose the dual colonization of Linaceae in India. The seasonally wet lineages dispersed from Africa to India via KLIA in the Maastrichtian-Paleocene. Whereas, the seasonally dry lineages of Linum migrated from Eurasia into India probably during the Oligocene when the climatic conditions were dry and warm arid. The decline in global temperature towards the end of Eocene escalated the diversification rates within Linaceae that is currently found in the regions of meso- and microthermal climate. The next major shift in diversification rate was detected on the crown node of North American Linaceae during the Middle Miocene Climate Transition.

Euphorbiaceae Juss. is a globally distributed angiosperm family with considerable diversity. It is divided into five subfamilies, each of which possesses pollen of distinct morphology. The subfamily Crotonoideae, occurring in evergreen, moist deciduous as well as dry deciduous forests of the world, shows a disjunct distribution pattern in Gondwana and Southeast Asia. This subfamily underwent multiple speciation and extinction events during the northward voyage of the Indian Plate during the Late Cretaceous-early Paleogene. We studied Crotonoideae fossil pollen from the Late Cretaceous Deccan Intertrappeans (Central India) and early Paleogene sediments from the western Indian lignite mines, and as a result, report 10 pollen fossils showing similarity with the extant genera Blachia, Croton, Endospermum, Jatropha, Klaineanthus, and Tetrorchidium, representing 4 tribes of Crotonoideae viz. Adenoclineae, Codiaeae, Crotoneae, and Jatropheae. Fossil evidences from the present study suggest a Gondwanan origin for Crotonoideae. Based on the extant and fossil species, Africa could be the place of origin for most of the Crotonoideae lineages that later dispersed to India via the Kohistan-Ladakh Island Arc during the late Maastrichtian-Paleocene time. The former distribution of Crotonoideae in mid-high latitudinal regions is due to the dispersal of the subfamily from Africa to mid latitudinal regions of northern hemisphere during the early Paleogene via the boreotropical dispersal route. This study also corroborates the "Out of India" hypothesis for the dispersal of Crotonoideae from India to Southeast Asia. The present deep-time fossil records from India discussed in this study substantiate the evolutionary and biogeographic history of subfamily Crotonoideae.

The evolution and diversification of ancient megathermal angiosperm lineages with Africa-India origins in Asian tropical forests is poorly understood because of the lack of reliable fossils. Our palaeobiogeographical analysis of pollen fossils from Africa and India combined with molecular data and fossil amber records suggest a tropical-African origin of Dipterocarpaceae during the mid-Cretaceous and its dispersal to India during the Late Maastrichtian and Paleocene, leading to range expansion of aseasonal dipterocarps on the Indian Plate. The India-Asia collision further facilitated the dispersal of dipterocarps from India to similar climatic zones in Southeast Asia, which supports their out-of-India migration. The dispersal pathway suggested for Dipterocarpaceae may provide a framework for an alternative biogeographic hypothesis for several megathermal angiosperm families that are presently widely distributed in Southeast Asia.

Many plant families lack substantive fossil records, limiting our understanding of their origin and evolution. The abundance and preservation potential of pollen through geological time have helped to overcome such limitations and have provided reliable fossils for reconstructing biogeographical history and character evolution in many angiosperm families. Here, using scanning electron microscopy, we identified six Ebenaceae-type fossil pollen grains from early Palaeogene sediments of western India. Phenetic and phylogenetic analyses using pollen characters of fossil and extant taxa reavealed affinities of these fossils to three genera of Ebenaceae (Euclea, Royena and Diospyros). Furthermore, our divergence dating analysis using these fossils as priors suggested a Gondwanan origin for the family during the mid-Cretaceous [c. 107 Mya, 95% highest posterior density (HPD): 100–112 Mya] and supports the boreotropical and ‘out of India’ dispersal hypotheses as the most probable explanations for the present global distribution of the family. The study also supports the dispersal of the family into India, from Africa, through the Kohistan–Ladakh Arc during the Palaeocene. Finally, comparative phylogenetic analyses suggest significant synapomorphic and phylogenetic signals for a few selected pollen characters in Ebenaceae. Our findings have important implications for understanding the biogeography and evolution of the highly diverse and ecologically and economically important family Ebenaceae.

AngiospermsAngiosperm being the most dominant plant community in the terrestrialTerrestrial landscape, naturally invite a look in to their evolutionEvolution/Evolutionary relationships. AngiospermsAngiosperm originated during the Middle Triassic in fern and gymnospermGymnosperm dominated ecosystemsEcosystem, diversified and completely covered the terrestrialTerrestrial landscape by the LateLate Cretaceous CretaceousCretaceous/Cretaceous-Paleogene Boundary. In this paper, consistent fossil angiospermAngiosperm pollenPollen grain evidences from across the globe are being assessed to unravel the evolutionary history of angiospermsAngiosperm. The bulk of fossil evidences suggestEarly Cretaceous Early CretaceousCretaceous/Cretaceous-Paleogene Boundary origin of angiospermsAngiosperm while some of the fossil evidences do point to the presence of angiospermsAngiosperm in the TriassicTriassic. Diversification of angiospermsAngiosperm in the low latitudinal regions during mid CretaceousCretaceous/Cretaceous-Paleogene Boundary period provides evidence that the warm and humidHumid climate during CretaceousCretaceous/Cretaceous-Paleogene Boundary must have played an important role in the proliferation and diversification of tropicalTropical angiospermsAngiosperm. Biogeography of most of the tropical angiospermAngiosperm familiesFamilies/Family can be linked with the continental plate tectonicTectonic history. This review is an attempt to bring together the palynologicalPalynological/Palynology evidences that place angiospermAngiosperm evolution in perspective.

The eastern state of Odisha, India is well known for its rich microlithic assemblages; over 400 sites have been reported, including some with tools for heavy-duty tasks. However, due to the lack of associated vertebrate fossils from stratified horizons and absolute dates, their antiquity and associated environments are yet to be established. We report here, for the first time, in situ fossils of a ruminant C-14 dated to 17,875 cal BP associated with microliths from a stratified Quaternary sequence exposed at Pratappur, District Mayurbhanj, Odisha. The dental remains of ruminants are taxonomically identified to be those of the cervid Rusa unicolor (sambar) and an unidentified bovid. Stable carbon and oxygen isotope values (delta C-13 = 1.9 parts per thousand; delta O-18 = - 1.83 parts per thousand, VPDB) on the Rusa unicolor tooth reveal that it was a C4 grazer and lived in an arid environment during the end of the Last Glacial Maximum. However, the bovid-yielding carbonaceous sediments that lie immediately above the R. unicolor horizon have yielded a large number of pollen and spores, belonging to moist deciduous forest suggesting moderate rainfall. Pollens belong to brackish mangrove Nypa and Barringtonia indicating tidal influence and the existence of a coastal environment nearby.

The Dipterocarpaceae plant family, that shows a disjunct distribution in Gondwanan continents and Southeast Asia, is a dominant constituent of the tropical rain forests of Southeast Asia.The high species diversity of Dipterocarpaceae in SE Asian rain forests suggests its origin from SE Asia.However, its fossil history is much younger, from Oligocene, from the region.Based on the pollen fossil records from the late Cretaceous-early Paleogene sedimentary sequences of Indian subcontinent and the contemporaneous distribution of its extant taxa, evolutionary history of Dipterocarpaceae has been traced.The study suggests a West Gondwanan origin for this family.Present study also provides first evidence of Dipterocarpaceae genus Vateriopsis (endemic in Seychelles) type fossil pollen record from the late Cretaceous and early Palaeogene sedimentary sequences of western Indian margin.

Angiosperm evolved and diversified during Cretaceous. During this course of evolution and radiation, various pollen of uncertain origin had evolved. Aquilapollenites represents the early stock of angiosperms attaining its acme with respect to diversity and dominance during Campanian and Maastrichtian age. It was globally present (except Antarctica) however more dominant in northern hemisphere (Canada, North America, Sakhlain Oblast and China). In India, the Aquilapollenites sp. is present in Maastrichtian aged deposits. The pollen affinity has been associated with Loranthaceae and Santalaceae plant families. Here, a comparative description of all the Aquilapollenites sp. comprising a wide range of morphological diversity has been discussed. The wider morphological diversity and ecological adaptability of Aquilapollenites sp. infer that it is globally significant and warrants a more detailed study.