Research Progress---- Nanjing Institute of Geology and Palaeontology Chinese Academy of Sciences

Fossils of Nemejcopteris haiwangii from the “vegetational Pompeii” provides new evidence for the climbing habit in late Paleozoic plants

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.Article information: 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. 675:113101https://doi.org/10.1016/j.palaeo.2025.113101Figure 1. 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. haiwangii.Figure 2.Nemejcopteris 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 2023.Figure 3. Quadrat-based field data showing that Nemejcopteris haiwangii primarily concentrated around the middle to lower pportions of a Psaronius tree fern. Quadrat data from 2015.

2025-06-26

Study of Ancient Rocks Helps Predict Potential for Future Marine Anoxia

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.Fig. 1. Paleozoic marine biodiversity, atmospheric composition, and seafloor oxygenation historyFig. 2. Geochemical, geologic, and biotic records for the late Carboniferous to early Permian, showing repeated occurrences of anoxic events (AE1–5).

2025-06-24

Major research advances have been made to the Ediacaran–Cambrian Boundary in Anti-Atlas, Morocco

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.Publication Details: 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.2025.05.003Figure 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

2025-06-17

First Discovery of Silurian Gastropod Pterotheca in China

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”.Article information: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.2024.49Figure 1. Pterotheca yongshunensis n. sp. from the Xiushan FormationFigure 2. Pterotheca xiushanensis n. sp. from the Xiushan Formation

2025-06-09

The Permian Fusuline Fauna in Exotic Limestone Blocks of the Western Yarlung Tsangpo Suture Zone: Insights into the Early Evolution of the Neo-Tethys Ocean

As the youngest ocean within the Tethyan Orogen, the opening time of the Neo-Tethys Ocean has remained a subject of debatewith different opinions such as prior to Middle Permian, Early Triassic, or Late Triassic. Resolving this issue is of great significance for understanding the geodynamic evolution of the Tethyan Orogen. Concurrently, as the remnants of the Neo-Tethys Ocean, the Yarlung Tsangpo Suture Zone (YTSZ) exhibits a complex structural background. In the east of Saga, it is characterized by a single ophiolite zone, but splits into northern and southern subzones west of Sage, with the Zhongba-Zhada microcontinent sandwiching between them. The fundamental question of whether both subzones represent a single suture or distinct sutures representing different oceans has remained a considerable debate.Recent researchers have increasingly focused on abundant exotic limestone blocks preserved in the mélange of the YTSZ. Much attention has been paid on the geochemistry and paleomagnetism of the associated basalt. However, the study on the biostratigraphy and paleobiogeography of these exotic limestone blocks remains scarce, with limited studies in the Gyanyima area, Purang County. With the Second Tibetan Plateau Scientific Expedition and other research funding, a research team lead by Prof. Yichun Zhang conducted fieldworks in 2022 and 2024. The works in the field discovered numerous exotic limestone blocks within the mélanges on both sides of the Zhongba-Zhada microcontinent. The exotic limestone blocks in the southern subzone suffer slight metamorphism, preserving diverse fusuline and coral fossils, but those in the northern subzone were strongly metamorphosed, leaving limited Permian foraminifers.The research team has recently conducted a systematic study on fusulines from the exotic limestone blocks in the Yarlung Tsangpo Suture Zone, focusing on fusuline fossils in the limestone blocks of the southern subzone. The Gyanyima section in Purang County contains a fusuline fauna dominated by Neoschwagerina, Kahlerina, and Yangchienia, with some species of Verbeekina, Chusenella, Colania, and Codonofusiella, indicating a Wordian-Capitanian age. In addition, the Zhalairi area in the south of Zhongba County is characterized by an assemblage rich in Codonofusiella and Lantschichites, accompanied by minor Neoschwagerina, Yangchienia, and Chenella, suggesting a late Capitanian age.Paleobiogeographic analysis reveals that these fusuline assemblages exhibit high abundance but low diversity, conspicuously lacking advanced genera (e.g., Sumatrina, Yabeina, Lepidoliolina). The paleobiogeographic affinities of the faunas indicate that these exotic limestone blocks were formed in a position between the northern Lhasa Block and the southern Indian Plate during the Middle Permian. Additionally, the limestone blocks lack terrigenous clastic but associated with basalt, strongly suggesting an origin of the seamounts in the Neo-Tethys Ocean. It deserves note that the occurrence of warm-water fusuline-containing limestones was in the south of the Zhongba-Zhada microcontinent with typical cold-water faunas. This phenomena strongly supports that the southern subzone was not in situ but originated from the northern subzone. The southern and northern subzones of the YTSZ belong to a same ophiolite belt, both representing the remnants of the Neo-Tethys Ocean.In conclusion, this study confirms that the Neo-Tethys Ocean opened in the late Early Permian, and subsequently developed series of seamounts in the ocean basin by the Middle Permian. During the collision between India and Eurasia, the ophiolites obducted and transported the mélange and limestone blocks to form the southern subzone. Those limestone blocks within the northern subzone, however, suffered from strong metamorphism. This study provides significant evidence in understanding the early evolution of the Neo-Tethys Ocean and the tectonic affinity of the subzones of the YTSZ.This research was supported by the Second Tibetan Plateau Scientific Expedition and the National Science Foundation of China.Publication Details: Hong-fu Zhou, Yi-chun Zhang*, Mao Luo, Xin Li, Hua Zhang, Hai-peng Xu, Ruo-lan Liao, Qi Ju, Xiao-Hui Cui, Jun-jie Liu, Yao-feng Cai, Shu-zhong Shen, 2025. Dismembered Guadalupian (Middle Permian) seamounts within the Yarlung-Tsangpo Suture Zone: Implications for the opening time of the Neo-Tethys Ocean. Palaeogeography, Palaeoclimatology, Palaeoecology, 675:113063. https://doi.org/10.1016/j.palaeo.2025.113063.Fig. 1. The exotic limestone in the ophiolite mélange of the Yarlung-Tsangpo Suture Zone. (A, Full view of the exotic limestone blocks in the Zhalairi area; B, The exotic limestone in the ZLR1 section; C, The exotic limestone in the ZLR3 section; D, The Bijiula section; E, The exotic limestone in the JYM2 section; F, The interlayered basalts in the JYM2 section.)Fig. 2. The cartoon showing the formation of the seamounts within the Neo-Tethys Ocean and its obduction to the south of the Zhongba-Zhada microcontinent during the collision between the Tethys Himalaya Terrane and the Lhasa Block

2025-06-04

Chinese scientists reported the the earliest known fossil record of blue-stain fungus

In a recent report published in National Science Review, a Chinese team of scientists highlights the discovery of well-preserved blue-stain fungal hyphae within a Jurassic fossil wood from northeastern China, which pushes back the earliest known fossil record of this fungal group by approximately 80 million years. The new finding provides crucial fossil evidence for studying the origin and early evolution of blue-stain fungi and offers fresh insights into understanding the ecological relationships between the blue-stain fungi, plants, and insects during the Jurassic period.Blue-stain fungi constitute a distinctive group of wood-colonizing fungi which lack the ability to decompose wood lignocellulose, yet are capable of causing significant wood discoloration. Though these fungi are generally nonfatal to their hosts, they often accelerate tree mortality when associated with wood-boring insects.Molecular phylogenetic analyses suggest that blue-stain fungi should be an old fungal group, which might originate during the Late Paleozoic or early Mesozoic. However, hardly anything is known about the geological occurrences of blue-stain fungi.Not until 2022, the first credible fossil record of blue-stain fungi was reported from the Cretaceous in South Africa with an age of approximately 80 million years.This research team was led by Prof. Ning Tian from Shenyang Normal University (SNU) and Prof. Yongdong Wang from Nanjing Institute of Geology and Palaenology, CAS (NIGPAS), and was jointly studied by Prof. Zikun Jiang from the Chinese Academy of Geological Sciences in Beijing as well as other scholars from SNU. They foundwell-preserved fossil fungal hyphae preserved within a Jurassic petrified wood from northeastern China, dated 160 million years ago. Microscopic examination reveals thefossil hyphae are dark in colour, which is indicative of pigmentation, a hallmark of contemporary blue-stain fungi which results in the discoloration of woods. Of interest, when penetrating the wood cell wall, the hyphae commonly form a very specialized structure called “penetration peg”. That is to say when pushing through the wood's cell walls, the hyphae commonly slim down in size, making it easier to pierce through the tough barrier. The discovery of the penetration peg enables the team to ensure that the fossil fungus that they found belongs to the blue-stain fungi. Unlike wood-decay fungi, which degrade wood cell walls through enzymatic secretion, the blue-stain fungi lack the enzymatic capacity to decompose wood structures. Instead, their hyphae mechanically breach wood cell walls via the penetration pegs.The finding of Jurassic blue-stain fungi from China pushes back the earliest known fossil record of this fungal group by approximately 80 million years, providing crucial fossil evidence for further understanding the origin and early evolution of blue-stain fungi.Additionally, it offers fresh insights into understanding the ecological relationships between the blue-stain fungi, plants, and insects during the Jurassic period. The bark beetle subfamily Scolytinae is considered as one of the major spore dispersal agents for extant blue-stain. However, both molecular biological and fossil evidence proposed that the origin time of Scolytinae dates back no earlier than the Early Cretaceous. Given the Jurassic age of present fossil fungus, it is hypothesized that its spore dispersal vector was not Scolytinae but rather other wood-colonizing insects prevalent during that period.This study was funded by the National Natural Science Foundation of China and the Liaoning Revitalization Talents Program.Article information:Tian Ning*, Wang Yongdong*, Li Fangyu, Jiang Zikun, Tan Xiao, 2025. Blue-stain fungus from the Jurassic provides new insights into early evolution and ecological interactions. National Science Review, 12(6): nwaf160. https://doi.org/10.1093/nsr/nwaf160.Figure 1 Anatomical details of the fungus-bearing wood Xenoxylon phyllocladoides Gothan from the Jurassic of western Liaoning, NE China(a) Transverse section, a insect-boring hole. (b, c) Transverse section, distinct growth rings with collapsed early wood. (d-e) Radial section, uniseriate distant bordered pits. (f, g) Radial section, window-like cross-field pits. Bars: (a) 500 μm; (b) 200 μm; (c) 100 μm; (d-g) 50 μm.Figure 2. Blue-stain fungus in wood tissues of Xenoxylon phyllocladoides Gothan from the Jurassic of western Liaoning Province, NE China.(a–c) Hyphae with septa (white arrow heads). (d) Hyphae growing in the cross-field zone. (e, h) Hyphae penetrating tracheid walls with appressorium-like structures and distinct hyphal pegs (white arrow heads). (f) Colonization of ray parenchyma cells by hyphae. (g, i–j, l) Hyphae horizontally penetrating the tracheid walls with appressorium-like structures. (k) Hyphae colonizing in the tracheid lumen, and passing through the bordered pits. (m–o) Slender hyphae within tracheid lumen with chlamydosporelike structures (white arrow heads).Bars: (a–d, f–n) 50 μm; (e) 25 μm.

2025-05-30

Research Links Trilobite Body Size Changes in Early Paleozoic with Marine Oxygen Levels

Exploring macroevolutionary patterns and processes using fossil records is vital to understanding how developmental drivers and ecological pressures shape biodiversity. Size is one of the most conspicuous organismal traits and serves as a crucial factor in determining how organisms interact with their environment, making patterns of animal body size evolution a focus of macroevolutionary research. Nevertheless, the macroevolutionary patterns of body size across numerous major metazoan clades and their constraining mechanisms remain enigmatic. Recently, Dr. SUN Zhixin, supervised by Professors ZHAO Fangchen and ZHU Maoyan from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), collaborated with Dr. ZENG Han (NIGPAS) and Pro. Douglas H. Erwin from the Santa Fe Institute to conduct a comprehensive study on body size evolution in trilobites, a highly representative group of fossil invertebrates. This research was published in Science Advances on May 2th, 2025.A recent study shows that marine oxygen levels were crucial to the evolution of Early Paleozoic trilobite body size, suggesting that oxygen may have influenced the evolution of other animals’ body size as well.The research, involving a comprehensive analysis of body size evolution in trilobites—a highly representative group of fossil invertebrates—was led by Prof. ZHAO Fangchen and Prof. ZHU Maoyan from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences. Results were published in Science Advances.Patterns of animal body size evolution have long been a focus of scientific research, with different theories attempting to explain it. For example, Cope’s Rule holds that animal species tend to evolve to become larger over time. In contrast, Bergmann’s Rule states that in warm-blooded animals, like mammals and birds, species living in colder climates tend to be larger than those living in warmer climates. Both of these theories were developed in the 19th century.Recently, some studies have emphasized the role of oxygen in animal body size evolution, but many of these studies are based on fossil vertebrates. Among invertebrates, research on body size evolution has been limited to a few groups, such as brachiopods and insects.The Early Paleozoic is an ideal period for testing the relative importance of oxygen levels and other environmental mechanisms on body size, due to environmental fluctuations in marine oxygen levels, marine chemistry, and temperature during this epoch.Trilobites have been a central focus of macroevolutionary studies—i.e., those involving large-scale changes in life forms rather than individual species—due to their long geological history, diverse ecological adaptations, and abundant fossil record. With adult body sizes ranging from ~2 mm (Acanthopleurella stipulae) to more than 700 mm (Isotelus rex or Ogyginus forteyi), they are an ideal clade for testing the evolutionary dynamics of body size. Additionally, few comprehensive assessments have been done on the evolution of body size in giant trilobites, despite long-standing interest in them.To explore the macroevolutionary potential of trilobites, the researchers compiled an extensive dataset of body size for Cambrian and Ordovician forms, covering 1,091 genera and representing over 90% of trilobite families during this period. They examined the role of marine oxygen and temperature in determining evolutionary trends in trilobite size. Their results highlight the long-term impact of marine oxygen levels on the evolution of trilobite body size, further confirming the significant role oxygen played in shaping the evolutionary dynamics of early metazoans.The dataset shows that the body size patterns of trilobites during the Cambrian and Ordovician periods can be divided into six phases (I-VI), with body size changes concentrated in five brief events: in early Age 4 (ca. 514 Ma), the late Wuliuan (ca. 506.5 Ma), the Guzhangian (ca. 500.5 Ma), the late Tremadocian (ca. 480 Ma), and the late Katian (ca. 450 Ma).The size differences across the six phases are significant—they are not the result of sample size differences across intervals. Major size changes occurred in each major geographic region, particularly during Age 4, the Guzhangian, and the middle Tremadocian, suggesting that global patterns mirrored regional trends. Collectively, these results imply that changes in trilobite body size were more likely to be influenced by global rather than regional factors.To investigate whether the episodic changes in body size obscure an underlying directional pattern, the researchers identified trends in average body size across the 24 most diverse trilobite families. Most well-sampled trilobite families showed no significant size changes through time, ruling out Cope's Rule at the family level. Moreover, the researchers reconstructed and plotted ancestral body size onto family-level phylogeny, fitting five different models of continuous trait macroevolution.The results indicate that most trilobite families were near the average size, with some clades independently evolving to larger or smaller sizes during different ages. However, none of the results support an overall trend in body size evolution. Overall, these analyses reveal no preferential direction in trilobite body size during the Cambrian and Ordovician periods that would support Cope’s Rule.In contrast, trilobite size was strikingly correlated with fluctuations in marine redox (i.e., marine oxygen levels), especially during the well-known anoxic events of this interval. For example, reductions in trilobite size during the early Cambrian Age 4, the Guzhangian, and the late Katian correspond with the Sinsk, SPICE, and HOAE anoxic events. The miniaturization phases after Sinsk and SPICE (phases II and V) also coincided with sustained marine anoxia. Furthermore, the end of the persistent Black Shale Anoxic Event (BSAE) in the late Tremadocian may have triggered the most pronounced increase in trilobite size.From the late Tremadocian, trilobite size remained stable for nearly 30 Myr (phase V), coinciding with the expansion of marine oxygenation. In contrast, although global cooling may have triggered the extraordinary Great Ordovician Biodiversity Event (GOBE), estimates of early Paleozoic temperature changes show little correlation with trilobite body size. In short, trilobite body size changes during the Cambrian and Ordovician periods correspond closely with marine redox fluctuations.It is reasonable to assume that marine redox influenced, if not directly controlled, trilobite body size changes across the world since larger bodies need more oxygen and smaller bodies need less. All in all, this study strongly supports a model in which oxygen levels constrained body size evolution in trilobites—whose size evolution, along with that of other marine metazoans, has not been understood as well as that of terrestrial clades.Furthermore, the study provides independent support for the hypothesis that oxygen was an important driver of early animal evolution more generally and may have influenced the body size evolution of other clades as well.This research was supported by the National Key Research and Development Program of China and the National Natural Science Foundation of China.Fig.1: Tempo and mode in the body size evolution of Cambrian-Ordovician trilobites. Changes in maximum size (red) and mean size (blue) for each time slice, with lines and shading representing the mean value and 95% confidence intervals. Discrete episodes of body size change are marked by red arrows, and these events demarcate six distinct phases.Fig. 2: Body size evolution of Cambrian-Ordovician trilobites in Laurentia (B), East Gondwana (C), West Gondwana (D), Baltica and Avalonia (E). Three episodes of change in body size during Cambrian Age 4, the Guzhangian and middle Tremadocian are marked 1, 2 and 3.Fig. 3: Phylogenetic based family-level body size evolution in Cambrian-Ordovician trilobites. (A) Ancestral state reconstruction of body size. (B) Evolutionary traitgram of trilobite body size. (C) Model-fitting results expressed as Akaike weights for five different evolutionary models.Fig. 4: Cambrian and Ordovician trilobite body size (A) and their correlation to the inferred oxygen levels (B) and temperature (C). (B) Ocean redox conditions and widespread anoxic intervals, showing strong links between trilobite body size and marine redox changes, blue and purple indicate oxic and anoxic states, respectively. (C) Temperature curves are based on bulk-rock (purple line) and skeletal material (gray line) δ18O datasets.

2025-05-03

Jurassic Fossil Sheds Light on Evolutionary Origins of Thorny-Headed Worms

A research team from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences has identified a fossil acanthocephalan, Juracanthocephalus, from the 160-million-year-old Daohugou Biota in Inner Mongolia, China. This finding was published in Nature.A research team from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences has identified a fossil acanthocephalan, Juracanthocephalus, from the 160-million-year-old Daohugou Biota in Inner Mongolia, China. This finding was published in Nature.Acanthocephalans, commonly known as thorny-headed or spiny-headed worms, are a group of endoparasitic worms found in both marine and terrestrial ecosystems. These medically significant parasites infect a wide range of hosts, including humans, pigs, dogs, cats, and fish. Acanthocephalans are characterized by their worm-like body shape and a retractable proboscis armed with rows of recurved (i.e., backward-facing) hooks for anchoring to the digestive tracts of their hosts. Historically classified as a distinct animal phylum, their highly specialized body plan has led to ongoing debates regarding their phylogenetic position.Morphological studies have proposed various hypotheses linking acanthocephalans to Platyhelminthes (flatworms), Priapulida (penis worms), or Rotifera (wheel animals). However, molecular phylogenetic analyses strongly suggest that acanthocephalans are a highly specialized subgroup within Rotifera. Despite this, the morphological disparity between endoparasitic acanthocephalans and free-living rotifers remains striking.Furthermore, the fossil record of acanthocephalans is exceptionally sparse due to their soft bodies—which were less likely to fossilize than harder ones—and concealed habitats. Until now, the only known fossil evidence consisted of four putative acanthocephalan eggs discovered in the coprolites of a Late Cretaceous crocodyliform. Due to the lack of body fossils, the origin and early evolution of acanthocephalans thus remain poorly understood.Using scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS), the research team conducted a detailed anatomical analysis of Juracanthocephalus and updated the morphological matrix of worm-like animals to support a comprehensive phylogenetic analysis.The results indicate that Juracanthocephalus represents a transitional form between free-living, jawed rotifers and jawless, endoparasitic acanthocephalans, bridging an evolutionary gap. This finding provides the first direct fossil evidence to help resolve the long-standing mystery of acanthocephalan origins.Juracanthocephalus has a fusiform body divided into a proboscis, neck, and trunk. The proboscis is equipped with strongly sclerotized, slightly curved hooks, while the ventral surface of the trunk features 38 lines of transverse, setaceous combs—a trait comparable to modern acanthocephalans. A possible alimentary tract is preserved in the proboscis, though no clear gut is visible in the trunk. The terminal end of the fossil displays a structure resembling the bursa of male acanthocephalans.Notably, Juracanthocephalus has a jaw apparatus composed of clustered, tooth-like units arranged in converging paired rows, with the jaws increasing in size posteriorly. This structure closely resembles that found in Gnathifera, a group that includes Gnathostomulida, Micrognathozoa, and Syndermata (which encompasses Rotifera and Acanthocephala).To determine the phylogenetic position of Juracanthocephalus, the research team compiled an updated morphological matrix incorporating both extant and extinct worm-like animals. The analysis identifies Juracanthocephalus as a stem-group acanthocephalan, sister to all extant acanthocephalans. This finding aligns with molecular phylogenetic analyses, which place acanthocephalans within Rotifera (including Monogononta, Bdelloidea, and Seisonidea).However, the precise placement of acanthocephalans within Rotifera remains contentious, with six competing hypotheses arising from molecular and morphological studies. When Juracanthocephalus is excluded from the morphological matrix, the results support Seisonidea as the sister group to all other Rotifera, consistent with previous morphological analyses but conflicting with molecular data.Conversely, incorporating Juracanthocephalus into the matrix positions Seisonidea as the sister group to Juracanthocephalus and all extant acanthocephalans, reconciling morphological and molecular phylogenetic analyses.The discovery of Juracanthocephalus provides a crucial reference for understanding the evolutionary innovations and body plan of acanthocephalans. Its hooked proboscis and large body size suggest that it was an endoparasite during the Jurassic period. Furthermore, this fossil implies that acanthocephalans may have originated in terrestrial environments and diverged from Rotifera no later than the Middle Jurassic.This study underscores the importance of transitional fossils in elucidating radical morphological changes in animal body plans. While molecular phylogenetics has revolutionized our understanding of evolutionary relationships, Juracanthocephalus highlights the indispensable role of fossil evidence in reconstructing the history of life.The research was supported by the National Natural Science Foundation of China, the IUGS “Deep-time Digital Earth” Big Science Program, and the Jiangsu Innovation Support Plan for International Science and Technology Cooperation Programme.Figure 1: Juracanthocephalus (a, overall view; b, artistic reconstruction) and the comparison with extant Acanthocephala (c). Scale bars, 2.0 mm (a, b), 0.5 mm (c).Figure 2: The backscatter scanning electron (BSE) image (a), overlay image of several elements concentrations (b) and elemental maps of carbon from energy-dispersive X-ray spectroscopy (c) of Juracanthocephalus. Scale bar, 2.0 mm.Figure 3: Simplified cladogram of Gnathifera showing Juracanthocephalus in red color.Figure 4: Phylogenetic tree from 50% majority rule bootstrap consensus tree of parsimony analysis. When Juracanthocephalus is included in the matrix, the results recover Seisonidea as the sister group to Juracanthocephalus + all extant acanthocephalans (a); when Juracanthocephalus is excluded from the morphological matrix, the results support the Seisonidea as the sister group of all other Rotifera (b).

2025-04-09

The Oldest Known Phosphatic Stromatoporoid Sponge Discovered in South China

International scientists have uncovered the oldest known phosphatic stromatoporoid sponge, dating back approximately 480 million years to the Early Ordovician, in South China.Stromatoporoid sponges were key reef builders during the Palaeozoic era, playing a crucial role in constructing biological frameworks—similar to the role of modern corals. They were especially important during the middle Paleozoic era (from the late Middle Ordovician to Devonian), a time marked by a major transition from microbial-dominated to skeletal-dominated reef ecosystems. Previously, stromatoporoid reefs were thought to have emerged suddenly in the late Darriwilian period (around 460 million years ago), leading to questions about their origins and early evolutionary history.Recently, an international research team led by scientists from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences discovered an exceptionally preserved phosphatic stromatoporoid sponge from the Early Ordovician, dating back about 480 million years, in Yuan’an, Yichang, South China.This newly identified stromatoporoid, Lophiostroma leizunia, not only extends the fossil record of stromatoporoid reefs by about 20 million years but also provides valuable insights into the early biomineralization strategies of ancient animals.South China is renowned for its exceptional fossil preservation and its diverse Early Paleozoic marine ecosystems. Researchers have extensively studied the Ordovician strata in this region, documenting the early diversification of marine life during the Great Ordovician Biodiversification Event (GOBE)—a critical period marked by dramatic increases in marine biodiversity.Lophiostroma leizunia is unique among all known sponges for constructing its skeleton using fluorapatite, a phosphate mineral. This finding establishes the phylum Porifera (sponges) as the first animal group known to utilize all three principal biominerals: silica, calcium carbonate, and calcium phosphate. This distinctive skeletal composition suggests that early sponges had the genetic capacity to employ diverse biomineralization strategies.Fossil evidence indicates that Lophiostroma leizunia formed complex reef structures and played a crucial role in framework construction, binding together other reef components, including calcimicrobes, lithistid sponges, Calathium, and echinoderms. These reef ecosystems exhibit remarkable ecological complexity—comparable to those found in later reef systems.This study was supported by the National Natural Science Foundation of China, the National Research Foundationof Korea, and the Korea Polar Research Institute project.This study enhances our understanding of early reef ecosystems and the evolution of biomineralization across the animal kingdom, providing new insights into how environmental factors influenced biological evolution during this critical period in Earth’s history.Figure 1. Thin section photographs of Lophiostroma leizuniaFigure 2. Mineralogical and micro-scaled features of Lophiostroma leizuniaFigure 3. Stromatoporoid-echinoderm reef type

2025-04-01

Microfossils in Chert Provide New Evidence for the Cambrian Explosion

The Cambrian explosion, which occurred from the late Ediacaran to the early Cambrian, stands as one of the most pivotal evolutionary events in Earth’s history. Across the Ediacaran-Cambrian boundary (ECB), the once-thriving Ediacara-type biota vanished, while metazoans forged a Phanerozoic-type ecosystem within approximately 18 million years (539–521 Ma). Our previous understanding of this critical evolutionary transition relied on relatively continuous records of small shelly fossils from shallow-water carbonates and phosphatic deposits, alongside Ediacara-type macrofossils and trace fossils mainly preserved in siliciclastic rocks. However, the widely developed sedimentary discontinuities near the ECB in shallow-water settings hindered a comprehensive understanding of the biological processes during this turning point.Recently, the research team led by Prof. Maoyan Zhu from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), proposed that chert deposits across the ECB offer a new window into this biological revolution. The study, with Dr. Cui Luo as the first author, was published online on March 10, 2025, in Geology.Cherts, being able to exquisitely preserve non-mineralized organisms and their anatomical details, have been exceptional taphonomic windows since the Archean. The Ediacaran-Cambrian cherts of South China have been investigated by Chinese paleontologists since the 1990s, with dozens of microalgal genera recognized. Built on this basis, the team examined cherts from eight ECB sections across South China and delineated two distinct fossil assemblages through integrated paleontological and carbon isotope stratigraphic analyses.The terminal Ediacaran fossil assemblage (550–539 Ma) is dominated by enigmatic string- and strap-like forms of uncertain affinity, with Horodyskia (bead-like strings) and Nenoxites (crescent-segmented strings) being particularly common. These fossils are preserved primarily as clay-mineral casts, differing from the carbonaceous or permineralized preservation typical of other chert Lagerstätten. In contrast, early Cambrian cherts (539–521 Ma) reveal a highly diverse assemblage with finely preserved anatomical details, encompassing acritarchs, algal microfossils, mineralized animal skeletons, and carbonaceous fossils of uncertain affinity. A large acanthomorphic acritarch from the Luxishao section echoes forms from the early Ediacaran, suggesting that some ancient taxa may have persisted into the Cambrian. Sponge spicules in cherts extend below the nadir of the basal Cambrian carbon isotope excursion (BACE), indicating that biomineralization in sponges, like that of small shelly fossils such as Anabarites, originated prior to the Cambrian. Especially noteworthy are the complex carbonaceous filmy fossils unique to the Cambrian assemblage, which are distinct from algal remains and absent in Precambrian cherts. These fossils, potentially representing animal cuticles, indicate an innovation in soft-tissue structures among multicellular eukaryotes at the dawn of the Cambrian.These findings align with prior insights from other taphonomic windows, confirming a rapid biospheric shift near the ECB; a few Ediacaran forms persisted into the Cambrian, while Cambrian-specific skeletal fossils extend below the BACE nadir. This consistency reinforces previous conclusions while highlighting the potential of chert fossil records as a new window for exploring ECB biological changes. The broad distribution of cherts across varying water depths and their capability of preserving delicate non-mineralized tissues could provide good complements to the skeletal fossil data from shallow-water settings. As such, this avenue of research merits heightened attention in future studies.The study also shows that representative members of both assemblages are widespread across the Yangtze craton, from west to east (Yunnan to Anhui) and from proximal shelf to distal upper slope facies. However, vertical overlap between the two assemblages is rare, with only one prior report noting their co-occurrence. Future investigations are required to test whether these assemblage differences stem from taphonomic bias or sedimentary hiatus.This study was supported by the National Key Research and Development Program and the National Natural Science Foundation of China. Numerous team members offered help in the extensive fieldwork. Dr. Soo-Yeun Ahn contributed significantly to the material collection during her postdoctoral project.Fig. 1 Investigated sections and their distribution in the Terreneuvian lithofacies paleogeographical map.Fig. 2 The contrasting characteristics between the terminal Ediacaran (A–F) and the early Cambrian fossil assemblages (G–O).Fig. 3 Some of the carbonaceous filmy fossils in the Cambrian cherts.Fig. 4 (A) Temporal distribution of chert Lagerstätten and other taphonomic windows across the Ediacaran-Cambrian transition, along with representative fossils in each window. (B) Spatial distribution of fossils in cherts across the Ediacaran-Cambrian transition.

2025-03-28