In many blocks on the Earth, the boundary between the Phanerozoic and Precambrian is consistently characterized by a huge sedimentary gap—the Great Unconformity. Recently, researchers from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), carried out a synthetic geochronological study for the late Ediacaran to early Cambrian strata on the southern North China craton, which provides a new perspective on the origin of the Ediacaran–Cambrian unconformity. In many blocks on the Earth, the boundary between the Phanerozoic and Precambrian is consistently characterized by a huge sedimentary gap—the Great Unconformity. Recently, researchers from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), carried out a synthetic geochronological study for the late Ediacaran to early Cambrian strata on the southern North China craton, which provides a new perspective on the origin of the Ediacaran–Cambrian unconformity. The relevant research was recently published in the international geological journal Earth and Planetary Science Letters. While this long-drawn exhumation has been argued to trigger the initiation of modern plate tectonics, the oxygenation of the ocean and atmosphere, and the Cambrian explosion. According to the thermochronologic and stratigraphic studies, the Great Unconformity has been confirmed to consist of one denudation before the Cryogenian and two exhumations during the Snowball Earth and the Ediacaran–Cambrian transitional period. While the major erosional processes before and during the Cryogenian were suggested to be associated with the Rodinia supercontinent cycle and the “Snowball Earth” event, respectively, the origin of the relatively shorter Ediacaran–Cambrian unconformity is still elusive. Multiple geological events have been proposed to be associated with the Ediacaran–Cambrian unconformity, including the final break-up of the Rodinia supercontinent, plume activity associated with the continental-scale rifting, tectonic response to the assembly of Gondwana, as well as other regional plate tectonics. However, it is still unclear how different tectonics could produce the widely comparable Ediacaran–Cambrian unconformity in different blocks. The Great Unconformity occurs widely in the North China Craton (NCC), recent studies suggested it is composed of a prolonged sedimentary break from late Paleoproterozoic/early Neoproterozoic to late Ediacaran and a short one between late Ediacaran and early Cambrian, which resembles the development pattern of the typical Great Unconformity in North America and Qaidam. In this regard, the NCC would provide us with an opportunity to understand the mechanism of the widespread exhumation that occurred from late Ediacaran to early Cambrian. Detrital zircon ages for the late Ediacaran–early Cambrian strata in the southern, western, and southeastern margins of North China craton show great similarities, with predominant age clusters peaking at ～1800 Ma and ～2500 Ma. The geochronological study reveals an apparent absence of synsedimentary zircons in the latest Ediacaran to earliest Cambrian strata, suggesting a significant tectonic quiescence in NCC. Similar situation also occurs in blocks outside the Gondwanaland in the late Neoproterozoic, indicating that the contemporaneous erosion represented by the widespread Ediacaran–Cambrian unconformity may have been dominated by a global sea-level fall, rather than regional tectonics. “However, our result does not preclude the influence of tectonism on the manifestation of the Ediacaran–Cambrian unconformity in other blocks, especially those that make up the Gondwanaland”, says SUN, “the late Neoproterozoic global sea-level fall was possibly associated with the assembly of the Gondwanaland”. This research was supported by the National Key Research and Development Program of China, the Chinese Academy of Sciences, and National Natural Science Foundation of China. Reference: Yunpeng Sun, Qing Ouyang, Xianguo Lang, Ke Pang, Chengxi Wu, Zhe Chen, Chuanming Zhou*. 2023. Global sea-level fall triggered Ediacaran–Cambrian unconformity in North China craton. Earth and Planetary Science Letters, 622: 118411. https://doi.org/10.1016/j.epsl.2023.118411. Fig.1. Outcrop photographs and representative fossils of the Ediacaran to Cambrian strata in the southern NCC. Fig.2. (A) Comparison of the Precambrian unconformities in different regions of NCC; (B) Simplified late Ediacaran to middle Cambrian paleogeographic maps of NCC. Fig.3. Hypothesized erosional history of the Great Unconformity.
Contact: LIU Yun, Propagandist Email: yunliu@nigpas.ac.cn Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences Nanjing, Jiangsu 210008, China
We reported the discovery of extraordinary early Cambrian (ca. 535 million years old, or Ma) microfossils that preserved the introvert musculature of cycloneuralians, a group of animals that include roundworms, horsehair worms, mud dragons, and many other creatures. The discovery added fleshy insights into early Cambrian cycloneuralians, which are closely related to arthropods, the most successful animals on Earth. An international research team led by Prof. ZHANG Huaqiao from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), reported the discovery of extraordinary early Cambrian (ca. 535 million years old, or Ma) microfossils that preserved the introvert musculature of cycloneuralians, a group of animals that include roundworms, horsehair worms, mud dragons, and many other creatures. The discovery added fleshy insights into early Cambrian cycloneuralians, which are closely related to arthropods, the most successful animals on Earth. The study was published in Proceedings of the Royal Society B (Biological Sciences) on Oct. 11th. Dr. XIAO Shuhai from Virginia Tech, Dr. ERIKSSON Mats E. from Lund University, Dr. DUAN Baichuan from the First Institute of Oceanography, Ministry of Natural Resource, and Dr. MAAS Andreas from Germany were also involved in the study. The Ecdysozoa represents the most diverse bilaterally symmetric animals. It contains the Scalidophora (Kinorhyncha, Loricifera, Priapulida), Nematoida (Nematoda, Nematomorpha), and Panarthropoda (Tardigrada, Onychophora, Arthropoda). The Scalidophora and the Nematoida constitute the Cycloneuralia, whose monophyly is debated. Molecular clock estimates indicate that the Ecdysozoa may have diverged in the Ediacaran Period, but unambiguous ecdysozoan body fossils first appeared in the early Fortunian Age (ca. 535 Ma) and are represented by the total-group ecdysozoan taxon Saccorhytus and several crown-group cycloneuralian species. However, the preservation of Fortunian ecdysozoans is limited to cuticular integuments, with no labile internal tissues (e.g., muscles or nerve tissues) preserved, hampering further understanding of their functional morphology and evolutionary significance. The authors described three phosphatized and millimeter-sized specimens from the early Fortunian Kuanchuanpu Formation (ca. 535 Ma) of China. Among them, one specimen (NIGP179459; Fig. 1) is better preserved and consists of five successively larger rings that are interconnected with 19 radial and 36 longitudinal structures. The rings were compressed to certain degrees, implying that they were pliable when alive. The first ring is separate from the remaining four larger rings by a gap, and is located almost co-planarly at the center of, or slightly apical to, the second ring. The radial structures connect the first ring with the third ring, whereas the longitudinal structures extend from the third ring to beyond the fifth ring. Some longitudinal structures become more fibrous in textural appearance toward the abapical end. In the reconstruction (Fig. 2), the second to fifth rings are coaxially stacked and constitute an apically truncated cone, with hexaradially arranged internal longitudinal structures. Based on their patterns of arrangement, the fibrous texture, and the inferred pliability, the rings as well as the radial and longitudinal structures were interpreted as fossilized muscles. The preserved musculature consists of four groups of muscles, i.e., an inner circular, four outer circular, 19 radial, and 36 longitudinal muscles. This complex topology differs from that of the body-wall musculatures of basal animals such as cnidarians or ctenophores, and instead it likely represents musculature of bilaterian animals. The hexaradial symmetry imparted by the arrangement of the longitudinal muscles invites a comparison with scalidophorans, whose introvert exhibits radial symmetry both externally (i.e., longitudinal rows of scalids are radially disposed) and internally (i.e., longitudinal muscles are radially arranged). With a scalidophoran affinity, the authors interpreted specimen NIGP179459 as the anterior introvert musculature (Fig. 3a, b). The authors interpreted the second to fifth rings as body-wall circular muscles, and the 36 longitudinal structures as body-wall longitudinal muscles. The body-wall circular and longitudinal muscles constitute a muscular grid. Since similar body-wall muscular grid is present in priapulans (Fig. 3c, d) but absent in loriciferans (Fig. 3e) or kinorhynchs (Fig. 3f), specimen NIGP179459 was proposed to belong to priapulans. Considering that the priapulan-like introvert may have characterized the last common ancestor of the Scalidophora, it is also possible that specimen NIGP179459 belongs to total-group Scalidophora (Fig. 4). The total-group scalidophoran affinity of NIGP179459 is further supported by the first ring and radial structures. The authors interpreted the first ring as an introvert circular muscle, and the 19 radial structures as introvert circular muscle retractors. Introvert circular muscle is present in loriciferans (Fig. 3e), kinorhynchs (Fig. 3f), and hatching larvae of priapulans (Fig. 3d), whereas introvert circular muscle retractors are present in kinorhynchs (Fig. 3f) and hatching larvae of priapulans (Fig. 3d). Furthermore, specimen NIGP179459 lacks mouth cone and scalid associated muscles, but these muscles are common in loriciferans (Fig. 3e) and kinorhynchs (Fig. 3f). Thus, the total evidence supports a total-group scalidophoran affinity, possibly related to the priapulans (Fig. 4). Scalidophorans as represented by specimen NIGP179459 may be millimeter-sized and have an introvert with hexaradially arranged scalids, which correspond to the hexaradially arranged body-wall longitudinal muscle bundles inside. This musculature may have controlled the inversion of the introvert, and thus facilitated locomotion and feeding. The absence of long introvert retractors indicates that the animals may have very limited ability to retract their introvert, differing from modern scalidophorans that have long introvert retractors and thus can completely retract their introvert. To sum up, this paper reported for the first time the extraordinary preservation of introvert musculature of early Fortunian cycloneuralians. This work underscores the significance of internal soft anatomy in resolving the affinities of the Cambrian cycloneuralians, and supports the evolution of scalidophoran-like or priapulan-like introvert musculature in cycloneuralians at the beginning of the Cambrian Period. Reference: Huaqiao Zhang*, Shuhai Xiao*, Mats E. Eriksson, Baichuan Duan, Andreas Maas, 2023. Musculature of an early Cambrian cycloneuralian animal. Proceedings of the Royal Society B (Biological Sciences), https://dx.doi.org/10.1098/rspb.2023.1803. Figure 1. SEM images of NIGP179459 (image credited to Dr. ZHANG Huaqiao) Figure 2. Reconstructions of NIGP179459 (image credited to Dr. ZHANG Huaqiao) Figure 3. Schematic representation of scalidophoran musculatures (image credited to Dr. ZHANG Huaqiao) Figure 4. Phylogenetic position of scalidophorans represented by NIGP179459 (image credited to Dr. ZHANG Huaqiao)
Contact: LIU Yun, Propagandist Email: yunliu@nigpas.ac.cn Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences Nanjing, Jiangsu 210008, China
Recently, researchers conducted phylogenetic reanalyses of the previously published anchored hybrid enrichment datasets, and solved the evolutionary relationships of extant weevil families. Weevils (superfamily Curculionoidea) represent a hyperdiverse and globally distributed group of phytophagous beetles, with approximately 62 000 described species in 5800 genera. Recently, Professor CAI Chenyang from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), in collaboration with colleagues, conducted phylogenetic reanalyses of the previously published anchored hybrid enrichment datasets, and solved the evolutionary relationships of extant weevil families. The result has been recently published in a Royal Society journal Biology Letters. The vast majority of weevils have a forward-facing rostrum that resembles an elephant's trunk, hence the name weevil. Weevils are divided into eight extant families, i.e. Cimberididae, Nemonychidae, Anthribidae, Belidae, Attelabidae, Caridae, Brentidae and Curculionidae. The evolutionary relationships among the families are largely resolved, with the Attelabidae, Caridae, Brentidae, and Curculionidae constituting a monophyletic group (ACBC clade), while the Cimberididae, Nemonychidae, and Anthribidae are basal lineages. However, the systematic position of Belidae is somewhat controversial, and most studies based on morphological and molecular data generally consider it as the sister group of the ACBC clade. However, a recent Anchored Hybrid Enrichment (AHE)-based phylogenomic study suggests that Belidae is sister to Nemonychidae and Anthribidae. In recent years, Prof. CAI's group has devoted itself to the research of molecular phylogenetics and timetree of insects, and used innovative methods in data curation and model selection to construct evolutionary relationships and time frameworks of several key insect lineages. Previously, the team used genome-scale data and site-heterogeneous models to construct a supertree of beetle evolution, and combined with a newly vetted set of fossil calibrations to build a more accurate beetle timetree (Cai et al. 2022). After its publication, it received extensive attention from the academic community, and is now indexed as ESI highly-cited papers and hot papers. Recently, under the supervision of Prof. Cai, Mr. LI Yanda, a doctoral student at the University of Bristol, in collaboration with colleagues from the American Museum of Natural History and the University of Bristol, compared different data filtering methods, different evolutionary models and different tree building strategies on the tree topology. Studies have shown that when appropriate data filtering is used to remove incorrectly aligned gene sequences, or when a more appropriate site-heterogeneity evolutionary model is taken, or the coalescent strategy is properly used, Belidae are always resolved as sister groups of the ACBC clade. “This result is fully consistent with the phylogenetic relationship based on morphological evidence”, CAI says, “weprovide a consistent and robust backbone phylogeny of weevils.” “More important, our analyses emphasize the significance of data curation and modelling compositional heterogeneity of molecular data in today’s phylogenomic studies”, says CAI. Financial support was provided by the Strategic Priority Research Program of the Chinese Academy of Sciences, the National Natural Science Foundation of China, and the China Scholarship Council. Reference: Li, Y.-D., Engel, M.S., Tihelka, E. & Cai, C.* (2023) Phylogenomics of weevils revisited: data curation and modelling compositional heterogeneity. Biology Letters, 19, 20230307. https://doi.org/10.1098/rsbl.2023.0307 Cai, C., Tihelka, E., Giacomelli, M., Lawrence, J.F., Slipiński, A., Kundrata, R., Yamamoto, S., Thayer, M.K., Newton, A.F., Leschen, R.A.B., Gimmel, M.L., Lü, L., Engel, M.S., Bouchard, P., Huang, D., Pisani, D. & Donoghue, P.C.J. (2022) Integrated phylogenomics and fossil data illuminate the evolution of beetles. Royal Society Open Science, 9, 211771. (Google Scholar, 115 citations) Figure 1. Backbone phylogeny of weevils based on AHE amino acid dataset. Figure 2. Comparison among tree topologies generated with different models and datasets. Topology D is our preferred topology for weevil phylogeny.
Contact: LIU Yun, Propagandist Email: yunliu@nigpas.ac.cn Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences Nanjing, Jiangsu 210008, China
Recently, Associate Research Professor LI Lixia and her collaborators from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), and University of Gottingen, Germany have conducted detailed studies on taxa of important evolutionary significance of the Beigong Biota. Beigong Biota is the first unusual deep-water sponge fauna across the Ordovician-Silurian boundary in the world. It contains abundant and diverse siliceous sponges that perfectly preserved with a nearly complete sponge skeleton. In general, this sponge fauna is a mixture of “old” Cambrian type as well as quite modern ones, showing characteristics of transitional groups. Moreover, it was found in the crucial interval of sponge evolution just between the Cambrian and the Devonian. Thus, further studies about this fauna is super important to reveal a more complete picture of the origin and evolution of Phanerozoic sponges. Recently, Associate Research Professor LI Lixia and her collaborators from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), and University of Gottingen, Germany have conducted detailed studies on taxa of important evolutionary significance of the Beigong Biota. Two new sponge taxa, Turgidaspongia porosa gen. et sp. nov. (Hexactinellida) and Ptilospongia hemisphaeroidalis gen. et sp. nov. (Demospongiae) were first reported from the Beigong Biota. The researchers also explored the biological, palaeoecological and macro evolutionary implications of the new taxa. The research articles were published inHistorical Biology and Estonian Journal of Earth Sciences. A new stiodermatid (Hexactinellida, Porifera) from the latest Ordovician Beigong Biota Stiodermatids are a group of hexactinellid sponges with rigid dermal layer, including 13 genera at present with the range extended from the Cambrian to Permian. It should be noted that most of the genera in Stiodermatidae were known from the Carboniferous to Permian. The specimens found earlier than the Carboniferous are mainly preserved as isolated spicules, almost no articulate specimens have been found. As for the Ordovician, even no definite isolated spicules have been reported till now. Due to the sparse fossil record, it is highly debatable that whether there is an evolutionary gap in the lineage of stiodermatids during the Ordovician. The new stiodermatid discovered from the Beigong Biota strongly suggests that there is no evolutionary gap in the lineage of stiodermatids during the Ordovician, filling the gap in the fossil records of stiodermatids during the latest Ordovician and providing a link between the Cambrian lineage and late Palaeozoic lineage. In light of the new material, all the taxa belonging to the Stiodermatidae are evaluated, combined with the restudying of its taxonomy. A large number of synonym were removed, which were previously established based on isolated spicules. The number of genera included in Stiodermatidae was reduced from 13 to 5 after reassessment. The uneven distribution of the swollen dermalia in the new species may relate to the sloughing of the dermal spicules causing by the nutrient deficiencyor seasonal development. The unique rigid skeleton structure and unusually large parietal gaps probably represent new attempts on the skeletal evolution of hexactinellids in the Palaeozoic. The earliest known fossil record of bubarids from the latest Ordovician Beigong Biota Bubarids are a popular and cosmopolitan demosponge mainly found in the modern deep-water ecosystems, reaching depths of up to 1300 meters. They are characterized by encrusting habit and a two-layer structure of choanosomal skeleton and referred to Halichondrida. At present, all the four genera included in Bubaridae are modern ones, no fossil species have ever been found. Therefore, the origin and evolution of bubarid lineage are still essentially unknown. A new halichondrid demosponge bubarid is reported from the latest Ordovician Beigong Biota. The new taxon is well-preserved with a two-layer choanosomal skeleton structure (basal layer and erect monactines layer) and three different types of megascleres (styles, strongyles, strongyloxeas), giving an excellent insight into a bubarid affinity and indicating a previously unknown group. The specimen shows almost the overall shape of the whole sponge, giving a reasonably complete knowledge of the structure of the new taxa. Thus, the new genus Ptilospongia is erected with Ptilospongia hemisphaeroidalis gen. et sp. nov as the type species. Ptilospongia probably represents the only and earliest known fossil record of bubarids, providing new information for understanding the phylogeny of bubarids, and also providing a more reliable calibration point currently available for taxonomic and molecular phylogenetic studies. The case studies mentioned above just one corner of the Beigong Biota. There are considerable number of taxa in this biota like the above two, representing numerous missing links in the evolution of the Phanerozoic sponge. So, further study on these remarkable sponges could open a new window to investigate the origin and evolution of Phanerozoic sponges This study was financially supported by the National Natural Science Foundation of China (NSFC) and Strategic Priority Research Program (B) of Chinese Academy of Sciences. Reference:Lixia Li, Joachim Reitner, Fangyi Gong, Guanzhou Yan, Rongchang Wu. 2023. A new stiodermatid (Hexactinellida, Porifera) from the latest Ordovician of Anhui, South China and its significance for searching the missing link between the Cambrian and late Palaeozoic stiodermatid lineage, Historical Biology, 35(1):116-126.https://doi.org/10.1080/08912963.2021.2024180. Lixia Li, Joachim Reitner. 2023. A remarkable new halichondrid demosponge, Ptilospongia hemisphaeroidalis, from the latest Ordovician Beigong Biota, South China. Estonian Journal of Earth Sciences, 72(1), 50–53. https://doi.org/10.3176/earth.2023.76. Fig.1 Turgidaspongia porosa gen. et sp. nov Fig.2 Reconstruction of Turgidaspongia porosa gen. et sp. nov（Image by YANG Dinghua） Fig.3 Ptilospongia hemisphaeroidalis gen. et sp. nov.
Contact: LIU Yun, Propagandist Email: yunliu@nigpas.ac.cn Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences Nanjing, Jiangsu 210008, China
The study reveals, although these taxa have been noted by striking similarities in reticulate venation patterns, their disparate positions on the major seed-plant phylogenies indicates, in most cases, structural similarities of meshed venation in many plant groups are likely to be superficially convergent traits adopted for similar functional benefits. A great number of fossil plant taxa are characterized by similar-shaped leaves, leaflets and anastomosing venation that have commonly been assigned to the wrong taxon where only fragmentary or ill-preserved material is available. Venation architectures and cuticular micromorphology of leaf fossils play pivotal roles in higher-level taxonomic segregation, therefore, the standardized descriptions of vein cross-connection types and stomatal features between analogical taxa are indispensable for their morphological comparisons and phylogenetic analysis. Recently, on leaf vein structure and epidermal characteristics of three morphologically similar fossil plant taxa commonly found in the Paleozoic and Mesozoic eras, which provided new insights into the systematic classification and evolutionary history of these taxa. The study provides new insights into the systematic classification and evolutionary history of these taxa. Recently, XU Yuanyuan, a PhD student at the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), under the joint guidance of Research Professor WANG Yongdong, and Prof. Stephen McLoughlin, Swedish Museum of Natural History, carried out in-depth comparative studieds on the investigations of standardized comparisons between three morphologically similar genera, i.e., Glossopteris, Sagenopteris and Anthrophyopsis, which provided more comprehensive and new perspectives to assess whether venational pattern or stomatal characters can indicate close affinities of fossil plant taxa. This study was published in the journal of Review of Palaeobotany and Palynology. Reticulate venations occur in a broad range of plant groups dating back at least to the Pennsylvanian (Fig. 1). In many cases, anastomosing venation styles are markedly similar, and unclear whether these similarities are superficial and convergent or are genuinely homologous. Detailed observations and standardized descriptions of vein cross-connection types of Glossopteirs, Sagenopteris and Anthrophyopsis led to the functional analyses of their reticulate vein systems (Fig. 2). “Our study reveals, although these taxa have been noted by striking similarities in reticulate venation patterns, their disparate positions on the major seed-plant phylogenies indicates, in most cases, structural similarities of meshed venation in many plant groups are likely to be superficially convergent traits adopted for similar functional benefits.”, XU says. Cuticular characters, especially the stomatal complexes are arguable among the most consistent micromorphological features in fossil plants. Several traditional comparative studies and phylogenetic analysis incorporating fossil seed plants have generally proposed Glossopterids (Glossopteris), Caytoniales (Sagenopteris) and Bennettitales (Anthrophyopsis) to be close relatives of angiosperms. However, Glossopteris has perigenous and monocyclic—normally stephanocytic to actinocytic—stomata commonly protected in pits or by overarching papillae; Sagenopteris has surficial anomocytic or stephanocytic stomata with weakly modified subsidiary cells; and Anthrophyopsis has distinctive paracytic stomata consistent with those of Bennettitales (Fig. 2). This study opens up new avenues for evaluating our understanding of ancient plant taxonomy and provides a foundation for future investigations in this field. In general, the findings in this study challenge some previous notion of putatively close relationship of glossopterids (Glossopteris), Caytoniales (Sagenopteris) and Bennettitales (Anthrophyopsis), and emphasize the importance of considering ecological convergence in the interpretation of ancient plant characteristics. XU says, “While leaf characteristics have historically been used for classification, the study underscores the need for greater emphasis on the examination of reproductive organs to provide a more accurate understanding of the diversity and evolutionary history of these ancient plants.” This study was co-sponsored by the National Natural Science Foundation of China, Strategic Priority Research Program (B) of the Chinese Academy of Sciences, State Key Laboratory of Palaeobiology and Stratigraphy, Swedish Research Council and CSC. Reference: Yuanyuan Xu, Yongdong Wang*, Stephen McLoughlin*, 2023. How similar are the venation and cuticular characters of Glossopteris, Sagenopteris and Anthrophyopsis. Review of Palaeobotany and Palynology, 316, 104934. https://doi.org/10.1016/j.revpalbo.2023.104934. Fig. 1. Geological range of some representative reticulate plant fossil taxa. Fig. 2. Representative leaf fragments of Glossopteris (A–D), Sagenopteris (E–G) and Anthrophyopsis (H–J), showing leaf forms and venation styles. Scale bars for A, C, E, G, H–J = 10 mm, for B, D, F = 5mm. Fig. 3. Micromorphological features of Glossopteris (A–G), Sagenopteris (H–J) and Anthrophyopsis (K–P). Scale bars for A–D, N = 100 μm, for E–G = 10 μm, for H = 100 μm, for I = 300 μm, for J, K–L = 50 μm, for J, M, O = 30 μm, P = 20 μm.
Contact: LIU Yun, Propagandist Email:yunliu@nigpas.ac.cn Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences Nanjing, Jiangsu 210008, China
Recently, Associate Research ProfessorLI Qijian Li and Research ProfessorLI Yue from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS) and their collaborators, have reported Late Ordovician sphinctozoan-bearing microbial reefs on the Zhe-Gan Platform, South China. Ordovician strata record a unique transition from microbial-dominated towards metazoan-dominated reefs. With their first radiation of sphinctozoan sponges during the Ordovician, they occur in thrombolites in South China, representing the initial expansion of sphinctozoan-grade sponges from level bottom to reef settings. Most previous studies mainly focused on the substantial ecological changes in the reef ecosystem. However, little is known about how abiotic carbonate precipitates link to the transition in biotic composition during the Great Ordovician Biodiversification Event. Recently, Associate Research ProfessorLI Qijian Li and Research ProfessorLI Yue from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS) and their collaborators, have reported Late Ordovician sphinctozoan-bearing microbial reefs on the Zhe-Gan Platform, South China. The study entitled “Katian (Late Ordovician) sphinctozoan-bearing reefs: Hybrid carbonates before the glacial maximum” has been published in Palaeogeography，Palaeoclimatology，Palaeoecology. The reefs show a three dimensional skeletal framework that is mainly constructed by Corymbospongia and Amsassia. Microbes and subsequent cementation cover the primary skeletons, enhancing the stability of the framework (Fig.1). Isopachous crystalline crusts are distinct in the boundstone of the reefs (Fig.2). Submarine synsedimentary cementation is critical to stabilization of reef frameworks and to limit mechanical erosion. Large amounts of marine cements are widely developed in modern tropical reefs, while early marine cementation has been rarely reported as an important process to promote carbonate accumulation in the early Palaeozoic reefs. The skeletal-microbial-cement reefs of the Sanqushan Formation share many similarities with reefs reported from contemporaneous strata in North China and Central Nepal. The substantial synsedimentary cementation on the seafloor found in this study provide key evidence to understand the complex feedback relationships between eco-evolutionary dynamics and early diagenesis in Late Ordovician reefs during the icehouse conditions (Fig.3). Reference: Li, Q.J.*, Na, L., Yu, S.Y., Mao, Y.Y., Kershaw, S., Yue, L., 2023. Katian (Late Ordovician) sphinctozoan-bearing reefs: Hybrid carbonates before the glacial maximum. Palaeogeography, Palaeoclimatology, Palaeoecology. 624(15): 111642. https://doi.org/10.1016/j.palaeo.2023.111642. Thin section photomicrographs of the Corymbospongia-Amsassia framestone. A) Overview of the framestone, showing the scaffold structure of crowded Corymbospongia (Co) and Amsassia (Am); B) Detail of the framework constructed by the intertwined Corymbospongia (Co) and Amsassia (Am), showing exaulos tubes (red arrows) of sphinctozoans and a few small cavities (yellow triangles); C) Close-ups of the framestone showing the details of sphinctozoan chambers (yellow triangles) and exaulos tubes (Ex). Note that red triangles indicate isopachous cements in the chambers, while red triangles indicate a small cavity; D) Allonema (Al) encrusts skeletons of Corymbospongia (Co). Yellow triangles indicate the wall of a chamber. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.) Details of abiotic cements, taken under (A & C) stereomicroscope and (B & D) cathodoluminescence microscope. 1: isopachous cement, 2: the second generation of cement, 3: the third generation of cement, Mi: microbial fabrics. Yellow triangles show matched points between stereomicroscope and cathodoluminescence photos. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.) The principal types of reefs in Ordovician (A-C). Category C possesses a macroskeletal framework. In category B, the skeletal forms are locally juxtaposed. Category A is the microbial reefs; D-E) Microscopic textures of the reefs, showing the changes in early diagenesis from Early Ordovician to Mid-Late Ordovician reefs.
Contact: LIU Yun, Propagandist Email: yunliu@nigpas.ac.cn Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences Nanjing, Jiangsu 210008, China
Recently, Associate Research Professor ZHENG Quanfeng and Research Professor CAO Changqun from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), made high-resolution sedimentological and ichnological studies on the upper member of the Talung Formation at Shangsi, Guangyuan City, Sichuan Province, to reveal the dynamic process of turbidity current-induced benthic-marine oxygenation evidenced by sequential ichnocoenoses. Trace fossils are fossilized structures produced on or within a substrate by the life processes of ancient organisms, including tracks, trails, burrows, borings, and other structures (eg, root molds, egg fossils, coprolites, etc). Ichnocoenosis is a suite of trace fossils representing the work of a particular benthic community. An ichnocoenosis is a powerful tool for reconstructing sedimentary settings and retrieving palaeoenvironmental factors (eg, relative oxygen content, water depth, salinity, etc). However, it is a challenge to recognize and apply ichnocoenoses in the geological record for the sake of time-averaging by non-deposition or slow depositional rates and the destruction and elimination by deeper-tiered traces. Additionally, turbidity currents have proven to be an important mixing way for stratified waterbodies in modern oxygen-deficient basins. These density flows transport sediments and oxygen-rich waters from shallow-water environments to deep basins, which can considerably change the chemistry and oxygen content of the deep-basin waters. However, turbidity current-induced oxygenation events in oxygen-deficient basins have rarely been directly demonstrated in the geological record. As a common mechanism for the oxygenation of water bodies in oxygen-deficient basins, turbidity current has not received the necessary attention. Recently, Associate Research Professor ZHENG Quanfeng and Research Professor CAO Changqun from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), made high-resolution sedimentological and ichnological studies on the upper member of the Talung Formation at Shangsi, Guangyuan City, Sichuan Province, to reveal the dynamic process of turbidity current-induced benthic-marine oxygenation evidenced by sequential ichnocoenoses. This study was published on Geological Journal on July 11. The research team found that the studied interval consists mainly of background sedimentation of black shale and rapid event sedimentation of fine-grained calciturbidite. The black shale contains fine laminations and weak bioturbation and lacks primary burrows (burrows produced during the deposition of the black shale), indicating anoxic benthic marine conditions. The calciturbidite was intensely bioturbated, and contain abundant primary burrows. Based on cross-cutting relationships and burrow-fill features, three successive ichnocoenoses can be recognized in the typical calciturbidites: (1) the early-phase Thalassinoides/?Scolicia ichnocoenosis, including Thalassinoides/?Scolicia, Zoophycos, and Planolites, which has the largest maximum burrow diameter (MBD) and maximum penetration depth (MPD) and represents the highest oxygen level among the three ichnocoenoses; (2) the later-phase Planolites-Zoophycos ichnocoenosis, including Zoophycos, Planolites, large Chondrites, and small Chondrites, which has the moderate MBD and MPD and represents the moderate oxygen level; (3) the latest-phase Zoophycos ichnocoenosis, composed of monospecific Zoophycos burrows, which has the smallest MBD and MPD and represents the lowest oxygen level. The Thalassinoides/?Scolica ichnocoenosis was produced at the very end and immediately after the emplacement of the turbidites, representing the climax of the turbidity-induced oxygenation. The Planolites-Zoophycos ichnocoenosis was produced during a later stage after the emplacement of the turbidites, indicating a relatively more reducing bottom-water condition. The Zoophycos ichnocoenosis was produced during a further later but relatively long stage after the emplacement of the turbidites, indicating a much more reducing bottom-water condition. “This study demonstrated that turbidity current is an effective way to locally oxygenate bottom waters in oxygen-deficient basins which has significant impacts on benthic communities”, says ZHENG. This research was supported by the National Natural Science Foundation of China and the Chinese Academy of Sciences. Reference: Zheng, Q.F.*, Cao, C.Q., 2023. Dynamic process of turbidity current-induced benthic-marine oxygenation evidenced by sequential ichnocoenoses: An example from a Late Permian oxygen-deficient basin. Geological Journal, https://doi.org/10.1002/gj.4837. Fig. 1. Lithofacies (a), microfacies (b ~ f), and sedimentological logs (g) of the study interval. (Image by NIGPAS) Fig. 2. Vertically polished slab (a) and line drawing (b) of the studied interval. (Image by NIGPAS) Fig. 3. Schematic drawings showing the ichnocoenosis succession and the dynamic process of turbidity current-induced benthic-marine oxygenations during the deposition of the studied interval. (Image by NIGPAS)
Contact: LIU Yun, Propagandist Email: yunliu@nigpas.ac.cn Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences Nanjing, Jiangsu 210008, China
Recently, the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences (NIGPAS), collaborated with other scientists from USA and UK, discovered 16 new mermithids associated with their insect hosts from mid-Cretaceous Kachin amber (about 100 million years ago). This study reveals what appears to be a vanished history of nematodes that parasitized Cretaceous insects, and has been published on eLife on July 14, 2023. Nematodes (roundworms) are distributed worldwide in almost all habitats, however, nematodes are exceedingly rare in the fossil record, since most of them are small, with soft bodies and concealed habits. The Mermithidae represent a family of nematodes that are large compared with other nematodes, and they tend to exit their hosts even before maturation if their hosts are stressed. Thus, mermithid nematodes are most likely of all nematodes to occur as recognizable fossils. Recently, the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences (NIGPAS), collaborated with other scientists from USA and UK, discovered 16 new mermithids associated with their insect hosts from mid-Cretaceous Kachin amber (about 100 million years ago). This study reveals what appears to be a vanished history of nematodes that parasitized Cretaceous insects, and has been published on eLife on July 14, 2023. Nematodes play key roles in ecosystems by linking soil food webs and facilitating nutrient element cycling. Mermithid nematodes are obligate invertebrate parasites which occur in insects, millipedes, crustaceans, spiders, molluscs and earthworms. They can affect the morphology, physiology, and even the behaviour of their hosts. Hosts usually die when the mermithids exit, which is why mermithids have been considered as biological control agents, especially against mosquito larvae that transmit malaria. Mermithid nematodes, these fossils mainly discovered from Eocene Baltic amber (11 species) and Miocene Dominican amber (9 species), but only four pre-Cenozoic species have previously been recorded. Therefore, little is known about their early evolution of parasitism. LUO Cihang, a PhD canditate student, supervised by Prof. WANG Bo from NIGPAS, carried out a systematic study on the 16 new mermithids of the Kachin amber. In this study, sixteen new mermithids associated with their insect hosts were described, including 9 new species, which triples the diversity of Cretaceous Mermithidae (from 4 to 13 species). Meanwhile, according to new records of this study, nine insect orders are now known to have been infested by mermithid nematodes in Kachin amber and this number is even higher than that of Baltic amber and Dominican amber (six and three insect orders, respectively). This result suggests that mermithid parasitism of insects was actually widespread during the mid-Cretaceous, and probably already played an important role in regulating the population of insects in Cretaceous terrestrial ecosystems. At the same time, it was found that 12 of these 16 mermithids of the Kachin amber include previously unknown hosts. There are no previous extant or extinct records of nematodes attacking bristletails (Archaeognatha), but one is now discovered in this study. No barklice (Psocodea) are parasitized by mermithids today, but three different barklouse were found parasitizing by mermithids. Two members of the extinct planthopper family Perforissidae were also parasitized by mermithids, thus providing the oldest record of mermithid parasitism of planthoppers. Furthermore, this study provides the first fossil records of mermithids parasitizing dragonflies (Odonata), earwigs (Dermaptera), crickets (Orthoptera) and cockroaches (Blattodea), four host associations predicted from extant records but without fossil evidences. These fossils indicate that mermithid parasitism of invertebrates was already widespread and played an important role in the mid-Cretaceous terrestrial ecosystem. In addition, among the insect hosts of mermithids preserved in Kachin amber, only one of the nine orders (Diptera) is holometabolous (i.e., insects with “complete” metamorphosis), whilst it is four out of six (Hymenoptera, Trichoptera, Lepidoptera and Diptera) in Baltic amber and all three insect host orders (Hymenoptera, Coleoptera and Diptera) are holometabolous in Dominican amber. The situation is similar when referring to the amount of nematode parasitism after compiling nematode–host records in these three best-studied amber biotas. In Kachin amber, only about 40% of the hosts are holometabolous, while this percentage increases to 80% in Baltic and Dominican amber. Holometabola are the most important hosts of extant mermithids as well as all invertebrate-parasitizing nematodes and this hexapod subgroup dominated the insect fauna during the Cretaceous. This study indicates that nematodes had not completely exploited Holometabola as hosts in the mid-Cretaceous, and non-holometabolous insects (i.e., insects without “complete” metamorphosis) were more available as hosts in the mid-Cretaceous. The widespread association between nematodes and Holometabola might have formed later. Furthermore, our study shows that in contrast to their Cenozoic counterparts, Cretaceous nematodes including mermithids are more abundant in non-holometabolous insects. This result suggests that nematodes had not completely exploited the dominant Holometabola as their hosts until the Cenozoic. The high diversity of mermithid nematodes during the mid-Cretaceous as shown in this study provides a glimpse into the structure of ancient parasitic nematode–host associations and their evolution over the past 100 million years,” says LUO, “these discoveries bring new opportunities to study the evolution of parasitism through the medium of amber and provide the direct evidence to reconstruct Cretaceous terrestrial ecosystem.” A related Insight article written by Kenneth De Baets et al. has also been published, and they commented that this paper provided a good example to study the coevolution of nematodes and their invertebrate and helped scientists to better estimate the extinction risk of modern species. This research was supported by the National Natural Science Foundation of China, Chinese Academy of Sciences, and Ministry of Science and Technology of China. Reference: Luo Cihang, Poinar G.O., Xu Chunpeng, Zhuo De, Jarzembowski E.A., Wang Bo, 2023. Widespread mermithid nematode parasitism of Cretaceous insects. eLife 12, e86283. https://doi.org/10.7554/eLife.86283. The information of related Insight article: De Baets K., Vanadzina K., Schiffbauer J., 2023. Trapped in time. eLife 12, e90008. https://doi.org/10.7554/eLife.90008. Fig.1 Mermithids and their insect hosts from mid-Cretaceous Kachin amber (~99 Ma; million years ago) (Part I). Fig.2 Mermithids and their insect hosts from mid-Cretaceous Kachin amber (~99 Ma; million years ago) (Part II). Fig.3 The fossil record of Mermithidae plotted on the phylogenetic tree of insects. Fig.4 The occurrence frequency of invertebrate–nematode associations from mid-Cretaceous Kachin amber, Eocene Baltic amber and Miocene Dominican amber.
Contact: LIU Yun, Propagandist Email: yunliu@nigpas.ac.cn Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences Nanjing, Jiangsu 210008, China
Recently, Early Land Plants working group of Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), led by Research Professor XU Honghe, conducted a synthetic study on palynological flora from the Llandoverian Kalpintag Formation of the Tarim Basin, southern Xinjiang. The related research results were published online on the international interdisciplinary journal, Journal of Asian Earth Sciences. The Middle Ordovician-early Silurian is the key period for the origin and early evolution of morphological innovations of land plants. It is widely accepted that the earliest unambiguous fossil evidence of land plants can be traced to the Middle Ordovician Dapingian-Darriwilian stages (ca.468-463Ma), which is represented by dyads and tetrahedral tetrads from the Gondwana continent. In the Sheinwoodian (Wenlock, Silurian) rocks (ca.432Ma), the earliest sporophytes of land plants, e.g., Cooksonia barrandei typically seen in textbook, were found. Strata of the Middle Ordovician-early Silurian interval are target horizon for study on the origin of early land plants. However, the progress of related research is signally delayed for the lacking of terrestrial remains from the lower Paleozoic. Recently, Early Land Plants working group of Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), led by Research Professor XU Honghe, conducted a synthetic study on palynological flora from the Llandoverian Kalpintag Formation of the Tarim Basin, southern Xinjiang. The related research results were published online on the international interdisciplinary journal, Journal of Asian Earth Sciences. In this study, the land plant microfossils revealed from the Kalpintag Formation mainly consist of cryptospores, with only a few tubes and cuticle-like sheets, but no trilete spores have been observed. The Kalpintag cryptospore-producing plants largely inherited, with slight variation, from their predecessors of a Late Ordovician age. Different from the typical MCA assemblage of early Silurian sporomorphs in China, the Kalpintag cryptospores do not lack dyads, and instead they are dominated by Dyadospora and Pseudodyadospora. Thus, it can be considered that the dyad-producing plants were once the dominant among early non-vascular land plants in the Tarim paleoterrain. By taxonomic comparisons of global coeval sporomorph records, combined with quantitative analyses (Cluster Analysis and Nonmetric Multidimensional Scaling Analysis), the Kalpintag cryptospores show more closely related to those in northern Chad, northeastern Libya and central Saudi Arabia. XU says, “the geographical zonation of sporomorph might emerge in the Llandovery, during which the geographical proximity of the Tarim Plate to western Gondwana is suggested”. This study was supported by the National Key R&D Program of China; and Chinese Academy of Sciences. This work is a contribution to the Deep-time Digital Earth (DDE) Big Science Program. Reference: Wang K, Liu B-C, Wang Y, Xu H-H*. A palynoflora of southern Xinjiang, China, and the proximity of the Tarim Plate to western Gondwana during the Llandovery (Silurian). Journal of Asian Earth Sciences. 2023, 105769. https://doi.org/10.1016/j.jseaes.2023.105769. Fig.1. Cryptospores from the Llandoverian (early Silurian) Kalpintag Formation, southern Xinjiang (Scale bar is 10μm for all images) Fig.2. (1) The paleogeographical distribution of sporomorphs (cryptospores and trilete spores) during the early Silurian (Llandovery, ca 440 Ma). The paleogeographical reconstruction is modified from Torsvik (2019). (2) Cluster analysis at the genus level for the Llandovery sporomorphs. (3) Nonmetric multidimensional scaling analysis at the genus level for the Llandovery sporomorphs. (4) Cluster analysis at the species level for the Llandovery sporomorphs. (5) Nonmetric multidimensional scaling analysis at the species level for the Llandovery sporomorphs.
Contact: LIU Yun, Propagandist Email: yunliu@nigpas.ac.cn Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences Nanjing, Jiangsu 210008, China
Recently, leading by Research Prof. ZHAO Fangchen and PhD student SUN Zhixin from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), Prof. YANG Aihua from Nanjing University and other colleagues, discovered a new lower Cambrian trilobite assemblage from the Lake Zone. This diverse trilobite assemblage provides new insights into trilobite evolution and early Cambrian biogeographic affinity of the Lake Zone. The study was published in Journal of Paleontology. As an important part of the Central Asian Orogenic Belt, Mongolia has a complex geotectonic history. Unlike several cratonal block in central Mongolia, the Lake Zone in western Mongolia formed part of the magmatic-arc systems in the Cambrian period, characterized by the extensive distribution of subduction complexes and magmatic rock. This makes the biological features of the Lake Zone very important for understanding the evolution and paleogeography of the Palaeo-Asian Ocean in the Cambrian. However, no detailed study has been done in this remote area except a small amount of preliminary investigation of Cambrian fossils in the last century. Recently, leading by Research Prof. ZHAO Fangchen and PhD student SUN Zhixin from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), Prof. YANG Aihua from Nanjing University and other colleagues, discovered a new lower Cambrian trilobite assemblage from the Lake Zone. This diverse trilobite assemblage provides new insights into trilobite evolution and early Cambrian biogeographic affinity of the Lake Zone. The study was published in Journal of Paleontology. The new assemblage is exposed in the Seer section, on the eastern side of Khovd, western Mongolia. Trilobite fossils were collected from uppermost Burgasutay Formation and corresponding to the earliest Cambrian Stage 4. This assemblage is dominated by dorypygids and consists of 13 trilobite genera belonging to 9 families including Catinouyia heyunensis sp. nov. These fossils comprise the youngest and richest lower Cambrian trilobite assemblage in Mongolia. “The composition of the Lake Zone fauna suggests its biogeographic affinity with the Siberian Platform and Altay-Sayan Foldbelt, but the presence of inouyiids also implies a connection of this region with East Gondwana”, says SUN. This study was supported by the National Key Research and Development Program of China and the National Natural Science Foundation of China. Reference: Sun, Z., Yang, A., Zhao, F., Zhuravlev, A., Pan, B., Hu, C., Feng, Q., Chen, X., Zhu, M. (2023). New trilobite assemblage from the lower Cambrian (upper Stage 4) of the Lake Zone, western Mongolia. Journal of Paleontology, 1-14. https://doi.org/10.1017/jpa.2023.23. Figure 1. Location and geological setting of the Seer Ridge section and correlation of lower Cambrian sections in Mongolia. Figure 2. The most abundant trilobite in Lake Zone assemblage, Kootenia spp. Figure 3. Representative genus in the Lake Zone assemblage:1-3, Pagetides; 4, Eoptychoparia; 5, Amecephalus; 6, Chondragraulos; 7, Catinouyia.
Contact: LIU Yun, Propagandist Email: yunliu@nigpas.ac.cn Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences Nanjing, Jiangsu 210008, China
