Based on 225 collected coral fossil specimens from the Buqu Formation in the Biluocuo area of northern Tibet, the research team prepared numerous thin sections, including 128 serial slices to observe morphological variations of the species. The results have recently been published in journal Palaeoworld.Members of the Qinghai-Tibet Scientific Expedition Team from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), have conducted the first systematic and detailed study of Middle Jurassic scleractinian corals in the Qiangtang Block of Tibet. Based on 225 collected coral fossil specimens from the Buqu Formation in the Biluocuo area of northern Tibet, the research team prepared numerous thin sections, including 128 serial slices to observe morphological variations of the species. The results have recently been published in journal Palaeoworld.The study found that previously reported species in Tibet, such as Montlivaltia xizangensis, M. caryophyllata, M. cornutiformis elliptica, and M. xainzaensis were distinguished based on features (e.g., local thickening of septa, basal thickening) that were actually artifacts caused by diagenetic differences or sectioning orientations. The key diagnostic features of these specimens were consistent with Montlivaltia zangbeiensis. Consequently, the study synonymized these four species into a single taxon: Montlivaltia zangbeiensis. Based on the revised taxonomy, the study clarified the composition of the Middle Jurassic (Bathonian) coral assemblage in the region: the dominant species was the solitary Montlivaltia zangbeiensis, while the branching colonial Pseudocoenia slovenica and the massive colonial Kobyastraea coquandi were relatively rare.With precise taxonomic identification, the study reveals that the Buqu Formation coral assemblage in the Qiangtang Block exhibits striking similarities to contemporaneous coral communities in East-Central Iran. This discovery indicates the existence of a strong biological connection between the Qiangtang Block and the Central Tethyan domain during the Middle Jurassic. Palaeomagnetic data suggest that both regions were at similar latitudes and situated in open shallow-marine carbonate platform environments, facilitating coral larval dispersal via ocean currents. Although the three coral genera (Montlivaltia, Pseudocoenia, and Kobyastraea) are also recorded in Middle Jurassic strata in Europe, their species-level composition differs significantly from that in Qiangtang. This suggests that the palaeobiogeographic affinity of the Qiangtang Block was closer to the eastern Tethyan domain (East-central Iran) rather than the western domain (Europe).This research was jointly conducted by ZHU Xiuping, LIANG Kun, and ZHANG Yichun, in collaboration with domestic experts on the Qinghai-Tibet Plateau. The findings not only fill a gap in the study of Middle Jurassic coral biostratigraphy and systematic palaeontology in the Qiangtang block but also provide robust palaeontological evidence supporting the tectonic-palaeogeographic hypothesis that "the Qiangtang block was an integral part of the eastern Tethys Ocean during the Middle Jurassic and maintained close connections with the Iranian block." This work significantly advances our understanding of the multi-block amalgamation history of the Tibetan Plateau and the evolution of the Tethys Ocean.This study was supported by the National Natural Science Foundation of China and the Second Tibetan Plateau Scientific Expedition and Research Program.Reference: Zhu, X.-P., Liang, K.*, Liao, W.-H., Yin, J.-R., Rao, X., Zhang, Y.-C. 2025. Scleractinian corals from the Middle Jurassic Buqu Formation, Qiangtang block and their palaeogeographic implications. Palaeoworld. https://doi.org/10.1016/j.palwor.2025.200978.Serial sections showing morphological variations of Montlivaltia at different growth stages in the Biluocuo area, Qiangtang. D: Diameter; SN: Septa number.Global palaeobiogeographic distribution of the Jurassic coral genera Montlivaltia, Pseudocoenia, and Kobyastraea, along with inferred oceanic circulation patterns. Locations: 1, Argentina; 2, Chile; 3, Mexico; 4, Morocco; 5, Portugal; 6, France; 7, UK; 8, Germany; 9, Italy; 10, Saudi Arabia; 11, India; 12, Uzbekistan; 13, East-Central Iran; 14, Qiangtang block; 15, Thailand; 16, Indonesia.
China and adjacent regions, particularly the South China Block, preserve uniquely continuous and complete stratigraphic records spanning the paleo-equator within the Tethyan domain. This serves as a natural laboratory for studying Earth system changes during crucial turning points. The international journal Palaeogeography, Palaeoclimatology, Palaeoecology has recently published a virtual special issue titled "Biotic crises and environmental changes during the critical transitions from the late Neoproterozoic to the late Triassic in China and adjacent regions".China and adjacent regions, particularly the South China Block, preserve uniquely continuous and complete stratigraphic records spanning the paleo-equator within the Tethyan domain. This serves as a natural laboratory for studying Earth system changes during crucial turning points. The international journal Palaeogeography, Palaeoclimatology, Palaeoecology has recently published a virtual special issue titled "Biotic crises and environmental changes during the critical transitions from the late Neoproterozoic to the late Triassic in China and adjacent regions".This issue focuses on major events like the Ediacaran-Cambrian biological radiation and the end-Permian mass extinction/recovery. It integrates cutting-edge multidisciplinary approaches (stratigraphy, geochemistry, palaeontology) to unravel the complex links between environmental upheavals and biological crises.The issue, led by Professor ZHANG Hua from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences (NIGPAS) and co-edited with scholars from China University of Mining and Technology, Lorestan University (Iran), and Nanjing University, compiles 31 innovative studies (Fig. 1). It provides unprecedented insights into environmental changes and life's responses during critical transitions from the late Neoproterozoic to the late Triassic (~600-200 million years ago), including the Late Ordovician, end-Guadalupian, and end-Permian mass extinctions.This issue highlights the complex interplay between environmental stressors (volcanism, anoxia, climate change) and biological resilience. It emphasizes the crucial role of regional factors like Tethyan palaeogeography and basin restriction in modulating global crises. These deep-time records provide vital analogues and scientific warnings for understanding how the modern biosphere might respond to rapid, human-driven environmental changes like global warming and ocean deoxygenation.Financial support for this album came from the National Natural Science Foundation of China, National Key R&D Program of China, CAS Strategic Priority Research Program, and Jiangsu Provincial International S&T Cooperation Program.Reference: Zhang, H., Yuan, D.-X., Arefifard, S., Wei, G.-Y., 2025. Editorial preface to special issue: Biotic crises and environmental changes during the critical transitions from the late Neoproterozoic to the late Triassic in China and adjacent regions. Palaeogeography, Palaeoclimatology, Palaeoecology, 113138. https://doi.org/10.1016/j.palaeo.2025.113138.Fig. 1 Topographic map of China and adjacent regions showing the study sites/areas covered in this Virtual Special Issue (VSI)
The study led by Profs WANG Guangxu, ZHAN Renben from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), along with their colleagues provides compelling evidence to resolve this longstanding controversy. Their findings were published in Gondwana Research.The Lhasa terrane, once part of Gondwana until the Permian/Triassic, rifted away and accreted to Eurasia, forming a core part of the Tibetan Plateau. Pinpointing its palaeogeographical position is essential for understanding both the reconstruction of Gondwana and the plateau’s evolution. However, considerable controversy persists over its exact position before separation, with geochemical and isotopic data suggesting ties to Australian, Indian or African sections of eastern Gondwana.The study led by Profs WANG Guangxu, ZHAN Renben from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), along with their colleagues provides compelling evidence to resolve this longstanding controversy. Their findings were published in Gondwana Research.Researchers systematically used newly acquired, palaeobiogeographically sensitive fossils from the Baingoin area of central Tibet to determine the terrane’s affinities. This late Darriwilian–Sandbian (Middle–Late Ordovician, ca. 457–453 Ma) biota lay along a palaeolatitudinally differentiated biotic gradient, indicative of a distinctly closer palaeobiogeographical affinity to northeastern India than to Australia or Africa.“This finding, confirmed by a critical review of existing fossil and geochemical data, strongly supports a northeastern Indian origin of the Lhasa terrane,” says WANG.Financial support for this study came from the National Key Research and Development Program of China, and the State Key Laboratory of Palaeobiology and Stratigraphy (LPS).Reference: Wang, G.X., Zhan, R.B., Jin, J., Chen, Z.Y., Percival, I.G., Wei, X., Liang, Y., Cui, Y.N., Wang, Y. & Zhang, Y.T. 2025. Northeastern Indian origin of the Lhasa terrane. Gondwana Research, 147, 184-191. https://doi.org/10.1016/j.gr.2025.06.010.Key fossils from the basal Dongka Group (upper Darriwilian–Sandbian) of the Baingoin area, central Tibet (northern Lhasa terrane)Results of the cluster analysis (a) and a Sandbian (early Late Ordovician) reconstruction of eastern Gondwana (b), supporting a northeastern Indian origin of the Lhasa terrane.
For several decades, the scientific consensus held that reef-building organisms like stromatoporoid sponges, corals, and bryozoans underwent sudden "explosive" development during the Great Ordovician Biodiversification Event (GOBE) in the late Darriwilian (Middle Ordovician), dramatically increasing marine biodiversity. However, recent discoveries by researchers from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences challenged this narrative. The team identified the oldest known stromatoporoid fossils (~480 million years old) in Yuan'an, Yichang, Hubei Province—pushing the record of stromatoporoid reefs back to Early Ordovician. Surprisingly, this was followed by a 20-million-year "reef gap" where fossil records nearly vanished, raising critical questions: Why did reef records disappear after the Early Ordovician? Why did reef-building organisms seemingly vanish for 20 million years? And why did they suddenly "explode" in diversity during the late Darriwilian?On June 30th, researchers led by Li Qijian (NIGPAS), Jeon Juwan (Korea University), and Lee Jeong-Hyun (Chungnam National University) integrated stratigraphic sequences and fossil occurrence data from major paleocontinents. Data based correlation analyses revealed that the apparent "explosion" may not reflect true evolutionary dynamics of reef ecosystem during the late Middle Ordovician. Instead, it likely stems from a global sea-level fall (~475–460 million years ago) that erased shallow marine carbonate environments—critical for reef development and fossil preservation. This regression caused widespread erosion, wiping out fossil records of early reef-builders. When sea levels rose again in the mid-late Darriwilian, already-diversified organisms rapidly recolonized newly flooded habitats, creating an illusion of sudden diversification.This phenomenon—termed the "Sppil-Rongis effect" (the inverse of the Signor-Lipps effect)—demonstrates how improved preservation conditions can generate false signals of abrupt biological radiation. Critically, the study reframes the GOBE not as a discrete "explosive event" but as part of a continuous evolutionary trajectory, repeatedly interrupted and reshaped by sea-level fluctuations and preservation biases. This supports the view that the Cambrian Explosion and Ordovician Biodiversification constitute a single extended diversification process.The research underscores how preservation biases fundamentally distort our understanding of evolutionary history, emphasizing the need to disentangle true biological signals from geological artifacts in reconstructing Earth's life story.Fig. 1. Diversity (number of genera) of reef-building metazoans (stromatoporoids, corals, and bryozoans) and reef occurrences through time.Fig. 2. Global sea-level curve during the Ordovician, schematic stratigraphic columns for Laurentia and Sino-Korean Block, and carbonate and siliciclastic sedimentary rock area.Fig. 3. Global paleogeographic maps of the Early, Middle, and Late Ordovician, showing the distribution of reef-building metazoans (stromatoporoids, tabulate and rugose corals, and bryozoans).Fig. 4. Schematic illustration of the Sppil–Rongis effect in reef evolution, coupled with sea-level changes.<!--!doctype-->
Researchers from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences and Columbia University, along with their collaborators, have analyzed sediments from the terrestrial Sangonghe Formation (Late Early Jurassic) in China’s Junggar Basin, revealing information both on Solar System chaos and the global carbon cycle. Their findings were published in the Proceedings of the National Academy of Sciences (PNAS).Researchers from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences and Columbia University, along with their collaborators, have analyzed sediments from the terrestrial Sangonghe Formation (Late Early Jurassic) in China’s Junggar Basin, revealing information both on Solar System chaos and the global carbon cycle. Their findings were published in the Proceedings of the National Academy of Sciences (PNAS).The team conducted a multidisciplinary study of the Junggar Basin’s well-preserved lake sediments, combining astrochronostratigraphy, sedimentology, geochemistry, and palynology. Their analyses uncovered a shifting long-term rhythm in the orbits of Mars and Earth—known as the Mars–Earth grand eccentricity cycle—which governs how elliptical Earth’s orbit becomes over multi-million-year timescales. These orbital changes affect how much sunlight Earth receives and, in turn, influence climate and the global carbon cycle.The study identified a previously unrecognized 1.6-million-year cycle in the carbon isotope record, distinct from the current 2.4-million-year grand eccentricity cycle. This variation provides concrete geological evidence of Solar System chaos—the idea that gravitational interactions among planets can lead to unpredictable orbital shifts over deep time. The findings extend our understanding of planetary behavior beyond the 60-million-year limit of modern orbital simulations.In parallel, the study sheds light on the Earth’s carbon cycle response during a major climate event: the Jenkyns Event, a global warming episode approximately 183 million years ago. The researchers linked this event to the 1.6-million-year orbital cycle and found that carbon isotope signals recorded in the shallow-lake environment of the Junggar Basin likely reflect changes in atmospheric CO₂ composition driven by orbital dynamics. Unlike marine and deep lake settings, where carbon fluctuations appear amplified, the Junggar Basin may preserve a more representative signal of the global carbon system.This research demonstrates how ancient sediments can serve as a window into both planetary dynamics and Earth system processes, helping scientists constrain the evolution of the Solar System and better understand how orbital variations can drive climate and carbon cycle changes on Earth.By bridging insights from planetary science and paleoclimatology, the study contributes to refining astronomical models, validating gravitational theories, and improving our knowledge of Earth’s long-term climate sensitivity.Reference: Fang Yanan, Olsen P. E., Sha Jingeng, Whiteside J. H., Chengguo Guan, Ikeda M., Li Sha, Zheng Daran, Zhang Haichun, Wang Bo, 2025. Jurassic constrains on the chaotic Mars-Earth eccentricity cycle linked to the volcanically induced Jenkyns event. PNAS, https://doi.org/10.1073/pnas.2419902122.Fieldwork photo of Yanan Fang and Paul Olsen in the Sangonghe Formation at the Haojiagou section in the Junggar BasinLocation map of the present-day and Early Jurassic Junggar BasinLithologic column of the Sangonghe Formation tuned to the 400-kyr eccentricity cycle (A), relative spore-pollen abundance (B), color (C), sedimentary facies and relative lake-level curve (D), total organic carbon (TOC) content (E), organic carbon isotope (F), and corresponding 1.6-Myr Mars-Earth super-long eccentricity and 400-kyr Jupiter-Venus eccentricity filteringAge distribution of the Karoo-Ferrar Large Igneous Province correlated with organic carbon isotopes from the Junggar Basin tuned to the 400-kyr eccentricity cycle, organic carbon isotopes from Mochras Farm (UK), biogenic silica flux from Inuyama (Japan), and magnetic susceptibility from Sancerre (France). All sections are aligned at the most negative T-OAE carbon isotope point, with the time scale derived from the Inuyama astronomical age model.Comparison of Mars-Earth super-long eccentricity cycles in astronomical solutions with geological records.
The Mesozoic Era was marked by long-term greenhouse climates and repeated hyperthermal events—periods of rapid global warming—that profoundly affected life, ecosystems, and petroleum systems. The Carnian Pluvial Episode (CPE, ~234–232 Ma), is characterized by global warming, intensified hydrological cycling, increased continental weathering and erosion, and expanded marine anoxia. Popularized as a “million‑year global rain” (Marshall 2019, Nature), and often linked to dinosaur emergence, the CPE’s trigger mechanisms and climate feedback patterns have long remained controversial.A multinational team led by Prof. Bo Wang from the Nanjing Institute of Geology and Palaeontology (CAS), with collaborators from the Institute of Vertebrate Paleontology and Paleoanthropology (CAS), Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Institute of Geochemistry (CAS), Guangzhou Institute of Geochemistry (CAS), Vrije Universiteit Brussel, University of Oxford, University of Münster, Alfred Wegener Institute,reported a continuous lacustrine sequence (Dalongkou section) in the southern Junggar Basin, northwestern China. Using methods of stratigraphy, sedimentology, geochemistry, cyclostratigraphy and Earth system modeling, they systematically investigated the mechanistic origin of the CPE, climate–carbon feedbacks, and precipitation patterns. Their findings were published online on June 30, 2025 in Nature Communications.1. Mechanistic origin of the CPEHigh-resolution mercury (Hg) concentrations and isotopes reveal that approximately 38,000 years before the CPE onset, the Wrangellia Large Igneous Province (LIP) began releasing isotopically light carbon. This release corresponded with Hg anomalies and an abrupt but relatively weak negative δ13C shift (POE), coinciding with initial warming. As temperatures passed a threshold, heat-sensitive carbon reservoirs, such as sedimentary organic matter, permafrost, and especially marine methane hydrates were triggered. The sequence of events, including evidence for volcanic activity followed by a large CIE may support a scenario whereby the emplacement of the Wrangellia LIP prior to the CPE induced net positive climate–carbon-cycle feedbacks.2. Climate–carbon-cycle interaction through the CPETheir findings show that the CPE terrestrial carbon cycling, at a δ13Corg scale of ±1‰, displays an in-phase relationship with the 405-kyr long-eccentricity metronome, which appears similar to the warmhouse climate–carbon-cycle present throughout the Oligo–Miocene interval. This result, together with previous long-term carbon-isotope records, shows that such a climate–carbon-cycle interaction may have been widespread throughout the warm Mesozoic Era, including hyperthermal intervals. Therefore, this climate–carbon interaction may be the norm after the emergence of vascular plants, whereas the coldhouse climate–carbon-cycle dynamics of the earliest Pliocene may represent a more unusual situation.3. The hydrological cycle during the CPEAnalysis of palynology and Earth system model simulations reveals thatprecipitation changes during the CPE exhibited spatial heterogeneity, accompanied by a poleward shift of pre-existing precipitation zones and no evidence for global humidification. The heterogeneous pattern of precipitation changes is characterised by predominantly increased precipitation near the Equator and at high latitudes, while subtropical latitudes exhibit diminished rainfall. In contrast to previous hypotheses regarding unusual global humidification during the CPE, the integrated stratigraphy and Earth system model highlight the spatial variations in global precipitation patterns, characterised by increased aridification in continental interiors and the emergence of multiple precipitation centres in low-latitude eastern continents and polar regions, including the Arctic, northeastern Tethys, northeastern Gondwana, and the Antarctic.4. Implication for understanding past hyperthermal eventsThe CPE shares key features and perhaps driving mechanisms with several other hyperthermal events including the Triassic–Jurassic hyperthermal event, Cretaceous OAEs, as well as the Paleocene–Eocene Thermal Maximum. Moreover, during the hyperthermal events, different regions may have experienced periods of extreme drought or severe flooding, reflecting the contrasting extremes of climate. Thus, despite differences in nomenclature, these events share a fundamental nature as hyperthermal episodes. These similarities suggest that understanding their commonality might hold essential information on the nature of hyperthermal events and specifically which elements in the climate and carbon cycle contribute to these anomalously warm periods.The research was supported by the National Natural Science Foundation of China and the Chinese Academy of Sciences.Reference: Zhao Xiangdong, Xue Naihua, Yang Hu, Zheng Daran, Peng Jungang, Frieling J., De Vleeschouwer D., Fu Xuewu, Jia Wanglu, Fang Yanan, Li Sha, Wang Meng, Zhao Xianye, Wang Qiang, Zhang Haichun, Sha Jingeng, Jenkyns H.C., Claeys P., Wang Bo (2025) Climate–carbon-cycle interactions and spatial heterogeneity of the Late Triassic Carnian Pluvial Episode. Nature Communications, https://doi.org/10.1038/s41467-025-61262-7.Fieldwork photo at the Dalongkou section, XinjiangThe integrated stratigraphy calibrated to the astronomical time scale of the Huangshanjie FormationMagnification of high-resolution data of the carbon-isotope excursions (CIEs) and model for the carbon cycle during the Carnian Pluvial EpisodeSimulated climate states before and during the Carnian Pluvial Episode
Climbing is a growth strategy in which plants rely on other plants or substrates for mechanical support to grow upward. Climbing plants occupy important ecological niches in natural communities and also hold significant value in horticultural landscapes. The origin of this growth habit can be traced back to the late Paleozoic, and its evolutionary diversification is closely correlated with the increasing structural complexity of forest ecosystems. However, due to the limitations of fossil preservation, direct fossil evidence of actual climbing height and ecological interactions between climbers and their host plants remains exceedingly rare in palaeobotanical studies.The early Permian fossil Lagerstätte “vegetational Pompeii” in the Wuda Coalfield of Inner Mongolia, owing to its unique mode of burial, preserves not only the external morphology and internal anatomy of plant fossils but also evidence of interactions between plants. Therefore, it often provides exceptional fossil evidence of climbing behavior in late Paleozoic plants.Recently, the research team lead by Prof. Jun Wang from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, in collaboration with colleagues from the Institute of Geology v.v.i. (Czech Academy of Sciences), the West Bohemian Museum in Pilsen, and Stanford University, conducted an in-depth study on the fern Nemejcopteris haiwangii. Their findings confirm that N. haiwangii exhibited a climbing habit. The results were published in the international journal Palaeogeography, Palaeoclimatology, Palaeoecology.Nemejcopteris haiwangii, first discovered in the Wuda “vegetational Pompeii,” was originally reconstructed as a ground-cover plant with a rhizomatous stem and upright fronds. Although previous studies identified prickle-like structures on its rachises, which could have assisted in climbing, direct evidence for this behavior had not been documented. This new study presents several exceptionally preserved specimens that clearly show physical interaction between the fronds of N. haiwangii and the trunks of Psaronius, thereby providing definitive fossil evidence of climbing behavior in this taxon.Prickles of varying sizes are present on all orders of N. haiwangii rachises, suggesting that the plant used a hook-climbing mechanism to gain support from nearby vegetation. However, compared to climbing strategies such as twining or adhesive pads, this hook-based mechanism appears relatively weak. Quadrat-based palaeoecological data further reveal that N. haiwangii fronds interacted primarily with the middle to lower portions of Psaronius trunks, suggesting a limited climbing height—likely no more than four meters. This further supports the interpretation of its weak climbing ability.Taken together, the new findings indicate that Nemejcopteris haiwangii typically grew as a ground-covering plant with a rhizomatous stem and erect fronds. However, when encountering a suitable host such as Psaronius, its fronds could bend and use the host for additional support. Contrary to the traditional view that plant climbing habits during the late Paleozoic were primarily controlled by local canopy closure, this study suggests that Nemejcopteris haiwangii could not reach the canopy and was therefore not regulated by forest canopy density. Its facultative climbing strategy more likely represents an adaptation to the periodically waterlogged conditions at the forest floor in swampy environments: when water levels rose, facultative climbers could ascend to higher positions, enabling their foliage to conduct gas exchange more effectively. This provides a novel explanation for the abundant occurrence of climbing plants in the Permo-Carboniferous wetland vegetation.This research was jointly supported by the National Key Research and Development Program of China, the National Natural Science Foundation of China, and the Youth Innovation Promotion Association of Chinese Academy of Sciences.Reference: Li F.Y., Li D.D., Votočková Frojdova J., Pšenička J., Boyce C.K., Wang J., Zhou W.M.*, 2025. Climbing habit confirmed in the early Permian zygopterid fern Nemejcopteris haiwangii and its palaeoecological significance. Palaeogeography, Palaeoclimatology, Palaeoecology. 675:113101 https://doi.org/10.1016/j.palaeo.2025.113101.Interaction between Nemejcopteris haiwangii and Psaronius. (A–C) Different portions of the same trunk, showing N. haiwangii fronds bending and leaning against the tree fern stem; (D–E) Climbing rachises of N. haiwangii and the prickles on their surface; (F–G) Ultimate and penultimate pinnae of N. haiwangiiNemejcopteris haiwangii (nh) climbing on the tree fern Psaronius (ps). (A) Drone photograph of the excavation site; (B) Crown of the host tree fern Psaronius; (C–D) Preservation of N. haiwangii mainly concentrated around the middle to lower portions of a Psaronius tree fern, field photos from 2023Quadrat-based field data showing that Nemejcopteris haiwangii primarily concentrated around the middle to lower pportions of a Psaronius tree fern. Quadrat data from 2015<!--!doctype-->
Earth’s current climate is considered an “icehouse climate” due to the existence of polar ice caps. This is important because previous icehouse climates can better predict how atmospheric oxygen and carbon dioxide (CO2) levels today may affect the risk of marine anoxia and subsequent marine biodiversity loss in the future.By combining these records with previously published carbonate carbon isotopes, paleo-CO2 data, and records of volcanic activity and plant evolution, the researchers quantitatively explored, through biogeochemical modeling, the global carbon cycle and marine oxygen conditions for this geological period. This work was published in the Proceedings of the National Academy of Sciences of the United States of America (PNAS).Earth’s current climate is considered an “icehouse climate” due to the existence of polar ice caps. This is important because previous icehouse climates can better predict how atmospheric oxygen and carbon dioxide (CO2) levels today may affect the risk of marine anoxia and subsequent marine biodiversity loss in the future.To understand the interplay among atmospheric oxygen and CO2 levels and oxygenation conditions in the ocean during an earlier icehouse climate, an international team led by Prof. CHEN Jitao from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences studied ancient sedimentary rocks in Naqing, South China, to analyze their chemical compositions.Specifically, the researchers derived high temporal-resolution records of carbonate uranium isotopes from a marine carbonate slope succession dating from the late Carboniferous to early Permian (310–290 million years ago). This geologic epoch is part of the Late Paleozoic Ice Age (LPIA) (360–260 million years ago), which is recognized as the longest icehouse climate since advanced plants and terrestrial ecosystems appeared.By combining these records with previously published carbonate carbon isotopes, paleo-CO2 data, and records of volcanic activity and plant evolution, the researchers quantitatively explored, through biogeochemical modeling, the global carbon cycle and marine oxygen conditions for this geological period. This work was published in the Proceedings of the National Academy of Sciences of the United States of America (PNAS).The study revealed rapid drops in levels of carbonate uranium isotopes, which occurred alongside rapid increases in atmospheric CO2 levels. This suggests that seafloor anoxia expanded even during the Phanerozoic maximum of atmospheric oxygen and the glacial peak of the LPIA.Using a carbon–phosphorus–uranium (C-P-U) biogeochemical model coupled with Bayesian inversion, the researchers quantitatively examined the interactions among marine anoxia, carbon cycling, and climate evolution during this paleo-glacial period. Model results indicated that enhanced burial of marine organic carbon likely drove the overall decline in atmospheric CO2 and the rise in oxygen levels in the atmosphere–ocean system throughout this interval. However, despite these high oxygen levels, episodic massive carbon emissions could have triggered recurrent global warming and seafloor deoxygenation.Furthermore, the team’s model showed an increase of 4–12% in the extent of the anoxic seafloor, which could have led to a pause or decline in marine biodiversity. This study emphasizes that under current icehouse conditions, which mirror the high-oxygen state of the LPIA, ongoing warming may still provoke widespread ocean anoxia.This study advances our understanding of the processes and feedback mechanisms within the Earth system during icehouse conditions, enabling more accurate projections of the future trajectory of current global warming and marine deoxygenation.Paleozoic marine biodiversity, atmospheric composition, and seafloor oxygenation historyGeochemical, geologic, and biotic records for the late Carboniferous to early Permian, showing repeated occurrences of anoxic events (AE1–5).<!--!doctype-->
The Ediacaran–Cambrian transition (ECT) marks one of the most pivotal intervals in evolutionary history, characterized by the emergence and rapid radiation of multicellular life. A robust global chronostratigraphic framework is crucial for elucidating the processes underlying this major biological innovation and its relationship to coeval paleoenvironmental changes. Morocco's Anti-Atlas region preserves one of the most complete late Ediacaran to early Cambrian carbonate successions globally (Figure 1), providing an exceptional natural laboratory for such investigations. Nevertheless, the absence of definitive biostratigraphic markers and incomplete understanding of basin tectonics have resulted in persistent uncertainties regarding both the precise placement of the Ediacaran–Cambrian boundary (the Cambrian Base) and its connection to the basin's tectonic-sedimentary evolution.To address these questions, Dr. Yiwei Xiong from the Early Evolution of Earth-Life System team at the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, under the guidance of Professors Bo Chen and Maoyan Zhu, collaborated with Professor El Hafid Bouougri (Cadi Ayyad University, Morocco) and colleagues. The team conducted a systematic, interdisciplinary study of the Tabia section in Morocco’s Anti-Atlas, their work yielded two key findings:First identification of four distinct tectono-sedimentary evolutionary phases in the Anti-Atlas Basin during the Ediacaran-Cambrian transition (Figure 2);A revised definition of the regional Ediacaran-Cambrian boundary.These results underwent peer review and were published in Gondwana Research on June 6, 2025.This study reveals that the Tabia Member experienced three distinct syn-rift tectono-sedimentary evolutionary stages, transitioning to a post-rift stage in the overlying Tifnout Formation (Figure 2). Systematic geochemical analyses support this interpretation. The syn-rift dolostones of the Tabia Formation display characteristically elevated ⁸⁷Sr/⁸⁶Sr ratios, positive Eu/Eu* anomalies, and significant enrichment in Mn, Pb, Fe, and Zn (Figure 3), indicating dolomitization influenced by mixed hydrothermal-seawater fluids (Figure 4). In contrast, the post-rift dolostones of the Tifnout Formation show substantially diminished hydrothermal signatures (Figure 3), consistent with seawater-dominated dolomitization (Figure 4). These contrasting geochemical patterns document the basin's tectonic transition from syn-rift to post-rift conditions.Furthermore, the investigation revealed the presence of Vendotaenia macroalgae, a diagnostic late Ediacaran index fossil, within shale horizons of the Tabia member's third sedimentary sequence (DS3). Integrated with regional chemostratigraphic correlations, this study precisely constrained the base of Cambrian (the BACE - Basal Cambrian Carbon Isotope Excursion) to a position approximately 50 meters above the Tamjout Dolomite (Figure 5). This defined boundary exhibits remarkable concordance with the basin's major tectonic transition surface. The study demonstrates that the BACE negative carbon isotope excursion represents a globally synchronous chronostratigraphic marker, thereby establishing a robust standard for identifying the Ediacaran-Cambrian boundary not only in the Anti-Atlas but also in coeval sedimentary basins worldwide.The research was supported by the National Key Research and Development Program of China and the National Natural Science Foundation of China.Reference: Yiwei Xiong, Bo Chen*, Xiaojuan Sun, Kai Chen, Ibtissam Chraiki, Aihua Yang, Chunlin Hu, Zhixin Sun, Bing Pan, Chuan Yang, Tianchen He, Miao Lu, Tao Li, Fangchen Zhao, Maoyan Zhu, El Hafid Bouougri. 2025. Integrated analyses of the Ediacaran-Cambrian boundary sequence in northern Gondwana (Anti-Atlas platform, Morocco). Gondwana Research 145: 79–106. https://doi.org/10.1016/j.gr.2025.05.003.Figure 1 Simplified map along the northern margin of West African Craton (WAC) showing the occurrence of the Late Ediacaran-Cambrian strata in the Anti-Atlas and composite δ13Ccarb profile of the Ediacaran-Lower Cambrian sequence in the Anti-AtlasFigure 2 Paleogeography and tectono-sedimentary evolution across the Ediacaran-Cambrian transition Synrift stage 1 (DS1): The rift initiationSynrift stage 2, (DS 2): Faults reactivated and rift propagation, Synrift stage 3 (DS3): Continued basin growth, tectonic subsidence and marine transgression, Postrift stage: Stable carbonate platform and thermal subsidenceFigure 3 Boxplot for comparing all data-features of the Dolomite type 1 and Dolomite type 2.Figure 4 Interpretative geological sectionshowing the conceptual model for the formation mechanism of the Dolomite type 1 (a) and Dolomite type 2 (b) (not to scale)Figure 5 Carbon isotope chemostratigraphic and biostratigraphic correlation between the Tabia, Oued Sdass, Oued N’Oulili and Zaouia sections in Anti-Atlas platform
Pterotheca Salter, 1853 is a morphologically highly unusual gastropod genus widely distributed in the Upper Ordovician and Llandovery Series (Lower Silurian) of North America and Europe. Its distinctive morphological features, including a bilaterally symmetrical shell shape, flattened shell, and a unique internal triangular septum, initially led to taxonomic confusion among early researchers, who misidentified it as a brachiopod, hyolith, pteropod, or cephalopod (operculum). Due to its highly specialized shell structure and striking morphology, which make it easily recognizable, the phylogenetic characteristics and paleoecological patterns of Pterotheca have long been a research focus in paleontology. However, as its fossil record has so far only been found in Europe and North America, with no reports from other regions, there remains controversy within the academic community regarding its paleogeographic distribution pattern.Recently, Assistant Researcher Li Wenjie from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, collaborating with multiple team members, discovered Pterotheca fossils for the first time in the Xiushan Formation (mid-Telychian, Llandovery Epoch) of Yongshun County, Hunan Province, China. This discovery represents the first record of the genus in the low-latitude peri-Gondwanan region. Based on these new specimens from the South China Block, researchers identified two new species according to the morphological characteristics of the Pterotheca fossils: Pterotheca yongshunensis n. sp. and Pterotheca xiushanensis n. sp. The morphologic analysis suggests that close relatives of these new species may be Pterotheca species from the Telychian of Scotland. The new species show continuous variations of marginal apex to submarginal apex, implying that one of the Pterotheca species may be ancestral to the Devonian Aspidotheca Spriesterbach, 1919.Sedimentological and paleoecological analyses suggest that the Pterotheca species from the Silurian of South China likely lived on soft silt-mud substrates, crawling slowly and feeding on algae and/or organic detritus within the sediment. They were adapted to shallow marine environments with substantial terrigenous input (Benthic Assemblage 2–3). Given that many localities yielding Silurian Pterotheca fossils (including South China and Spain) lack records of Ordovician Pterotheca, and considering that all known Silurian Pterotheca fossils occur in fine-grained siliciclastic rocks, with most sedimentary features representing periods of sea-level fall and lowstand, it is hypothesized that geographic isolation and enhanced oceanic circulation during the global sea-level fall in the early Silurian promoted speciation of Pterotheca in different regions worldwide. Conversely, the connection of sea routes during the Rhuddanian transgression following the end-Ordovician glaciation may have facilitated the initial dispersal of Silurian Pterotheca.The research findings were recently published in the international paleontological journal Journal of Paleontology. The related research received support from Ministry of Science and Technology and National Natural Science Foundation of China. This study is a contribution to IGCP project 735 “Rocks and the rise of Ordovician life”.Reference: Li, W.J.*, Fang, X., Song, J., Zhang, Y.D., 2024. Pterotheca (Gastropoda) from the Telychian (Silurian) Xiushan Formation of South China: taxonomy, paleoecology, and paleogeography. Journal of Paleontology 98, 981–995. https://doi.org/10.1017/jpa.2024.49.Pterotheca yongshunensis n. sp. from the Xiushan FormationPterotheca xiushanensis n. sp. from the Xiushan Formation<!--!doctype-->
