The Upper Pennsylvanian is characterised by significant climatic fluctuations and marks the expansion of complex dryland ecosystems. However, these ecosystems are much less well-documented than the coal-forming environments of the Carboniferous, since plant fossils preserve poorly in dryland environments. One of the markers of Upper Pennsylvanian mesophytic to xerophytic environments is Lesleya Lesquereux. Here we report a new assemblage of Lesleya from the Westphalian D of the La Mure Basin (Isère, France). Nearly 68 specimens were recovered, belonging to two taxa, L. cf. grandis and L. belledonnensis sp. nov. In addition, the informal taxon Lesleya Ře 3, described previously from the Westphalian B–D of the Bohemian Massif (Czech Republic), is reassigned to L. belledonnensis sp. nov. Lesleya belledonnensis sp. nov. occurs in plant fossil assemblages dominated by giant leaves of Cordaites and rare taxa exhibiting xerophilous characters both in France and Czech Republic. Moreover, the extensive sampling at Vaulnaveys-le-Bas allows us to identify successive stages of taphonomic degradation of Lesleya leaves and provided insights into the taxonomic and paleoecological significance of margin-related leaf characters of the genus Lesleya.
The Middle Jurassic plant macrofossil assemblage from the Stoilensky opencast mine (Belgorod Region, European Russia), of which some representatives of ginkgoaleans, leptostrobaleans and conifers had been published earlier, comprises remains of cycadophytes. Among them, bennettitalean leaves are numerous. A new species of the Bennettitales, Pterophyllum oskolicum sp. nov., is described based on the study of morphology and epidermal features. Leaves of this species are characterized by very thin segments and by the presence of one stomatal zone in the abaxial epidermis, which is not sunken in a groove. In addition, we have found a leaf fragment similar to the leaves of Ptilophyllum riparium from the Middle Jurassic of the Moscow Region, Russia. Remains of cycadaleans occur in small numbers of specimens only. Two species of Ctenis, Ctenis sp.1 and Ctenis sp.2, are described. Besides these remains, several unidentifiable dispersed cuticles of bennettitaleans and cycadaleans have been encountered. We were unable to assign them to any genus because data on their leaf morphology are either absent or insufficient. Data on fossil cycadophytes from the Middle Jurassic of the Stoilensky opencast mine were obtained for the first time. A comparison of data on cycadophytes from the Belgorod Region with that of Middle Jurassic floras of the East European platform reveals that all identified taxa are common elements of these floras.
The Cenozoic fossil record of Myrsine (Primulaceae) in Europe is largely based on leaf macroremains of uncertain taxonomical attribution and consequently remains poorly understood. In this study, we report the first well-documented European fossil pollen record attributable to early representatives of Myrsine based on exceptionally preserved palynological assemblages from the As Pontes and Laracha basins (northwestern Spain). The studied material, assigned to Eucommiopsispollenites compactus, was analyzed using light microscopy, scanning electron microscopy, and confocal laser scanning microscopy. The pollen grains exhibit a distinctive combination of characters that allow confident attribution to extant Myrsine, including tetra- to pentacolporate apertures, short colpi, thick exine, and weakly scabrate ornamentation. The occurrence of Myrsine in Rupelian deposits dated to approximately 30 Ma demonstrates that the lineage had already reached the westernmost margins of Eurasia by the early Oligocene, shortly after the estimated origin of the crown-group in the Indo-Malayan region. This finding predates the timing proposed by current molecular biogeographic models for the colonization of the Palearctic. A reassessment of the fossil record indicates that most previous Eurasian reports of Myrsine are based on generalized laurophyllous leaf morphologies lacking unequivocal diagnostic features, whereas fossil pollen provides more reliable evidence for tracing the history of the genus. The Iberian record further supports the persistence of humid evergreen and thermophilous forests in southwestern Europe during the Oligocene and suggests that warm palaeotropical vegetation corridors across Eurasia may have facilitated the rapid dispersal of Myrsine and other palaeotropical taxa during the Palaeogene. These findings provide a calibration point for future molecular phylogenetic and biogeographic analyses of pantropical Primulaceae.
Non-pollen palynomorphs (NPPs) are important ecological indicators and are increasingly used in the study of Arctic ice-wedge polygon mires in Siberia. This paper provides an overview of NPPs found in high-spatial-resolution (1 m sample distance) surface samples along transects crossing various polygon microtopographical elements, and in high-temporal-resolution (sample distance 0.5 cm) contiguous samples in peat profiles. Whereas algal palynomorphs - of e.g. Botryococcus, Pediastrum, and various Zygnemataceae - show a distinct presence in open water settings, testate amoebae tests - of Arcella, Assulina, and Amphitrema flavum - are typical for dry peatland settings such as polygon rims. Various other NPPs were encountered including types not yet described. The latter have been denominated using morphological terms to facilitate future identification. These types are often typical for distinct polygon microhabitats and thus have indicator values that allow the reconstruction of past ecological settings without knowing the taxa that produce them.
The succession of prehistoric cultures is intricately linked to changes in climatic and hydrological environments. However, research concerning the paleoenvironmental context and subsistence patterns of the Xuejiagang culture-situated at the transitional zone between the middle and lower reaches of the Yangtze River-remains notably limited. Utilizing the T1402 excavation profile from the Chishan site in the middle Yangtze River region, this study integrates high-precision AMS 14C dating with multiproxy analyses, including phytoliths, grain size, organic matter, and magnetic susceptibility. This approach aims to reconstruct the paleoenvironmental evolution from the Xuejiagang culture period to the Shang Dynasty, exploring how human societies adapted to dynamic riverine landscapes. Results indicate that during the natural deposition phase preceding extensive human occupation, the region experienced a warm and humid climate characterized by intense fluvial hydrodynamics driven by a robust monsoon. During the early Xuejiagang period (ca. 5600–4700 cal yr BP), the climate demonstrates a downward trend in temperature and the hydrological environment stabilized. This stability allowed early populations to exploit riparian lowlands, fostering the expansion of rice agriculture and promoting settlement prosperity. Conversely, during the late Xuejiagang (after ca. 4700 cal yr BP) and Shang periods (since 3100 cal yr BP), climate variability intensified, and hydrological stability deteriorated sharply, severely disrupting lowland agricultural systems. Consequently, rice cultivation contracted. The resulting unstable food supply ultimately compelled inhabitants to migrate toward areas with more favorable hydrological conditions, precipitating settlement contraction and regional cultural decline.
Studies on non-pollen palynomorphs have rapidly multiplied. However, detection of subterranean fungi spores is usually limited to Glomeromycota. In this study, we describe five new morphotypes from the soil profile of a cultivation terrace - located on the northern coast of the Mediterranean Sea (NW Italy) - which were recognised as spores of Ascomycota and Basidiomycota whose sporomata are produced in the soil. The morphotypes are tentatively related to the genera Terfezia, Tuber, Wakefieldia, Gautieria, and Hymenogaster. Taxonomic attribution is based on spore morphology and comparison with mycological literature; due to the absence of sporomata features and the potential alteration of spores caused by extraction techniques the described entities are treated as morphotypes (‘NPP-types’), rather than rigorously defined taxa. These hypogeal fungi are associated with more or less specific plants. The distribution of these spores within the stratigraphic sequence suggests the influence of soil reworking and animal-mediated dispersal, thus influencing the interpretation of palynological diagram and offering new insights into the reconstruction of the terrace's history. Because hypogeous fungal spores are produced below ground but can reach the soil surface through animal-mediated dispersal, their initial pathways of incorporation may differ from those of pollen. However, subsequent soil processes, including bioturbation and reworking, may affect both pollen and fungal spores. Their stratigraphic distribution should therefore be interpreted cautiously and in combination with other proxies.This study highlights potential and limitations of hypogeous fungal morphotypes as environmental indicators, emphasising the need for integrated approaches combining morphology, modern calibration datasets, and molecular data.
The Early Cretaceous palaeogeography of eastern China remains debated, with limited biological evidence available to constrain palaeotopographic differentiation. Palynological records provide a delicate archive of vegetation composition and ecological heterogeneity, offering valuable insights into palaeoenvironmental conditions. This study presents a high-resolution palynological record from the Huangyadi profile in the Laiyang Sag of the Jiaolai Basin, North China Craton, based on 42 shale samples. Quantitative palynological data are integrated with published palaeobotanical macrofossil records to reconstruct vegetation composition and assess their palaeoenvironmental significance. Assemblages are dominated by Pinuspollenites, Abietineaepollenites, Piceaepollenites, Classopollis, and Cicatricosisporites, indicating that plant communities adapted to contrasting ecological conditions. The persistent co-occurrence of taxa exhibiting warm–hot humid, warm–hot arid, and cool temperate semi-arid ecological affinities indicates pronounced ecological heterogeneity. Horizons containing the xerothermic conifer Elatides laiyangensis coincide with increased abundances of Cicatricosisporites, Osmundacidites, and Pinuspollenites, implying a spatial association between ecologically distinct vegetation types. The long-term coexistence of taxa with divergent ecological affinities does not reflect a homogeneous, low-relief landscape but instead indicates environments featuring local to regional topographic relief, possibly representing an intermontane basin setting. Comparison with coeval records from northeastern China and the Hebei–western Liaoning region reveals similar mixed vegetation patterns, indicating that topography-related ecological heterogeneity was prevalent across eastern China. Overall, these high-resolution palynological assemblages help to constrain vegetation distribution and palaeoenvironmental heterogeneity, highlighting the potential of palynofloral ecological data as a proxy for palaeotopographic differentiation in Early Cretaceous continental basins.
Accurately interpreting fossil pollen sequences requires a robust understanding of the modern relationship between vegetation and its pollen signature. This study addresses this challenge at the southern margins of the French Massif central by defining and classifying modern peatland plant communities and quantifying the representativeness of the local pollen rain. Based on 93 floristic surveys, multivariate analyses including two-way indicator species analysis (TWINSPAN) identified 17 distinct plant communities across a continentality/oceanity biogeographical gradient. Then, we evaluated the correspondence between these communities and their palynological records based on 68 pollen surface samples using Davis indices, one-way ANOVAs, and correlation tests. Our results demonstrate that biogeographical context and abiotic parameters significantly influence both vegetation and pollen assemblages, introducing a notable regional variation in local signatures. Despite the inherent biases of pollen dispersal, we successfully identified diagnostic pollen indicator taxa for 14 of the 17 communities. In conclusion, this work provides a new, high-resolution vegetation–pollen calibration that refines our ability to reconstruct past local successions and anthropogenic changes in Mediterranean-Atlantic peatlands.
A fossil leaf from the Middle Miocene of Germany is described as Buxus winterscheidii sp. nov. and, based on its leaf venation, is assigned to the Central American section Tricera (Schreb.) Baill. The leaf largely resembles the modern B. vahlii Baill., which occurs in Puerto Rico and St. Croix in subtropical forests with pronounced dry seasons. Similar ecological preferences can therefore be assumed for the fossil species as well, even though no pronounced xeromorphic characteristics are evident.Our leaf is currently the only known macrofossil specimen of this section. This section has been documented palynologically in Europe since the Palaeogene, whereas no fossil evidence exists from the Americas. It can therefore be concluded that its early representatives spread from Europe to the Americas and the Caribbean via the North Atlantic land bridge. Based on molecular phylogenetic calibrations, this occurred during the Oligocene.The leaf exhibits various types of damage. Brown spots on the leaf margin correspond to fungal infections caused by the extant boxwood blight pathogen. At least in parts they probably have been caused by arthropod feeding. A mine at the base, on the other hand, cannot be attributed to any of the feeding damages commonly found on modern Buxus species. It exhibits a type of leaf mining that does not, however, resemble the insect pests typically found on boxwood today, but could also be attributed to sediment feeders.
Borreria G. Mey. is a complex genus within the Spermacoce clade (Rubiaceae). Although pollen morphology is a well-documented diagnostic character within the clade, the taxonomic delimitation of Borreria s.s. and its relationship with the closest genus, Spermacoce, has been historically disputed. This study aims to evaluate the variation in pollen morphology within Borreria s.s. using a statistical approach and to assess its contribution to the taxonomy of the genus. Pollen morphology was studied using light microscopy (LM) and scanning electron microscopy (SEM). Pollen data were collected for 62 species and two infraspecific taxa, and were statistically evaluated through Principal Coordinate Analysis (PCoA) and Cluster Analysis (UPGMA). The obtained data confirm that Borreria s.s. is eurypalynous, characterized by small to medium-sized pollen grains with suboblate, oblate-spheroidal, or spheroidal shapes, compound apertures (zonocolporate or pantoporate), and a tectate-perforate to microreticulate exine with nanospines. Statistical analysis identified two main groups based on the type of ectoaperture (colpi vs. pores). Six pollen types were recognized for the group, refining and updating previous classifications for American species. The pollen morphology of 21 taxa was described for the first time. This study highlights that aperture type, position, and number are the most robust features for species clustering. Palynological evidence supports the distinction of Borreria s.s. as a separate genus from Spermacoce in America, providing a solid framework for future phylogenetic studies and evolution of characters within the Spermacoce clade.
The environmental evolution of volcanic barrier-lake systems is shaped by complex interactions between climate forcing and local geomorphological processes. This study presents a high-resolution multi-proxy record from the sedimentary sequence of Pla de les Preses volcanic barrier-palaeolake (Vall d'en Bas, NE Iberia), spanning the Late Glacial–Early Holocene transition. Particular emphasis is placed on the contribution of non-pollen palynomorphs (NPPs) to palaeoenvironmental reconstruction.Pollen data indicate that regional vegetation dynamics broadly follow the expected transition from open Late Glacial landscapes to temperate deciduous forests during the Early Holocene. However, notable deviations occur, including a marked decline in broadleaf forests, suggesting a strong influence of local disturbance processes.Sedimentological and palaeobiological proxies document the formation of a volcanic barrier lake following the damming of the Fluvià River, and its subsequent evolution through three main stages: (i) shallow, unstable conditions with pioneer aquatic communities, (ii) progressive deepening and establishment of a persistent lacustrine system, and (iii) lake shallowing, wetland expansion and final terrestrialisation linked to barrier erosion and fluvial reactivation. Hydrological changes do not always align with regional climatic trends, indicating a decoupling between climate and local environmental processes.NPP assemblages provide key insights into these dynamics, recording variations in water depth, aquatic productivity, trophic conditions and lake–catchment interactions. Algae and cyanobacteria reflect limnological variability, while pteridophyte spores and fungal remains document wetland development, soil erosion processes and terrestrial inputs. In addition, NPPs capture short-term ecological responses to volcanic activity and fire. This study demonstrates the value of NPPs for reconstructing highly dynamic lacustrine systems, complementing pollen-based approaches and enabling a more detailed understanding of palaeoenvironmental change.
The study of modern pollen-vegetation relationships is fundamental for improving the reliability of palaeovegetation reconstructions. This study investigates the spatial variation of pollen assemblages, pollen depositional processes, and the spatial representation of regional vegetation in Liangzi Lake-a large shallow lake in the middle reaches of the Yangtze River. Results indicate that the surface pollen assemblages can be clearly divided into western and eastern zones with significant compositional differences. The western zone exhibits greater spatial heterogeneity and lower evenness, whereas the eastern zone shows higher consistency and diversity, positioning the latter as an ideal coring area. Different palynomorph groups respond differentially to hydrological gradients. Arboreal pollen is insensitive to water depth and distance from shore, providing a stable record of regional vegetation. In contrast, terrestrial herb pollen diversity decreases significantly with increasing water depth, reflecting the attenuation of near-shore signals in deeper waters. Algal spores are the most sensitive to hydrological variables; specifically, Coelastrum reticulatum increases significantly with water depth, while Pediastrum simplex abundance rises with distance from shore. Quantitative comparison between Regional Estimates of Vegetation Abundance from Large Sites (REVEALS) reconstructions and remote sensing vegetation data identifies an optimal vegetation representation scale of approximately 95 km, with a near-optimal interval of 85-100 km. The REVEALS model improves the consistency between reconstructions and satellite data. This study demonstrates that while surface pollen in Liangzi Lake serves as a robust indicator of regional vegetation, it is also markedly influenced by intra-lake depositional environments. For palaeoenvironmental reconstructions, it is crucial to distinguish the responses of different taxa to regional background signals from those to local hydrological processes.
Frenelopsis Schenk is a well-established genus within the extinct family Cheirolepidiaceae and was an important component of the Cretaceous floras in Portugal. The genus attained its maximum diversity during the Early Cretaceous (especially during the Barremian–Aptian), but its species richness declined progressively during the Late Cretaceous. The species Frenelopsis oligostomata Romariz was described from the Late Cretaceous Esgueira flora, in the northern subdomain of the Lusitanian Basin, Beira Litoral region, western Portugal. This species was erected especially on the basis of its irregular spacing of stomata and low stomatal density. However, no holotype was chosen by Romariz (1946) for the new species. A few years later, Alvin (1977) re-examined the type collection of Frenelopsis oligostomata housed in the Geological Museum of Lisbon and emended the species diagnosis, but no lectotype was designated. In this paper we reassess the species Frenelopsis oligostomata based on the type material studied by Romariz and new specimens recently collected from the type locality at Esgueira. According to the new data obtained, we designate the lectotype and emend the species diagnosis.
A new cheirolepidiaceous conifer species, Brachyphyllum ordosensis sp. nov., is described from the Lower Jurassic Fu’xian Formation in the Ordos Basin, northern China. This represents the first confirmed record of this genus Brachyphyllum from the Lower Jurassic of China, significantly expanding its paleogeographic distribution. Brachyphyllum originated in the Late Triassic, expanded rapidly during the Early Jurassic, peaked in the Early Cretaceous, and gradually declined in the Late Cretaceous. It was widely distributed across the Northern Hemisphere with sparse records in the Southern Hemisphere, and predominantly thrived in tropical arid zones, serving as a reliable indicator of hot climates. The flourishing and expansion of Brachyphyllum during the Toarcian Oceanic Anoxic Event (T-OAE) and Cretaceous OAEs 1a and 1b reflect its adaptive response to these extreme climatic events. Using the stomatal ratio method based on well-preserved fossil cuticles, the paleoatmospheric CO2 concentration of the Toarcian in the Ordos Basin is reconstructed as 1280.05 ppmv (Carboniferous standardization), indicating a significant rise in paleo-CO2 levels. The elevated CO2 concentration, coupled with contemporaneous negative carbon isotope excursion and mercury enrichment, is interpreted to be linked to the massive magmatism of the Karoo–Ferrar Large Igneous Province in southern Gondwana during the T-OAE, which released voluminous greenhouse gases. This discovery provides critical paleobotanical evidence for reconstructing Early Jurassic paleogeography and paleoclimate, and offers new insights into the coevolution of plants and environments during this critical geological interval.
Modern pollen datasets provide an important basis for quantitative reconstruction of past vegetation and climate, but model selection and application to fossil records remain major methodological challenges. In this study, we used AutoGluon, an automated machine learning (AutoML) framework, to train and evaluate multiple algorithms for mean annual temperature (MAT) regression and vegetation type classification based on a modern pollen dataset from China. The base algorithms showed comparable performance on the modern testing set, whereas the weighted ensemble model generally achieved higher predictive performance. The trained models were then applied to Early Oligocene fossil pollen assemblages from the Dahonggou section in the Qaidam Basin. Despite similar testing performance, MAT and vegetation reconstructions varied among algorithms and presets, indicating substantial model-dependent uncertainty in fossil applications. The weighted ensemble model under the “best” preset showed the highest agreement with independent macrofossil evidence. Samples dominated by fossil taxa poorly represented in the modern calibration dataset produced notably low MAT estimates. This indicates that strong predictive performance on the modern testing set does not necessarily ensure reliable fossil reconstruction when comparable modern assemblages are limited. These results suggest that AutoML provides a useful comparative framework for evaluating reconstruction uncertainty rather than a direct route to a single optimal fossil reconstruction. Reliable interpretation therefore requires not only strong model performance, but also rigorous ecological evaluation, modern-analogue assessment, and support from independent paleoecological evidence.
