Marine strata of Cretaceous age are widely distributed and well exposed in the Gamba area of South Tibet. A pre-requisite for understanding the depositional and palaeoenvironmental processes, which formed these deposits, is a reliable stratigraphic framework. The strata of the Qiangdong section in the Gamba area yielded calcareous nannofossils which provide a powerful tool for establishing a detailed biostratigraphic subdivision. They also allow for a supra-regional correlation, ideally on a global scale.Recently, an international research team consisting of PhD student HAN Meiling, Prof. LI Gang from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), alongside Prof. Jörg Mutterlose from Ruhr University Bochum, Germany, and Prof. Ulrich Heimhofer from Leibniz University Hannover, Germany, conducted a systematic study on the mid-Cretaceous calcareous nannofossil biostratigraphy of the Qiangdong section in the Gamba area, southern Tibet. This study has been published in the international journal “Cretaceous Research”.A total of 76 species have been identified in the 159 m thick section, allowing for the recognition of seven bioevents (calcareous nannofossil zones UC0 to UC7) covering the upper Albian–lower Turonian interval. The first occurrences of the calcareous nannofossil marker species Corollithion kennedyi (base UC1a, 100.5 Ma) and Quadrum intermedium (base UC5c, 94.1 Ma) constrain the Albian/Cenomanian and Cenomanian/Turonian boundaries in the Qiangdong section.The dominance of Watznaueria barnesiae throughout the studied interval suggests that diversity and abundance of the assemblages were clearly driven by diagenesis. Interval 1 (0–11 m) is barren of calcareous nannofossils. Within Interval 2 (12–43 m), the coexistence of Biscutum constans, Zeugrhabdotus spp. and Nannoconus spp. indicates a deep nutricline. Interval 3 (44–122 m) shows a decrease of B. constans, Discorhabdus ignotus and Nannoconus spp. along with an increase in W. barnesiae, suggesting enhanced diagenesis. Interval 4 (123–159 m), dominated by W. barnesiae, indicates a diagenetically highly altered environment with limited species diversity. A significant negative correlation between species diversity and the relative abundance of W. barnesiae further supports the idea that strong diagenetic alteration affected the nannofossil assemblages.A regional comparison with findings from the Tingri area, about 150 km west of the studied section, enhances the precision of biostratigraphic correlations in South Tibet. In addition, moderate to poor nannofossil preservation suggests a diagenetic influence for both the Tingri and Gamba areas, highlighting the necessity of critically evaluating nannofossil preservation when interpreting nannofossil assemblages for reliable palaeoceanographic reconstructions. The temperature and nutrient indices obtained in this study deviate from those published in past studies. These findings emphasize that preservation and diagenetic influence need to be critically considered when interpreting nannofossil assemblages for palaeoenvironmental reconstructions.This research was supported by the National Natural Science Foundation of China.Reference: Han, M., Li, G.*, Heimhofer, U., Mutterlose, J., 2025. Late Albian–early Turonian calcareous nannofossils from southern Tibet—implications for preservation, biostratigraphy and palaeoecology. Cretaceous Research, 171:106101. https://doi.org/10.1016/j.cretres.2025.106101Figure 1.Structural diagram of the study area and the location of the sectionFigure 2. Lithology, CaCO3 content, relative abundances of selected nannofossil taxa, temperature (MTI) and nutrients (MNI) in the Qiangdong section. ACB = Albian/Cenomanian boundary, CTB = Cenomanian/Turonian boundary.
The western Thailand and the Baoshan area of western Yunnan, China, were both part of the Sibumasu Terrane during the Early Paleozoic, located at low-latitudes of the peri-Gondwana. In November 2019, the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), and Mahasarakham University in Thailand signed a Memorandum of Understanding, initiating an in-depth collaboration in the field of geology and paleontology. Supported by this memorandum, the Early Paleozoic research team from NIGPAS conducted field investigations in Thailand in January 2020 and March 2023. Together with colleagues from Thailand, the team collected abundant conodont samples from the Ordovician and Silurian strata.Recently, Associate Professor Dr. CHEN Zhongyang, Dr. FANG Xiang, Assistant Professor Dr. LI Wenjie and other colleagues from the Early Paleozoic research team at NIGPAS, together with Professor Clive Burrett, Associate Professor Mongkol Udchachon, and Hathaithip Thassanapak from Mahasarakham University, Thailand, conducted analyses and systematic studies on these conodont samples. The significant findings, enriching the fossil records of Early Paleozoic conodonts in western Thailand and providing new insights into the paleobiological communities and paleogeographic environments. The research result was published in Journal of Palaeogeography and Palaeoworld.(1) New insights into Ordovician conodonts from the Ban Tha Kradan area in western ThailandNine genera and 11 species of conodonts were reported in the Ban Tha Kradan area of western Thailand for the first time. By the analysis of lithology and stratigraphic ages, the upper part of the Tha Manao Formation in the western Thailand was revised as the Pa Kae Formation. Based on conodonts and macrofossils, the Tha Manao Formation in western Thailand is assigned to the upper Floian to Darriwilian, and the conformably overlying Pa Kae Formation to the Sandbian to lower Katian.(2) First report of early Silurian conodont fauna in western ThailandFor the first time, the early Silurian conodonts were documented in western Thailand. Samples from the Kroeng Kravia Forest Park area revealed the upper Telychian Lower Pterospathodus amorphognathoides amorphognathoides Subzone. Analysis of microfacies and conodont fauna indicate that these fossils originated from a relatively deep marine environment. Furthermore, the conodont fauna is similar to that from Baoshan area of Yunnan Province and Langao area of Shaanxi Province in West China and resembles that from similar depositional environments in Australia, Laurentia, and peri-Gondwana, suggesting good connections among these regions by ocean currents.This series of studies was supported by the National Key Research and Development Program of China, the Second Tibetan Plateau Scientific Expedition and Research Program, the Strategic Priority Research Program of the Chinese Academy of Sciences, the National Natural Science Foundation of China, the Chinese Academy of Geological Sciences, and the Mahasarakham University.Reference:Chen, Z.Y., Li, W.J., Fang, X., Li, C., Burrett, C., Udchachon, M., Zhang, Y.D., 2024. Ordovician conodonts from the Ban Tha Kradan area, western Thailand. Palaeoworld, 33(3), 546-558. https://doi.org/10.1016/j.palwor.2022.12.004Chen, Z.Y., Thassanapak, H., Li, W.J., Wu, X.J., Udchachon, M., Fang, X., Burrett, C., 2025. First documentation of early Silurian conodonts from western Thailand and its geological implications. Journal of Palaeogeography, 14(1): 157-171. https://doi.org/10.1016/j.jop.2024.08.010Fig. 1. Ordovician conodonts from the Tha Manao Formation, Ban Tha Kradan area, western ThailandFig. 2. Silurian conodonts from the Kroeng Kravia Forest Park area, western ThailandFig. 3. Correlation of the stratigraphical successions of the Floian to Katian between the Sibumasu Terrane and the Upper Yangtze Platform of South ChinaFig. 4. Distribution of the upper Telychian conodont faunas containing Pterospathodus pennatus procerus, Panderodus langkawiensis, and Dapsilodus spp.
The Qinghai-Tibetan Plateau, recognized as the largest and highest plateau on Earth, is often referred to as the “Roof of the World/Third Pole/Water Tower of Asia”. The plateau is characterized by its geological evolution history and abundant rock outcrops, providing a unique perspective for investigating the history of the Earth. The Himalaya Terrane is located at the southernmost part of the Qinghai-Tibetan Plateau. A multitude of studies had suggested that the Himalaya Terrane was located in the peri-Gondwanan region and a warm low latitude zone during the Ordovician. Strata in the Mt. Qomolangma region of southern Xizang yields a significant number of fossils, including brachiopods, gastropods, graptolites and conodonts, resulting in the recognition of the Ordovician in this area. Ordovician cephalopod fossils from southern Xizang have been studied for nearly half a century, while biological composition and relative palaeobiogeography was unclear due to sporadic occurrences.Recently, the Early Palaeozoic research team from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, and researchers from other affiliations studied Middle to Upper Ordovician cephalopod material from southern Xizang. The results were recently published on Palaeogeography, Palaeoclimatology, Palaeoecology.Based on a collection of 43 cephalopod specimens from the Jiacun section, 30 species within 16 genera belonging to 10 families and 6 orders have been identified (including two new species: Wutinocerasmultiseptum and Wennanocerasremotum). Genera Lituites, Rhynchorthoceras, Trocholites and Deiroceras are firstly identified in southern Xizang, improving the cephalopod records and deepening the understanding of the cephalopod fauna diversity. Some new cephalopod occurrences suggested the lower part of the Hongshantou Formation is likely of early to middle Katian age. Furthermore, all the cephalopod fossil collections from southern Xizang have been summarized, and the biological diversity and composition research have been conducted. Actinocerid cephalopods were suggested as the dominant group during the Middle Ordovician. Subsequently, in the Late Ordovician, orthocerid and lituitid cephalopods were predominant.Igraph R package-based network analysis detects the existence of transitional cephalopod communities in the northeastern peri-Gondwana region, which were essential biogeographic bonds facilitating the exchange of cephalopods among various regions during the Middle and Late Ordovician.This work was supported by the Second Tibetan Plateau Scientific Expedition and Research Program, the National Natural Science Foundation of China and the Chinese Academy of Geological Sciences. This is a contribution to IGCP Project 700 (Palaeozoic Carbonate Build-ups in Southeast Asia) and Project 735 (Rocks and the Rise of Ordovician Life).Reference: Song, J.Q., Fang, X.*, Li, W.J., Wang, W.H., Burrett, C., Yu, S.Y., Qie, W.K., Zhang, Y.D., 2025. New cephalopod material of Middle to Upper Ordovician from southern Xizang (Tibet), China: Taxonomy, diversity and palaeobiogeography. Palaeogeography, Palaeoclimatology, Palaeoecology, 662, 112744. https://doi.org/10.1016/j.palaeo.2025.112744Figure 1 Geological and locational map of the Ordovician Jiacun sectionFigure 2 New Ordovician cephalopod material from southern Xizang (Tibet), ChinaFigure 3 Network analyses on cephalopod genera in the northeastern peri-Gondwana region during the Ordovician, and palaeogeographical maps showing the communities
The initial radiation of land vascular plants, as evidenced by the increase of both diversity and morphological disparity during the Silurian and Devonian periods, has been regarded as plant terrestrialization, which can be considered the equivalent in terrestrial environments of the Cambrian explosion of marine animals. Novel structures such as tracheids, stomata, leaves, roots and secondary xylem evolved during this time interval. However,how life-history strategies evolved in early land plants is not well understood.
Recently, Dr. Pu Huang from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, together with other collaborators, reported on a new species of Zosterophyllum, Z. baoyangense,from the Lower Devonian of Guizhou Province. Meanwhile, they built a multi-morphological-character dataset of the zosterophyllopsids from late Silurian to Early Devonian ages, and revealed the divergent life-history strategies in this group.The initial radiation of land vascular plants, as evidenced by the increase of both diversity and morphological disparity during the Silurian and Devonian periods, has been regarded as plant terrestrialization, which can be considered the equivalent in terrestrial environments of the Cambrian explosion of marine animals. Novel structures such as tracheids, stomata, leaves, roots and secondary xylem evolved during this time interval. However,how life-history strategies evolved in early land plants is not well understood.As a predominant and typical component of Early Devonian floras, the Zosterophyllopsida has a long history of research, and was widely documented in palaeontology textbooks. This group appeared in the late Silurian and extended to the Late Devonian. Zosterophyllum has been reported around the world, especially in the South China Block, where at least 14 species of Zosterophyllum had been described. Some species are preserved as complete or nearly complete plants, such as Z. shengfengense. Thus, zosterophyllopsids are important material for the studies of life-history strategies of early land plants.Recently, Dr. Pu Huang from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, together with other collaborators, reported on a new species of Zosterophyllum, Z. baoyangense,from the Lower Devonian of Guizhou Province. Meanwhile, they built a multi-morphological-character dataset of the zosterophyllopsids from late Silurian to Early Devonian ages, and revealed the divergent life-history strategies in this group.The plant bodyof the newly discovered Zosterophyllum baoyangense is ca 45.4 mm in whole length and its spikes are 5.8−10.8 mm high. The smaller body size with tiny spikes represents the smallest extreme among the early land plants.Morphological characters of Zosterophyllum species and zosterophyllopsids were collected, including the width and length of axes, width and length of spikes as well as the sporangial height and width. Meanwhile, a new descriptor, total sporangial accommodation (TSA), was proposed to evaluate the mass or energy investment for spore production in each plant.Pu Huang and his colleagues found that the length and width of axes generally follow the same trend of the diversity of species of Zosterophyllum, increasing from the Ludlow to Early Devonian, with the maximum range being reached in the Early Devonian. The TSA values and sporangial size of Zosterophyllum also show a similar pattern, with a huge different in vegetative and reproductive organ in Early Devonian. The minimum value of the TSA is represented by Z. baoyangense, only 4.3 to 16.8 mm3, while the TSA of Z. australianum is 29.6 to 499.0 mm3 occurred in the same bed of the Baoyang section. In additional, The TSA seems to be closely related to axial width. For the members of Lycophytina sensu Kenrick & Crane and Zosterophyllopsida sensu Hao & Xue, the length and width of axes generally follow the same trend of evolution.The authors considered that highly morphologically diverse zosterophyllopsids in Pragian represent two groups in different life-history strategies. Like the r-selected species, one group is characterized by the smaller sizes and smaller TSA, shorter lifespan and lower vegetative and reproductive output, and seems to adapt to turbulent environment, such as Zosterophyllum baoyangense. The other group, such as Z. australianum, on the contrary to the former, like K-selected species. The authors argued that the transition from the Rhyniophytic Flora to the Eophytic Flora was probably driven by the evolution of divergent life-history strategies in Zosterophyllum and more broadly in zosterophyllopisds generally.This work was financially supported by the National Key R&D Program of China and the National Natural Science Foundation of China. The authors include Dr. Pu Huang, and Dr. Jinzhuang Xue, Dr. Jiashu Wang (now at Geological Museum of China) and Mr. Yiling Wang from the Peking University,Dr. Lu Liu from the National Natural History Museum of China, and Dr. Jingyu Zhao from Suzhou University.Article information: Huang,P.*,Wang,J.S.,Wang,Y.L.,Liu,L.,Zhao,J.Y.,Xue,J.Z.,2025. The smallest Zosterophyllum plant from the Lower Devonian of South China and the divergent life-history strategies in zosterophyllopsids. Proceedings of the Royal Society B 292: 20242337. https://royalsocietypublishing.org/doi/10.1098/rspb.2024.2337Figure 1. Zosterophyllum baoyangense sp. nov., showing a fertile axis with K-shaped branching and a terminal spike. (The specimen was collected by Pu Huang, Lu Liu and Jinzhuang Xue in 2017)Figure 2.Diversity and morphology of Zosterophyllum species through the late Silurian to Early Devonian. (a) Species richness;(b) Maximum length of axes; (c) Width of axes; (d) TSA; (e) Crossplot of sporangial width and height of different time bins; (f, g) Crossplot of TSA and axial width for all sampled Zosterophyllum species. (Data curation: Pu Huang, Yiling Wang; visualization: Jiashu Wang)Figure 3. Artist’s restoration of part of the Early Devonian Mangshan flora, with plant communities of Zosterophyllum baoyangense at the front, andZ. australianum and an unnamed plant to the back. (Conceptualization: Pu Huang; visualization: Chao Tan)
Microbe-mineral interactions play a crucial role in driving geological and geochemical processes. In these processes, mineral supply energy and nutrients essential for microbial growth and metabolism, while microbes influence mineral dissolution, transformation, and formation processes through their metabolic activities. These interactions occur at microscopic interfaces at the single-cell level, shaping both microbe and mineral evolution while profoundly influencing geological events, biogeochemical cycles, and ore formation. Fungi, one of Earth's oldest and most diverse life forms, are unique due to apical growth mode of the hyphae. This growth mode enables hyphal tips to exert biophysical forces of up to 10−20 μN/μM², allowing them to explore and penetrate substrates. The study of fungi’s roles in geological and geochemical processes has emerged as a distinct field called Geomycology. Increasing evidence highlights the critical role of fungi play in soil formation, ore genesis, biogeochemical cycling of elements, and the evolution and reproduction of terrestrial plants.In 1997, Jongmans et al. discovered that fungi significantly accelerate the weathering of silicate minerals, leading to the formaiton of tunnels. In 2009, Bonneville et al. demonstrated that biophysical forces excerted by fungal hyphal tips directly distort the crystal structure of silicate mineral, while subsequent biochemical actions derived from metabolites (e.g., proton, organic acids, and siderophores) dissolve and mobilize elements. These biophysical and biochmeical mechanisms act synergistically to enhance mineral weathering. Our previous studies showed that fungal hyphae instantly initiate mineral weathering upon contact (Li et al., 2022) and highlighted the critical role of biophysical forces generated at hyphal tips in the fungal weathering process (Li et al., 2016). However, most studies to date have focused on freshly prepared silicate minerals, leaving the fungal weathering of aged minerals with altered layers (Si-rich deposits) laygely unexplored. Altered layers form rapidly during silicate mineral dissolution and significantly inhibit further dissolution under abiotic conditions. Thus far, only Wild et al. (2018) have reported on bacterial activity on aged silicates (olivine and labradorite), showing only a 30% enhancement compared to abiotic conditions. Notably, fungal weathering of aged silicate minerals remains unstudied.To bridge this knowledge gap, Dr. Zibo Li from the Nanjing Institute of Geology and Paleontology, Chinese Academy of Sciences, collaborated with Professor Xiancai Lu from Nanjing University and a team of researchers, including Professors Maoyan Zhu and Zongjun Yin (Nanjing Institute of Geology and Paleontology), Professors Jun Chen and Gaojun Li (Nanjing University), Professor Zhangdong Jin (Institute of Earth Environment, CAS), and Professor Hui Teng (Tianjin University). Their study explored fungal interactions with aged olivine and lizardite, demonstrating that fungal hyphae can degrade altered layers and continuously promote silicate mineral weathering. The study was recently published in Geophysical Research Letters.Key Findings:1. Fungi significantly enhance the dissolution rates of aged silicate minerals. Aged olivine and lizardite, pretreated in acidic solutions, developed Si-rich altered layers. As pretreatment duration increased, the thickness of these altered layer grew, and mineral dissolution rates under abiotic condition gradually declined. Under fungal influence, the dissolution rates of aged silicate minerals increased by 1−2 orders of magnitude, with olivine dissolution rates enhanced by 9−14 times and lizardite dissolution rates by 71−123 times compared to abiotic conditons.2. Fungal hyphae penetrate altered layers and etch underlying fresh minerals. Within 24 hours of cultivation, fungal hyphae produced dissolution channels on the surfaces of both fresh and aged silicate minerals, with channel depths ranging from 18−65 nm on olivine and 10−32 nm on lizardite. After 20 days, the hyphae penetrated the altered layers, facilitating further elemental dissolution from the fresh minerals beneath.3. Fungi facilitate matter and energy diffusion within altered layers. For olivine pretreated for 480 hours, the thickness of the altered layer increased from ~110 nm to ~230 nm at the hyphal tip-mineral interface and from ~20 nm to ~380 nm at the hyphal end-mineral interface. Beneath the altered layers, fungi oxidized structual Fe(II). For lizardite pretreated for 96 hours, fungal hyphae dissolved elements within altered layers and the thickness of altered layers at hypha-mineral interface expanded from ~3.3 μm to 6.2 μm. Although fungi had a weaker effect on dissolving altered layers with normalized Mg/Si molar ratios below 0.65, prolonged contact between fungi and minerals eventurally led to further dissolution of the fresh minerals below.This study reveals that fungi actively regulate their growth behavior in response to the bioavailability of nutrients in the envirments, effectively degrading altered layers through etching and penetration. Biophysical forces exerted by fungal tips disrupt altered layers, while the enhanced interdiffusion of metabolic byproducts (e.g., protons, small-molecule complexes, and reactive oxygen species) and released cations across altered layers continuously prmote the weathering of silicate mineral. These findings not only deepen our understanding of microbially-mediated geological and geochemical processes but also provide a theoretical framework for searching mineralogical biosignatures.This study was funded by the National Natural Science Foundation of China.Citations:AG Jongmans, N Van Breemen, U Lundström, PAW Van Hees, RD Finlay, M Srinivasan, T Unestam, R Giesler, P-A Melkerud, and M Olsson. 1997. Rock-eating fungi, Nature, 389: 682-83. https://doi.org/10.1038/39493S. Bonneville*, M. M. Smits, A. Brown, J. Harrington, J. R. Leake, R. Brydson, and L. G. Benning. 2009. Plant-driven fungal weathering: Early stages of mineral alteration at the nanometer scale, Geology, 37: 615-18. https://doi.org/10.1130/G25699A.1Zi-Bo Li*, Lianwen Liu, Xiancai Lu, Yi Cao, Junfeng Ji, and Jun Chen. 2022. Hyphal tips actively develop strong adhesion with nutrient-bearing silicate to promote mineral weathering and nutrient acquisition, Geochimica et Cosmochimica Acta, 318: 55-69. https://doi.org/10.1016/j.gca.2021.11.017Zibo Li, Lianwen Liu, Jun Chen, and H. Henry Teng*. 2016. Cellular dissolution at hypha- and spore-mineral interfaces revealing unrecognized mechanisms and scales of fungal weathering, Geology, 44: 319-22. https://doi.org/10.1130/G37561.1Bastien Wild, Gwenaël Imfeld, François Guyot, and Damien Daval. 2018. Early stages of bacterial community adaptation to silicate aging, Geology, 46: 555-58. https://doi.org/10.1130/G40283.1Figure 1: The concentration of dissolved Fe in fungal and abiotic weathering experiments over a 20‐day period. Values within square brackets denote the enhancement factor (Fefungal,max/Feabiotic,max).Figure 2: The lengths of T. flavus hyphae on olivine and lizardite and hyphal etching and penetration.Figure 3: The normalized Mg/Si molar ratios beneath T. flavus hypha- and solution-olivine/lizardite interfaces as determined by TEM-EDS after 24 h of cultivation.Figure 4: T. flavus hypha-induced transformation of the crystal structure and the oxidation of Fe(II) in olivine pretreated for 480 h after 24 h of cultivation.Article informaiton:Zi-Bo Li*, Xiancai Lu*, Gaojun Li, Zhangdong Jin, Lianwen Liu, Zongjun Yin, Maoyan Zhu, Hui Henry Teng, Junfeng Ji, and Jun Chen. 2024. Continuable Weathering of Silicate Minerals Driven by Fungal Plowing, Geophysical Research Letters, 51: e2024GL111197. https://doi.org/10.1029/2024GL111197
The closing of the Tethys Ocean during the Mesozoic and Cenozoic dramatically affected the palaeogeography, palaeoenvironment and biotic evolution of the Tibetan Plateau and surrounding areas. The timing of closure of the Tethys Ocean in different areas is recorded by the youngest marine deposits. In the western Kunlun area of northwestern Tibet, the Tielongtan Group represents the youngest marine deposits, and is rich in rudist bivalves; however, its depositional age, particularly the age of final deposition, is poorly constrained. Systematic and palaeobiogeographic analyses were conducted on rudists from the Tielongtan Group in the eastern Loqzung Mountains. Four genera and two species were identified: Biradiolites boldjuanensis, Gorjanovicia acuticostata, Durania sp. and Radiolites sp. The occurrence of the lower Maastrichtian index fossil, Biradiolites boldjuanensis, indicates that deposition of the Tielongtan Group continued until the early Maastrichtian. Therefore, the results of this and previous studies indicate that deposition of the Tielongtan Group spanned from at least the Turonian to the early Maastrichtian. Palaeobiogeographical analyses show that B. boldjuanensis was endemic in Central Asia, whereas G. acuticostata might have extended beyond the Mediterranean region. During the Late Cretaceous, the shallow ocean in the western Kunlun area contained both cosmopolitan and endemic rudists.Professor Zhang Qinghai, Academician Ding Lin, and doctoral candidate Gao Bintao from the Institute of Tibetan Plateau Research, Chinese Academy of Sciences and Associate Professor Rao Xin from the Key Laboratory of Palaeobiology and Petroleum Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences jointly completed the research.This study is financially supported by the Second Tibetan Plateau Scientific Expedition and Research Program (STEP; 2019QZKK0708), the National Natural Science Foundation of China (41972032, 42272027), and CAS Pioneer Hundred Talents Program.
An international research team led by Prof. ZHANG Huaqiao from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, has reported the discovery of extraordinary fossil embryos of Ecdysozoa, a group of animals that include roundworms, horsehair worms, mud dragons, penis worms, velvet worms, water bears, insects, shrimps, and crabs, from the early Cambrian Kuanchuanpu biota (ca. 535 million years ago, or Ma) in southern Shaanxi Province, China.The discovery expands our understanding of the morphological disparity and diversity of the early Fortunian fossil embryos and ecdysozoans.The study was published in Palaeogeography, Palaeoclimatology, Palaeoecology on Dec. 11.Invertebrate embryos have relatively low fossilization potential; however, when preserved, they can offer crucial insights into the evolutionary developmental biology of extinct animals. Invertebrate embryos have been reported from the early Cambrian through the Early Ordovician, but are represented only by cnidarians and a single scalidophoran taxon Markuelia. In the early Cambrian Kuanchuanpu biota, cnidarian embryos and their hatched stages are abundant and diverse. In contrast, fossil embryos belonging to the Ecdysozoa are still unknown in the Kuanchuanpu biota, although their hatched stages have been reported since ten years ago.In this study, the researchers described exceptionally preserved fossil embryos from the early Fortunian (early Cambrian) Kuanchuanpu Formation at Zhangjiagou section, Xixiang County, Hanzhong City, Shaanxi Province, China. In total, seven specimens are illustrated, and they are all three-dimensionally phosphatized. Micro-CT analysis shows that they are internally hollow, thus leaving no trace of internal soft anatomies. Based on the differences of the number and arrangement of the sclerites at their anterior and posterior ends, these embryos are assigned to two new taxa, Saccus xixiangensis gen. et sp. nov. (Fig. 1) and Saccus necopinus gen. et sp. nov. (Fig. 2).The study shows that the embryos are enclosed within a thin and smooth envelope, ranging in diameter from 730 μm to 1 mm. The embryos are relatively large, indicating that their eggs are yolk-rich and thus can provide enough energy for development (lecithotrophy). The embryos have a bag-shaped body with no introvert or paired limbs. High-resolution scanning electron microscopic images show that the integument is non-ciliated. The sclerites at the anterior end are radially arranged, whereas those at the posterior end are bilaterally arranged. The integument shows soft deformation, while the sclerites remain largely undeformed, suggesting that the sclerites are stiffer and likely cuticularized. The embryos lack any orifice, thus representing a developmental stage prior to the formation of a mouth or anus.The bilaterally arranged sclerites at the posterior end imparts bilaterality, classifying these new embryos as bilaterians. Furthermore, the absence of cilia or cilium insertion sites and the presence of cuticularized sclerites suggest an ecdysozoan affinity. The presence of cuticle implies that the embryos are in later embryonic stages, possibly close to hatching.In the absence of hatched specimens, the developmental mode of Saccus is unknown. It is inferred that it underwent indirect development, hatching as lecithotrophic (yolk-feeding) larvae. In this case, the morphology of the juvenile and adult forms is uncertain due to metamorphosis during later growth. Alternatively, it could undergo direct development, hatching as lecithotrophic juveniles, with both juveniles and adults potentially having a similar bag-shaped body without an introvert or paired limbs, closely reminiscent of Saccorhytus (Fig. 3). In either case, the embryos reply on yolk as the only source of energy until they develop a functional mouth and begin to take food.The direct development hypothesis has implications for the body shape evolution of early ecdysozoans. If Saccus and Saccorhytus are constrained to be total- or stem-group ecdysozoans (Fig. 3), it indicates that a bag-shaped body may be primitive to the ecdysozoans, whereas a vermiform one, which characterizes the crown-group ecdysozoans, evolved later.
The DOUNCE (DOUshantuo Negative Carbon isotope Excursion) was marked by a significant shift in δ13Ccarb from ~+5‰ down to ~−12‰ in the upper part of the Ediacaran Doushantuo Formation of South China. As an equivalent event of the Shuram/Wonoka anomaly, the DOUNCE isthe largest negative δ13Ccarb excursion in geological history and denotes a global ocean oxygenation event (Figure 1). Consequently, it has been widely used as a chemostratigraphic tool for correlating the Ediacaran strata globally. Nonetheless, the DOUNCE exhibits variable stratigraphic expressions across sections and depositional environments, raising questions about its representation as a primary indicator of the Ediacaran seawater δ13C value. Such variability casts doubt on the reliability of the DOUNCE for global correlation, and its implications for the carbon cycle, oceanic oxygenation, and biological evolution during the Ediacaran period.To elucidate the DOUNCE event as a synchronous global occurrence and a chemostratigraphic tool, Dr. Yinggang Zhang, a postdoc in Prof. Maoyan Zhu’s group at the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, has compiled the “DOUNCEraq” database. This global-scale database currently includes 9375 valid δ13Ccarb analyses from 156 sections/boreholes documenting the DOUNCE/Shuram/Wonoka event (Figure 2).The meta-analysis of DOUNCEraq highlights the global scope of the DOUNCE event and reveals the presence of an instant rise stage post the abrupt δ13Ccarb decline as an inherent feature of the DOUNCE pattern. Moreover, it also emphasizes the impacts of palaeolatitude, palaeocontinent, water depth, and lithology on the DOUNCE’s pattern and variability: (1) lower pre-DOUNCE δ13Ccarb values and smaller shift magnitudes within 30–0°N compared to the southern hemisphere; (2) compared to the shallower sections, deep-water sections exhibit lower pre-DOUNCE and DOUNCE nadir δ13Ccarb values with smaller shift magnitudes relative to shallower sections; (3) dolostones demonstrate lower pre-DOUNCE values, higher values at the DOUNCE nadirs, and smaller shift magnitudes compared to limestones (Figure 3). Such local impacts on the DOUNCE pattern provide important constraints on the causes of the DOUNCE event and could be explained within the DOC-oxidation hypothesis via regulating oxidants supply. Overall, the present meta-analysis enhances our understanding of the DOUNCE’s global stratigraphic expressions and provides important constraints on the DOUNCE causes.This study was recently published under the title of “Meta-analysis of the DOUNCE event (Shuram/Wonoka excursion): Pattern, variation, causal mechanism, and global correlation” in the journal Earth-Science Reviews. This research was financially supported by the National Key Research and Development Program of China, the National Natural Science Foundation of China, China Postdoctoral Science Foundation, and the Jiangsu Funding Program for Excellent Postdoctoral Talent.Article information：Zhang, Y. & Zhu, M., 2024. Meta-analysis of the DOUNCE event (Shuram/Wonoka excursion): Pattern, variation, causal mechanism, and global correlation. Earth-Science Reviews, 105000. https://doi.org/10.1016/j.earscirev.2024.105000Figure 1. Ediacaran fossil ranges (panel A), key evolution events (panel B), and carbonate δ13C variations during the Ediacaran (panel C).Figure 2. Palaeogeographic map ca. 570 Ma showing the approximate locations of all the DOUNCE entries. The location of each entry included in the DOUNCEraq is marked by a circle, colour-coded by water depth, and the entry numbers are collected and summarized in the rectangle of the palaeocontinent.Figure 3. The magnitudes of the δ13Ccarb negative shift during the DOUNCE event. Entries are grouped by four grouping variables, in order: (A) palaeolatitude band, (B) palaeocontinent, (C) water depth, and (D) dominated lithology in the falling stage.<!--!doctype-->
In a remarkable leap forward for paleontological research, a team of scientists from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, have developed a novel approach to analyze the three-dimensional structure and chemical composition of Ediacaran embryo-like fossils. These ancient microfossils, dating back to 590–570 million years ago, have long puzzled scientists due to their enigmatic affinities and the challenges associated with studying their delicate structures.The study, published in the Journal of Earth Science, introduces an integrated method that harnesses the power of 3D X-ray microscopy (3D-XRM) and focused ion beam scanning electron microscopy (FIB-SEM). This cutting-edge technique allows researchers to peer into the microscopic intricacies of fossils with unprecedented clarity, offering a dual advantage: the non-destructive 3D visualization capabilities of 3D-XRM and the nanoscale chemical and structural analysis prowess of FIB-SEM.Traditional fossil analysis techniques have reached their limits, struggling to provide the detailed, in-depth information required to understand the complex structures and chemical compositions of ancient organisms. The Ediacaran embryo-like fossils, in particular, with their spherical structures reminiscent of animal embryos, demanded a more sophisticated approach.The researchers' innovative strategy involves a two-pronged attack: first, using 3D-XRM to create a non-destructive, high-resolution 3D model of the fossils, and then employing FIB-SEM to uncover the structural and chemical composition at the nanometer scale. This synergy between the two techniques overcomes the individual limitations of each, providing a comprehensive view of the fossils' structure and chemistry.Through this advanced imaging technique, the team has successfully reconstructed the intricate, multi-layered structures within the cell nuclei of the Ediacaran embryo-like fossils. They discovered a concentric ring structure composed of two distinct mineral facies: one rich in clay minerals and the other in apatite, a form of calcium phosphate. This finding sheds new light on the preservation processes of these ancient organisms and their subcellular structures.The ability to distinguish between biological structures and those formed through geological processes is a game-changer for paleobiologists. This research not only enhances our understanding of early life on Earth but also refines our ability to interpret the fossil record, offering insights into the evolutionary history of life.The combined use of 3D-XRM and FIB-SEM is expected to open new avenues in paleontological and geological research. This method has the potential to transform the study of not only Ediacaran embryo-like fossils but also a wide range of geological specimens, from understanding the formation of minerals to exploring the origins of life on our planet.Workflow diagram of the combined 3D-XRM and FIB-SEM technology methodThe 3D structure and elemental composition of the cell nuclei in the embryo-like fossils from the Ediacaran Weng'an Biota
Pyrite sulfur isotopic composition (δ34Spy) is a crucial proxy for reconstructing ancient Ediacaran marine environments. However, recent in situ isotopic analyses of sedimentary pyrite have revealed distinct δ34Spy signatures among different pyrite morphologies, indicating that secular changes in bulk δ34Spy may reflect variations in proportions of different pyrite morphologies rather than environmental signals. Up to now, intragrain isotopic patterns within individual pyrite grains have not yet been extensively investigated for Ediacaran samples. The absence of this specific data set has hindered our ability to understand current complexities of bulk δ34Spy in reconstruction paleoenvironment.In this study, Yongliang Hu, Wei Wang, and other co-authors elucidated δ34Spy patterns by conducting scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), Raman spectroscopy, and nanoscale secondary ion mass spectrometry (NanoSIMS) to examine the crystal texture, element atomic ratios (S/Fe), mineral composition, and in situ isotopic composition of individual pyrite grains from Ediacaran drill-core samples. The results highlight significant microenvironmental heterogeneity and dynamic sulfur pool mixing on rapid short-term timescale during pyrite growth.Key findings of this study include:(1) The observed pyrite grains exhibit significant variations in in situ δ34Spy values across μm-scale regions. Targeted euhedral/subhedral pyrite crystals generally show uniform mineral texture, although some grains show varying degrees of dissolution edges and surface cavities. These pyrite grains are found in banded aggregations, positioned parallel or subparallel to bedding planes or scattered around lens-shaped pyrite, surrounded by authigenic clay and calcite. This distribution suggests they formed in sediment pores. In situ isotopic analysis reveals significant intragrain δ34S heterogeneity, with differences reaching up to 69.3‰ on a micrometer scale.(2) This heterogenous intragrain δ34S pattern of pyrite may be related to the formation model of pyrite grains. Targeted euhedral/subhedral pyrite grains formed rapidly, originating from numerous nucleation sites simultaneously. The sulfur in pyrite could originate from several sources, including diffusive sulfate ions from the upper part of the sulfate reduction zone (SRZ), sulfide diffusion from the water column or shallow sediments, which produces more 34S-depleted isotopic signals, or from deeper sediments where sulfate-driven anaerobic oxidation of methane generates 34S-enriched isotopes. Shallow sediment depth and low sedimentation rates create a stable pore-water microenvironment, resulting in consistent pyrite formation with uniform δ34S values. In contrast, deeper sediment depths and higher sedimentation rates lead to highly positive and divergent δ34S values. This variability highlights dynamic environmental conditions and complex mixing processes of sulfur pools over rapid geological timescale during pyrite growth.(3) Differences in elemental or mineral composition have minimal impact on the sulfur isotope heterogeneity of pyrite grains. The δ34Spy values show a slight positive correlation with the S/Fe ratios of the pyrite, implying that lower δ34Spy values generally coincide with lower pyrite S/Fe ratios. Raman spectroscopy indicates the possible presence of pyrrhotite minerals within the pyrite grains. However, their influence on the generation of in situ δ34S heterogeneity within the grains appears to be less pronounced due to their small isotopic fractionation during mineral conversion.Recently, this study has been published on line in Marine and Petroleum Geology. The publication issues are as follows:Yongliang Hu, Wei Wang*, Xianye Zhao, Chengguo Guan, Chuanming Zhou, Chenran Song, Hongyi Shi, Yunpeng Sun, Zhe Chen, Xunlai Yuan, 2025. Extreme sulfur isotope heterogeneity in individual Ediacaran pyrite grains revealed by NanoSIMS analysis. Marine and Petroleum Geology, 171, 1−14. https://doi.org/10.1016/j.marpetgeo.2024.107201.Fig. 1 Microscopic features and mineralogy of pyrite in samples LTS01-02Fig. 2 Pitting locations, histograms and box-and-whisker diagrams of in situδ34Spy measurements on targeted pyrite grainsFig. 3 Growth patterns for the pyrite grains in the Lantian drill-core samples
