Polyploidy is an important evolutionary force increasing plant diversity and environmental resilience. Reconstructing genome size (GS) and ploidy of plant fossils advances our understanding of plant evolution and stress adaptation. Palaeopolyploidy is usually inferred from molecular data, but precise timing of polyploidy events requires improvement. So far there has been no robust fossil evidence for palaeopolyploidy in angiosperms. Here, the GS of late Eocene (similar to 34.6 Ma, the Markam flora) and Middle Miocene (similar to 15 Ma, the Namling flora) sclerophyllous oak (Quercus sect. Heterobalanus) fossils from southern Tibet, and three Late Pliocene fossils from Yunnan, China, were derived using the strong positive correlation between guard cell length (GCL) and GS. The estimated GS of the Namling fossils was approximately double those of late Eocene and Late Pliocene fossils as well as extant samples, indicating that the Namling fossils probably experienced a polyploidisation event. These tetraploids seemingly conferred greater resilience to aridity and cold-induced stress after similar to 15 Ma, reflected by two distinct fossil assemblages preserved in this flora, coincident with uplift of the Gangdese. Our discovery of sclerophyllous oak tetraploids provides compelling fossil evidence for palaeopolyploids in angiosperms, and demonstrates plant adaptation at the genome level to regional climatic change triggered by mountain uplift. GCL analysis serves as a promising tool for investigating GS changes across land plant evolution. Future research of elucidating the drivers of GCL variation is essential for enhancing the precision and reliability of this proxy.

The Eocene-Oligocene transition (EOT) represents a critical period in Earth's climate system, marked by a shift from a "warmhouse" to a "coolhouse" climate. This critical interval, spanning approximately 34 million years ago, was primarily characterised by a rapid decline in atmospheric CO2 concentrations. This decline ultimately triggered pronounced global cooling, aridification and the initial development and growth of the Antarctic ice sheet, all of which profoundly influenced the evolution, distribution, and diversity of vegetation. While there is a consensus regarding the decline in sea surface temperatures during the EOT, the terrestrial temperature response to the EOT remains a subject of ongoing debate, particularly concerning spatial heterogeneity and latitudinal gradients. The primary drivers of the EOT are also under active investigation. Although various hypotheses-including orbital forcing, a drop in CO2 concentrations, and thermal isolation-have been supported by numerical simulations, a single dominant forcing factor has yet to be identified. The global vegetation response to the EOT is evident in the retreat of forests, a decrease in thermophilic flora, and the expansion of drought-tolerant species. However, significant regional variations exist in species diversity. Currently, systematic research is still relatively sparse regarding how EOT global climate change comprehensively drove the co-evolution of terrestrial ecosystems across broader spatial and continuous temporal scales. Currently, spatiotemporal uncertainty in palaeovegetation data makes it difficult to link the co-evolution of ecosystems with climate change across the EOT. To better resolve this, we integrate palaeo-vegetation proxies with palaeoclimate simulations from HadCM3 with interactive vegetation, as well as an offline vegetation model (SDGVM). Our analysis indicates that consistent global terrestrial cooling across all latitudes (high, mid, and low) during the EOT drove changes in ecosystem development, with high latitudes experiencing more pronounced seasonal temperature variations. The vegetation simulations reveal trends of forest opening and the expansion of C-4 grasses, although these findings occasionally show local inconsistencies with fossil records. To bridge these gaps, future research should integrate big data with numerical simulations, establish high-precision spatiotemporal frameworks, and develop more reliable climate and vegetation models. This approach will enhance our understanding of the co-evolutionary mechanisms between climate and vegetation during the EOT. This review offers a deep-time perspective for predicting how terrestrial ecosystems may respond to future climate change. By integrating multi-source data and models, we can unravel the complexities of climate-biosphere interactions, thereby providing crucial theoretical support for global change research.

Resolving the elevation history of the Gangdese Mountains (GMs) is key to understanding the evolution of the entire Tibetan Plateau (TP). Multiproxy paleoelevation reconstructions indicate that the Namling (Wuyu/Oiyug) Basin, eastern GMs, experienced uplift from the late Oligocene to Middle Miocene, accelerating at ∼15 Ma as inferred from a significant sediment provenance shift at that time. However, whether the rapid rise actually occurred still lacks direct evidence, and the magnitude of this uplift in quantitative terms remains unknown. In this study, pollen analysis of a well-dated section in the Namling Baisn, reveals a distinct vegetation shift from a temperate–subalpine forest to an alpine shrubland/shrub-meadow within the basin at ∼15 Ma. By integrating pollen and megafossil records, and utilizing high-resolution climate-vegetation modeling, we demonstrate that this vegetation change most likely resulted from a rapid uplift of the Namling Basin at ∼15 Ma rather than global and/or regional climate changes. We calculate the uplift to be between 525 and 1050 m, exceeding the present-day elevation (∼4.5 km) by ∼1.5–2 km and reaching > 6 km. Based on our modeling results and contemporaneous pollen records from the Central TP, it seems the uplift at ∼15 Ma was localized and cannot be extended to the entire GM chain. Subsequent subsidence may have been due to ongoing subduction of the Indian plate causing downward drag on the overlying southern Lhasa terrane combined with late Cenozoic east-west extensional collapse of the southern TP.

Understanding the Cenozoic vegetation history of what is now the Qinghai-Tibetan Plateau is crucial for elucidating the co-evolutionary dynamics between plateau development, its environment, and the organisms it hosts. In this study, we conduct a comprehensive analysis of phytoliths within the late Oligocene-Early Miocene lacustrine sedimentary section of the Lunpola Basin, central Qinghai-Tibetan Plateau. The diverse phytolith morphotype assemblages indicate that the vegetation of the central Tibetan region mainly comprised a mixed coniferous and broad-leaved forest. Grasses in the understory primarily consisted of Pooideae, distinguished by phytolith morphotypes such as rondel, crenate and Stipa-type bilobate forms. Combined with previous work, we infer that riparian vegetation of the central Tibetan region transitioned from a humid subtropical forest, dominated by broad-leaved woody plants during the middle Eocene, to a more seasonally arid open woodland containing abundant woody and herbaceous plants during the late Eocene, before developing into a cooler mixed coniferous and broad-leaved forest during the late Oligocene-Early Miocene. The growth of the central Tibetan region and retreat of the Tethys Ocean, together with the uplift of the Himalaya, contributed to this vegetation change. This study provides new evidence from the phytolith perspective for the evolutionary history of Qinghai-Tibetan Plateau vegetation being tied to plateau formation and regional climate change.

The transgression and regression of the Tethys Sea profoundly influenced the environment and biodiversity patterns of Eurasia, which had implications for global climate dynamics by altering the land-sea distribution and the broader moisture transport scheme. Despite its importance, few comprehensive studies have integrated fossil data and climate modeling to explore the climate evolution in the Tethys Sea region during the Cenozoic. In this paper, we reconstruct 10 climate parameters using macrofossil flora from 363 sites across the Tethys Sea region throughout the Cenozoic, and we compare these reconstructions with simulations from the Hadley Center Coupled Model (HadCM3). Additionally, we propose a new Mediterranean Climate Index (MCI), which combines precipitation and temperature, to analyze the evolution of the Mediterranean climate. Our results indicate that the climate in the Tethys Sea region gradually changed from predominantly tropical and subtropical conditions during the Paleogene to a warm temperate and cold temperate climate in the Neogene-Quaternary. The distribution pattern of the coldest month mean surface air temperature (CMMT) changed from a predominantly zonal pattern in the Paleogene to a topographically influenced distribution in the eastern and central Tethys regions since the Neogene. The precipitation patterns in the Tethys Sea region exhibited significant fluctuations. In the western Tethys region, the summer precipitation experienced increased variability, while the winter precipitation decreased slightly. The central Tethys region became significantly drier due to sea regression and mountain uplift. Both the summer and winter precipitation increased markedly in the eastern Tethys region with the development of the Tibetan Plateau. From the Eocene to the early Oligocene, the Mediterranean climate prevailed in Central Asia and Europe, but its extent contracted sharply during the Miocene, primarily due to the decrease in the summer precipitation. The Oligocene-Early Miocene was a critical period for climate evolution in the Tethys Sea region, which was driven by changes in the land-sea distribution, topographic evolution, and global CO2 concentration. The results of this study provide a crucial reference for exploring the evolution of ecosystems and species diversity in Eurasia driven by climate change since the Cenozoic.

Different regions of the tropics vary in overall tree species diversity, with the tropical Americas exhibiting strikingly higher regional tree species richness than Africa and Southeast Asia. We investigated whether these differences also occur at the local scale and whether the environmental conditions associated with tree species richness are consistent across tropical regions despite highly dissimilar species pools. A spatial random forest model was trained by using a network of 429 1-hectare plots across the tropics, together with 24 environmental variables, to predict plot-level tree α diversity. A combination of climatic, soil and topographical variables explained ∼86% of the variation in richness. Despite differences in regional species pools and the potentially disruptive effects of different geological, climatic and evolutionary histories, the relationship between environmental variables and local-scale tree species richness is closely similar across different continents. Our findings imply a pervasive role of niche-based mechanisms in structuring local tree species richness, regardless of the regional species assemblages. This pantropical convergence in the richness-environment relationship poses a challenge for ecology to explain.

Angiosperms are the most diverse and abundant plant taxon today and dominate the majority of Earth's terrestrial ecosystems. They underwent rapid divergence and biogeographic expansion from the early to the middle Cretaceous. Yet, transformative ecosystem change brought about by the increased ecological dominance of angiosperms unfolded progressively until the Late Cretaceous. After the Cretaceous-Paleogene (K-Pg) boundary, angiosperms restructured terrestrial ecosystems towards a modern form. By the Neogene, crown groups that make up modern terrestrial angiosperm biodiversity radiated, and regional floristic distinctions were established concurrently with the steepened latitudinal and vertical temperature gradients. Here, we summarize, based on fossils and molecular evidence, when and how angiosperms came to diversify, dominate, and shape terrestrial ecosystems, leading to the emergence and spread of angiosperm-dominated floras. We highlight five major phases of angiosperm evolution that took place against a background of palaeogeography and climate changes. There is a consistent delay in ecological dominance after lineage origination and taxonomic diversification, as a result of which angiosperms did not achieve ecological dominance across terrestrial biomes in a single step. The patterns of diversity seen among extant angiosperms, the dominant angiosperm groups within modern ecosystems, and the restriction of different groups of angiosperms to different parts of the world, reflect the contingent nature of the process of lineage diversification in the context of long-term, substantial and ongoing environmental change. Determining the origins, diversification, and ecological dominance of angiosperms continues to be a challenge and requires elucidation of their early forms, functions, habitats, and environmental interactions throughout evolutionary history.

Increasing drought pressure under anthropogenic climate change may jeopardize the potential of tropical forests to capture carbon in woody biomass and act as a long-term carbon dioxide sink. To evaluate this risk, we assessed drought impacts in 483 tree-ring chronologies from across the tropics and found an overall modest stem growth decline (2.5% with a 95% confidence interval of 2.2 to 2.7%) during the 10% driest years since 1930. Stem growth declines exceeded 10% in 25% of cases and were larger at hotter and drier sites and for gymnosperms compared with angiosperms. Growth declines generally did not outlast drought years and were partially mitigated by growth stimulation in wet years. Thus, pantropical forest carbon sequestration through stem growth has hitherto shown drought resilience that may, however, diminish under future climate change.

The Himalaya,a majestic mountain range often referred to as the"Roof of the World,"is distinguished by exceptional environmental heterogeneity,rich biodiversity,and high taxonomic endemism(Kitamura,1963;Tabata,1988;Sun,2002).

Magnoliaceae are absent from present-day European vegetation but were accessory elements in the Paleogene and Neogene vegetation of the continent. Most European fossil sites with fossil leaves of Magnolia PLUM. ex L. revealed only a few remains, preventing detailed knowledge of the variability of morphological and anatomical characters and hampering detailed comparison with extant species. Moreover, the shared biological identities of most of the fossil-species based on detached leaves and isolated seeds are still unresolved. Thus, the systematic and paleobiogeographic relationships of fossil European species are rather incompletely known. Here, a new fossil-species is described from an Eocene riparian setting in the coastal lowlands of the Paleo-North Sea in Sachsen-Anhalt, Germany, based on more than 300 leaves and leaf fragments that are preserved as compressions (coalified organic matter). Magnolia dorotheae sp. nov is defined using characters of leaf architecture and micromorphological features of leaf cuticles mirroring epidermal cell structures. The most distinctive character is the presence of uniseriate two-celled trichomes on the densely pubescent abaxial surface, identified as the Manglietia trichome type of the classification system of BARANOVA & JEFFREY. All together, features fit best to those from the extant species of Magnolia section Manglietia (BLUME) BAILL., which is native to tropical and subtropical regions in SE Asia. M. dorotheae sp. nov is considered an evergreen element in a fossil assemblage derived from a subtropical evergreen broadleaved forest without conifers. The new fossil-species is compared to other European fossil-species and extant representatives. The new record adds valuable data to the ancient history of Magnolia in Europe, which is briefly considered based on other Paleogene species of leaves and carpological fossil-taxa from the western and central European regions of the Atlantic-Boreal Phytoprovince.

The Eocene-Oligocene transition (EOT; ~34 million years ago) marks a critical shift from a greenhouse to an icehouse climate. Whereas temperatures derived from marine records show a consensus ~ 4°C cooling worldwide, there is an emerging picture that the terrestrial realm experienced a heterogenous response to rapid climate change. Here, we reconstruct an 8-million-year terrestrial temperature record across the EOT at a tectonically unresolved location at the margins of the Tibetan Plateau, Lühe Basin (Yunnan, China). Our multi-proxy organic geochemistry approach, complemented by sedimentological interpretations, shows that Lühe Basin was a dynamic fluvial environment that maintained relatively stable average temperatures from ~ 35 − 27 million years ago. These palaeotemperatures match our model-based estimates, as well as palaeobotany-based estimates at a nearby site; these stable palaeotemperature trends differ from the global marine cooling, supporting a heterogenous response of terrestrial sections. Furthermore, these palaeotemperature estimates match present-day values at this location, suggesting that this area has not undergone significant temperature change – and possibly no significant uplift – since the late Paleogene.

Evergreen broad-leaved forests (EBLFs) are widely distributed in East Asia and play a vital role in ecosystem stability. The occurrence of these forests in East Asia has been a subject of debate across various disciplines. In this study, we explored the occurrence of East Asian EBLFs from a palaeobotanical perspective. By collecting plant fossils from four regions in East Asia, we have established the evolutionary history of EBLFs. Through floral similarity analysis and paleoclimatic reconstruction, we have revealed a diverse spatio-temporal pattern for the occurrence of EBLFs in East Asia. The earliest occurrence of EBLFs in southern China can be traced back to the middle Eocene, followed by southwestern China during the late Eocene–early Oligocene. Subsequently, EBLFs emerged in Japan during the early Oligocene and eventually appeared in central-eastern China around the Miocene. Paleoclimate simulation results suggest that the precipitation of wettest quarter (PWetQ, mm) exceeding 600 mm is crucial for the occurrence of EBLFs. Furthermore, the heterogeneous occurrence of EBLFs in East Asia is closely associated with the evolution of the Asian Monsoon. This study provides new insights into the occurrence of EBLFs in East Asia.

Understanding how East Asian subtropical evergreen broad-leaved forests(EBLFs)have evolved over time is not only vital for biodiversity conservation but also facilitates predictive modeling of ecosystem services under global change scenarios.During recent decades,numerous studies have been devoted to investigating the evolution of EBLFs.However,there are often contradictory interpretations of the different taxa associated with different geological events and environmental backgrounds.Here,we synthesize several key aspects of the spatiotemporal evolution of EBLFs.First,the EBLFs emerged concomitantly with the development of Asian monsoon systems,occurring no earlier than the Eocene.While the southernmost region was inhabited by tropical elements,EBLFs are not the direct relic of boreotropical flora because of the presence of a broad arid belt at that time.Rather,they represent a unique assemblage including boreotropical relics,tropical floras and deciduous broad-leaved forests.Second,the evolution of EBLFs should not be contextualized within an enclave,the adjacent vegetation systems to elucidate the potential connections between EBLFs and other biomes should be considered to avoid an isolated phenomenon.Third,the adaptive response of EBLFs to environmental changes caused by anthropogenic disturbance in subtropical regions remains understudied.Such a knowledge gap must be addressed to develop effective conservation strategies to sustain the ecosystem amid the dual pressure of climate change and human activity in the future.Finally,current research has predominantly focused on the dominant tree species in EBLFs,whereas comprehensive understanding requires expanding the investigation of associated flora,including understory trees and herbaceous plants.This review not only consolidates contemporary perspectives on the evolution of EBLFs but also proposes a framework to navigate the Anthropocene challenges.By bridging historical patterns with future projections,we aim to catalyze transformative research on EBLFs' resilience and sustainable management,fostering further research and development regarding the resurgence.

Premise of research. Abundant fossil records of Altingiaceae have been discovered from all Northern Hemisphere continents and suggest its widespread occurrence during the Paleogene, shedding light on its evolutionary history. However, records of unlobed Altingiaceae leaf fossils are rare and discovered only in East Asia to date. Methodology. Plant fossils were collected from the lignite opencast mine Profen-Sud in central Germany from late Eocene sediments of an alluvial coastal plain. From a total of 140 compressed leaves, cuticles were obtained from 52 specimens for studying epidermal characters. Leaf architecture and cuticle micromorphology were described and compared with fossil and extant species sharing similar characteristics. Pivotal results. The new material belongs to a rare and incompletely known fossil species from the same region and age. For taxonomic reasons, a new fossil genus-Zlatkophyllum gen. nov.-associated with Altingiaceae is established. Zlatkophyllum fischkandelii sp. nov. et comb. nov. is redescribed and reconsidered on the basis of the simple dentate, almost circular leaves with semicraspedodromous secondary vein framework; Omega-shaped anticlinal walls of epidermal cells; and brachyparacytic stomata. Conclusions. The new fossil genus is the first representative of Altingiaceae from the European Cenozoic with exclusively unlobed leaves, thus providing important implications for the evolutionary history of the family. In the fossil assemblage, Z. fischkandelii co-occurs with abundant Steinhauera subglobosa infructescences from the same family, and thus the new fossil taxon is hypothetically the previously unknown foliage of the S. subglobosa-producing fossil plant.

The Eocene-Oligocene transition (EOT) marked a rapid global cooling event, often considered as the beginning of the modern icehouse world. Influenced by various factors, including tectonic activity and paleogeographic settings, the terrestrial records indicate a diverse response of fauna and vegetation to this global event. We examined nine macrofossil assemblages from seven fossil localities on the southeastern margin of the Tibetan Plateau and from the mid-latitudinal Europe ranging from the latest Bartonian and Priabonian (37.71–33.9 Ma) to the Rupelian (33.9–27.82 Ma). Our aims were to trace and compare the vegetation history of both regions in the late Eocene and early Oligocene. The results show that both regions experienced changes in vegetation composition in response to climate change, characterized by a decrease in the percentages of broad-leaved evergreen elements and distinctive changes in general vegetation types. A general change in the overall vegetation type from subtropical broad-leaved evergreen forests in the late Eocene to temperate broad-leaved mixed deciduous evergreen forests, or mixed mesophytic forests, in the early Oligocene is recognized in both regions. The results indicate a clear change in leaf architecture, leaf margin states, and secondary venation types in the mid-latitudinal Europe, while the results from the south-eastern margin of the Tibetan Plateau show a distinct reduction in leaf size. Our data suggest that both global and regional factors played key roles in shaping the vegetation in the two regions.

As one of the most important accommodation zones during the India-Asia collision, the southeast margin of the Tibetan Plateau (SEMTP) is characterized by many large-scale strike-slip faults, a regional low-relief relict that has been deeply incised by several continental scale rivers that originate from central Tibet, and numerous plant and vertebrate fossil biotas residing in Cenozoic sedimentary basins. Therefore, the SEMTP not only provides a meaningful constraint on the geodynamic evolution of the Tibetan Plateau, but also serves as an exemplar to understand the various interactions among surface uplift, drainage network reorganization, climate change, and biodiversity. Precise dating of Cenozoic sediments in the basins of the SEMTP is crucial for understanding these processes. Previously, the geochronologic framework of Cenozoic sediments in the SEMTP largely relied on fossils and regional stratigraphic correlations, which often involved circular reasoning and large uncertainties. In the past two decades, high-resolution magnetostratigraphy, detrital zircon geochronology, and isotopic dating of interbedded tephra layers have been carried out on SEMTP Cenozoic sedimentary basins in Yunnan and eastern Xizang provinces, SW China. Using these new data, we build a revised chronostratigraphic framework for Cenozoic sediments in SEMTP, and use this updated temporal framework to contextualize regional tectonics and climate change. The new chronostratigraphic framework shows that (1) many of the "Neogene" sedimentary basins based on plant fossils and regional lithostratigraphic correlation in the SEMTP were actually formed in the late Eocene and early Oligocene; (2) most of the Paleogene sedimentary successions in the SEMTP ended at the late Eocene-early Oligocene and were unconformably overlaid by Middle-Late Miocene sediments. OligoceneEarly Miocene sediments are often regionally absent. Sedimentary structures within the basin successions show that Paleogene basins were generally formed in compressional settings while the Late Miocene basins were mostly developed in extensional settings. The new chronostratigraphic framework, together with analyses of sedimentary basin structures, suggests that the SEMTP began to experience crustal shortening early in the IndiaAsia collision (similar to 50 Ma), producing Paleogene sedimentary basins and giving rise to the subsequent widespread surface uplift and regional erosion in the Oligocene-Middle Miocene. Tectonic inversion from compression to extension since the Middle Miocene precludes significant uplift of the SEMTP after this time, which may be related to geodynamic changes in the evolution of the Tibetan Plateau.

Within the ongoing controversy regarding the orogeny of the Tibetan Plateau region, two directly conflicting endmember frameworks have emerged in which either: (1) a high central ‘proto-plateau’ existed before the onset of India–Asia continental collision; or (2) the early Paleogene central Tibet comprised a wide east–west-oriented lowland c. 1–2 km above sea-level, bounded by high (>4.5 km) mountain systems. Reconstructing the development of the plateau correctly is fundamental to running realistic Earth system models that explore monsoon and biodiversity evolution in the region, and understanding the interplay between monsoon dynamics, landscape and biodiversity is critical for future resource management. We explore the strengths and weaknesses of different palaeoaltimetric methodologies as applied across the Tibetan region. Combining methodologies, appreciating the vulnerabilities arising from their underlying assumptions and testing them using numerical climate models produces consilience (agreement), allowing further refinement of both models and proxies. We argue that an east–west-oriented Paleogene Central Tibetan Valley was a cradle and conduit for thermophilic biota, seeding the modern regional biodiversity. The rise of eastern Tibet intensified regional rainfall and erosion, which increased topographic relief and biodiversification. Gradual monsoon development reflected the evolving topography, but modern-like Asian monsoons developed only after a plateau formed in the Miocene.

Indochina, as a global biodiversity hotspot, offers the potential for understanding the evolution of biodiversity. However, the historical narrative of plant diversity in this region remains enigmatic due to limited fossil records. Here we report a newly discovered megafossil flora from the late Miocene of the Yen Bai Basin, northern Vietnam. This megafossil flora suggests that the late Miocene vegetation in northern Vietnam comprised mixed tropical evergreen and deciduous broadleaved forest components mainly characterized by Fabaceae, Fagaceae, and Lauraceae bearing strong resemblance to the modern vegetation in northern Vietnam. Paleoclimate reconstruction for this plant fossil assemblage using the Coexistence Approach indicates a mean annual temperature (MAT) of 18.5–23.0 °C and a mean annual precipitation (MAP) of 1183.1–2078.5 mm. Similarly, employing the Climate-Leaf Analysis Multivariate Program yields an MAT of 21.3±2.3 °C and a growing season precipitation (GSP) of 1328.6±606.0 mm. The length of the growing season was about eleven months. Overall these results indicate a modern-like warm and humid tropical monsoon climate in northern Vietnam during the late Miocene. Climatic comparison of the Yen Bai with other fossil floras in northern Vietnam and southern China reveals the relative stability of temperature seasonality since the middle Eocene but obvious long-term variation in precipitation seasonality, particularly in respect of precipitation during the three consecutive driest months (X3.DRY). This suggests the Asian monsoon in northern Vietnam underwent important changes from the middle Eocene to the late Miocene, and intensified significantly during the middle and late Miocene. Our results show the modernization of plant diversity in northern Indochina had its origin in the Paleogene and further developed in the late Miocene, and was linked to the evolution of the Asian monsoon mainly in terms of changes in dry season precipitation.

The Eocene-Oligocene transition (EOT, -33.9 Ma), a period of dramatic global cooling marking the onset of the Antarctic ice sheet. However, paleoclimatic reconstructions indicate a notable spatial heterogeneity in both the marine and terrestrial realms. While limited temporal resolution terrestrial records have hindered the precise understanding of short-term climate events and orbital-scale changes during this transition. Here, we present a chemical weathering data sequence from a fluvial-lacustrine deposition from Luhe Basin, which is located at southeastern margin of the Tibetan Plateau. Based on the radioisotope, paleomagnetic and 405 kyr orbital tuning of the elemental datasets, the deposition age of Luhe Basin is dated to -35.5-25.5 Ma. Two weakening stages of the weathering intensity are detected around Eocene-Oligocene boundary: 34.1 to 33.9 Ma and 33.8 to 33.6 Ma, which are temporally equivalent to the two global main climatic steps of EOT (EOT-1 and Oi-1). We find the chemical weathering intensity sequence paced the 1.2 Myr obliquity amplitude modulation and 405 kyr longeccentricity cycles. Notably, the minima of 1.2 Myr obliquity amplitude and 405 kyr eccentricity are synchronous with the Oil-1 event. These patterns highlight the role of orbital forcing in shaping the cooling trend across the EOT and may trigger Antarctic glaciation.

We reported alpine oak fossil leaves ( the Heterobalanus group, Quercus section Ilex, Fagaceae) rediscovered on Mount Shisha Pangma. According to twice field investigations, the fossil site is located at the front of the No. 5 glacier tongue on the south side of the Dasuopu Glacier at an altitude of about 5800m on the north slope of Shisha Pangma Peak. These fossils are from the siltstone interlayer dominated by sandy conglomerate in the lower part of the Yebokangjiale Group. These newly discovered fossil leaves have typical characteristics of alpine oaks, including oval or oblong leaf, thick and short petiole, entire or toothed leaf margin, and 5 similar to 6 pairs of secondary veins, which is completely consistent with the leaf morphology of alpine oaks from Mount Shisha Pangma reported previously. Through morphological comparison with living and fossil species in this group, as well as quantitative analysis combined with geometric morphometry, these fossil leaves from Mount Shisha Pangma were assigned to Quercus preguajavifolia Tao. Alpine oaks may originate in southeastern margin of the Qinghai -Tibetan Plateau, then thrive locally and spread into regions nearby accompanying by the uplift of the plateau. The implication of alpine oak fossil leaves from Mount Shisha Pangma on paleoelevation needs to be further investigated due to the present wide range and the uncertainty of these fossils. The rediscovery of alpine oak fossils from Mount Shisha Pangma not only helps to clarify the specific layers bearing these fossils, but also further enriches the morphological characteristics of this fossil record and its systematic position. This discovery would provide important basis for better revealing the evolution of biodiversity and environmental changes in the middle part of the Himalaya during the Cenozoic.