Fossil Plants Research Articles

First indisputable fossil Ilex (Aquifoliales: Aquifoliaceae) flower found in Baltic amber.

The genus Ilex (holly) in the monotypic family Aquifoliaceae contains more than 600 species distributed worldwide. Pollen fossils and macrofossils of fruits of Ilex are known from the late Cretaceous (90Ma) and verified leaves from the upper Miocene (10Ma), but until now only a few more or less incomplete flower fossils have been suggested as referable to this genus. This paper reviews the fossil flowers earlier attributed to Ilex and presents a complete and indisputable staminate Ilex flower from Baltic amber (34-38Ma) examined in detail with synchrotron X-ray tomography. This finding may challenge the hypothesis of late Neogene dispersal of the genus from a center of origin in subtropical East Asia.

The Indo–Pacific Pollen Database – a Neotoma constituent database

Abstract. The Indo–Pacific Pollen Database (IPPD) is the brainchild of the late professor Geoffrey Hope, who gathered pollen records from across the region to ensure their preservation for future generations of palaeoecologists. This noble aim is now being fulfilled by integrating the IPPD into the online Neotoma Paleoecology Database, making this compilation available for public use. Here we explore the database in depth and suggest directions for future research. The IPPD comprises 226 fossil pollen records, most postdating 20 ka but with some extending as far back as 50 ka or further. Over 80 % of the records are Australian, with a fairly even distribution between the different Australian geographical regions, with the notable exception being Western Australia, which is only represented by three records. The records are also well distributed in the modern climate space, with the largest gap being in drier regions due to preservation issues. However, many of the records contain few samples or have fewer than five chronology control points, such as radiocarbon, luminescence or Pb-210, for the younger sequences. Average deposition time for the whole database, counted as years per centimetre, is 64.8 yr cm−1, with 61 % of the records having a deposition time shorter than 50 yr cm−1. The slowest deposition time by geographical region occurs on Australia's east coast, while the fastest times are from the western Pacific. Overall, Australia has a slower deposition time than the rest of the Indo–Pacific region. The IPPD offers many exciting research opportunities to investigate past regional vegetation changes and associated drivers, including contrasting the impact of the first human arrival and European colonisation on vegetation. Examining spatiotemporal patterns of diversity and compositional turnover/rate of change, land cover reconstructions, and plant functional or trait diversity are other avenues of potential research, amongst many others. Merging the IPPD into Neotoma also facilitates inclusion of data from the Indo–Pacific region into global syntheses.

Study on carbon emissions of a small hydropower plant in Southwest China

Hydropower plants with a small installed capacity, which are widely distributed in mountainous areas with abundant rainfall and steep rivers, play an important role in resolving energy problems in remote rural areas. These plants are a crucial source of clean electricity generated from water power. Harnessing local water resources not only helps alleviate energy shortages, but also reduces reliance on fossil fuels, contributing significantly to China’s national goals of achieving peak carbon emissions and carbon neutrality. This study investigates the carbon footprint of the Huangshadong Reservoir Project in Chongqing, China. The entire life cycle of the hydropower plant is assessed, including the preparation, construction, operation and maintenance, and demolition phases. The uncertainty was evaluated using the error propagation method. Following analysis, suggestions for carbon footprint reduction measures were proposed. Results showed that the total carbon footprint and the carbon intensity of the Huangshadong Reservoir Project over its entire life cycle are 33,148.29 t CO2e and 417.75 g CO2e/kWh, respectively. Of the total carbon footprint, the preparation phase, construction phase, operation and maintenance phase, and demolition phase account for 0.04%, 67.06%, 26.2%, and 6.7%, respectively. It means that the requirement for cement during the construction phase represents an important contribution to the entire life cycle carbon footprint of a small hydropower plant. As an integrated water conservancy project, the carbon intensity of the Huangshadong Reservoir Project is higher than that of medium-sized and large hydropower plants. However, its carbon intensity is lower than the emission factor of fossil power plants. The research results provide reference for both planning and construction of small hydropower plants and low-carbon development of rural hydraulic engineering.

Relationships between pollen assemblages and modern vegetation of the southern Gaoligong Mountains region, southwest China

Comprehensive understanding of the modern pollen–vegetation relationship is crucial for utilizing fossil pollen to reconstruct palaeovegetation, especially in mountainous areas of southwestern China. In this study, we present forty-five modern surface samples collected from five different vegetation communities of the southern Gaoligong Mountains region, and the vegetation composition was investigated at each sample site. The modern pollen assemblages were analyzed through multivariate analysis to evaluate the relationships between vegetation types and pollen assemblages, and to investigate the representation of major pollen types in different vegetation types. The results indicate that the surface pollen assemblages of different vegetation types reliably represent the modern vegetation. The median R-values of dominant pollen taxa in the Gaoligong Mountains region can be ordered as follows: Pinus > Alnus > Poaceae > evergreen Quercus. The over-representation of Pinus pollen, attributed to its high productivity and strong dispersal ability, makes it the dominant component of exotic pollen. Conversely, the under-representation of evergreen Quercus suggests that the presence of its pollen within a sample might indicate the growth of the local parent plant in the study area. The human activities in the region have a recognizable effect on the surface pollen spectra and also exert a significant negative impact on pollen diversity. Our study supplements the modern pollen database of the mountain regions in southwestern China, and provides representative modern pollen analogues to interpret fossil pollen records from southwestern China and similar regions.

The integration and transformative design research of plant dyeing techniques in Dong brocade with sustainable materials

Dong brocade, a fabric renowned for its intricate patterns and ethnic symbolism, has been woven by the Dong people for generations, showcasing their cultural significance. Traditional plant dyeing technology is one of the main aspects of Dong brocade but the documentation and understanding of this is still rather limited. With regard to the use of plant dye in Dong brocade, it is not as well explored as it should be since it has a traditional aspect. The main purpose is to investigate and apply the traditional plant dyeing technique to Dong brocade for the improvement of that sustainable concept and the preservation of cultural assets. Therefore, 121 Dong villagers were interviewed to elicit their awareness regarding prehistoric plant dyeing. By observing the dyeing conditions, this study provided accurate perception and learned how to differentiate between natural and synthetic mordants through ethnobotanical perception. The strategy is intended to integrate sustainable products into Dong brocade, employing orthogonal array development to find the right dyeing conditions for corresponding plant dyes. Research revealed that 8 genera of plants which include 7 species are used in dyeing Dong brocade. The findings presented in this work prove the effectiveness of the use of plant dyes in Dong brocade, showing its advantages with 30% of frequency and CI (Color Index) indices, 8% of them being cultural. 5 for ethnic cultural sustainment, developmental and bio-diversity reasons respectively. The unique integration between the traditional dyeing technique in Dong brocade and the utilization of sustainable resources is very promising for the improvement of identity enhancement and embodiment, and the preservation of the environment.

Reconstructing Terrestrial Paleoclimate and Paleoecology with Fossil Leaves Using Digital Leaf Physiognomy and Leaf Mass Per Area.

Climate and environment strongly influence the size, shape, and toothiness (physiognomy) of plants' leaves. These relationships, particularly in woody non-monocotyledonous angiosperms, have been used to develop leaf-based proxies for paleoclimate and paleoecology that have been applied to reconstruct ancient terrestrial ecosystems for the last ~120 million years of Earth's history. Additionally, given that these relationships have been documented in living plants, they are important for understanding aspects of plant evolution and how plants respond to climatic and environmental changes. To conduct these types of analyses on modern and fossil plants, leaf physiognomy must be measured accurately using a reproducible methodology. This protocol describes a computer-based method for measuring and analyzing a variety of leaf physiognomic variables in modern and fossil leaves. This method allows for the measurement of leaf physiognomic traits, in particular variables related to leaf serrations, leaf area, leaf dissection, and linearity that are used in the digital leaf physiognomy proxy for reconstructing paleoclimate, as well as petiole width and leaf area, which are used for reconstructing leaf mass per area, a paleoecological proxy. Because this digital leaf trait measurement method can be applied to fossil and living plants, it is not limited to applications related to reconstructing paleoclimate and paleoecology. It can also be used to explore leaf traits that may be informative for understanding the function of leaf morphology, leaf development, phylogenetic relationships of leaf traits, and plant evolution.

Review on Biodegradable Aliphatic Polyesters: Development and Challenges.

Biodegradable polymers are gaining attention as alternatives to non-biodegradable plastics to address environmental issues. With the rising global demand for plastic products, the development of non-toxic, biodegradable plastics is a significant topic of research. Aliphatic polyester, the most common biodegradable polyester, is notable for its semi-crystalline structure and can be synthesized from fossil fuels, microbial fermentation, and plants. Due to great properties like being lightweight, biodegradable, biocompatible, and non-toxic, aliphatic polyesters are used in packaging, medical, agricultural, wearable devices, sensors, and textile applications. The biodegradation rate, crucial for biodegradable polymers, is discussed in this review as it is influenced by their structural properties and environmental conditions. This review discusses currently available biodegradable polyesters, their emerging applications, and the challenges in their commercialization. As research in this area grows, this review emphasizes the innovation in biodegradable aliphatic polyesters and their role in advancing environmental sustainability.

Long-term Holocene warming trend in Southern China revealed by corrected pollen data

Holocene temperature changes and their forcings serve as pivotal references for current and future warming trends. However, significant discrepancies exist between proxy reconstructions and model simulations of Holocene temperature evolution. Pollen evidence, often central to these discrepancies, have been criticized for potentially reflecting human influence rather than pure temperature variations, complicating our understanding of Holocene temperature changes. Our study focuses on southern China, a region with pronounced discrepancies between models and proxies. We introduce and validate a novel methodology to isolate genuine temperature signals from pollen data. This approach employs an arboreal pollen-based temperature index and correct biases inherent in raw pollen data using the Regional Estimates of Vegetation Abundance from Large Sites (REVEALS) model. Applying this method, we present a new winter/annual temperature record for the past 10,000 years based on two fossil pollen data from the Luoxiao Mountains. Simultaneously, we reconstruct the historical impact of human activities in the region. Our temperature records reveal a sustained warming trend during the Holocene, closely matching model-simulated mean annual temperatures (R = 0.97), and temperature reconstructions based on branched glycerol dialkyl glycerol tetraethers from regional terrestrial and marine archives. In contrast, uncorrected pollen data indicate a cooling trend during the late Holocene, coinciding with significant human impact since approximately 3 ka BP. Our analysis and regional comparison with existing temperature records indicate that such contrasting temperature trends stem from a human-induced cooling bias, particularly pronounced in uncorrected pollen data. We infer that the early to middle Holocene warming was due to various factors, while late Holocene warming was predominantly driven by local annual insolation changes. Our findings challenge previously widely identified late-Holocene cooling trends based on uncorrected pollen data, demonstrating that the correction of pollen data can effectively mitigate human-induced cooling biases in temperature reconstructions. This study confirms the accuracy of climate models in simulating a Holocene warming trend, both temporally and spatially, at least in southern China.

Discovery of the enigmatic taeniopterid plant Ilfeldia from the lower Permian of North China and its palaeophytogeographical implications

ABSTRACT The recognition of plant biogeographic ranges over time and migration routes is crucial for understanding ancient global plate tectonic configurations. This paper deals with a new fossil plant from the uppermost part of the Taiyuan Formation (earliest Asselian) in the Wuda Coalfield, Inner Mongolia, China. It has a taeniopterid morphology comprising strap-shaped leaves with a prominent midrib and arching secondary veins, and it exhibits dimorphism between its fertile and vegetative leaves. The fertile leaf has a slightly lobed margin, with each lateral vein terminating in a marginal lobe that bears a synangium. Each synangium consists of primarily two, occasionally three, oval sporangia. Based on these distinctive characteristics it is identified as a new species of Ilfeldia. Previously, Ilfeldia had a highly restricted record in the Upper Pennsylvanian of Portugal and Germany into the lower Permian of Germany. The sedimentary and floral context suggests Ilfeldia was a xerophilous element that underwent long-distance dispersal during the Late Pennsylvanian to earliest Asselian, migrating from Gondwana (Iberia) to Cathaysia (North China) via Euramerica (Eastern Avalonia). The palaeogeographical distribution over time of Ilfeldia supports the continental model of the Wegenerian Pangaea configuration and underscores the continental connection between Euramerica and Cathaysia in the Late Pennsylvanian.

Understanding the presence of Cannabis across the Holocene in Central India

Pollen records from sediment cores do not allow understanding of past human use of Cannabis because Cannabis may also grow naturally or increase incidentally in the presence of human settlements. This is particularly true in Asia, where Cannabis was not used as hemp as often as it was in Europe; hemp retting makes it easy to identify Cannabis use as it causes characteristically high increases in Cannabis fossil pollen in strata where it was used. In this study, we evaluate the evidence for Cannabis cultivation and use in Central India, where Cannabis fossil pollen occur in sediment cores from ∼ 12.2 ka (1 ka= 1000 y ago). While the public perception is that Cannabis has a long history of use in South Asia, textual sources suggest significant increases in Cannabis use ∼1–2 ka. To disentangle Cannabis presence due to natural dispersal and due to use, we develop a new approach. Artemisia grows alongside Cannabis and disperses in similar conditions, whether naturally or due to increase in human settlements. We investigate when Cannabis increased in the paleo-record independent of Artemisia, and find that Cannabis increased ∼ 2.5 ka in areas close to major early historic settlements, where Cannabis displays characteristic patterns of cultivation. Cannabis does not display these patterns away from the early historic settlements. These dates are similar to findings of Cannabis use as hemp in the Himalayas (2.5 ka) and as a drug in China (2.7 ka), but pre-date the proliferation of Cannabis presence in textual sources. Overall, Cannabis pollen presence in pre-historic India (<2.5 ka), although common, is likely to be because of natural dispersal of Cannabis.

A palynological zonation for the Neogene of the Solimões/Amazon Basin, northwestern Amazonia

The tropical rainforests of northwestern Amazonia possess the highest plant diversity of any biome in the world. Understanding their origin, development, maintenance, and future in the face of ongoing global warming requires study of the plant fossil record and a predictive time framework. In this region, palynology is the best biostratigraphic tool because palynomorphs are the most abundant fossils. To construct a biostratigraphic zonation for the Neogene of the Solimões/Amazon basin in northwestern Amazonia, we analyzed palynological information from 25 sections, a total of 143,411 palynomorph grains from 622 samples. Using graphic correlation, we propose seven palynological zones that comprise the Miocene and a portion of the Pleistocene—the Pliocene is absent in the region. We then calibrated these zones against the geological timescale through correlation with a previously calibrated zonation and U/Pb geochronology.

The role of fossils for reconstructing the evolution of plant development.

Many of the developmental innovations that underpin the diversity of plant form alive today, such as those facilitating apical growth, branching, leaves, roots, wood and seeds, all evolved over 360 million years ago. Fossils, as our only direct record of plant form in the past, are thus essential for interpreting the origin and evolution of these innovations. The focus of this Spotlight is to showcase the rich plant fossil record open for developmental interpretation and to cement the role that fossils play at a time when increases in genome sequencing and new model species make tackling major questions in the area of plant evolution and development tractable for the first time.

The middle Miocene Hamjin flora and preliminary palaeoclimatic analysis of the Democratic People's Republic of Korea

The Hamjin flora was discovered from the Miocene Hamjin Formation of Hamjin-ri, Myonggan County, North Hamgyong Province. Taxodiaceae, Fagaceae, Betulaceae and Aceraceae are dominated and there are also plant fossils that are extinct in our country, such as dozens of extant species, and Liriodendron, Cercidiphyllum, Saysfras, Nyssa and so on. The Hamjin flora show that the climate at that time was warm and temperate. The plant fossils found in Hamjin area are of great importance for studying the evolution of flora and climate change from the Middle Miocene to the present.

The Passo das Tropas outcrop complex and the Dicroidium Flora in southern Brazil

The Dicroidium flora, composed of different genera of fossil plants, has its first records dating back to the Permian, expanded significantly in diversity in the Triassic, occupying several regions of the Gondwanan territory, becoming a biostratigraphic landmark for the Triassic. In Brazil, this paleoflora is found in the sedimentary rocks of the Santa Maria region, state of Rio Grande do Sul, in locations close to the Passo das Tropas Creek, an informal type section of the Passo das Tropas Member, of the Santa Maria Formation. Pioneering studies on the subject in the region began in 1952, at the Passo das Tropas outcrop, which described the first records of the Dicroidium flora. Over the years, different outcrops were found in this region, which also revealed this paleoflora, such as: “Dom Antônio Reis” outcrop, “Zenir Aita” outcrop and “Espuma” outcrop, where several paleontological collections were carried out. In addition to plant fossils, fish scales and insect wings were recorded in these outcrops. However, these outcrops were totally or partially buried due to the urbanization process in the city of Santa Maria and its surroundings, making further studies impossible. This article presents a historical and stratigraphic review, compiling the work carried out in the last 70 years on the outcrops of the Passo das Tropas Member and presents a new fossil site, the outcrop called Estância dos Montes. A total of 125 specimens were recovered from the Estância dos Montes outcrop, belonging to Dicroidium odontopteroides, D. zuberi, D. lancifolium, Umkomasia sp., Pteruchus sp., Neocalamites sp. and seeds. The fossils presented in this work come from a paleontological rescue carried out at the Estância dos Montes outcrop and are currently deposited in the Paleontological Collection of the Laboratório de Estratigrafia e Paleobiologia of the Universidade Federal de Santa Maria. Not only the importance of preserving and protecting fossil sites and their contents is highlighted, but also the uniqueness of these fossils for the valorization of the regional heritage of Santa Maria and the global relevance of adding more data to understand the biota during the Gondwanan Triassic.

Highland forest dynamics across equatorial East Africa during the end of the African humid period

Tropical mountain ecosystems hold immense ecological and economic importance, yet they face disproportionate risks from shifting tropical climates. For example, present-day montane vegetation of East Africa is characterized by different plant species that grow in and are restricted to certain elevations due to environmental tolerances. As climate changes and temperature/rainfall zones move on mountains, these species must rapidly adjust their ranges or risk extinction.Paleoenvironmental records offer valuable insights into past climate and ecosystem dynamics, aiding predictions for ongoing climate change impacts. In particular, warming and wetting in tropical East Africa during the mid-Holocene resulted in both lowland and highland forest expansion. However, the relative impacts of rainfall and temperature change on montane ecosystems along with the influence of lowland forest expansion on montane communities is not completely understood. We use fossil pollen to study the vegetation changes in two lakes at different altitudes in the Rwenzori Mountains, Uganda: Lake Mahoma (Montane Forest belt) and Upper Kachope Lake (Afroalpine belt). Further, using the newly relaunched African Pollen Database and recent temperature reconstructions, we provide a regional synthesis of vegetation changes in the Rwenzori and then compare this with changes observed from other equatorial East African montane sites (particularly Mt Kenya).In the early to mid-Holocene in the Rwenzori Mountains, trees common today in lowland forests dominated, driven largely by warmer temperatures. After 4000 years ago (4ka), Afromontane forest trees along with grasses progressively replaced lowland trees. Not all sites experienced identical transitions. For instance, at Lake Rutundu on Mt Kenya at the same elevation as Lake Mahoma, bamboo expansion preceded Afromontane forest growth, likely influenced by variations in fire. Variance partitioning indicates that each site responded differently to changes in temperature and rainfall. Therefore, these site-specific ecological responses underscore the importance of considering biogeographic legacies as management strategies are developed, despite similarities in modern ecology.

Atlas of the Oman pollen flora – Pollen morphology of the arid Arabian Peninsula vegetation

A precise and consistent fossil pollen identification is crucial for the reconstruction of (long-term) vegetation and climate dynamics. The inspection of local reference material serves as the best basis for meaningful results. Digital pollen reference collections, especially for the hyper arid regions of North Africa and the Arabian Peninsula are still sparse. Therefore, we want to contribute a descriptive and illustrated atlas of pollen from plants of the Sultanate of Oman. The atlas comprises around 400 pollen taxa on 43 plates from various habitats (e.g., mountains, wadis, deserts, coastal areas, and places shaped by human activities) characteristic for the arid environments of the Arabian Peninsula. It covers approximately 45% of all plant genera found in Oman. We provide high-resolution images of 402 taxa of 70 families as well as useful information on habitus, pollination, and habitat for each plant species as a useful guide for environmental reconstructions and interpretations from palynological investigations as well as the identification of pollen in honey.

The southwesternmost record of late Silurian (Pridolian) early land plants of Gondwana.

The Silurian-Devonian transition played a crucial role in the development of early terrestrial ecosystems due to the rapid diversification of early vascular plants. However, records of Pridolian plants in western Gondwana are scarce, limited to outcrops located in southern Bolivia. In this contribution, an association of fossil plants housed in the Rinconada Formation is presented. This association corresponds to primitive fossil flora with reproductive structures and sterile axes linked to basal tracheophytes. The fossil assemblage is composed of Aberlemnia caledonica, Caia langii Cooksonia cf. cambrensis, C. paranensis, C. cf. pertoni, Hostinella sp, Cf. Isidrophyton sp, Salopella marcensis, Steganoteca striata, two morphotypes of doubtful taxonomy, and graptolites colonies. The association between flora remains and graptolites, represents a parautochthonous assemblage in an inner marine platform, dominated by gravity flows. This record has paleophytogeographic importance indicating the extension of the northwest Gondwana-southern Laurusia unit to more southern areas of Gondwana. This expansion would have been favored by the post-glacial climatic improvement of the Late Silurian, together with a great radiation capacity and environmental flexibility of the flora. Furthermore, the biochron is extended of three taxa (A. caledonica, C. paranensis and Cf. Isidrophyton sp) first known from the Lochkovian, to the Pridoli.

Modern Abies, Picea, and Tsuga pollen distribution along the elevation gradient in East Asia

Sub-alpine dark coniferous forests (SCFs) exhibit distinct latitudinal and longitudinal elevation distributions in East Asia. The SCF genera Abies, Picea, and Tsuga produce distinctive pollen and have specific elevation and climate requirements, allowing for the reconstruction of paleo-climatic and paleo-elevational changes from fossil pollen sequences. However, the relationship between SCF elevational distribution and the percentage of coniferous pollen has not been elucidated at the continental scale. In this study, we determined the relationship between Abies, Picea, and Tsuga pollen percentages and SCF elevation distributions in East Asia using an integrated pollen dataset comprising 4863 modern samples. The total percentage of these pollen types showed bimodal patterns with elevation and unimodal patterns with climate. Maximum pollen percentages occurred at elevations of 0–1000 and 2000–4600 m, mean annual temperatures of −5–10 ℃, and mean annual precipitation values of 100–1500 mm. The elevation with the highest proportion of Abies + Picea + Tsuga pollen increased with decreasing latitude: from 500 m (>43°N) to 2300 m (37–43°N), to 3500 m (30–37°N), and to 4000 m (18–30°N). Elevation also exhibited non-monotonic variations with longitude, first increasing from 2500 m (<93°E) to 3500 m (93–102°E), and then decreased to 2500 m (102–113°E) and 500 m (>113°E). The spatial patterns of Abies, Picea, and Tsuga pollen abundance were closely correlated with modern SCF distributions, which are largely modulated by climate and elevation. This study lays the foundation for reconstructing paleo-climate and paleo-elevation variations across East Asia.

Reevaluation of pollen differentiation in Altingiaceae: Challenges in distinguishing deciduous (Liquidambar) and evergreen (Altingia) types using multivariate statistics and machine learning

Altingiaceae, a family of woody plants, comprising evergreen Altingia and deciduous Liquidambar groups, exhibits distinct leaf morphology, yet both groups overlap in geographical range and climatic conditions. While some tropical Altingia species are confined to Myanmar, Thailand, Cambodia and India without Liquidambar, and some temperate Liquidambar species to northern China without Altingia. Their fossil pollen have significant implications in reconstructing palaeoclimate and historical biogeography, based on classification of Altingia-type and Liquidambar-type. However, the results of previous studies to differentiate pollen types of evergreen Altingia and deciduous Liquidambar were based on limited pollen specimens. Therefore pollen morphology of Altingiaceae and differentiation of above mentioned types needs reevaluation using more specimens from wider geographical range.In this study, we present new findings on Altingiaceae pollen morphology from extensive collection of specimens and reassess the diagnostic features to distinguish evergreen and deciduous types. To improve the credibility of palaeoecological and palaeoclimatic interpretations, we applied multivariate statistical analyses to pollen size, number of pores, pollen wall thickness, and size and density of ornamental elements from light microscopy (LM) and Scanning Electronic Microscope (SEM) images. Additionally, random forest classification models were applied to test the accuracy of differentiating Altingiaceae pollen types. Our results reveal significant morphological overlap between the pollen of evergreen Altingia and deciduous Liquidambar, with classification models showing limited accuracy and explainability. Thus, fossil pollen of Altingiaceae cannot be confidently classified into evergreen or deciduous types, highlighting challenges in using their pollen morphology for taxonomic classification in palaeoecological research.

A new superfamily of freshwater mussels Deccanoidea nov. (Mollusca: Unionida) from an intertrappean deposit of Saurashtra province (Gujarat state, western India): An example of disjunct distribution

The Cretaceous-Palaeogene intertrappean deposits of the Deccan Volcanic Province of India comprise vertebrate, invertebrate and plant fossils of the dominantly continental realm. A 3–4 m thick shaly-sandstone lacustrine intertrappean sequence of Early Palaeogene (Palaeocene-Early Eocene) Bamanbor Formation, Chotila Basin (Saurashtra province, Gujarat State, western India) has yielded a collection of molluscans (bivalve and few gastropods) fauna. High-resolution digital photography and radiography of the recovered bivalves allowed us to gain detailed inferences on shell morphology. In a taxonomical context, we herein propose a new unionid molluscan superfamily Deccanoidea nov. represented by a single new family Deccanoidae nov. that includes two new subfamilies, that is, Deccanoinae nov. (represented by two new genera Deccanoida gen. nov. [including four new species: D. conrugis sp. nov., D. aleta sp. nov., and D. costaria sp. nov.] and Bamanboria gen. nov. [including one new species Bamanboria oblongis gen. et sp. nov.] and Chotiloinae nov. [represented by one new genus Chotilia gen. nov. and three new species: Chotilia trappeansis sp. nov., C. tuberculata sp. nov. and C. deccanensis sp. nov.]). Inorganic geochemistry of host (unionid-yielding) lithologies reveals oxic-freshwater conditions, humid-climate and moderate rainfall. The data on historical biogeography reveals that the Indian subcontinent hosted unionids during the late Cretaceous; however, the presence of new (at family/generic level) unionid fauna during the Early Palaeogene (Palaeocene-Early Eocene) in India indicates changes in the geographic position and ecologic condition linked to northward drift and lava outpouring, respectively. A disjunct distribution of unionid fauna in the erstwhile Gondwanan continents and insular India during the Cretaceous-Palaeogene interval can be explained in terms of both vicariance and dispersal.