The Liuqu Formation in southern Tibet, China, archives the late Palaeocene Liuqu flora (ca. 56 Ma) and represents ancient vegetation on the northern margin of the Indian Plate near the India–Asia collision zone. It therefore provides critical evidence for evaluating early biotic interactions between India and Eurasia. Here, we report on Syzygium (Myrtaceae) fossil leaves from the Liuqu flora. Detailed morphological comparisons suggest that these specimens represent a new fossil species, namely Syzygium ovatum Y. Gao et T. Su sp. nov. By integrating fossil records with deep-time ecological niche modelling, we infer that Syzygium originated on the Indian Plate before or during the Palaeocene. By the middle Eocene, Syzygium had migrated to the northeast along the Asian Pacific coastline to East Asia, consistent with an “Out-of-India” dispersal scenario. Fossil evidence demonstrates that the genus reached New Zealand and Australia by the Early Miocene, likely through a Southeast Asian dispersal corridor. During the Pliocene, the distribution of Syzygium resembled that of its modern range. Although the African fossil record of Syzygium only dates to the early Pliocene, climatic suitability and favourable paleogeographic conditions suggest an earlier arrival: 1) during the Palaeocene via the Kohistan–Ladakh Island Arc and associated island systems or 2) during the Oligocene, when more suitable areas for Syzygium linked Africa and India. Generally, our results suggest a Palaeocene origin of Syzygium on the Indian Plate instead of an early Eocene Australian origin as previously proposed.

Premise of study. Davidia involucrata Baill. (Nyssaceae) is considered a "living fossil" species, with a natural distribution in the mountains of southwestern and central China presently, but its historical distribution is still unclear because of limited fossil records. This study reported Davidia endocarp fossils in appreciable numbers from the early Eocene (similar to 55-52 Ma) sedimentary sequence of India, comprising the first fossil record of this genus in South Asia. Methodology. We determined the studied fossils' taxonomic position based on their detailed morphological features in comparison to modern and fossil endocarps of Cornales. The paleoclimate conditions of Davidia were quantitatively reconstructed using the coexistence approach. Pivotal results. These fossil specimens, characterized by vertically and laterally compressed ellipsoid to obovoid endocarps; five to eight prominent, external, longitudinal, and meridianal ribs; five to seven elliptical locules; and the presence of fibers at the inner endocarp wall, are described as a new species, namely, Davidia indica A. Ali, T. Su et M. A. Khan sp. nov. Conclusions. This discovery supports the close biogeographic lineage between India and other parts of the Northern Hemisphere. This discovery suggests that, like other "living fossil" species, Davidia had a much wider ecological niche in the geological past than it has in the present day, emphasizing the need for further studies regarding the factors in shaping its modern restricted distribution.

Sequoia was widely distributed across the Northern Hemisphere during the Cenozoic, yet our understanding of its biogeographic history remains limited due to relatively scarce fossil records in certain regions, particularly East Asia. A new Sequoia leaf fossil record from the Late Eocene to Early Oligocene in Yunnan Province of southwestern China displays morphological similarity to the fossil species S. maguanensis, such as an alternate leaf arrangement with a decurrent base, straight epidermal cell walls, and stomata surrounded by four subsidiary cells. Using the MaxEnt model and S. sempervirens (the only extant species of Sequoia) as a reference, we identified optimal potential distribution areas for Sequoia from the Palaeocene to the Pliocene. Our results indicate that Sequoia, which thrived in warm and humid conditions, progressively shifted its range southward as global temperatures declined from the Eocene to the Pliocene, contracting its habitat towards lower latitudes. Our analysis suggests that Sequoia likely originated in East Asia during the Early Cretaceous and subsequently spread to North America via the Bering Land Bridge. During the Palaeocene, it extended its range to Greenland and Svalbard, eventually reaching western Europe during the Eocene. In the Oligocene, Sequoia was widespread across Europe and reached Siberia, later expanding from East Asia to the Mediterranean and northern Thailand by the Miocene. Quaternary glaciations led to its near-complete disappearance in Eurasia and North America, with only remnant populations surviving along the western coast of the United States. This study also highlights the role of morphological stasis in Sequoia alongside the intensification of the monsoon climate as key factors contributing to its eventual disappearance in southwestern China.

Relict plants are those that once had a wide distribution but are now restricted to small areas. It is important to study the process of their distribution in the geological past to better understand the climatic factors that shape their current distribution. Metasequoia is one of the best-known genera of relict plants in Asia, with rich fossil records dating back to the Late Cretaceous. In this study, we used Deep-time Ecological Niche Modelling (DENM) and 755 Cenozoic megafossil records of Metasequoia to understand the pattern of its historical distribution and driving factors. The results showed that Metasequoia was widely distributed across mid-high-latitude regions during the Paleogene. Its distribution range contracted toward lower latitudes during the Neogene due to global aridification and cooling. Our results indicate that mean annual precipitation was the key factor shaping the distribution of Metasequoia during the Paleogene and Neogene. Later during the Pleistocene, a dramatic contraction of its distribution occurred due to glaciations, which also shaped the modern distributions of many relict plants in China. Our study supports that climate change is the main factor driving the distribution of relict plants and therefore provides crucial evidence for understanding their biogeographic histories and future conservation under climate change.

Palms are mainly distributed in the pantropical regions and although the fossil records are rich globally, their evolutionary and biogeographic histories remain unresolved largely due to the uneven spatial distribution of fossil records. Here, we report late Paleocene palm leaf fossils from Lazi County, southern Tibetan Plateau. These fossil leaves, characterized by induplicate fan-shaped costapalmate laminae with unarmed petioles, suggest an affiliation with the subfamily Coryphoideae. With morphological comparisons to other palm leaf fossil records, we place these palm leaf fossils within the fossil genus Sabalites, specifically Sabalites striatipetiolaphyllum Y. Gao et T. Su sp. nov. Together with previous palm fossil records, we propose that the Kohistan-Ladakh Island Arc served as a steppingstone for the dispersal of palms from India to southern Tibet by the late Paleocene, and palms spread into central Tibetan region by the late Eocene. Overall, palm fossils in this study provide crucial evidence for floristic interchange between India and Asia during the Paleogene, as well as a warm climate in southern Tibet at that time.

Picea is widely distributed in the Hengduan Mountains of southwestern China nowadays, but its megafossil records there are still rare, which prevents a full understanding of the evolutionary history of Picea in this region. In this study, we describe well-preserved fossil seed cones of Picea from the early Miocene Mula Basin in Litang County, central Hengduan Mountains. These fossil seed cones are characterized by oblong or ovate seed cones, broadly obovate seed scales with bifid apices, longitudinal striations on their abaxial surfaces, and triangular-spathulate bracts. Detailed morphological comparisons allowed us to identify these specimens as Picea sp. (cf. P. asperata). This finding implies that the ancestor of modern species for Picea in the Hengduan Mountains might have survived there by the early Miocene, much earlier than molecular phylogenetic estimates that placed their divergence there during the Pliocene. Combined with previously discovered fossil species from the same sediment, the Mula flora represents a subalpine coniferous forest, which is similar to modern vegetation nearby. It suggests that the central Hengduan Mountains were warmer and more humid during the early Miocene than today, in agreement with the global climate condition at that time.

The genus Mezoneuron Desf. (Caesalpinioideae, Fabaceae) comprises 23 extant species distributed throughout the Old World tropics and subtropics, yet its fossil record is scarce with finds restricted to Europe and North America. Here, we report a new Mezoneuron pod fossil from the lower Miocene Sanhaogou Formation of Jinggu Basin in Southwest China, representing the first fossil occurrence of this genus in Asia and the only one within its current distribution range. The fossil presents a vascularized wing along the placental suture and with poorly developed, irregular reticulate venation, which are typical pod characters in Mezoneuron. With detailed morphological observation and comparison, it is assigned as a new species, namely M. zhekunii Y.S. Zhao, L.B. Jia et T. Su sp. nov. Together with the historic and modern distribution of Mezoneuron and its relatives, we propose that Mezoneuron originated in the Northern Hemisphere no later than the middle Eocene. Mezoneuron attained relatively low latitudes in Asia no later than the early Miocene, with our fossil representing the lowest latitudinal record. The oblique and fine wrinkles of pod probably suggest a papery texture and low weight observed in mature pods of some extant Mezoneuron species, which favors wind dispersal.

Dalbergia is a pantropical genus of Fabaceae with a limited fossil records. In this study we describe diverse and well-preserved Dalbergia fossils distributed through Cenozoic (Eocene to Pliocene) strata in Yunnan Province, southwest China. Comparison with newly collected modern samples from Eurasian forests and herbarium specimens allows accurate identification of our fossil materials, and we demonstrate that Yunnan Province represents an hitherto unrecognised hotspot for the diversification of Dalbergia. Our findings also include evidence of the earliest known mining damage reported on Dalbergia leaflets, which sheds light on their interactions with various arthropods (Leucoptera and other insects) during the early Neogene. As such, our results improve knowledge of Dalbergia fossils in East Asia and are crucial for understanding the evolutionary history of analogous mining behavior observed from modern Dalbergia.

Bauhinia s.s. is a large genus in the family Fabaceae, but its evolutionary and biogeographical history is still unclear due to the scarcity of fossil records compared to the highly diverse modern species in pantropic regions. Here, we report the earliest fossil record of Bauhinia s.s., namely Bauhinia tibetensis Y. Gao et T. Su sp. nov., based on leaves from the latest Paleocene of the southern Tibetan region. Combined with palaeoecological niche simulations and ancestral state reconstruction, the new fossils suggested a Paleocene origin of Bauhinia s.s. in the Afrotropical realm that subsequently dispersed to the Neotropical and Indomalayan realms. Bauhinia tibetensis belongs to the Asian clade of Bauhinia s.s. that reached the southern Tibetan region from the Afrotropical realm via the Kohistan-Ladakh Island Arc in the early Paleocene. This clade spread to south-eastern China during the Oligocene and entered northern India during the Neogene or earlier. The discovery of the oldest Bauhinia s.s. from what is now the southern Tibetan Plateau updates our understanding of the biogeographical history of this genus and demonstrates that the Kohistan-Ladakh Island Arc is an ancient corridor for floristic interchange between Africa and India.

锦葵科(Malvaceae Juss.)翅子树属(Pterospermum Schreb.)主要分布于热带亚洲,该属化石目前只在印度有少量记录.本研究报道了产自云南省景谷县(23°31′N,100°42′E)下中新统三号沟组的翅子树属叶片化石.通过形态学研究鉴定出3个种:双兴翅子树(P.shuangxingii Y.S.Zhao,J.Huang et T.Su sp.nov.),叶片偏小型,顶端截形并具3浅裂,与现今分布于东南亚地区的大花翅子树(P.grandiflorum Craib)形态较为相似;云南翅子树近似种(P.cf.yunnanense H.H.Hsue),叶片偏小型,顶端不分裂;翅子树属一未定种(Pterospermum sp.),叶片中型,叶片顶端具齿.景谷县翅子树属化石的发现证明,早中新世该属就在我国西南地区分化并繁盛至今.综合本研究以及已有证据,翅子树属可能从印度次大陆起源,随后向亚洲东部和东南部的热带地区扩散,最终形成了现今热带亚洲的分布格局.此外,本研究还描述了翅子树属化石叶片上的9种昆虫取食类型,与该属现生种叶片的昆虫取食形态一致,表明该属现今的植食性昆虫取食行为可能在早中新世就已经出现.

Despite much research we still lack a comprehensive understanding of the formation and evolution of the northeastern (NE) Tibetan Plateau. The West Qinling is regarded as the northeastward front of the transmission of the compression induced by the India-Asia collision and convergence, and thus its Cenozoic morphotectonic evolution can be used to elucidate the growth history of the northeastern plateau. The Cenozoic deposits of the intermontane Wushan basin of the West Qinling provide a long-term and continuous archive of information about the morphotectonic evolution of the plateau on its northeastern margin. Based on magnetostratigraphy and mammalian biostratigraphy, these deposits are well dated to similar to 34-6 Ma, and here we present the results of apatite fission-track thermochronology (AFT), sedimentation rates and facies, color reflectance and magnetic susceptibility, and structural and provenance analyses. Our results indicate a series of exhumation events, likely related to tectonics, with ages ranging from Paleocene through Late Miocene. Morphologic analyses indicate two levels of relict low-relief surfaces at high elevations in the source regions of the Wushan basin sediments. Based mainly on analyses of bedrock AFT and regional deformation signals, we speculate that these landscape remnants developed at low elevations during quiescent phases of orogenic construction, with the age ranges of Middle Eocene and Early-Middle Miocene, respectively. We use a synthesis of our data with existing records of deformation and paleo-altimetry to produce a morphotectonic scenario for West Qinling during the Cenozoic. This suggests that far-field stress due to the India-Asia collision was propagated to the modern northeasternmost boundary as early as the Paleocene. Subsequently, the topography of the West Qinling developed via discrete episodes of tectonic uplift activity/quiescence, or by enhanced denudation, until the Late Miocene, when the modern morphology of the northeasternmost plateau finally developed. Our accurate chronology of surface processes related to tectonic uplift-exhumation-denudation-sedimentation for the West Qinling provides key morphotectonic criteria for a comprehensive understanding of the pulsed growth history of the NE Tibetan Plateau.

Recent paleobotanical investigations in Vietnam provide a good opportunity to improve our understanding of the biodiversity and paleoclimatic conditions in the geological past of Southeast Asia. Palms (Arecaceae) are a diverse family of typical thermophilous plants with a relatively low tolerance for freezing. In this study, we describe well-preserved fossil palm leaves from the Oligocene Dong Ho Formation of Hoanh Bo Basin, northern Vietnam. Characters of the fossil leaves, such as a fan-shaped costapalmate lamina, an unarmed petiole, a costa slightly enlarged at the base that then tapers distally into the blade, and well-preserved amphistomatic leaves with cuticles, suggest that they represent a new fossil species, which we herein designate Sabalites colaniae A. Song, T. Su, T. V. Do et Z.K. Zhou sp. nov. Together with other paleontological and palaeoclimatic evidence, we conclude that a warm climate prevailed in northern Vietnam and nearby areas during the Oligocene.

近年来,随着DNA测序技术的发展,青藏高原及周边地区的生物地理学研究取得重大成果,从生物演化方面着手探讨了青藏高原隆升历史及其气候效应.综合近年来地质学、古生物学与生物地理学研究进展,我们发现高原及周边地区高寒生物类群的起源和分化时间以及多样性演化过程表明早在渐新世青藏高原部分地区就已经存在高寒生态系统,晚中新世以来青藏高原不同组成部分的地貌与气候格局发生重大改变,高寒生物的祖先类群不断迁入正在生长的高原或在高原上就地演化出适应高寒生境的新物种.晚上新世高寒区物种分化速率快速升高,多样性增加,可能是高原巨大山系和水系以及冰川作用造成地理隔离的结果.同时,生物地理学研究发现青藏高原及周边地区的高寒区与北半球高纬度地区存在密切联系,在第四纪冰期期间并未形成覆盖整个青藏高原的大冰盖,高原面上仍存在很多生物避难所.地质学、古生物学与生物地理学等进行的多学科交叉研究对全方位理解青藏高原隆升历史及其气候效应具有重要意义.

Three fossil species of Equisetum (Equisetaceae) were reported from the Neogene of south-western China and northern Vietnam, based on well-preserved rhizomes with tubers. Equisetum cf. pratense Ehrhart from the middle Miocene of Zhenyuan County, Yunnan Province, China is characterised by a bunch of three ovate tubers with longitudinal ridges on the surface. Equisetum yenbaiense A.T. Aung, T. Su, T.V. Do & Z.K. Zhou, sp. nov. from the late Miocene of Yenbai Province, Vietnam is characterised by four bunches of elongate tubers arranged in a whorl on a node. Equisetum yongpingense A.T. Aung, T. Su & Z.K. Zhou, sp. nov. from the late Pliocene of Yunnan is characterised by fibrous roots on most nodes and two to four bunches of large cylindrical tubers arranged in a whorl on a node. Floristic assemblages suggest that these species might have grown near a riverside or lakeshore. These new fossil records improve our understanding of species richness of Equisetum and their distribution range during the Neogene in Asia.

The synorogenic basin deposits and bedrocks of their source terranes within and along the Tibetan Plateau contain fundamental information regarding the spatiotemporal evolution of the largest orogenic plateau on Earth. The Guide–Xining region is located on the northeastern portion of the Tibet and its Eocene–early Pleistocene basin succession is well preserved. By integrating apatite fission-track thermochronology from sedimentary and basement samples, with heavy minerals and paleocurrent data, we decipher an almost complete sequence of exhumation and depositional events during the Cenozoic. Our data indicates that the initial deformation along the Guide–Xining region occurred since the Eocene, with the reorganization of the regional tectonomorphology and the formation of a broad basin. Thereafter, this single large basin was disrupted by multiple episodes of exhumation and deformation. Our study illuminate that the multiple-stage active processes (occurred at 49–42, 36–32, 23–19, 16–13 and 8–4Ma) work together to produce the current NE Tibetan Plateau.

近几年显微成像技术和计算机自动化技术的突破性进展,使裂变径迹的自动统计成为可能,并产生了新一代测量仪器.主要基于兰州大学新置的裂变径迹高级自动测试系统的建设和运转情况,对其发展历史、理论基础及研究进展、使用方法和技术规范进行介绍和评述.实例分析发现该套系统稳定、可靠、功能特性优良,具备多重优点,但也存在局限,需要后续研究解决.