In recent years, a research team led by Prof. WANG Yongdong from the Nanjing Institute of Geology and Paleontology of the Chinese Academy of Sciences, and Dr. Tian Ning, an associate professor from Shenyang Normal University, carried out a comprehensive study on the Mesozoic wood fossils containing fungal mycelia with some update discoveries. Recently, two new reports from this team have been published on the journals Cretaceous Research and Acta Geologica Sinica (Chinese Edition). Structurally preserved petrified woods contain not only information of wood anatomy, but also plenty of physiological and ecological information, including trace fossils of insect boring, fungal hyphae and other micro-organisms. Study of these permineralized plants is helpful to reveal the ecological and co-evolutionary relationships among plants, insects, fungi and other organisms in geological past. Abundant and diverse Cretaceous wood fossils have been recorded in China. However, previous studies of petrified wood mainly focused on their anatomy and taxonomy, little work has been reported on the fungal remains and the interaction between the wood hosts and fungi. In recent years, a research team led by Prof. WANG Yongdong from the Nanjing Institute of Geology and Paleontology of the Chinese Academy of Sciences, and Dr. Tian Ning, an associate professor from Shenyang Normal University, carried out a comprehensive study on the Mesozoic wood fossils containing fungal mycelia with some update discoveries. Recently, two new reports from this team have been published on the journals Cretaceous Research and Acta Geologica Sinica (Chinese Edition)(cover story). Well-preserved fossil mycelium consisting of clamp-bearing septate hyphae is found in a petrified conifer wood (Cupressinoxylon baomiqiaoense Zheng et Zhang) from the Lower Cretaceous Yunshan Formation in Heilongjiang Province, NE China. The fungal hyphae are tubular in shape with septa and typical clamp-connections. Taxonomically, the occurrence of clamp-connections indicates that the present fungal remains should be referred to the Basidiomycota. Ecologically, the present fossil mycelium is proposed to be a saprotroph, i.e. a wood rotting fungus. The decomposition of the tracheary middle lamina of the wood host strongly implies that the present fungal mycelium to be a white-rotting fungus. Additionally, similar basidiomyceous fossils with white rot function were found in fossil conifer wood of Agathoxylon sp. from the Lower Cretaceous Guantou Formation in Xinchang of Zhejiang Province, SE China. The present new finding of basidiomyceous fossils represents the first unequivocal records of Cretaceous wood-rotting fungi, provides increasing data on the fossil diversity of fungi in China, and contributes to further understanding the plant-fungal interaction in the Cretaceous terrestrial ecosystem. Reference: Tian Ning*, Wang Yongdong*, Zheng Shaolin, Zhu Zhipeng, 2019. White-rotting fungus with clamp-connections in a coniferous wood from the Cretaceous of Heilongjiang Province, NE China. Cretaceous Research, doi.org/10.1016/j.cretres.2018.11.011 (*authors for correspondence) Zhu Zhipeng, Li Fengshuo, Xie Aowei, Tian Ning, Wang Yongdong, 2018. New record of Early Cretaceous petrified wood with fungal infection in Xinchang of Zhejiang Province, Acta Geologica Sinica-Chinese Edition, 92: 1149-1162 (cover story). Fungal hyphae from the Early Cretaceous petrified wood in Heilongjiang Province, NE China (Image by TIAN Ning) Fungal hyphae from the Early Cretaceous petrified wood in Heilongjiang Province, NE China (Image by TIAN Ning) Fungal hyphae from the Early Cretaceous petrified wood in Zhejiang Province, SE China (Image by ZHU Zhipeng) Contact: Prof. WANG Yongdong, Principal Investigator Email: ydwang@nigpas.ac.cn Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences Nanjing, Jiangsu 210008, China
What exactly controlled the Cambrian Explosion has been a subject of scientific debate since Darwin’s time. Recently, a joint China-UK-Russia research team gives strong support to the hypothesis that the oxygen content of the atmosphere and ocean was the principal controlling factor in early animal evolution. Early Cambrian sections of the Lena River in Siberia (Image by ZHU Maoyan) The Cambrian Explosion around 540 million years ago was a key event in the evolutionary history of life. But what exactly controlled the Cambrian Explosion has been a subject of scientific debate since Darwin’s time. A multidisciplinary study, published on May 6 in Nature Geoscience by a joint China-UK-Russia research team, gives strong support to the hypothesis that the oxygen content of the atmosphere and ocean was the principal controlling factor in early animal evolution. In past decades, important fossil discoveries revealed a puzzling pattern of episodic radiations and extinctions in early animal evolution. This pattern coincides with dramatic fluctuations in the carbon isotopic composition of seawater, according to study co-author ZHU Maoyan from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences. Lower Cambrian strata along the Aldan and Lena rivers in Siberia consist of continuous sequences of limestone with abundant fossils and reliable age constraints, making these rocks ideal for analysing ancient seawater chemistry. The isotopic signatures of the rocks correlate with the global production of oxygen, allowing the team to determine oxygen levels in shallow sea water and the atmosphere during the Cambrian Period. The study is the first to show that the pattern of episodic radiations and extinctions in early animal evolution closely matches extreme changes in atmospheric and oceanic oxygen levels. This result strongly suggests that oxygen played a fundamental role in the Cambrian Explosion of animals. “The complex creatures that came about during the Cambrian Explosion were the precursors to many of the modern animals we see today. By analysing carbon and sulphur isotopes found in ancient rocks, we are able to trace oxygen variations in Earth’s atmosphere and shallow oceans during the Cambrian Explosion. We found that evolutionary radiations follow a pattern of ‘boom and bust’ in tandem with the oxygen levels,” said Dr. HE Tianchen, study lead author and postdoctoral researcher at the University of Leeds. According to Prof. Graham Shields, study co-author from UCL Earth Sciences, this is the first study to show clearly that our earliest animal ancestors experienced a series of evolutionary radiations and bottlenecks caused by extreme changes in atmospheric oxygen levels. The result was a veritable explosion of new animal forms during more than 13 million years of the Cambrian Period. Study co-author Dr. Benjamin Mills, from the School of Earth and Environment at Leeds, said, “The Siberian Platform gives us a unique window into early marine ecosystems. This area contains over half of all currently known fossilised diversity from the Cambrian Explosion.” “This has been an incredibly successful and exciting joint study. The question of the Cambrian Explosion trigger has puzzled scientists for years. Now, the results give us convincing evidence to link the rapid appearance of animals as well as mass extinction during the early Cambrian with oxygen,” said co-author Andrey Yu Zhuravlev from Lomonosov Moscow State University. Study co-author YANG Aihua from Nanjing University said, "In the last decade, progress has been made in the Cambrian Explosion; this study shows the interactions between the biodiversity of animal and environment during the early Cambrian." Contact CHEN Xiaozheng Nanjing Institute of Geology and Palaeontology E-mail: chxzh@nigpas.ac.cn DOI: https://doi.org/10.1038/s41561-019-0357-z
Prof. LI Chunxiang from Nanjing Institute of Geology and Palaeontology of Chinese Academy of Sciences and her colleagues analyzed the combined data of morphology and molecular data available to re-evaluate the systematic position of Coniopteris. The researchers therefore propose that Coniopteris may be more closely related with Polypodiales than with Dicksoniaceae, and Coniopteris is probably a stem group of Polypodiales. This interpretation is consistent with the vertical annuli of Coniopteris, an apparent synapomorphy of Polypodiales.It is generally recognized that the fossil records are incomplete in nature, yet fossils had very important impact on our development of evolutionary theory. The value of a particular fossil in contributing to our knowledge in evolutionary history for any lineage depends upon an adequate description of sufficient characters including synapomorphies, necessary for the accurate identification of its affinities or precise phylogenetic placement. Here is a case of such kind of study. The extinct fern genus Coniopteris was a typical component in the Mesozoic flora with a wide distribution in both Northern and Southern Hemispheres from Early Jurassic to Early Cretaceous, and it played a very important role in stratigraphic correlation, while its character evolution and systematic position have both been unsolved mysteries.Prof. LI Chunxiang from Nanjing Institute of Geology and Palaeontology of Chinese Academy of Sciences and her colleagues analyzed the combined data of morphology and molecular data available to re-evaluate the systematic position of Coniopteris.The study produced the results as: (1) all extant genera in Dicksoniaceae have bivalvate indusia, while most species of Coniopteris have cup-shaped indusia; (2) most Dicksoniaceae occur in the tropical zone, different from the temperate habitats for most Coniopteris species; (3) Coniopteris may be herbaceous, whereas extant Dicksoniaceae are mostly tree-like ferns; and (4) Dicksoniaceae and Thyrsopteridaceae all have oblique annuli, while most species of Coniopteris have vertical ones.Based on these differences, Coniopteris should not be treated in Dicksoniaceae. Its systematic position was further evaluated by a cladistic analysis using morphological characters of spore-producing organs and spores and integrated with studies of fern molecular phylogeny as a constraint (molecular backbone). The results show that Coniopteris is clustered with Dennstaedtia, Lindsaea, and Odontosoria, not with Calochlaena, Dicksonia, and Lophosoria in Dicksoniaceae.The researchers therefore propose that Coniopteris may be more closely related with Polypodiales than with Dicksoniaceae, and Coniopteris is probably a stem group of Polypodiales. This interpretation is consistent with the vertical annuli of Coniopteris, an apparent synapomorphy of Polypodiales.The research was supported by Project from Shanghai Landscaping & City Appearance Administrative Bureau (Grant No. G162422), Projects of State Key Laboratory of Palaeobiology and Stratigraphy (Nanjing Institute of geology and Palaeontology, CAS) (Grant No. Y626040108), and Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDB26000000). Reference: Chunxiang Li, Xinyuan Miao, Li-Bing Zhang, Junye Ma, Jiasheng Hao (2019). Re-evaluation of the systematic position of the Jurassic–Early Cretaceous fern genus Coniopteris. https://doi.org/10.1016/j.cretres.2019.04.007 Sori of Coniopteris (G) and related species of Dennstaedtia (A-D) and Calochlaena straminea (F). Image by LI Chunxiang.. Majority-rule consensus tree of Coniopteris and its related extant groups corresponding to cladistic analysis based on reproductive structure characters and a molecular phylogenetic tree for the extant taxa as constraints. Sporangia types among the main clades are indicated on the right side of the tree (note: annuli are in illustrated). Image plotted by LI Chunxiang. Contact: Prof. LI Chunxiang, Principal Investigator Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences Nanjing, Jiangsu 210008, China
Abundant Triassic radiolarian fossils were obtained from varicolored bedded cherts exposed in the Buruocang section near Jinlu village, Zedong, southern Tibet. The radiolarian‐bearing rocks represent fragmented remnants of the Neotethys oceanic sediments belonging to the mélange complex of the east part of the Yarlung‐Tsangpo Suture Zone. Two new middle Late Anisian radiolarian assemblages recognized from this section named Oertlispongus inaequispinosus and Triassocampe deweveri, respectively, are compared with those known from Europe, Far East Russia, Japan, and Turkey. These Anisian radiolarian fossils are the first reported in southern Tibet and the oldest radiolarian record within the Yarlung‐Tsangpo Suture Zone. They improve time constraints for the evolution of Neotethys in southern Tibet. In recent years, abundant Triassic-Cretaceous radiolarian fossils have been collected within the Yarlung Zangbo Suture Zone (YTSZ) in Zedong area of southern Tibet by the research group of Prof. LUO Hui from the Nanjing Institute of Geology and Paleontology of the Chinese Academy of Sciences. PhD candidate CHEN Dishu and others from Prof. Luo’s research group, in cooperation with Prof. Atsushi Matsuoka of Niigata University in Japan, documented an Anisian radiolarian fuana obtained from varicolored bedded cherts exposed in the Buruocang section near Jinlu village in Zedong recently. The radiolarian-bearing rocks represent fragmented remnants of the Neotethys oceanic sediments belonging to the mélange complex of the east part of the Yarlung-Tsangpo Suture Zone. Two new middle Late Anisian radiolarian assemblages recognized from this section named Oertlispongus inaequispinosus and Triassocampe deweveri, respectively, are compared with those known from Europe, Far East Russia, Japan, and Turkey. These Anisian radiolarian fossils are the first reported in southern Tibet and the oldest radiolarian record within the Yarlung-Tsangpo Suture Zone so far. They provide a valuable new age constraint and allow the researchers to infer the timing of the early stage of the Neotethyan evolution in southern Tibet. At least in the Anisian, the eastern YTSZ had a pelagic sedimentary environment. This research was supported by the Strategic Priority Research Program (B) of the Chinese Academy of Sciences, National Natural Science Foundation of China and also in part by the Japan Society for the Promotion of Science KAKENHI. Reference: Chen D, Luo H, Wang X, Xu B, Matsuoka A. Late Anisian radiolarian assemblages from the Yarlung-Tsangpo Suture Zone in the Jinlu area, Zedong, southern Tibet: Implications for the evolution of Neotethys. Island Arc. 2019: 1–10. https://doi.org/10.1111/iar.12302 Outcrop photographs of Buruocang section of the bedded cherts, in Zedong , southern Tibet, Image by CHEN Dishu. Correlation of Triassic radiolarian zones and subzones, Image plotted by CHEN Dishu. Late Anisian radiolarians from Sample 14BRC-11 at the Buruocang section, Image by CHEN Dishu. Contact: Prof. LUO Hui PhD Corresponding author Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences Nanjing, Jiangsu 210008, China
Recently, the famous international geological journal Palaeogeography, Palaeoclimatology, Palaeoecology (commonly referred to as "Palaeo 3") published a new special issue on the topic of Mesozoic and Cenozoic evolution of eastern Tethys co-edited by Prof Li Jianguo and Prof. Sha Jingeng in the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, and their international cooperation team (volume 515, 2019). Since the 1960s when the theory of plate tectonics became established, the Tethys region has attracted the attention of many geologists because it has experienced a complex evolution involving numerous continental fragments drifting in several stages from the Gondwanan margin in the Southern Hemisphere northward to amalgamate with Eurasia in the Northern Hemisphere. This process and the subsequent orogenies caused great changes to the regional or even global topography and environments, which researchers now realize had important impact on climate and biotas. The vast literature on the evolution of the Tethys Ocean highlights several critical scientific issues that require further investigation. These include especially: (1) what was the extent of the Tethys and its surrounding landmasses at the time that Pangea began to break up?; (2) when and how did the Cimmeride terranes rift from Gondwana and collide with proto-Eurasia?; (3) what was the motion history of the Indian plate during its northward journey, and when and where did it collide with Eurasia?; (4) when did the Neo-Tethys come into being and subsequently close up?; (5) what was the driving force behind continental fragmentation that gave rise to the Neo-Tethys?; (6) what processes were involved in the uplift of the Qinghai-Xizang Plateau, and what was the chronology of uplift events?; (7) what were the impacts of these events on Earth’s climate and biotas? (Fig. 1). The answers to each question in above are complex and require a large number of facts or data from multiple regions and disciplines. So far, the data and findings revealed and accumulated by scientists are still very scarce, restricting our progress in the study of Tethys tectonics and biological evolution. The newly published special issue reports the latest research results of scientists from multiple countries in magmatic petrology, geochemistry, palaeontology and sedimentology from the eastern Tethys. A total of 13 research papers and one reviewing paper as preface are contained. These papers cover a multitude of issues relating to the evolution of the Tethys, such as the timing of initiation of the Neo-Tethys, the properties of the Bangong-Nujiang Tethys, the rifting process of the Indian plate, palaeoenvironmental events during Tethyan evolution, the impact on terrestrial ecosystems of closure of the Tethys and uplift of the Qinghai-Xizang Plateau. These advances provide insights into and will stimulate further research on the evolution of the eastern Tethys. This SI is a joint product of years of collaboration and efforts by scientists from various countries and is supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB03010103, XDB26000000 and XDA20070202), the National Natural Science Foundation of China (41872004), and UNESCO -IUGS project IGCP 632. Special issue information: Li, Jianguo, Sha, Jingeng, McLoughlin, Stephen, Wang, Xiaoming, eds., 2019. Palaeogeographic, palaeoclimatic and palaeoecologic evolution of eastern Tethys during the Mesozoic and Cenozoic. Palaeogeography, Palaeoclimatology, Palaeoecology 515. A summary of key events in the evolution of Tethys as studied by previous researchers and authors in this issue
Our understanding of the early evolutionary history of sponges is largely impeded by the scarcity of early sponge fossil record, In spite of the purported sponge fossil from the Ediacaran Weng’an Biota, the earliest sponge spicules were found in the Protohertzina anabarica zone of about 535 Ma old. However, the taxonomically informative sponge fossils, which should preserve articulated skeletal frames, were only known from the shale Lagerstatten started from the terminal Cambrian Stage 2. Examples include the black shale of the Niutitang and Hetang Formations, the Chengjiang Biota, the Sirius Passet Biota, the Kaili Biota, the Burgess Shale, etc..A recent study of Dr. LUO Cui from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences and Prof. Dr. Joachim REITNER from the University of Goettingen, published online on Feb 28, 2019 in PalZ, revealed in situ, three-dimensionally preserved sponge fossils from the Terreneuvian phosphorites from Hunan, China.These phosphorites underlying the Ni-Mo layer of the Niutitang Formation is inferred to be no younger than the Cambrian Age 2 based on the previous radiometric dating and biostratigraphic studies of correlative strata. In situ preserved sponge fossils are distributed as nodular bodies in the authigenic carbonaceous cherty phosphorites which exhibit laminated and clotted cryptocrystalline fabrics. Some of the fossils are completely embedded in the honey-colored cryptocrystalline phosphates, while most of them are preserved in the way that the spicules are immediately encrusted by isopachous cryptocrystalline phosphate, with the remaining interspace filled by later phosphate or siliceous cements, and/or pyrobitumen.The morphology of two fossils was described as examples:One of them, preserved in the former state mentioned above, is thick-walled, consisting of similar triaxons of three different size hierarchies. The small spicules in the 2nd and 3rd hierarchies are randomly distributed. The other one, preserved in the latter state mentioned above, was investigated using grinding tomography to reconstruct its 3D architecture in a 6mm×5mm×1mm space. This fossil is mainly composed of pentactins, few hexactins, diactins, and other forms. Some pentactins are distributed with the paratangential rays more or less parallel to the surface of the nodular body, a way similar to hypodermalia.Other spicules are generally irregularly arranged, but sometimes also exhibit a perpendicular arrangement with respect to contacting spicules and to other spicules in the 3D space. These morphological types were previously unknown from the lower-middle Cambrian shale Lagerstatten, although they appear to be in accordance with the hexactinellid stem groups hypothesized by some researchers (e.g. Mehl, 1996; Dohrmann et al., 2008).In addition, various forms of disarticulated sponge spicules were also observed in these lower Cambrian phosphorites, some of which showing demosponge-specific features or combined features of hexactinellids and demosponges, indicating still unexplored sponge biodiversity in this particular age and taphonomic window.This study was financially supported by the National Natural Science Foundation of China, the Chinese Academy of Sciences, the CAS Key Laboratory of Economic Stratigraphy and Palaeogeography (NIGPAS), and the German Excellence Initiative (Goettingen Courant Center).Reference: Luo, Cui, and Joachim Reitner*. 2019. Three-dimensionally preserved stem-group hexactinellid sponge fossils from lower Cambrian (Stage 2) phosphorites of China. PalZ. doi:10.1007/s12542-018-00441-y. Petrology of the nodular phosphorites and the preservation of sponge fossils. Projection of the 3D architecture of the spicules in a nodular body in a 2D surface.
Recent advances in Devonian palaeoecosystems and palaeoenvironments of South China have been published in a special issue of “Palaeobiodiversity and Palaeoenivronments”. The eight contributions in this volume cover different fossil groups, including tentaculitids, brachiopods, conodonts, tabulate corals, ostracods, and ammonoids, meant to advance the understanding of Devonian palaeoecosystems and palaeoenvironments of South China, with a special emphasis on interplay between different fossil groups and environments during this critical period of Earth history.The issue was co-edited by Drs. Wenkun Qie and Kun Liang from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences and Dr. Peter Konigshof from the Senckenberg Forschungsinstitut und Naturmuseum Frankfurt.The Devonian (419.2–358.9 Ma) was a critical period for the evolution of life in both terrestrial and marine ecosystems. It witnessed the appearances of first forest and amphibian on land, the largest metazoan reef ecosystem in Earth history, and two greatest biocrisises of the Phanerozoic (the Frasnian-Famennian and Hangenberg mass extinctions).The colonization of land by vascular plants caused major changes with respect to processes in the geo-, hydro-, and atmosphere. Continental weathering became strongly influenced by chemical processes, and thereby causing changes in riverine nutrient flux, and atmosphere CO2 concentration dropped abruptly to near modern level, all of which exert major impacts on the marine ecosystem. As many as global events, characterized by eustatic sea-level changes, anoxic/hypoxic events, and/or biological extinction/turnovers took place during the Devonian, demonstrating complex interactions between the Earth’s biotic, climatic, and environmental systems. Understanding the different fossil groups and the evolution of Devonian marine ecosystem at global or regional scale would help to gain important insights for the interplay between life and environment in deep time. South China is the most important area for the study of the Devonian system in China, where all the stratotype sections for the Chinese regional stages were established in shallow water facies of this region. Following the Kwangsian Orogeny, a transgression occurred in central Guangxi during the Lochkovian, and each sequences in South China starts with some siliciclastic sediment overlying a discontinuity surface. With intensified rifting, major differentiation of lithofacies and biofacies took place in the Emsian and Givetian stages, and the deposition of extensive carbonate platform was separated by deep-water interplatform basins. As a result, there are numerous well-preserved Devonian stratigraphic successions recording a variety of lithofacies and biofacies in South China, providing excellent materials to investigate the biotic and environmental events and their possible causes and effects.This special issue includes 1 editorial and 8 scientific papers, details are as following:1. Qie, W. K., Liang, K., Konigshof, P. 2019. Devonian palaeoecosystems and palaeoenvironments of South China. Palaeobiodiversity and Palaeoenvironments. 99:1–5.2. Wei, F., Zong, R. & Gong, Y.M. (2019). Tentaculitids and their evolutionary significance in the Early Devonian Dashatian section, South China. Palaeobiodiversity and Palaeoenvironments, 99(1).3. Guo, W., Nie, T., & Sun, Y.L. (2019). New data on biostratigraphy of the lower Devonian “Spirifer” tonkinensis Brachiopod fauna in South China and adjacent region. Palaeobiodiversity and Palaeoenvironments, 99(1).4. Lu, J.F., Valenzuela-Ríos, J.I., Wang, C., Liao, J.-C. & Wang, Y. (2019). Emsian (Lower Devonian) conodonts from the Lufengshan section (Guangxi, South China). Palaeobiodiversity and Palaeoenvironments, 99(1). https://doi.org/10.1007/s12549-018-0325-4 5. Zhang, M. & Ma, X. (2019). Origination and diversification of Devonian ambocoelioid brachiopods in South China. Palaeobiodiversity and Palaeoenvironments. Palaeobiodiversity and Palaeoenvironments, 99(1). https://doi.org/10.1007/s12549-018-0333-4 6. Qiao, L. & Qie, W.K. (2019). Palaeobiogeographic dynamics of brachiopod faunas during the Frasnian-Famennian biotic crisis in South China. Palaeobiodiversity and Palaeoenvironments, 99(1). https://doi.org/10.1007/s12549-018-0336-17. Liang, K., Qie, W., Pan, L. & Yin, B. (2019). Morphometrics and palaeoecology of syringoporoid tabulate corals from the upper Famennian (Devonian) Etoucun Formation, Huilong, South China. Palaeobiodiversity and Palaeoenvironments, 99(1). https://doi.org/10.1007/s12549-018-0363-y8. Song, J.J. & Gong, Y.M. (2019). Ostracods from the Devonian-Carboniferous transition in Dushan of Guizhou, South China. Palaeobiodiversity and Palaeoenvironments, 99(1). https://doi.org/10.1007/s12549-018-0322-79. Zhang, M., Becker, R.T., Ma, X., Zhang, Y. & Zong, P. (2019). Hangenberg Black Shale with cymaclymeniid ammonoids in the terminal Devonian of South China. Palaeobiodiversity and Palaeoenvironments. Palaeobiodiversity and Palaeoenvironments, 99(1). https://doi.org/10.1007/s12549-018-0348-xThis special issue is partly supported by the Strategic Priority Research Program (B) of Chinese Academy of Sciences (XDB26000000) and NSFC grant (41772004).
The end-Ordovician mass extinction (EOME) was the first of the “Big Five” extinctions of the Phanerozoic. It is widely interpreted as consisting of two pulses associated with the onset and demise of the Gondwana glaciation, respectively, with the second pulse eradicating the distinctive, glacially related Hirnantian benthic biota (HBB). This two-pulse model has become a widely accepted paradigm within which tempo, magnitude, pattern and dynamics of the EOME and the subsequent recovery have been variously interpreted.Recent investigations in South China, however, indicate an erroneous temporal and causal link between the “HBB” and the Gondwanan glaciation, which, if confirmed globally, will hence underpin a critical reevaluation of the tempo and nature of the EOME.To further elucidate this key issue, Dr. WANG Guangxu from the Nanjing Institute of Geology and Palaeontology of Chinese Academy of Sciences and his colleagues made a global review of occurrence data of latest Ordovician benthic marine organisms, which reveals that virtually all warm-water benthic assemblages previously assigned to the HBB comprise two distinct and clearly postglacial faunas, both younger (middle and late Hirnantian, respectively) than the cool-water Hirnantia fauna (latest Katian to early Hirnantian).The newly recognised three Transitional Benthic Faunas (i.e., TBFs 1–3) can be closely tied to graptolite, conodont, and chitinozoan biozonations, the Hirnantian Isotope Carbon Excursion (HICE), and the glaciation, thereby providing an integrated, much higher resolution timescale for understanding the tempo and nature of the EOME.At such a finer resolution, these authors also postulate a more profound impact of the first pulse of the EOME than hitherto envisaged, as evidenced by opportunistic expansion of the Hirnantia fauna globally and the complete absence of metazoan reefs in its immediate aftermath. They also argue, based on high-quality data from well-documented benthic groups in South China (i.e., brachiopods, tabulate and rugose corals, trilobites, and sponges), that the magnitude of the second pulse of the EOME caused by the deglaciation has been overestimated because the two postglacial faunas (i.e., TBFs 2–3) were part of a subsequent recovery phase of marine ecosystems rather than contributing to biodiversity decline. Thus, they reinterpret the EOME as a single-pulse, rapid event that was followed by a prolonged initial recovery intermittently impeded by climatic shocks through the Hirnantian, prior to the onset of a progressive reestablishment of marine ecosystems during the early Silurian (Rhuddanian and Aeronian) associated with an overall amelioration of climatic conditions.Reference: Wang, G.X., Zhan, R.B. and Percival, I.G., 2019. The end-Ordovician mass extinction: A single-pulse event? Earth-Science Reviews, 192: 15–33. Models of latitudinal patterns of TBFs 1–3 through the Hirnantian. A refined integrated Hirnantian stratigraphic framework, against which biotic and environmental changes across the EOME are also shown.
During the Ordovician, most Chinese continental blocks were located near the tropical area around the Gondwanan supercontinent, containing South and North China, Tarim, Himalaya, Lhasa and Sibumasu (Baoshan). Their paleogeographic locations and movements have always been research hotspots. Recently, Dr. FANG Xiang and Prof. ZHANG Yuandong from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, and Prof. Clive Burrett from Mahasarakham University, Thailand, conducted a quantitative statistical analysis of Middle to Late Ordovician cephalopods from the northeastern peri-Gondwana region, in order to reconstruct palaeobiogeographic distributions and their dynamic variation which indicate palaeoplate movements during the Middle to Late Ordovician Cephalopods have a very strong swimming ability. But because of the septal strength index, cephalopods would implode if they got deeper than their limited depth. Based on studies on living Nautilus, cephalopods need to rest on the sea floor after swimming for a long time. We can use this to assess the palaeogeographic provincialism of cephalopods and then speculate on the relative dynamic locations of Gondwana and the Asian blocks. In this study, based on published literature and the latest palaeontological researches on South China, several statistical methods, including cluster analysis, nonmetric multidimensional scaling and network analysis, of Middle to Late Ordovician cephalopod occurrences in the northeastern peri-Gondwanan region were conducted. For the Middle Ordovician, three biogeographic provinces may be recognized in the northeastern peri-Gondwana region: the Australia, the North China–Tibet–Sibumasu (NTS), and the South China–Altun (SA) provinces. However, this biogeographic pattern changed significantly in the Late Ordovician, when the cephalopods in the Tibetan and Sibumasu terranes changed markedly to show greater similarity to South China, and form the South China–Tarim–Tibet–Sibumasu (STTS) Province. The study shows that different composition of these two provinces and different types of cephalopods indicating that during the Middle Ordovician, the NTS province should be located in the tropical zones, and SA province in a slightly higher latitude region. During the Late Ordovician, South China was drifting slowly northwards, closer to Australia, meanwhile North China was drifting gradually away from northeastern peri-Gondwana. This dynamic variation of cephalopod provincialism for Middle and Late Ordovician cephalopods was related to alterations of palaeolatitude and the changing locations of the palaeoplates during the Middle and Late Ordovician. This study was financially supported by the National Natural Science Foundation of China, Ministry of Science and Technology of China and Chinese Academy of Sciences. This study is a contribution to IGCP projects 653 and 668. Reference: Xiang Fang*, Clive Burrett, Wenjie Li, Yunbai Zhang, Yuandong Zhang, Tingen Chen, Xuejin Wu, Dynamic variation of Middle to Late Ordovician cephalopod provincialism in the northeastern peri-Gondwana region and its implications. Palaeogeography, Palaeoclimatology, Palaeoecology, 521: 127-137. https://doi.org/10.1016/j.palaeo.2019.02.015 Cluster analysis (upper left), nonmetric multidimensional scaling (lower left) and network analysis (right) recognize the palaeobiogeographic provinces in Middle and Late Ordovician Published typical cephalopods from NTS Province in the Middle Ordovician (left) and published typical cephalopods from STTS Province in the Late Ordovician (right)
Recently, an international team led by Prof. ZHOU Chuanming from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences reported two new high-precision U-Pb zircon dating data from two layers above the Cryogenian Sturtian and Marinoan in South China, which provides evidence for the globally synchronous and rapid termination of Cryogenian glaciations. The result and related analysis were published in Geology.Cryogenian Sturtian and Marinoan glaciations represent the most severe paleoclimatic events in Earth history. The global distribution of presumably synchronous Cryogenian glacial deposits is one of the key observations that stimulated the initial formulation of the Snowball Earth Hypothesis or SEH. The formalization of the SEH leads to explicit predictions about the global synchroneity and duration of Cryogenian Snowball Earth glaciations. Specifically, the SEH predicts a globally synchronous and rapid termination of Cryogenian glaciations on the time scale of 103–104 years.Wherever the deglaciation began is difficult to define in the sedimentary record, the sharp transition from glacial diamictite to postglacial cap dolostone, which represents a landmark event during deglaciation, can be used to demarcate the final stage of deglaciation. A direct test of rapid and globally synchronous deglaciation requires high-resolution (better than ± 1.0 Ma) geochronological data to tightly bracket the transition from diamictite to cap dolostone in multiple paleocontinents or basins.Currently available geochronological data are consistent with the occurrence of two global glaciations in the Cryogenian Period (~ 720？635 Ma), i.e., the Sturtian and Marinoan glaciations. However, high-precision radiometric dates are few and do not have a sufficient paleogeographic and stratigraphic coverage to allow a positive test of global synchroneity and rapidity as predicted by the SEH. For example, on the basis of currently available data, the Marinoan deglaciation in Australia, Namibia, and South China are constrained to be <636.41 ± 0.45 Ma, <635.21 ± 0.59 Ma, and between 636.3 ± 4.9 Ma and 635.23 ± 0.57 Ma, respectively. These ages, while consistent with global synchroneity, are not sufficient to determine synchronous deglaciation among these three paleocontinents. Thus, to positively determine global synchroneity and rapidity of Cryogenian deglaciation events, we need more high-precision radiometric dates from glaciogenic diamictite and postglacial cap dolostone to tightly bracket the final deglaciation on each paleocontinent. To this end, Prof. ZHOU Chuanming and colleagues from the University of California at Davis and Virginia Tech, reported two new high-precision U-Pb zircon CA-ID-TIMS of 658.80 ± 0.50 Ma and 634.57 ± 0.88 Ma from tuffaceous layers that occur, respectively, within the cap dolostone atop the Tiesi’ao diamictite (Sturtian age) and at the topmost Nantuo diamictite (Marinoan age) in South China. The 658.80 ± 0.50 Ma age represents a high-precision minimum age constraint on the termination of the Sturtian-age glaciation. The 634.57 ± 0.88 Ma age and a previously published age of 635.23 ± 0.57 Ma from the topmost cap dolostone are indistinguishable within uncertainty, and together they provide tight constraints on the termination of the Marinoan glaciation in South China at ca. 635 Ma and directly bracket the duration of the cap dolostone to be <106 yrs. The new data support the rapid termination of the Marinoan glaciation in South China and are consistent with global synchroneity of Cryogenian deglaciation events. To positively test whether the same is true on other continents and for the Sturtian deglaciation requires additional high-resolution ages on each paleocontinent.Reference: Chuanming Zhou, M. H. Huyskens, Xianguo Lang, Shuhai Xiao, Qing-Zhu Yin, 2019. Calibrating the terminations of Cryogenian global glaciations. Geology, 47: 251-254. https:// doi .org /10 .1130 /G45719.1 206Pb/238U ages of individual zircons for samples 17LSJ-17 and ES-1 Compilations of radiometric ages and their relationship with the supposed Sturtian and Marinoan glaciations on different continents.
