In recent years, the Lower Paleozoic research team from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), has conducted extensive field investigations across the Miaolingian to early Floian shallow-water areas of the Yangtze Platform. Based on detailed field reconnaissance and a systematic review of published data, the team has generated new insights into stratigraphic subdivision, correlation, and spatiotemporal distribution patterns. These results have recently been published online in the Geological Journal of China Universities.The interval from the middle Cambrian to the Early Ordovician is a crucial transition connecting two major evolutionary events, the "Cambrian Explosion" and the "Great Ordovician Biodiversification Event", making it key to deciphering their intrinsic relationship. The Yangtze Platform in South China, with its complete and well-developed stratigraphic successions from this interval, serves as an exceptional window for exploring this significant transition. During the Miaolingian-Furongian, however, thick, massive dolostone successions were widely distributed across the platform. Due to their lithological monotony and fossil scarcity, their stratigraphic subdivision, nomenclature, and regional correlation have long posed challenges. Furthermore, a lack of detailed studies on the Early Ordovician (Tremadocian-early Floian) shallow-water deposits in the Upper Yangtze region, coupled with highly variable lithofacies, has prevented the establishment of a refined stratigraphic framework and high-resolution correlation. Collectively, these issues have hindered a comprehensive, basin-scale understanding of the relationship between these two major biotic evolutionary events in South China.In recent years, the Lower Paleozoic research team from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), has conducted extensive field investigations across the Miaolingian to early Floian shallow-water areas of the Yangtze Platform. Based on detailed field reconnaissance and a systematic review of published data, the team has generated new insights into stratigraphic subdivision, correlation, and spatiotemporal distribution patterns. These results have recently been published online in the Geological Journal of China Universities.The studies clarified the spatiotemporal distribution patterns of Miaolingian–early Floian stratigraphic successions in the study region and, adhering to modern stratigraphic nomenclature codes, systematically proposed a revised framework.For the Miaolingian-Furongian, researchers recognized three sedimentary facies belts: a marginal mixed dolomite/clastic facies belt, a shallow-water dolomite facies belt, and a deeper-water dolomite/limestone facies belt. It is proposed that the Hsihsiangchih, the Loushankuan, and the Sanyiutung groups represent the sedimentary successions of these three facies belts, respectively. Based on lithological differences, the Sanyiutung Group was further subdivided in ascending order into the Guanshannao, Xinping, Houba, and Maotian formations. Integrating existing stratigraphic data, these formations correspond to the middle-upper Drumian, Guzhangian-Paibian, Jiangshanian, and Stage 10, respectively. For the Early Ordovician (Tremadocian-early Floian), the team clarified the spatiotemporal distribution pattern of shallow-water deposits in the Upper Yangtze region by identifying three distinct sedimentary facies zones: a coarse-grained siliciclastic facies, a mixed coarse-grained siliciclastic-dolostone facies, and a dolomite facies. The Tangchih Formation, the Wanjuanshu-Lohanpo formations (the latter equivalent to the Putaojing-Dacao formations), and the "Tungtzu"-"Hunghuayuan" formations are now applied to designate the sedimentary successions of these three zones. Furthermore, by integrating existing stratigraphic data, the researchers reassessed the age assignments of these lithostratigraphic units.This revised stratigraphy provides a refined temporal framework for a basin-scale understanding of the coevolution of environments and biotas in South China throughout the Miaolingian to early Floian.These studies were jointly supported by the National Key Research and Development Program of China and the State Key Laboratory of Palaeobiology and Stratigraphy.Reference: Wang, G. X., Zhan, R. B., Wei, X., Yan, G. Z. 2026. Lithostratigraphy, age and distribution of Miaolingian-Furongian (Cambrian) rocks on the Yangtze Platform, South China. Geological Journal of China Universities, https://doi.org/10.16108/j.issn1006-7493.2026057.Wang, G. X., Zhan, R. B., Wei, X., Yan, G. Z., Cui, Y, N. 2026. Tremadocian-early Floian (Early Ordovician) shallow-water deposits on the Yangtze Platform of South China: Lithostratigraphy, age and distribution. Geological Journal of China Universities, https://doi.org/10.16108/j.issn1006-7493.2026094.Fig.1 Spatial pattern of the Miaolingian-Furongian (Cambrian) strata on the Yangtze Platform, South ChinaFig.2 Revised stratigraphic framework of the Miaolingian-Furongian (Cambrian) strata on the Yangtze Platform, and their correlation with strata of the Jiangnan SlopeFig.3 Spatial pattern of the Tremadocian-early Floian (Early Ordovician) shallow-water deposits on the Upper Yangtze Platform, South ChinaFig.4 Revised stratigraphic framework of the Tremadocian- early Floian (Early Ordovician) strata of near-shore facies on the Upper Yangtze Platform, and their correlation with coeval strata of the interior Yangtze region
Recently, Dr. NA Lin and Associate Professor LI Qijian from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), in collaboration with Dr. Ádám T. Kocsis and Professor Wolfgang Kiessling from Friedrich-Alexander University Erlangen–Nuremberg, Germany, investigated the Cambrian radiation from a spatial perspective. Their findings have been published in Geological Society, London, Special Publications.The Cambrian radiation represents one of the most significant evolutionary events in the history of life, marked by the rapid appearance and diversification of major animal groups and the increasing complexity of marine ecosystems. Previous studies have largely focused on the dramatic rise in global biodiversity and morphological disparity during this interval. However, an increase in global diversity can result either from greater species richness within individual communities or from increasing differences in species composition among regions. How these two processes contributed to the Cambrian radiation remains an important question in evolutionary palaeobiology.Recently, Dr. NA Lin and Associate Professor LI Qijian from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), in collaboration with Dr. Ádám T. Kocsis and Professor Wolfgang Kiessling from Friedrich-Alexander University Erlangen–Nuremberg, Germany, investigated the Cambrian radiation from a spatial perspective. Their findings have been published in Geological Society, London, Special Publications.A key data source for this study was the Geobiodiversity Database (GBDB), an independently developed palaeontological database with proprietary intellectual property rights held by NIGPAS. The researchers integrated fossil occurrence records from GBDB with those from the international Paleobiology Database (PBDB). Because the global fossil record is unevenly sampled across different palaeocontinents, the incorporation of GBDB records, particularly those from South China and neighbouring Gondwanan terranes, helped improve data coverage along the eastern margin of Gondwana.The combined dataset comprised 9,800 fossil collections, 39,972 species occurrences, 3,527 genera, and 11,220 species, providing a substantial foundation for quantitatively reconstructing the spatial organization of marine biodiversity from the latest Ediacaran to the earliest Ordovician.Using plate tectonic reconstructions, the research team restored fossil occurrences to their palaeogeographic positions and analysed biodiversity patterns across multiple spatial frameworks, including equal-area grids, palaeogeographic plates, and palaeolatitudinal bands. They combined diversity partitioning, network analysis, and assessments of endemism and latitudinal differentiation to investigate how marine faunal distributions changed throughout the Cambrian.The researchers first partitioned global diversity (gamma diversity, γ) into local diversity (alpha diversity, α) and differences in taxonomic composition among regions (beta diversity, β). Their results revealed that, after accounting for sampling differences, global diversity increased substantially from the Fortunian to Cambrian Stage 3, whereas average local diversity did not show a corresponding increase. Instead, beta diversity rose sharply during the early Cambrian and was strongly associated with changes in global diversity.These findings indicate that the early Cambrian increase in global biodiversity was driven to a considerable extent by increasing differences in faunal composition among regions, rather than simply by the accumulation of more taxa within individual local communities. Further partitioning of beta diversity showed that these differences were overwhelmingly dominated by taxonomic turnover, rather than nestedness, suggesting that different regions increasingly hosted distinct assemblages of marine animals.Network analyses provided additional evidence for this emerging spatial structure. Faunal networks showed relatively low connectivity throughout the Cambrian, while modularity increased markedly from the Fortunian to Cambrian Stage 4. This pattern indicates the progressive establishment of relatively distinct regional faunas during the early stages of animal diversification. In other words, the Cambrian radiation involved not only the rapid diversification of animal taxa but also the emergence of pronounced biogeographic provinciality. The development of geographically differentiated marine communities was therefore an integral component of the early evolution of complex marine ecosystems.The study also identified persistently high levels of endemism throughout the Cambrian. Species-level endemism was consistently higher than genus-level endemism across the different spatial frameworks and time intervals examined, indicating stronger geographic restriction at finer taxonomic levels. Although estimates of endemism may be influenced by incomplete fossil sampling, these patterns suggest that geographic differentiation remained a prominent feature of Cambrian marine faunas.Importantly, the early Cambrian increase in beta diversity persisted even after endemic taxa were excluded from the analyses. This suggests that the emergence of distinct regional faunas was not driven solely by the evolution of geographically restricted taxa. The spatial reorganization of more widely distributed taxa also contributed substantially to the development of Cambrian biogeographic structure. The researchers propose that environmental heterogeneity among palaeocontinents and continental shelves, including differences in substrate conditions, water depth, and redox environments, together with variation in dispersal capabilities among organisms, may have promoted regional differentiation. Ecological changes associated with the Cambrian substrate revolution may also have contributed to this process.Interestingly, the study found that Cambrian biogeographic differentiation was not primarily organized along simple latitudinal gradients. Comparisons of beta diversity within and between palaeolatitudinal bands revealed relatively modest differences. Even within Gondwana and its associated terranes, faunal differentiation between latitudinal bands was only slightly greater than that within the same bands. These findings suggest that palaeogeographic configuration, regional environmental heterogeneity, and dispersal limitations may have been more important than latitude alone in shaping Cambrian marine biogeography.During the middle and late Cambrian, the biogeographic structure established earlier did not disappear but underwent continued reorganization. Although endemism remained high, increasing sharing of non-endemic taxa among regions contributed to a decline in overall beta diversity. This suggests that Cambrian biogeographic patterns evolved through a dynamic interplay of extinction, dispersal, recolonization, and environmental change, rather than following a simple transition from provinciality to global faunal homogenization.Overall, the study demonstrates that the Cambrian radiation cannot be understood solely in terms of how many animal taxa evolved globally. The rapid increase in global biodiversity was accompanied by pronounced differentiation among regional faunas and the early establishment of biogeographic provinces. In this sense, the Cambrian radiation was not only a “radiation of taxa” but also a “radiation of places.” These findings provide a new spatial perspective on the emergence and early evolution of marine animal biodiversity.Beyond its scientific findings, the study highlights the growing value of GBDB as a research infrastructure for global palaeobiodiversity studies. By integrating the extensive fossil records of China and neighbouring Gondwanan regions available through GBDB with data from international databases, researchers can improve the geographic coverage of deep-time biodiversity datasets and strengthen quantitative investigations of palaeobiogeography and macroevolution.The research was published in Volume 565 of Geological Society, London, Special Publications, as part of the volume Geography and Life Before Pangaea: a Volume in Honour of Robin Cocks.Reference: Na, L., Li, Q., Kocsis, Á. T. & Kiessling, W. (2026). From radiation to provinces: spatial scaling of Cambrian diversity. Geological Society, London, Special Publications, 565. https://doi.org/10.1144/gslspecpub2026-20.Fig. 1. Palaeogeographic distribution of fossil occurrences from the latest Ediacaran to the earliest Ordovician (Tremadocian). Each panel shows occurrences reconstructed to their palaeogeographic positions using the PALEOMAP v3 plate motion model (Scotese 2016). Continental configurations are reconstructed at the middle age of each interval. Orange dots represent occurrences from the Paleobiology Database (PBDB); red dots represent occurrences from the Geobiodiversity Database (GBDB). Ma, millions of years ago.Fig.2. Genus- and species-level endemism through Cambrian calculated at three geographic scales (cell5, cell7 and geoplates). Endemism remains persistently high throughout the Cambrian. Species-level endemism is consistently higher than genus-level endemism in all intervals. Bootstrap means (400 replicates) and 95% confidence intervals are shown. Ages are in millions of years (Ma).
Recently, an international research team led by Professor WANG Yongdong from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS) conducted a multidisciplinary integrated study on the Middle Jurassic floras of Central Iran. The research clarified the floral composition, palaeoecological and palaeoenvironmental conditions, and Eurasian palaeobiogeographic affinities of the region, challenging the long-standing classical hypothesis of widespread homogeneous Middle Jurassic vegetation across Eurasia by Vakhrameev. The findings have been published in the international geoscience journal Palaeogeography, Palaeoclimatology, Palaeoecology.The Middle Jurassic represents a critical greenhouse climate epoch in Earth's evolutionary history. During this period, the Pangea supercontinent underwent extensive breakup, and terrestrial plants experienced significant radiation and diversification, fundamentally shaping the landscape of Mesozoic terrestrial ecosystems. Located on the southern margin of Eurasia, the Iranian Plateau is a key component of the Cimmerian microcontinent and serves as a vital biogeographic hub linking European and Central Asian floras, making it an ideal region for comparative research on Eurasian palaeophytogeography.Although previous studies have documented fossil plants from Iran, systematic and comprehensive investigations of Middle Jurassic floras from the Tabas and Kerman basins in central Iran remain lacking. The biodiversity, palaeoecology, and systematic relationships of these floras with coeval Eurasian assemblages are poorly understood, hindering a holistic understanding of vegetation evolution on the southern Eurasian margin during the Middle Jurassic.Recently, an international research team led by Professor WANG Yongdong from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS) conducted a multidisciplinary integrated study on the Middle Jurassic floras of Central Iran. The research clarified the floral composition, palaeoecological and palaeoenvironmental conditions, and Eurasian palaeobiogeographic affinities of the region, challenging the long-standing classical hypothesis of widespread homogeneous Middle Jurassic vegetation across Eurasia by Vakhrameev. The findings have been published in the international geoscience journal Palaeogeography, Palaeoclimatology, Palaeoecology.The study was first-authored by Dr. Mohammad Taghi Badihagh, a special research assistant at NIGPAS, and corresponded by Professor WANG Yongdong. It was jointly completed by palaeobotanists from Poland, Germany, Romania and Italy. The team integrated newly obtained fossil materials from Exploration Well 233 in the South Kochak-Ali area of Iran and compiled published palaeobotanical data from 21 fossil localities in the region, establishing a comprehensive palaeoflora dataset for the Middle Jurassic (early Bajocian) Hojedk Formation in Central Iran consists of Kerman and Tabas basins.A total of 93 macrofossil taxa belonging to 37 plant genera were identified. The flora is dominated by ferns (35.62%), nilssonialeans (25.82%), and conifers (12.09%), while sphenopsids, seed ferns (pteridosperms), ginkgophytes, and bennettitaleans constitute subordinate components. Lycopsid fossils are extremely rare and only found in a few localities, indicating their marginal ecological role in the contemporary vegetation.Multi-proxy evidence from sedimentology, palaeobotany and palynology indicates that central Iran was dominated by a warm temperate to subtropical humid climate during the Middle Jurassic. The palaeoenvironment consisted of a complex landscape of fluvial, deltaic, swamp and tide-influenced coastal settings. Frequent sea-level fluctuations drove alternating marine and terrestrial sedimentation, forming a stratigraphic sequence of interbedded coal seams and terrigenous clastic rocks.Using quantitative methods including the Sørensen-Dice similarity index and network analysis, the team systematically compared the floral assemblages of Central Iran with coeval floras from the Alborz Mountain, Afghan Block, Europe, and Central Asia. The results of statistical analyses reveal a close floral affinity between the Tabas and Kerman basins as an integral unit with an strong biogeographic links with Alborz Mountain and Afghan Block, confirming that these terranes all belong to the Cimmerian microcontinent during the Middle Jurassic.In contrast, significant floral differences exist between Central Iran and most coeval regions in Europe and Central Asia. This indicates that regional environmental heterogeneity and basin sedimentary evolution, rather than palaeolatitudinal gradients, served as the primary controlling factors of regional vegetation composition. The study does not support the widely accepted model of uniform Eurasian Middle Jurassic vegetation proposed by Vakhrameev, and reveals the complex evolutionary characteristics of terrestrial vegetation on the southern Eurasian margin during the Middle Jurassic.This study provides fundamental data for reconstructing the palaeovegetation and palaeoenvironmental evolution of the Cimmerian microcontinent and partitioning Middle Jurassic palaeophytogeographic regions of Eurasia. It also offers new empirical evidence for understanding the responses of terrestrial ecosystems to tectonic and climatic evolution during the breakup of Pangea.The research was jointly supported by the Key Program of the National Natural Science Foundation of China, the National Major Science and Technology Project for Deep Earth Exploration, the ANSO Talent Scholarship of the Chinese Academy of Sciences, and the Open Project of the State Key Laboratory of Palaeobiology and Stratigraphy.Reference: Mohammad Taghi Badihagh, Maria Barbacka, Dieter Uhl, Mihai Emilian Popa, Giovanni Giuseppe Scanu, Yongdong Wang*. A comprehensive synthesis of the Middle Jurassic flora of Central Iran: Integrating new data and approaches for unravelling the Eurasian palaeobiogeography. Palaeogeography, Palaeoclimatology, Palaeoecology, 2026, 701:114112. https://doi.org/10.1016/j.palaeo.2026.114112Fig.1 Showing the position of Iran in relation to the Northern Hemisphere and a detail showing Jurassic outcrops in the Tabas Block and the location of well No. 233.Fig.2 Represented Middle Jurassic floral composition in Central Iran, Tabas Basin. Specimens come from well No. 233 from the South Kochak–Ali area.Fig.3 Diversity and abundance of the Middle Jurassic palaeovegetation elements of Central Iran (Tabas and Kerman basins. The filled black boxes indicate the absence of taxa. Ferns represent the most diverse component of the flora at the species level, whereas among gymnosperms, Nilssoniales exhibits the highest species diversity.Fig.4 Palaeogeographic position of the Middle Jurassic flora of Central Iran and coeval floras from Europe and Mid–Asian (modified from Thierry, 2000). The numbers roughly indicate the European and Mid–Asian floras.Fig.5 Network analysis illustrating taxonomic connectivity among Middle Jurassic floristic assemblages across Europe and Mid–Asia. Node size (circles) represents individual sites and reflects taxonomic richness. Numbers inside the nodes represent the number of shared and common taxa between localities. Edge thickness corresponds to the strength of connectivity, with thicker lines indicating a higher number of shared taxa between localities. Nodes and edges are colour–coded by geographic region
A new study combining genomic analyses and fossil evidence sheds light on the century-old “Palaeoptera Problem,” a longstanding debate over the evolutionary relationships among major groups of winged insects.
The findings, published in PNAS on October 13, support the hypothesis that mayflies (Ephemeroptera) and dragonflies and damselflies (Odonata) form a single evolutionary group, Palaeoptera, which is the sister group of Neoptera, the lineage comprising insects capable of folding their wings over their bodies.A new study combining genomic analyses and fossil evidence sheds light on the century-old “Palaeoptera Problem,” a longstanding debate over the evolutionary relationships among major groups of winged insects.The findings, published in PNAS on October 13, support the hypothesis that mayflies (Ephemeroptera) and dragonflies and damselflies (Odonata) form a single evolutionary group, Palaeoptera, which is the sister group of Neoptera, the lineage comprising insects capable of folding their wings over their bodies.The study, conducted by Professor CAI Chenyang’s team from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences (NIGPAS) and Professor ZHOU Changfa’s team from Nanjing Normal University, reconstructs the early evolutionary history of winged insects and provides new estimates for when their major lineages emerged.[Note: “led” implies that other people besides these teams participated in the research. If the research was solely accomplished by these teams, use the term “conducted” instead of “led.”]Insects are the most species-rich group of animals on Earth, with more than one million formally described living species. The evolution of winged insects (Pterygota) stands among the most transformative events in terrestrial evolution. However, the timing of the origin of winged insects and the phylogenetic relationships among the three major pterygote lineages, Ephemeroptera (mayflies), Odonata (dragonflies and damselflies), and Neoptera (insects with foldable wings), have remained unresolved for over a century, making the Palaeoptera Problem a longstanding challenge in reconstructing the insect tree of life.To address the problem, the researchers sequenced 16 new genomes from Chinese mayflies and integrated genomic and transcriptomic data from more than 100 insect species, achieving unprecedented coverage of this historically undersampled key lineage and substantially addressing gaps in taxon and gene sampling from previous studies.The researchers first constructed two large amino-acid supermatrices using universal single-copy orthologous nuclear genes. They then systematically examined phylogenetic signals using concatenation and multispecies coalescent methods, multiple evolutionary models, topological tests, site-level signal dissection, and simulation analyses.The results from these diverse phylogenomic approaches consistently support the monophyly of Palaeoptera. The genomic data also strongly indicate that Ephemeroptera and Odonata are sister groups—together forming Palaeoptera, the sister clade of Neoptera. These findings suggest that the non-foldable wings of Palaeoptera and the foldable wings of Neoptera are both novel traits independently acquired from ancestral winged insects, thereby largely resolving the long-standing Palaeoptera Problem.The researchers found that during the rapid early radiation of winged insects, a combination of incomplete lineage sorting (ILS) and gene tree estimation error (GTEE) affected approximately 40% of gene trees, creating topological discordance between gene trees and the species tree. This phenomenon caused competing conclusions across different analytical frameworks and explains why earlier phylogenomic studies failed to fully resolve the phylogenetic relationships of basal winged insects. It also highlights the systematic rigor of the present study’s analytical approach.The researchers also used molecular-clock analyses calibrated with 13 carefully selected fossil reference points to estimate the timing of early winged-insect evolution. Their results indicate that crown-group Pterygota originated in the Early Devonian, while crown-group Palaeoptera arose in the Late Devonian. Insect wings evolved only once. The neopteran wing-folding mechanism, enabled by rotation of the independent third axillary sclerite to tuck hindwings over the abdomen, provided morphological and ecological foundations for the explosive radiation of Neoptera after the Carboniferous. In contrast, both mayflies and dragonflies evolved highly specialized rigid wing-base complexes adapted for gliding or high-speed predatory flight. The reconstructed evolutionary scenario shows that after the initial divergence of winged insects, Palaeoptera and Neoptera rapidly diverged and evolved distinct wing structures, with Neoptera evolving its unique wing-folding apparatus and Palaeoptera developing rigid wing bases for high-performance direct flight.Together, these innovations shaped the flight biomechanics and species diversity of winged insects observed in nature today.This study was funded by the National Key R&D Program of China, the National Natural Science Foundation of China, and the China Postdoctoral Science Foundation.Reference: Du, S., Wang, Y., Zhang, F., Engel, M. S., Zheng, X., Gong, D., Zhou, C., Cai, C. (2026). Phylogenomics confirms Palaeoptera monophyly and illuminates the origin of winged insects. Proceedings of the National Academy of Sciences, https://doi.org/10.1073/pnas.2614706123.Fig.1 Three hypotheses for the early branching events within pterygote evolution. (A) Palaeoptera hypothesis (H1): [[Ephemeroptera + Odonata] + Neoptera]. (B) Chiastomyaria hypothesis (H2): [Odonata + [Ephemeroptera + Neoptera]]. (C) Metapterygota hypothesis (H3): [Ephemeroptera + [Odonata + Neoptera]].Fig.2 Phylogeny of Pterygota. Main topology inferred from Matrix1 using the CAT-PMSF molecular evolutionary model.Fig.3 Analysis of incomplete lineage sorting and gene tree estimation error.Fig.4 Divergence time estimation of winged insects.
A new discovery from the early Cambrian Kuanchuanpu Biota in Shaanxi, South China, offers a surprising answer. A team led by Prof. Zongjun Yin at the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, has described a new multicellular alga, Polyostiosphaera operculata gen. et sp. nov. The study is published as the cover article in Proceedings of the Royal Society B.The Cambrian explosion is often told as an animal story: predators, filter feeders and a rapidly expanding food web. But what about the planktonic algae at the base of the food chain? Did they simply wait to be eaten?A new discovery from the early Cambrian Kuanchuanpu Biota in Shaanxi, South China, offers a surprising answer. A team led by Prof. Zongjun Yin at the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, has described a new multicellular alga, Polyostiosphaera operculata gen. et sp. nov. The study is published as the cover article in Proceedings of the Royal Society B.The fossils are tiny spheres, only 0.53—0.85 mm across. High-resolution X-ray microtomography reveals a three-part anatomy: an outer envelope of many small cells; an inner cluster of about 200—500 larger cells; and, in the best-preserved specimens, a non-cellular membrane between them. The envelope surface bears regular circular apertures. Some are sealed by plug-like opercula with concentric rings—like tiny hatches on a capsule.Cell measurements show a clear bimodal size distribution, suggesting spatial and functional differentiation. The researchers interpret the small outer cells as somatic or vegetative cells, and the larger internal cells as reproductive cells or propagules. When propagules mature, the plugs may detach, allowing them to exit through pre-formed channels without catastrophic rupture of the parent. This makes staged or repeated release anatomically plausible, although the fossils do not directly prove multiple reproductive events, and the fate of released propagules remains unknown.Using 27 phenotypic traits, the team compared Polyostiosphaera with Cambrian multicellular algae and modern Volvocaceae. It ranks among the most complex Cambrian algae examined and falls within the range of highly organized volvocine algae in preserved cell differentiation and reproductive architecture. It is not a direct ancestor of Volvox, but a useful functional benchmark.Why evolve such an elaborate system? The study proposes a life-history trade-off. During the Cambrian radiation, animal consumers increased mortality risks, while environmental conditions fluctuated. Investment in a protective envelope and controlled release could protect fragile propagules and spread reproduction over time. Polyostiosphaera thus shows that early Cambrian primary producers were active participants in ecological change. Consumer–producer interactions may have shaped not only who ate whom, but also when and how producers reproduced.This research was supported by the National Key Research and Development Program, the National Natural Science Foundation of China, and the Guizhou Provincial Science and Technology Fund.Reference: Chen L, Yin Z, Liu W, Xiang K, Qin S, Yang X, Li G, Zhu M. 2026 Complex reproduction reflects life-history trade-offs in early Cambrian multicellular algae. Proc. R. Soc. B 293: 20261709. https://doi.org/10.1098/rspb.2026.1709.The holotype of Polyostiosphaera operculata gen. et sp. nov. from the early Cambrian Kuanchuanpu BiotaThe paratype of Polyostiosphaera operculata gen. et sp. nov. from the early Cambrian Kuanchuanpu BiotaArtistic reconstruction and hypothesized propagule-release process of Polyostiosphaera operculata gen. et sp. NovComparison of complexity and traits in Cambrian and modern multicellular algae
Recently, a research team led by Associate Professor ZHANG Yong at the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), investigated the Troodos ophiolite in Cyprus (Fig.1). By integrating rock magnetic measurements, triple oxygen isotope analyses, mineralogical observations, and major-element geochemistry, the researchers identified serpentinization processes associated with different tectonic stages and established links among fluid sources, reaction temperatures, Fe redistribution, magnetite formation, and rock magnetic properties. These findings provide new constraints on the mechanisms responsible for the formation of secondary magnetic minerals during chemical remagnetization. The results have been published in the international geoscience journal Geology.Following rock formation, primary magnetic records are commonly modified by diagenesis, tectonic deformation, and fluid activity, resulting in secondary magnetization, or remagnetization. Chemical remagnetization (CRM), which results from fluid–rock reactions and the formation of new magnetic minerals, can not only overprint primary paleomagnetic records but also preserve information about subsequent tectonic, diagenetic, and fluid-related processes. Understanding the mechanisms of chemical remagnetization therefore requires addressing not only when a magnetic record was acquired, but also why the secondary magnetic minerals carrying that record formed, and under what conditions of fluid source, temperature, and fluid–rock interaction.Magnetite is an important carrier of remanent magnetization in natural rocks, and its formation is closely associated with Fe mobilization and redistribution during fluid–rock reactions. Serpentinization, a typical fluid–rock reaction that can generate abundant secondary magnetite, provides a natural laboratory for investigating the physicochemical conditions governing magnetic mineral formation. However, previous studies have rarely established direct, systematic links among reaction temperature, Fe redistribution, magnetite formation, and rock magnetic properties within the same samples. Furthermore, identifying fluid sources and reaction temperatures can help distinguish serpentinization associated with oceanic crust formation at mid-ocean ridges from that occurring in later subduction settings.Recently, a research team led by Associate Professor ZHANG Yong at the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), investigated the Troodos ophiolite in Cyprus (Fig.1). By integrating rock magnetic measurements, triple oxygen isotope analyses, mineralogical observations, and major-element geochemistry, the researchers identified serpentinization processes associated with different tectonic stages and established links among fluid sources, reaction temperatures, Fe redistribution, magnetite formation, and rock magnetic properties. These findings provide new constraints on the mechanisms responsible for the formation of secondary magnetic minerals during chemical remagnetization. The results have been published in the international geoscience journal Geology.1. Rock Magnetism and Triple Oxygen Isotopes Distinguish Different Stages of Fluid–Rock InteractionOphiolites may undergo multiple episodes of serpentinization during their evolution, from formation in an oceanic setting through subduction-related processes to eventual emplacement. Because fluid–rock interaction signatures acquired at different stages may overlap, distinguishing their formation environments remains challenging.The research team combined rock magnetic measurements with triple oxygen isotope analyses, using δ18O to constrain reaction temperatures and Δ’17O to trace potential fluid sources. Together with magnetite abundance and rock magnetic properties, these measurements enabled the identification of distinct serpentinization episodes.The results reveal two types of serpentinization in the Troodos ophiolite, characterized by markedly different temperatures and magnetic properties. The Cumulate–STTFZ zone mainly experienced seawater-related serpentinization at approximately 200–310 °C, producing relatively high magnetite contents, magnetic susceptibilities, and natural remanent magnetization intensities. In contrast, the Olympus–Artemis zone predominantly records lower-temperature serpentinization at approximately 150–220 °C, associated with slab-derived fluids, and exhibits substantially lower magnetite contents and weaker magnetic properties (Fig.2).Combined with paleomagnetic evidence and the regional tectonic framework, these two serpentinization processes are interpreted to record fluid–rock interactions associated with oceanic crust formation and subsequent subduction-related processes, respectively.2. Temperature Controls Fe Redistribution and Magnetite FormationThe study identifies a significant quantitative relationship between serpentinization temperature and magnetite formation. Both magnetic susceptibility and magnetite abundance increase rapidly above approximately 200–220 °C.At lower temperatures, Fe is largely retained in Fe-rich serpentine minerals, limiting magnetite formation. At higher temperatures, Fe is redistributed from serpentine, accompanied by the formation of Fe-poor serpentine and increased magnetite production. The temperature interval of approximately 200–220 °C therefore represents an important transition in Fe redistribution and magnetite formation within the investigated serpentinization system.These findings establish a quantitative link among reaction temperature, Fe behavior, magnetite formation, and rock magnetic properties. They demonstrate that even where fluid–rock reactions occur, the resulting magnetic mineral assemblages and magnetic responses can differ substantially depending on reaction temperature (Fig.3).3. Implications for Understanding the Mechanisms of Chemical RemagnetizationChemical remagnetization requires the formation of secondary magnetic minerals capable of carrying stable remanent magnetization during subsequent geological processes. Consequently, fluid activity alone does not necessarily produce significant chemical remagnetization. Instead, fluid sources, reaction temperatures, elemental mobility, and mineral reactions can all influence the formation and magnetic properties of secondary minerals.This study demonstrates that, in serpentinization systems, temperature governs Fe redistribution between serpentine and magnetite, thereby influencing secondary magnetite formation and the enhancement of rock magnetic properties. These findings provide new evidence for how fluid–rock reactions can modify rock magnetism through mineralogical and chemical transformations, offering important insights into the physicochemical conditions that may favor chemical remagnetization.More broadly, the study highlights the potential to extend remagnetization research beyond the traditional objectives of identifying secondary magnetization and determining its acquisition age toward understanding the physicochemical mechanisms governing magnetic mineral formation.Integrating rock magnetism and paleomagnetism with stable isotope geochemistry, mineralogy, and other geochemical approaches offers opportunities to constrain the fluid sources, temperatures, and fluid–rock reaction conditions under which secondary magnetic minerals form. Such an integrated framework may provide new avenues for using chemical remagnetization to investigate ancient fluid activity in fault zones, sedimentary basins, orogenic belts, and mineralizing systems.ZHANG Yong is the corresponding author of the paper. Dr. Qi Liang of the Institute of Geology and Geophysics, Chinese Academy of Sciences, and Dr. WU Guanghui of Nanjing University are co-first authors.This research was supported by the National Natural Science Foundation of China.Reference: Qi, L.#, Wu, G.#, Muxworthy, A.R., Cao, X., Yang, X., Allerton, S., and Zhang, Y.*, 2026. From ridge to subduction zone: Dual-temperature serpentinization of the ophiolitic mantle revealed by triple oxygen isotopes and magnetite formation. Geology. https://doi.org/10.1130/G54915.1.Fig.1 Sampling locations and regional geological setting.Fig.2 Scanning electron microscopy (SEM) images, geochemical data, and rock magnetic results.Fig.3 Relationships among temperature, magnetite formation, and iron redistribution.
Now, a team led by Prof. HUANG Diying at the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), has described a rare giant two-pronged bristletail from the Middle Jurassic Daohugou Biota (~ 165 myr) in Inner Mongolia. They named it Sinojapyx giganteus and established a new family, Sinojapygidae. The find offers fresh anatomical evidence for the group's evolutionary history and new clues for rethinking hexapod mouthpart evolution and Jurassic soil ecosystems. The results were published online in Proceedings of the Royal Society B.Two-pronged bristletails (Diplura) are a group of non-insect hexapods, living alongside springtails and proturans as one of the earliest branches in hexapod evolution. Because they are closely related to insects, they are key to understanding how insects originated and evolved. Two-pronged bristletails live almost everywhere, in caves, soil, and leaf litter, and play a role in soil ecosystems. Their most striking feature is a pair of highly specialized cerci. But their soft bodies and underground lifestyle make them hard to fossilize, so their fossil record is extremely sparse. The oldest known fossil before this study came from the Early Cretaceous of Brazil.Now, a team led by Prof. HUANG Diying at the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), has described a rare giant two-pronged bristletail from the Middle Jurassic Daohugou Biota (~ 165 myr) in Inner Mongolia. They named it Sinojapyx giganteus and established a new family, Sinojapygidae. The find offers fresh anatomical evidence for the group's evolutionary history and new clues for rethinking hexapod mouthpart evolution and Jurassic soil ecosystems. The results were published online in Proceedings of the Royal Society B.1. Mouthparts: "Hidden" jaws may have evolved more than onceHexapods include insects plus three early-diverging groups: proturans, springtails, and two-pronged bristletails. Traditionally, only insects were thought to have exposed mouthparts (ectognathy), while the other three had mouthparts hidden inside the head capsule (entognathy) — which is why they were once grouped as "Entognatha." But Sinojapyx giganteus, though clearly a two-pronged bristletail, has exposed mouthparts, especially visible mandibles. The team proposes that the common ancestor of all hexapods had exposed mouthparts, and that the "hidden" condition evolved independently in the three non-insect groups rather than from a single shared origin.+2. Pincer-like cerci: a snapshot of evolution in progressOne of the best-known groups of two-pronged bristletails, the superfamily Japygoidea, is famous for its hard, pincer-like tail cerci, usually used for hunting and defense. Evolutionary analysis places Sinojapyx giganteus on the stem lineage of living Japygoidea. Unlike modern forms with highly specialized, tooth-bearing pincers and tightly fused abdominal segments, this Jurassic giant had symmetric pincers with smooth inner edges and an abdomen that was neither shortened nor heavily armored. This mix of features suggests the fossil captures a transitional stage, cerci shifting from sensory organs into efficient hunting weapons, and points to an arms race between predator and prey lasting hundreds of millions of years.3. Over 5 cm long: a top predator in the Jurassic undergroundLiving two-pronged bristletails are usually tiny (mostly under 2 cm) and hide deep in the soil. Sinojapyx giganteus was over 5 cm long, larger than almost all living species, making it the oldest confirmed and largest two-pronged bristletail fossil known. The team notes it had very strong mandibles with sharply curved teeth and thick, robust pincers. In the warm, humid Daohugou forest soil 165 million years ago, this giant likely played a role similar to modern centipedes or scorpions — lurking in leaf litter and soil cracks, ambushing small invertebrates with its powerful pincers and jaws, sitting at the top of the Jurassic soil food web.Notably, although the Daohugou Biota has yielded hundreds of thousands of insect fossils, no two-pronged bristletail had ever been found there. The specimen was collected 20 years ago, and after decades of fieldwork and screening hundreds of thousands of specimens, the team found just this one. The study is part of the institute's ongoing research on the origin and evolution of modern ecosystems; the team has previously reported the earliest fleas, webspinners, and gladiators from Daohugou. Researchers from the University of Valencia, Spain, contributed to the work. The study was supported by the National Key Research and Development Programme of China.Reference: Wang Y, Cai C, Sánchez-García A, Sendra A, Huang D. 2026. A giant Jurassic hunter: the earliest dipluran and its implications for hexapod body pattern evolution. Proc. R. Soc. B 293: 20261207. https://doi.org/10.1098/rspb.2026.1207.Fig.1 General morphology of Sinojapyx giganteusFig.2 Holotype details of Sinojapyx giganteus and comparison with extant taxaFig.3 Phylogeny and evolutionary framework of DipluraFig.4 Palaeoecological reconstruction of Sinojapyx giganteus
Recently, an international research team led by Professor Hua Zhang of the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, published a study in Earth and Planetary Science Letters. The researchers investigated the South Taodonggou (STDG) terrestrial section in Northwest China, which represents a mid-latitude setting at the Permian–Triassic transition. Combining a high-resolution chronological framework with multiproxy geochemical, wildfire, and paleontological records, the team reconstructed the environmental and ecological evolution of mid-latitude terrestrial ecosystems during the end-Permian crisis.Approximately 252 million years ago, Earth experienced the most severe biotic crisis of the Phanerozoic at the Permian–Triassic transition, resulting in profound disruptions to both marine and terrestrial ecosystems. Extensive geological evidence has linked this global crisis to large-scale magmatism, particularly the Siberian Traps Large Igneous Province and associated volcanic activity in the Tethyan realm. However, how volcanic activity at different stages influenced terrestrial ecosystems through successive environmental processes, and whether terrestrial ecosystems at different latitudes responded synchronously, remain poorly understood within high-resolution chronological frameworks.Recently, an international research team led by Professor Hua Zhang of the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, published a study in Earth and Planetary Science Letters. The researchers investigated the South Taodonggou (STDG) terrestrial section in Northwest China, which represents a mid-latitude setting at the Permian–Triassic transition. Combining a high-resolution chronological framework with multiproxy geochemical, wildfire, and paleontological records, the team reconstructed the environmental and ecological evolution of mid-latitude terrestrial ecosystems during the end-Permian crisis.The study shows that the end-Permian terrestrial crisis at mid-latitudes was not triggered by a single, instantaneous environmental stress. Instead, it developed through a sequence of successive environmental perturbations, characterized by a transition from intensified surface wildfires to subsurface volcanic pyrolysis, ultimately contributing to terrestrial ecosystem collapse and reorganization.The study reveals: 1. Volcanism initiated the mid-latitude terrestrial environmental crisis at ~252.165 Ma, while ecosystem responses differed among latitudesThe research team used high-resolution mercury (Hg) records to trace the environmental influence of volcanic activity. The results show that terrestrial environmental deterioration in the Northern Hemisphere mid-latitudes began at approximately 252.165 Ma, accompanied by pronounced Hg enrichment, a negative carbon-isotope excursion, and a decline in terrestrial organic carbon accumulation.The temporal coincidence of Hg enrichment and carbon-cycle perturbation within the uncertainty of the age model indicates enhanced volcanic input and associated disruption of the global carbon cycle during this interval. These findings provide important chronological evidence linking volcanism with the onset of terrestrial environmental deterioration.The high-resolution age framework further reveals that the collapse of mid-latitude forest ecosystems preceded the final collapse of tropical rainforest ecosystems by approximately 300 kyr. This asynchronous pattern indicates that terrestrial ecosystems did not collapse simultaneously worldwide. Instead, the end-Permian terrestrial crisis exhibited pronounced spatial and temporal heterogeneity, potentially reflecting differences in wildfire activity, hydroclimate conditions, vegetation composition, and the timing and distribution of volcanic disturbances.2. Mid-latitude forests experienced severe wildfire disturbance during the early phase of the crisisDuring the early phase of environmental deterioration, charcoal abundance and combustion-derived polycyclic aromatic hydrocarbons (PAHs) increased substantially, indicating enhanced landscape-scale wildfire activity. Combined with previously documented palynological and plant-fossil evidence, these records suggest that environmental stress during this interval was closely associated with the decline of mid-latitude gymnosperm-dominated forests.The intensified wildfire activity likely represented an important disturbance mechanism affecting terrestrial ecosystems during the early stage of the end-Permian crisis. However, wildfire activity did not persist throughout the entire crisis interval.During the Early Triassic, charcoal abundance declined markedly, indicating a reduction in large-scale combustion of surface vegetation. Meanwhile, a distinct high-temperature combustion-related geochemical signal emerged, suggesting a fundamental shift in the dominant combustion process affecting terrestrial environments.3. A transition from surface burning to subsurface volcanic pyrolysisThe researchers identified a distinct combustion signal in charcoal-poor Early Triassic sediments. These deposits contain anomalously high concentrations of thermally generated PAHs, accompanied by exceptionally high fluoranthene/pyrene ratios.Unlike typical signatures produced by surface wildfires, these geochemical characteristics are more consistent with high-temperature thermal alteration of buried organic matter. The results suggest that combustion-related processes shifted from surface biomass burning during the early crisis phase to subsurface pyrolysis of sedimentary organic carbon during the later stage.The researchers propose that intrusive magmatism associated with large igneous province activity may have provided a prolonged heat source for this process. When magma intruded into organic-rich sedimentary basins, sustained heating could have caused buried peat, coal, and dispersed organic matter to undergo high-temperature pyrolysis, releasing thermally generated compounds and producing geochemical signals distinct from those associated with landscape fires.This mechanism is consistent with previously proposed volcanic combustion and pyrolysis models from regions such as the Tunguska Basin of Siberia and South China. However, the continuous, high-resolution, and age-constrained record from the STDG section provides new constraints on the temporal succession between wildfire activity and subsurface thermal alteration.The findings indicate that as volcanic activity and its thermal effects evolved, terrestrial combustion processes may have transitioned from early surface biomass burning to later subsurface volcanic pyrolysis. Therefore, the environmental impacts of volcanism may have extended beyond volcanic eruptions and atmospheric emissions, involving a prolonged pathway of: magma intrusion → heating of sedimentary organic matter → subsurface pyrolysis → release of thermally generated compounds. This process may have provided a sustained source of environmental stress during the recovery interval.4. Sequential environmental stress prolonged the terrestrial crisis and ecosystem reorganizationBy integrating combustion, weathering, and paleontological records, the researchers reconstructed a sequence of environmental and ecological changes extending from the initial wildfire phase into the Early Triassic.The transition from intensified surface wildfires to subsurface pyrolysis was accompanied by changes in weathering regimes and major reorganizations of terrestrial biota. Plant communities underwent substantial turnover, while terrestrial vertebrate communities experienced major restructuring, including the decline of Permian dicynodonts and the subsequent appearance and expansion of the stress-tolerant herbivore Lystrosaurus.Together, these observations suggest that the terrestrial crisis was not simply a short-lived episode of widespread fire. Instead, it developed through a sequence of interacting processes: volcanic forcing → carbon-cycle perturbation → wildfire intensification → vegetation loss and environmental degradation → subsurface volcanic pyrolysis → prolonged ecosystem reorganization.The researchers suggest that continued intrusive heating may have contributed to the delayed recovery of terrestrial ecosystems. Thus, even after large-scale surface wildfires diminished, terrestrial environments may have remained exposed to persistent thermal and geochemical disturbances associated with intrusive magmatism, potentially prolonging ecological stress and delaying recovery.Overall, this study reveals a stage-dependent structure of the end-Permian terrestrial crisis. Different phases of volcanic activity generated distinct environmental pressures, which interacted with ecosystem vulnerability and feedbacks to drive terrestrial ecosystem collapse and reorganization.The high-resolution record from Northwest China provides new geological evidence that deep Earth volcanic processes can influence terrestrial ecosystems through both surface and subsurface pathways. It also demonstrates that terrestrial ecosystem collapse during global environmental crises may occur asynchronously across latitudes, reflecting complex interactions among volcanism, climate change, wildfire dynamics, and ecosystem resilience.The findings emphasize that understanding the environmental consequences of large igneous provinces requires consideration of both eruptive and intrusive magmatism, as well as their potentially different effects on terrestrial ecosystems. They also demonstrate that terrestrial mass extinction may unfold as a prolonged and spatially heterogeneous process, in which successive environmental stressors interact with the intrinsic vulnerability of different biomes.This study provides new geological evidence for understanding how large igneous province activity can drive terrestrial ecosystem crises through successive surface and subsurface processes, and how terrestrial ecosystems at different latitudes may respond differently to global environmental change.Professor Hua Zhang led the study. PhD student Shenglin Jiao and Assistant Researcher Yaofeng Cai of the Nanjing Institute of Geology and Palaeontology are co-first authors. Other members of the research team include Professor Wan Yang of Missouri University of Science and Technology, Professor Mingli Wan of the Nanjing Institute of Geology and Palaeontology, and Professor Shuzhong Shen, an Academician of the Chinese Academy of Sciences at Nanjing University.The study was supported by projects funded by the National Natural Science Foundation of China, the National Key Research and Development Program of China, the Jiangsu Innovation Support Plan for International Science and Technology Cooperation Program, and the U.S. National Science Foundation.Reference: Jiao, S.L.#, Cai, Y.F.#, Yang, W., Wan, M.L., Shen, S.Z., Zhang, H.*, 2026. Succession of environmental stressors from wildfires to volcanic pyrolysis drove mid-latitude terrestrial ecosystem collapse during the end-Permian crisis. Earth Planet. Sci. Lett. 695, 120319. https://doi.org/10.1016/j.epsl.2026.120319.Fig.1 High-resolution, age-calibrated proxy records of environmental change and terrestrial ecosystem collapse across the Permian–Triassic transition.Fig.2 Comparative synthesis of the end-Permian terrestrial crisis across paleolatitudes.Fig.3 Paleoecological reconstructions of terrestrial ecosystems from the Lopingian to Early Triassic based on fossil records, wildfires, climatic conditions, and sedimentological evidence from the STDG section.
Recently, Associate Professor LI Lixia from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), in collaboration with Professor Joachim Reitner from the University of Göttingen, Germany, conducted a systematic study of sponge fossils from the Early Ordovician Cabrières Biota in France. The findings were published in the journal Lethaia.The Cabrières Biota in the Montagne Noire region of southern France is one of the key Early Ordovician faunas, as it represents a Lagerstätte close to the Ordovician South Pole. This biota exhibits remarkably high biodiversity, with more than 30 taxa identified to date, including algae, arthropods, brachiopods, echinoderms, bryozoans, sponges, and worms. It has fundamentally transformed our view of Early Ordovician ecosystems by preserving both characteristic Ordovician taxa and typical Cambrian animals, thereby highlighting a continuum between the Cambrian Explosion and the Great Ordovician Biodiversification Event. As one of the closest Early Ordovician Lagerstätten to the ancient South Pole, the Cabrières Biota probably served as a high-latitude biotic refuge, and shows ecological structures comparable to those of modern polar communities. Consequently, it offers invaluable insights into Early Paleozoic polar ecosystems.Of special interest are active filter-feeding benthic organisms such as sponges. Given that sponges play a significant role in modern polar environments, the presence of Lower Ordovician polar sponges holds considerable importance for understanding early high-latitude ecosystems.Recently, Associate Professor LI Lixia from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), in collaboration with Professor Joachim Reitner from the University of Göttingen, Germany, conducted a systematic study of sponge fossils from the Early Ordovician Cabrières Biota in France. The findings were published in the journal Lethaia.The studied material consists of nine specimens collected from the Cabrières Lagerstätte, located in the southern Montagne Noire, France. According to the associated trilobites, the Cabrières Lagerstätte from the Landeyran Formation corresponds to the trilobite Apatokephalus incisus biozone, indicating the late Floian age (ca. 470 Ma). Palaeogeographically, this Lagerstätte is part of Gondwana in high-latitude close to the South Pole.A detailed study of the sponge fauna from the Cabrières Biota revealed four distinct hexactinellid morphotypes that can be assigned to the Hintzespongiidae and Protospongiidae, indicating potentially unknown groups. The discovery of two isolated root tufts with hexactinellid affinity also supports this interpretation, as these features collectively indicate the presence of previously undocumented diversity.All currently identifiable sponges in the Cabrières Biota are hexactinellids, including two types of reticulosan sponges (hintzespongiids and protospongiids) along with root tufts attributable to two distinct hexactinellid morphotypes. Phylogenetically, hintzespongiids exhibit characteristics of both Cambrian protospongiids (regular arrangement of stauractines) and late Palaeozoic brachiospongiids (irregular hexactines in the sponge wall), potentially representing an intermediate form between these groups. Although our current specimens have yielded body fossils of only protospongiids and hintzespongiids, with no brachiospongiids identified, the isolated root tufts that have been discovered show a close similarity to those of brachiospongiids (Stioderma or Hyalostelia). Therefore, the hexactinellids in the Cabrières Biota appear to combine both Cambrian and late Palaeozoic sponge characteristics, providing a link between these two evolutionary lineages.From an ecological perspective, the presence of long and flexible root tufts in the Cabrières Biota serves as an indicator of the palaeoenvironment. Hexactinellid sponges possessing such structures typically inhabited high-energy hydrodynamic environments, which enabled them to regulate their osculum and canal systems in adaptation to water currents, thereby enhancing their efficiency in filtering nutrients from the surrounding water. Moreover, the long root tufts probably enabled the sponges to anchor to soft bottoms in the absence of hard substrate. The evidence presented above coincides with sedimentological interpretations, which indicate that the Cabrières Biota inhabited a soft-substrate in the distal mid-shelf environment.The sponges of the Cabrières Biota show both shared and distinct features when compared to those of other Early Ordovician polar ecosystems, such as the Fezouata and Klabava biotas. The Cabrières Biota shares hintzespongiids and protospongiids with Klabava Biota. The Fezouata Biota exhibits higher sponge diversity, is demosponge-dominated, with low-diversity monospecific populations near storm wave base. The Cabrières and Klabava biotas are reticulosan-dominated, indicating deeper, open-marine settings below normal wave base. Thus, water depth and local environmental conditions strongly shaped faunal composition across these polar ecosystems, revealing greater ecological complexity. Therefore, sponges from the Cabrières Biota offer key insights into the complexity and environmental dynamics of Early Ordovician polar ecosystems.This research was supported by the National Key Research and Development Program of China, the National Natural Science Foundation of China, and the Strategic Priority Research Program of the Chinese Academy of Sciences (Category B).Reference：Lixia Li* & Joachim Reitner. 2026. Hexactinellid sponges from the Early Ordovician Cabrières Biota, France: insights into Early Palaeozoic polar ecosystems. Lethaia, 59(2),1-9. https://doi.org/10.18261/let.59.2.13.Fig.1 Hintzespongiids from the Cabrières BiotaFig.2 Root tufts from the Cabrières Biota
Recently, an international research team including Prof. CAI Chenyang (Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences) and Erik Tihelka (joint-training PhD student, University of Cambridge), together with collaborators from the United States, Spain and other countries, reported a new stem‑group insect, Chosha praecursor Tihelka, Engel & Cai, 2026 (Fig. 1), from the Late Mississippian (~324 Ma) of Texas, USA. The team also investigated enigmatic stem‑insect material from the Early Devonian chert biota of Britain and the Late Carboniferous Mazon Creek biota of the United States (Fig. 2). These insect fossils fill critical gaps in early insect evolution, revise long‑standing interpretations of insect body-plan transformation and pancrustacean terrestrialization, and furnish key empirical evidence for the gradual aquatic‑to‑terrestrial evolutionary transition of insects. The findings were published online 26 August 2026 in Nature.The establishment of complex terrestrial ecosystems represents a milestone innovation in the evolutionary history of life on Earth. It marks the definitive release of organisms from marine constraints and inaugurates a brand-new phase for the diversification of terrestrial biota. Evidence from molecular‑clock estimates, trace fossils and exceptional‑preservation biotas indicates that the terrestrialization of arthropods stretches back to the Cambrian‑Ordovician, far earlier than inferred from conventional body-fossil records. As the most species‑rich animal group on our planet, insects have long posed major gaps in research regarding their early origins and the evolutionary transition to land.Paleontology has long grappled with the well-known hexapod gap. Molecular‑clock reconstructions suggest that hexapods diverged from marine crustacean relatives and initiated terrestrial adaptation as early as the Cambrian‑Ordovician. However, globally undisputed hexapod body fossils are only documented from the Early Devonian Rhynie Chert (ca. 405 Ma), and unambiguous insect fossils do not occur in abundance until the Late Carboniferous. This creates an 80-million-year gap in the fossil record. Moreover, direct fossil evidence documenting how early insects gradually adapted to terrestrial habitats from aquatic and semi‑aquatic settings, as well as the transformation of their body plans, has remained scarce. Consequently, evolutionary pathways, morphological innovations and ecological adaptive mechanisms underlying insect terrestrialization have remained poorly constrained.Recently, an international research team including Prof. CAI Chenyang (Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences) and Erik Tihelka (joint-training PhD student, University of Cambridge), together with collaborators from the United States, Spain and other countries, reported a new stem‑group insect, Chosha praecursor Tihelka, Engel & Cai, 2026 (Fig. 1), from the Late Mississippian (~324 Ma) of Texas, USA. The team also investigated enigmatic stem‑insect material from the Early Devonian chert biota of Britain and the Late Carboniferous Mazon Creek biota of the United States (Fig. 2). These insect fossils fill critical gaps in early insect evolution, revise long‑standing interpretations of insect body-plan transformation and pancrustacean terrestrialization, and furnish key empirical evidence for the gradual aquatic‑to‑terrestrial evolutionary transition of insects. The findings were published online 26 August 2026 in Nature.Fossils of Chosha praecursor derive from calcareous claystone concretions within the Tesnus Formation of the Marathon Uplift, western Texas, and exhibit exquisite, well‑preserved anatomical details. Using cross-polarized light imaging, the team resolved its distinctive morphological traits and corrected long‑standing misinterpretations that these specimens represented crustacean larvae. The studied material corresponds to adult females with a body length of 32.09 mm; a median caudal filament plus two cerci extend the total length to 49.66 mm. The fusiform body displays derived traits diagnostic of hexapods and insects, while retaining plesiomorphic ancestral features (Fig. 1).Systematic analyses demonstrate that Chosha praecursor possesses hallmark insect structures including an ovipositor and terminal caudal filament. Its thorax bears a segmented trunk and six walking legs, conforming to the canonical insect body plan. Most strikingly, however, segments 1‑9 of the abdomen bear segmented appendages; posterior abdominal limbs are modified into paddle‑like structures — a morphology unknown among extant crown‑group insects (Fig. 1). Palaeoenvironmental reconstructions indicate that the host strata represent near‑shore shallow‑water delta‑coastal settings, confirming that this early stem‑insect led a semi‑aquatic, amphibious lifestyle, occupying humid microhabitats across aquatic‑terrestrial interfaces.Based on detailed comparative morphology and phylogenetic analyses, the researchers re‑evaluated three enigmatic Palaeozoic hexapod fossils: Leverhulmia from the Early Devonian of Scotland, and an unnamed hexapod from the Mazon Creek biota, USA. Phylogenetic results recover Chosha praecursor together with these taxa as a primitive insect stem clade. Representing the oldest documented insect assemblage globally, this clade substantially connects the evolutionary genealogy of early insects (Fig. 3).This study delivers paradigm-shifting scientific advances that reshape our framework for understanding insect terrestrial evolution. First, it fills the long‑persistent 80‑million‑year hexapod gap. Reliable evidence for insect origins and early diversification is pushed back from the Late Carboniferous into the Early Devonian, reconciling to some degree discrepancies between molecular‑clock estimates and the body-fossil record. Prior models assumed that insects evolved fully terrestrial body plans immediately following land colonization. The paddle‑shaped abdominal appendages and amphibious habit demonstrated here prove that insect terrestrialization was not an abrupt leap, but unfolded via a prolonged semi-aquatic amphibious transitional phase (Fig. 4).Second, the fossils illuminate pivotal transformations in the insect body plan. Extant hexapods retain only six thoracic legs; abdominal appendages are almost entirely lost. By contrast, Palaeozoic stem-insects commonly preserve segmented abdominal limbs. This confirms that reduction of abdominal appendages constituted a key evolutionary innovation for terrestrial adaptation. These structures were progressively simplified and lost from the swimming appendages of crustacean ancestors, ultimately yielding the body organization seen in modern insects. The findings clarify the morphological transition from pancrustacean ancestors to hexapod insects (Figs 1, 4). Furthermore, the plesiomorphic ovipositor preserved in Chosha praecursor demonstrates that early insects already possessed diverse oviposition adaptations, providing the structural foundation for subsequent colonization of heterogeneous terrestrial microhabitats and later insect radiations.In addition, the research reconstructs ecological scenarios for early insects. Stem-group insects combined aquatic locomotor and respiratory adaptations with terrestrial body architectures. Their diets likely included humus, plant detritus and fungal spores. Early insects thus fulfilled multifunctional ecological roles as decomposers and consumers within aquatic‑terrestrial ecotones, acting as pivotal components driving the maturation of Palaeozoic terrestrial ecosystems (Figs 2, 4).Fossils of Chosha praecursor and related Palaeozoic stem-insects reconstruct the early terrestrialization trajectory of Earth’s most species‑rich animal group, revising interpretations of body-size evolution, ecological adaptation and co‑evolution with terrestrial ecosystems. Terrestrial colonization by insects was a gradual process; retention, remodelling and reduction of ancestral aquatic structures permeated their early evolutionary history. An amphibious transitional phase formed the critical evolutionary bedrock enabling insects to conquer land. These results supply invaluable fossil evidence for deciphering hexapod origins and body‑plan evolution, and offer fresh perspectives on the origin and early diversification of complex terrestrial ecosystems on Earth.This research was supported by the National Key Research and Development Program of China and the National Natural Science Foundation of China. Mr. Chao Tan prepared the palaeoecological reconstructions.Reference: Tihelka E., Vásquez C., Engel M.S., Schram F.R., Lozano‑Fernandez J., Cai C., 2026. Amphibious stem‑insect sheds light on colonization of land. Nature. https://doi.org/10.1038/s41586‑026‑10961‑2. Fig. 1 The stem-group insect Chosha praecursor Tihelka, Engel & Cai, 2026 from the Carboniferous Tesnus Formation (ca. 324 Ma), Texas, USA.Fig. 2 Comparative anatomical details of stem-insects and extant apterygote insects.Fig. 3 Phylogeny of early hexapods and the evolution of key morphological traits.Fig. 4 Palaeoecological reconstruction of the Carboniferous stem-insect Chosha praecursor.
