Abstract
The Indian Colloquium on Micropalaeontology and Stratigraphy (ICMS), started in 1971, has become a much-anticipated distinguished event. It is a pleasure to present this special volume, emerging from the 29th ICMS, held at the Department of Geology, University of Delhi, from 17 to 19 October 2024. As the convener of the conference and Guest Editor for this volume, I had the opportunity to watch the meeting take shape from its earliest planning stages to the lively discussions that unfolded across three days.
The colloquium brought together a broad spectrum of participants. Senior researchers, industry experts from the oil and mineral exploration sector, mid-career scientists and early-career scholars all contributed to the breadth and energy of the event. Their work spanned evolutionary micropalaeontology, taxonomy, Precambrian and Phanerozoic stratigraphy, palaeoceanography of the Atlantic, Pacific and Indian Oceans, palaeoclimate studies using multiproxy records, organic evolution, vertebrate palaeontology, palaeogeography and quantitative analyses of microfossil data. Delegates represented universities, IITs, National research institutes and industry, reflecting the long-standing strength and diversity of the micropalaeontological community in India.
Nineteen selected contributions represent all the major fields covered in the colloquium as per the theme of the 29th ICMS Fossils in stratigraphy, palaeoceanography and paleoclimate research. These contributions were invited and subjected to a rigorous peer-review process. I wish to put on record the valuable help, prompt responses and recommendations offered by the reviewers; without their help, this volume would not have been completed.
This special volume brings together papers that reflect that diversity. Many of the studies build on material presented at the conference, while several grew from discussions that took place during the meeting. The collection mirrors the themes that defined the colloquium: advancing biostratigraphy, improving environmental and climatic reconstructions, documenting evolutionary patterns, and applying microfossils to both fundamental and applied problems.
Palaeoceanography is the scientific study of how the ocean system has changed through Earth’s history. It aims to reconstruct past ocean conditions, enabling us to understand the evolution of the ocean–climate system and its role in shaping the planet’s environment. The field relies heavily on evidence preserved in marine sediments, which accumulate on the seafloor over millions of years and act as natural archives of physical, chemical and biological processes. A central component of these archives is microfossils. These are the remains of tiny marine organisms such as foraminifera, coccolithophores, diatoms and radiolarians. Because they are abundant, widely distributed and sensitive to changes in temperature, salinity, nutrient levels and water mass properties, microfossils serve as some of the most powerful tools for reconstructing past ocean conditions. Their shell chemistry records information about past seawater temperatures, variations in the carbon cycle and ocean circulation. Their species composition and abundance reflect shifts in productivity, nutrient supply and ecological responses to climate events. Palaeoceanographers, by combining microfossil evidence with geochemical tracers, isotopic signatures and sedimentary structures, can reconstruct past ocean temperature patterns, circulation pathways, sea-level changes, biogeochemical cycles and the timing of major climate transitions. This long-term perspective helps us understand how the oceans responded to natural climate variations in the past and provides key context for predicting future changes.
Studying past upwelling systems and the exchange of waters between the Indian and South Atlantic oceans is important because these processes shape how heat, nutrients and carbon move across basins. Upwelling zones drive high biological productivity and influence atmospheric carbon levels, so understanding how they shifted in the past helps explain changes in global climate and marine ecosystems. The interoceanic exchange through regions such as the Agulhas system plays a key role in linking the Indian Ocean to the Atlantic Ocean, thereby affecting the strength of the Atlantic Meridional Overturning Circulation. Reconstructing how these connections varied through time offers insight into past climate transitions and helps clarify how ocean circulation may respond to future warming.
A paper by Shrivastava and others discusses the palaeoceanography of the Benguela Upwelling System (BUS). This significant coastal upwelling zone affects regional productivity and influences the global climate through its connection to exchanges between the Indian and Atlantic Oceans. This study reconstructs one million years of BUS history using planktic foraminifera and stable oxygen isotopes from ODP Hole 1085A in the mid-Cape Basin. The assemblages, dominated by Neogloboquadrina pachyderma (Dex), Globorotalia inflata and the Agulhas Leakage Fauna (ALF), outline three phases of upwelling change: intense and persistent upwelling in the latest Early Pleistocene (1,000–800 kyr); a Middle Pleistocene interval marked by oligotrophic episodes and system reorganisation (800–400 kyr); and the rise of clear glacial–interglacial cyclicity in the Late Pleistocene (400 kyr to present). Upwelling in the latest Early Pleistocene was more intense and stable than in later intervals, matching the influence of obliquity-driven climate cycles. The Middle Pleistocene exhibits significant shifts, including weakened upwelling and a northward displacement of oceanic fronts during the Mid-Pleistocene Transition (MPT). In the Late Pleistocene, upwelling strength follows glacial cycles, with more vigorous activity during glacial and reduced Agulhas Leakage, reflecting interactions among trade winds, frontal movements and global ice volume. The study by Shrivastava and others shows that changes in Agulhas Leakage, closely tied to upwelling variability and large-scale climate processes, played a central role in the long-term evolution of the BUS and its contribution to the Atlantic Meridional Overturning Circulation.
The work by Singh and others complements these findings by further examining the dynamics of the Agulhas Current (AC) upstream. Based on planktic foraminifera and stable isotopes from IODP Hole U1474A, they reconstruct AC strength through the Pliocene and identify 11 episodes of weakening, including five in the Early Pliocene (4.35–3.6 Ma) and six in the Late Pliocene (3.4–2.67 Ma). These events align with periods of glacial expansion and growth of the Antarctic Ice Sheet, which likely pushed polar fronts northward, reducing both AC strength and Agulhas Leakage. Such weakening may have played a significant role in shaping the global thermohaline circulation during the Pliocene. Although the Pliocene was generally warm, it included four major glacial events at 4.8, 4.0, 3.3 and 2.7 million years ago (Ma) that altered ice-sheet behaviour and ocean circulation, as Singh and others revealed.
The Indonesian Throughflow (ITF) and the broader circulation of the Indian Ocean both play a significant role in shaping the AC as it flows along the Southeastern African coast. Warm, low-salinity waters from the western Pacific enter the Indian Ocean through the Indonesian seas and move westward as part of the South Equatorial Current (SEC). This water forms a significant fraction of the upper-ocean mass that feeds the Agulhas system. Variations in the strength of the ITF, driven by changes in Pacific winds, ENSO patterns and regional heat content, can shift the volume and properties of water entering the Indian Ocean. These changes affect the amount of warm water reaching the southwest Indian Ocean, which, in turn, influences the intensity of the AC and the rate of leakage into the South Atlantic. Indian Ocean dynamics, including monsoon-driven circulation, basin-wide temperature gradients and subtropical gyre variability, further modulate this transport. Together, these processes create a strong link between Indo-Pacific climate variability and the behaviour of the AC on timescales ranging from seasonal to glacial–interglacial. The Indian Ocean’s surface circulation, including the influence of ITF, has been discussed by Baruah and others, who present a study on the Indian Ocean’s surface circulation, which shifts seasonally with the monsoon, creating alternating intervals of nutrient-rich upwelling during the southwest monsoon and stratified, low-productivity waters during the northeast monsoon. This study reconstructs Early Pliocene (4.5–3.6 Ma) conditions in the Central Equatorial Indian Ocean using planktic foraminiferal assemblages from ODP Hole 716A to assess the influence of ITF restriction, monsoon strength and productivity. Habitat groups (mixed-layer, thermocline, eutrophic and oligotrophic indicators) and Principal Component Analysis show repeated switches between nutrient-poor and nutrient-rich states. Warm mixed-layer species dominate at 3.66–3.72 Ma, 3.81–4.0 Ma and 4.15–4.24 Ma, indicating stronger stratification, reduced nutrients and enhanced northeast monsoon conditions. Higher abundances of thermocline dwellers and productivity-related species in the 3.72–3.78 Ma record indicate upwelling events linked to Wyrtki Jet activity. The delayed first appearance of Pulleniatina obliquiloculata (P. obliquiloculata) around 3.6 Ma and the continued absence of P. spectabilis indicate limited intermediate-water exchange between the Pacific and Indian Oceans, consistent with a partially closed ITF. Such ITF restriction likely reduced Pacific inflow, shoaled the thermocline, lowered productivity, strengthened the northeast monsoon and contributed to the waning of the regional biogenic bloom. These results indicate that the Early Pliocene ITF restriction had a significant impact on Indian Ocean hydrography and monsoon variability during a warm climate interval.
The South China Sea plays an indirect but essential role in shaping the ITF and, in turn, the surface circulation of the Indian Ocean. As part of the western Pacific marginal seas, it exchanges water with the Indonesian seas through passages such as the Makassar and Karimata Straits. During periods of high sea level and strong winter monsoon conditions, more low-salinity surface water flows southward through the Karimata Strait, freshening the upper ITF and altering its density structure. Variations in wind patterns, monsoon strength and regional sea level further modify the volume and properties of water entering the Indonesian seas, which ultimately affect the flow entering the eastern Indian Ocean and shape the SEC, regional heat content and the broader Indo-Pacific climate connection. Within this broader Pacific–Indo-Pacific framework, Vats and others examine how climate variability rooted in the Pacific influences the East China Sea, a region directly affected by the Kuroshio Current (KC), which branches from the West Pacific Warm Pool. Their study focuses on the ENSO, which governs the distribution of heat, monsoonal rainfall and the vertical thermal structure of the Pacific. Using about 400 thousand years of thermocline-sensitive planktic foraminifera from IODP Site U1429, they apply Singular Value Decomposition to abundance data of N. dutertrei, G. inflata and P. obliquiloculata to extract three climate-linked modes. The first represents subsurface Kuroshio intrusion, the second captures Kuroshio-driven seasonal upwelling, and the third reflects residual ENSO-like variability. Trend-synchronisation tests indicate that stronger Kuroshio flow during interglacial periods, such as MIS 9, 7 and 5, was associated with La Niña-like conditions, characterised by deeper thermoclines. The results also indicate a strengthening of La Niña-like states over the last 150 thousand years and confirm that local insolation did not influence thermocline depth in the East China Sea.
The East China Sea is sensitive to large-scale climate processes originating in the tropical Pacific, particularly changes in the Eastern Equatorial Pacific (EEP), where variations in upwelling, thermocline depth and equatorial wind patterns influence the strength of the El Niño–Southern Oscillation. These shifts affect the position and properties of the KC, which transports heat and saline water from the western Pacific into the East China Sea. As a result, changes in the EEP—such as fluctuations between El Niño and La Niña-like states, cooling events driven by high-latitude forcing or reorganisations of tropical circulation—can leave a clear imprint on East China Sea hydrography, thermocline structure and regional climate. Mallick and others explore these far-field drivers by examining high-resolution planktic foraminiferal assemblages from ODP Hole 846B to reconstruct Quaternary palaeoceanographic variability in the EEP. Their record demonstrates that the EEP has been a highly dynamic system, shaped by repeated shifts in water-column structure, upwelling intensity and faunal composition, under the combined influence of tropical atmospheric variability and high-latitude forcing. The recurring appearance of the temperate species Globorotalia (Globoconella) inflata indicates episodes of cold-water incursions into the equatorial zone, suggesting stronger eastern boundary currents and connections with Antarctic climate processes. The persistent dominance of Neogloboquadrina dutertrei reflects the long-term influence of the equatorial cold tongue. At the same time, its weak association with coastal upwelling taxa suggests a decoupling between equatorial and Peruvian margin upwelling. Alternating patterns in mixed-layer and thermocline dwellers track shifts between El Niño- and La Niña-like conditions, and a major faunal reorganisation after the MPT signals intensification of glacial–interglacial cycles. Together, these findings highlight the strong influence of the EEP on regional oceanography and underscore the mechanisms by which tropical Pacific variability can propagate to marginal seas, such as the East China Sea.
Besides census counts and stable isotopes, planktic foraminiferal shell weight is widely used as a proxy in palaeoceanography because it reflects a combination of calcification conditions in surface waters and the degree of dissolution the shells experience as they sink through the water column and accumulate on the seafloor. Heavier, well-calcified tests often form when surface waters are supersaturated with respect to calcium carbonate. In contrast, reductions in shell weight can indicate lower carbonate saturation, enhanced dissolution, or changes in growth conditions linked to temperature, productivity, or seawater chemistry. When paired with test-size measurements and microscopic observations, shell weight provides valuable insight into past variations in carbonate chemistry, ocean circulation, nutrient supply and deep-water ventilation. Athul and others apply this approach to Late Pleistocene sediments from two deep-sea cores in the Central Indian Basin (BC 37 at 4,252 m and SVBC 37 at 3,992 m) to evaluate patterns of calcification and dissolution across glacial–interglacial cycles. They analyse shell weight, test size and SEM characteristics in three species with differing sensitivities to dissolution: G. menardii, P. obliquiloculata and N. dutertrei. Their results show that shell-weight variations track both climate-driven changes in surface-water calcification and deep-water carbonate saturation. Heavier tests during glacial intervals in G. menardii and N. dutertrei indicate improved preservation linked to higher carbonate ion concentrations. At the same time, SEM images reveal progressive test degradation during intervals prone to dissolution, such as MIS 11. Weak correlations between shell weight and size point to diagenetic overprinting, including wall thinning near the lysocline. Shifts in the lysocline and CCD, together with changes in monsoon-driven productivity, further influence preservation trends. The study highlights that shell-weight proxies capture the combined effects of calcification, dissolution and carbonate chemistry, providing insight into biogenic carbonate dynamics that are crucial for understanding both past climate shifts and future ocean acidification.
Uplifted Neogene marine sections on land provide a valuable complement to deep-sea cores, offering direct access to continuous, well-exposed sedimentary successions that can be studied in detail without the disturbances often associated with drilling. These outcrops preserve microfossil assemblages, sedimentary structures and geochemical signatures in their original stratigraphic context, allowing for the linkage of palaeoenvironmental trends with tectonic uplift, sea-level change and basin evolution. When combined with deep-sea records, land-based sections help build a more complete picture of past ocean conditions by connecting local and regional changes to broader oceanographic processes. Ghosh and others apply this approach to the uplifted Neogene sequences of the Andaman–Nicobar Islands, which preserve an exceptional archive of Miocene and Pliocene oceanographic history in the northeastern Indian Ocean. The basin contains mostly deep-water facies, with some shallow-water units, and its sediments comprise diverse fossil groups, including diatoms, radiolarians, Silicoflagellates, Calcareous nannofossils, and both planktic and benthic foraminifera. These onshore deposits, combined with micropalaeontological data from deep-sea cores, enable detailed biostratigraphy and the reconstruction of regional oceanographic changes. Microfossil evidence documents several significant events: The Middle Miocene Climate Optimum, stronger Indian summer monsoon winds and enhanced upwelling during the late Miocene and reduced biogenic silica, along with cooler conditions, in the Early Pliocene. A morphometric study of long-ranging calcareous nannofossils spanning approximately 16.4 to 4.54 million years reveals that size variations enabled these taxa to persist through changing environments, while radiolarian shell-volume trends indicate a gradual decline across the late Neogene. Silicoflagellates also add constraints on past sea-surface temperatures. Together, these uplifted sections and offshore cores provide a coherent view of Neogene palaeoceanographic evolution in the region, illustrating how land-based archives enrich interpretations drawn from deep-sea records.
Planktic foraminifera are among the most valuable archives for reconstructing past monsoon variability because their species distributions, vertical habitat preferences and ecological tolerances respond quickly to changes in surface hydrography. Variations in upwelling intensity, mixed-layer structure and nutrient supply all leave clear imprints on assemblage composition. Oligotrophic species tend to thrive when winds and nutrient delivery are weak, while eutrophic and upwelling-linked taxa increase when monsoon winds intensify and drive higher productivity. By tracking these shifts through time, planktic foraminifera offer a direct window into past changes in the strength and structure of the Indian summer monsoon. Majumder and others build on this approach by analysing Core SK291/GC17 from the eastern Arabian Sea, which spans roughly the last 25,000 years. Their results indicate that during the Last Glacial Maximum, the dominance of oligotrophic and mixed-layer species, along with reduced proportions of eutrophic and thermocline taxa, suggests a weak monsoon and suppressed upwelling. A significant transition occurs with the early Holocene, when higher abundances of G. bulloides, G. glutinata and P. obliquiloculata indicate stronger winds, enhanced productivity, and a shoaling thermocline. A later decline in these taxa, between approximately 6,000 and 3,500 cal yr BP, marks a return to reduced monsoon strength, deeper thermocline conditions and a landward shift of the upwelling zone as sea-level rose. Their record, when compared with other G. bulloides datasets across the region, highlights the spatial complexity of eastern Arabian Sea hydrography and underscores how planktic foraminiferal assemblages capture the shifting imprint of monsoon variability over glacial–interglacial and Holocene timescales.
Planktic foraminiferal morphology provides a powerful tool for reconstructing past oceanographic, climatic and ecological conditions. Variations in shell size, chamber arrangement, aperture shape, coiling and wall thickness reflect environmental factors such as water temperature, salinity, nutrient availability, productivity and water mass properties. These morphological traits can record adaptive responses to both short-term ecological stress and long-term climatic shifts, making them valuable proxies for understanding past ocean conditions and ecosystem dynamics. Chaudhary and colleagues applied this approach to N. pachyderma in the Southeast Atlantic Ocean, documenting eight distinct morphotypes based on detailed morphometric measurements and analyses of surface ultrastructure. N. pachyderma, a polar-dwelling species, has historically been used to track glacial–interglacial cycles through coiling ratios, and its morphology continues to reflect changes in water mass properties and climatic conditions. Differences in chamber arrangement, packing and aperture shape capture subtle environmental variations, highlighting the species’ sensitivity to polar water dynamics.
Similarly, Shinde and colleagues examined G. menardii in the Bay of Bengal to understand its morphological and ecological responses over the past ~34,000 years. Their analyses of size parameters, including maximum and intermediate diameters and keel thickness, showed clear links to climate and stratification-driven productivity. Abundances and test sizes increased during warm intervals, such as the Bølling–Allerød, the Holocene and the Medieval Warm Period. In contrast, they declined during cold events, including the LGM and Heinrich events. Depth-wise patterns revealed well-developed, symmetrical tests in younger sediments, whereas in older layers they were irregular and underdeveloped, reflecting ecological stress. Correlation analyses confirmed proportional development among size parameters and highlighted the interplay between climate, nutrient availability and depositional depth in shaping morphology. Together, these studies demonstrate how planktic foraminiferal morphological variation can serve as a sensitive proxy for past oceanographic and ecological changes.
Diachronism in the first and last appearances of planktic foraminifera provides critical insights into past oceanographic conditions. Differences in the timing of species’ first occurrences (FOs) or last occurrences (LOs) across regions can reveal variations in local environmental conditions, migration pathways and changes in ocean circulation. By tracking these diachronous patterns, researchers can infer shifts in water mass properties, dispersal routes and the influence of climatic events on species distributions, offering a dynamic view of past marine ecosystems and circulation networks. Singh and Sinha applied this approach to examine the extinction dynamics of G. obliquus and G. extremus across multiple deep-sea cores in the Indo-Pacific region. They document pronounced diachrony in the last occurrence of G. obliquus, which persisted beyond the mid-Quaternary and survived into the Holocene at several sites. In contrast, the extinction of G. extremus was relatively synchronous. The diachronous persistence of G. obliquus is attributed to local palaeoceanographic conditions, particularly oligotrophic upper-ocean mixed layers, whereas the synchronous disappearance of G. extremus reflects competitive exclusion and large-scale ocean reorganisation that began in the Late Pliocene. Shifts in dominance within Ecogroup-1 planktic foraminifera, coinciding with the onset of Northern Hemisphere Glaciation, highlight major changes in mixed-layer hydrography and interspecific interactions. Their findings demonstrate that diachronous first and last appearances can illuminate regional ocean circulation patterns, migration pathways and ecological controls, while also cautioning against using single-species LOs as universal stratigraphic markers.
Beyond the periodic monsoon, driven by the land–sea thermal contrast and the seasonal movement of the ITCZ, cyclones have also played a major role in reshaping lagoonal environments and influencing their biodiversity. In many coastal lagoons, the position of the sea mouth has never been fixed. Before large-scale engineering interventions, cyclones and intense storms were often the main forces altering these inlets. Their surge and wave energy could breach natural barriers, redirect channels and periodically flush the system with seawater. These episodic events affected salinity, sedimentation and oxygen levels, leaving distinct ecological signatures in benthic communities. Sediment archives from such settings preserve these shifts and help clarify how storm-driven inlet dynamics shaped lagoon ecosystems through time. Rath and others illustrate this well in their study of Chilika Lagoon, where they reconstructed ecological shifts over the past two centuries using foraminiferal assemblages from a dated sediment core. Their results show that between 1820 and 1940, the lagoon remained highly restricted as the sea mouth migrated northward, with Ammonia beccarii dominating under low-salinity, poorly flushed conditions. From 1940 to 1975, the system evolved into a moderately brackish environment, characterised by the rise of agglutinated taxa associated with suboxic bottom waters resulting from tidal restriction and sediment accumulation. Between 1980 and 2000, the near-closure of the natural sea mouth led to severe ecological stress and an almost complete loss of foraminifera, broken only by short-lived appearances tied to cyclonic incursions of seawater. After 2000, the creation and maintenance of an artificial sea mouth restored more stable marine exchange, yielding higher foraminiferal abundance, greater diversity and improved oxygen conditions. Their work demonstrates how storm-driven shifts in the natural inlet, combined with subsequent human intervention, have shaped Chilika’s ecological trajectory over the past 200 years.
Tree rings are valuable proxies for reconstructing past climate variability because their growth responds sensitively to temperature, precipitation and other environmental factors. By analysing annual or seasonal growth increments, researchers can infer variations in rainfall, drought, temperature extremes and broader climatic drivers over centuries. One key driver investigated using tree-ring records is solar activity, which influences Earth’s climate through changes in irradiance and interactions with atmospheric circulation. Dutt and Pandey applied this approach to explore the impact of solar variability on climate in the northwestern Indian Himalaya. They developed long chronologies from Himalayan cedar and Neoza pine from Lahaul, Himachal Pradesh (1384–2017
Foraminifera are also recognised as sensitive indicators of environmental stress in marine ecosystems due to their rapid response to changes in water quality, pollutants, and sediment chemistry. Their short life cycles, abundance, and species-specific tolerances make them effective bioindicators for monitoring marine pollution, particularly heavy metal contamination. By analysing morphological abnormalities, growth patterns, and mortality in foraminiferal populations, researchers can assess the impact of pollutants on benthic communities and infer ecological health and water quality. Kurtakar and colleagues applied this approach to investigate the toxicological effects of arsenic on benthic foraminifera, focusing on juvenile specimens of the shallow-water species Rosalina sp. Exposed to arsenic concentrations ranging from 20 to 220 µg/L over 26 days under controlled laboratory conditions, the foraminifera exhibited progressively greater morphological abnormalities and mortality as arsenic levels increased. Specimens subjected to higher concentrations (180–220 µg/L) exhibited early mortality within 12–16 days, whereas those at intermediate concentrations survived longer but showed limited growth, indicating stress. These results highlight the extreme sensitivity of Rosalina sp. to arsenic contamination and reinforce its utility as a reliable bio-indicator for marine ecotoxicological studies, demonstrating the broader importance of foraminifera in tracking coastal pollution and ecosystem health.
The evolution of life on Earth, particularly the rise and diversification of eukaryotes, is intricately recorded in the fossil record of microscopic organic-walled microfossils. Acritarchs and similar Proterozoic-age microfossils are especially valuable because their abundance, diversity and morphological complexity provide insights into early eukaryotic evolution, ecological adaptations, and global biogeochemical cycles. By analysing these microfossils, researchers can track the timing of evolutionary innovations, shifts in marine ecosystems, and the appearance of complex cell structures long before the advent of macroscopic life. Yogesh Kumar and colleagues emphasise this importance through their study of organic-walled microfossils from the Owk Shale of the Kurnool Group, Cuddapah Supergroup, South India. The described assemblage includes Weissiella grandistella, Galeasphaeridium bicorporis, Galeasphaeridium sp., Germinosphera bispinosa and Tanarium tuberosum, all characteristic of the Ediacaran Period. Using high-power binocular microscopy and Confocal Laser Scanning Microscopy (CLSM), the authors reveal detailed morphological features, many of which were previously unobservable under transmitted light microscopy. The Owk Shale acanthomorphic acritarch assemblage closely resembles Ediacaran Complex Acanthomorphic Palynomorphs (ECAP) documented elsewhere, demonstrating increased complexity and diversity in late Neoproterozoic microfossils. This study not only reinforces the Ediacaran age of the Kurnool Group but also provides clear evidence for the presence of ECAP in the southern Indian subcontinent, highlighting the broader significance of acritarchs as markers of early eukaryotic evolution and biogeographic patterns.
Understanding Early Permian floral diversity and associated palaeoenvironments is crucial for reconstructing past terrestrial ecosystems, climate conditions, and the depositional settings that supported coal formation. Plant assemblages, both macrofloral and palynofloral, offer insight into vegetation composition, ecological interactions and climatic preferences. Palynofacies analyses, on the other hand, help identify the nature of sedimentary environments and energy conditions. Studying these assemblages allows palaeobotanists to track evolutionary trends, biogeographic patterns and the responses of plant communities to changing climate during the Permian, a period marked by major environmental and tectonic shifts. Saxena and colleagues employed a multiproxy approach to reconstruct the Early Permian flora and palaeoenvironment of the Kurasia Colliery, Chirimiri Coalfield, Son Basin, India, utilising morphotaxonomy, palynology and palynofacies analyses of a coal-bearing sequence. The megafloral assemblage shows moderate diversity, comprising three main groups: Cordaitales, Glossopteridales, and Equisetales. Cordaitales include Noeggerathiopsis (N. elongata, N. hislopi, N. minor, and Noeggerathiopsis sp.) and two seed genera, Cordaicarpus karharbariensis and Samaropsis ganjrensis. Glossopteridales are represented by Gangamopteris (G. angustifolia, G. cyclopteroides, G. major, G. rajaensis, and Gangamopteris sp.), Glossopteris (G. communis, G. decipiens, G. major, G. nautiyalii, G. raniganjensis, G. spatulata, and Glossopteris sp.) and the seed genus Alatocarpus. Equisetales include Paracalamites sp. and Raniganjia bengalensis. Palynological analysis revealed a monosaccate-dominated assemblage with Parasaccites, followed by Plicatipollenites, bisaccate Scheuringipollenites, and other marker taxa such as Crucisaccites and Callumispora, correlating well with the Upper Karharbari Formation of the Godavari Basin. The combined megafloral and palynofloral composition, including abundant bisaccate pollen and large leaves, indicates warm, temperate, and humid conditions suitable for coal formation. Palynofacies analysis further suggests a dominance of structured phytoclasts, reflecting deposition in low-energy, suboxic-to-dysoxic forest-swamp environments. This study underscores the value of Early Permian floral records in reconstructing palaeoecology, climate, and depositional environments.
Echinoids are important palaeontological indicators for reconstructing past marine environments, biogeography and evolutionary patterns, owing to their sensitivity to water depth, temperature, and substrate conditions. In the Cenozoic sediments of the northeastern Himalaya, echinoid fossils provide critical evidence for the timing of marine transgressions, the retreat of the Tethys Ocean, and the progressive uplift of the Himalayan orogen. Their stratigraphic and biogeographic distributions allow researchers to trace ancient marine connections and understand how tectonic events influenced sedimentation and faunal dispersal in the region. Lokho and colleagues report the first occurrence of Eupatagus faurai and Echinolampas vilanovae from the Sylhet Limestone of the Mikir Hills, Assam, representing middle Eocene (SBZ 16–18; late Lutetian–Bartonian) deposits. These species, found alongside echinoid spines, provide strong evidence for a direct marine connection via the Neo-Tethys Seaway between northeastern India, the northwestern Himalayas, and Western Europe during the Eocene. The presence of these echinoids indicates a warm, shallow marine environment, contributing to an understanding of the culmination of the Neo-Tethys Seaway and shedding light on its role in shaping the Himalayan uplift and the retreat of the Tethys Ocean.
Miocene shark teeth are valuable palaeontological tools, providing insights into the diversity, ecology, and evolutionary history of ancient marine ecosystems. Due to their high preservation potential and species-specific morphology, shark teeth enable the reconstruction of past faunal assemblages, trophic structures and environmental conditions, as well as the biogeographic and migration patterns of elasmobranchs. Their occurrence also helps interpret depositional settings, sea-level changes and connectivity between marine basins. Amardas Singh and colleagues highlight this significance through their study of the Baripada Beds (Upper Miocene) along the eastern coast of India, a fossil-rich sequence yielding sharks, batoids, teleost fishes, reptiles, mammals, invertebrates and microfossils such as foraminifera and ostracods. Recent fieldwork at Mukurmatia and Itamundia recovered over 200 additional shark and batoid teeth, documenting nine families, including Carcharhinidae, Hemigaleidae, Alopiidae, Myliobatidae, Dasyatidae, Pristidae, Rhynchobatidae, Rajidae and Sphyrnidae. The study reports the discovery of new elasmobranch species from the Indian Miocene, including Carcharhinus amblyrhynchoides, C. brevipinna, C. perezi, C. plumbeus, Physogaleus hemmooriensis, Physogaleus sp., Aetobatus cappettai and Taeniurops sp. The associated fauna and microfossils indicate deposition in a coastal, lagoonal, nearshore environment under neritic conditions connected to the open ocean. Beta diversity analyses reveal close affinities with South Pacific and Indo-Pacific Miocene elasmobranch faunas, suggesting shifts in migration pathways following the permanent closure of the eastern Mediterranean Seaway. This study underscores the value of Miocene shark teeth in understanding ancient marine biodiversity, palaeoecology and biogeographic patterns.
Geochemical analysis of clastic sediments is a fundamental tool for reconstructing the history of sedimentary basins, as it provides information on sediment provenance, weathering intensity, tectonic setting and palaeoclimate. By examining the compositions of major and trace elements, geochemists can infer the sources of sediments, the degree of chemical maturation, and the depositional environments, thereby revealing the evolution of sedimentary basins over geological time. Such analyses also help link sedimentary records to regional tectonics, including basin formation, fault activity and source-area uplift, thereby offering a comprehensive picture of basin development and sediment dynamics. Sen and others applied this approach to the Vindhyan Basin (~1.7–1.0 Ga), the largest Precambrian sedimentary succession in India, which spans the central regions (Son Valley, Bundelkhand) and the western parts (Rajasthan). Their study focused on the Lower Kaimur Sequence (LKS), particularly the Chittor Fort Sandstone (CFS; ~1.1 Ga) in Rajasthan, and compared it with contemporaneous Son Valley deposits, including the Sasaram Sandstone, Ghurma Shale and Markundi Sandstone. The CFS exhibits alternating sandstone and shale lithofacies. Geochemical indices, such as SiO2/Al2O2, K2O/Na2O and CIA values, indicate moderate to intense chemical weathering under a warm, humid climate, producing compositionally mature sediments. Tectonic setting analyses using Th-Sc-Zr/10 and La/Sc–Ti/Zr diagrams suggest deposition in a passive margin environment for sandstones. In contrast, the shales reflect a continental island arc signature. Trace element ratios and plots, including Th versus Sc and [Gd/Yb]n versus Eu/Eu*, indicate a post-Archean continental to intermediate source. Provenance analyses reveal that the Hindoli Group (~1.8 Ga) of the Aravalli–Delhi Fold Belt supplied the shales, while sandstones derived mainly from the Berach Granite (~2.5 Ga) of the Banded Gneissic Complex. The study highlights that collisional tectonics around ~1.6 Ga and reactivation of the Great Boundary Fault influenced sediment supply, with lower LKS receiving detritus from the Hindoli Belt and the upper part dominated by material weathered from the Berach Granite, illustrating how geochemical analyses can trace basin evolution, provenance shifts and tectono-sedimentary processes over Precambrian timescales.
The success of this conference was made possible through the support of many individuals and institutions. I am especially grateful to the Honourable Vice-Chancellor, Professor Yogesh Singh, for serving as Chief Patron and providing the necessary facilities and financial support to host the event. The University of Delhi offered generous assistance, and colleagues in the Department of Geology contributed steady help at every stage of planning and execution. Generous financial support by ONGC, ONGC Videsh, Oil India, Beicip-Franlab India, CSIR, SERB, MoES, NCESS, NCPOR and INSA played an essential role in making the 29th ICMS a reality. I am grateful to Professor Anil Kumar Gupta, President of the 29th ICMS, for delivering the illustrious Presidential Address. It was published separately as a booklet. I also thank Professor M. P. Singh and Dr Rajiv Nigam, former and present President, respectively, Professor Mukund Sharma, Chief Editor of the Journal of the Palaeontological Society of India and Vice President of the Palaeontological Society of India, for accepting the proposal to publish a special issue for the 29th ICMS held at the University of Delhi. Finally, I would like to thank all contributors for their hard work and look forward to the continued growth of this community.
No event of this magnitude is possible without the dedicated efforts of students, research scholars, and postdoctoral fellows, who worked tirelessly throughout the event. I am grateful to all of them.
It is satisfying to see the work from the conference carried forward into this volume. I hope it serves as a valuable record of current research, encouraging new collaborations and ideas. Micropalaeontology and stratigraphy continue to play a central role in understanding the Earth’s past, and the studies included here demonstrate the richness and activity of the field.