The end-Permian mass extinction is the greatest life crisis during the Phanerozoic, which eliminated more than 90% species in the marine realm, resulting in widespread development of microbialites for the dramatical decrease of grazing pressure and bioturbation. Common occurrence of microbialites is the feature of the Precambrian strata, so the widespread microbialites near the Permian-Triassic boundary is regarded as an anachronistic facies, which indicates a primitive ecosystem similar to that of the Precambrian after the end-Permian mass extinction. The end-Permian mass extinction is the greatest life crisis during the Phanerozoic, which eliminated more than 90% species in the marine realm, resulting in widespread development of microbialites for the dramatical decrease of grazing pressure and bioturbation. Common occurrence of microbialites is the feature of the Precambrian strata, so the widespread microbialites near the Permian-Triassic boundary is regarded as an anachronistic facies, which indicates a primitive ecosystem similar to that of the Precambrian after the end-Permian mass extinction. Although lots of studies have been performed on the Permian-Triassic boundary microbialites (PTBMs), these works mainly focused on stratigraphy, morphology, structures and macro-/microfossils of the PTBMs. We still know little about the microbes constructing the PTBMs, because on the one hand microbes can hardly be mineralized to fossils, and on the other hand the PTBMs were commonly undergone intense diagenesis, making the preservation and identification of microbe fossils more difficult. Recently, Dr. ZHENG Quanfeng, Prof. LI Yue and ZHANG Hua from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, collaborating with researchers from South China Sea Institute of Oceanology of Chinese Academy of Sciences and Nanjing University, made a comprehensive study on the PTBMs from 8 localities in South China. The research results have been published in the international journals Palaeogeography Palaeoclimatology Palaeoecology. Their study found that a specific type of microbe fossils with high abundance and low diversity commonly occurred in the PTBMs of South China. This microbe fossil comprises a laminated stalk and an endpoint spheroid. The spheroid is about 20-40 μm across, composed of micritic magnesian calcite/dolomite wall and calcite spar infillings. The laminated stalk, generally several to hundreds of microns, consists mainly of multiple “stacked-cup” laminae of micron-sized magnesian calcites/dolomites. Calcite microspars and spars can fill the inter-laminae spaces. This microbe fossil is very similar to the Precambrian benthic cyanobacteria fossil Polybessurus bipartitus in morphology. And a modern morphological counterpart, which is also a cyanobacterial benthos, is living in coastal Bahamian environments. So we tentatively named this microbe fossil as Polybessurus-like, and interpreted it as the calcified remains of a benthic unicellular coccoid cyanobacteria and its extracellular polymeric substances (EPS). These coccoid cyanobacteria secreted EPS unidirectionally to form laminated stalks, through which they can not only attach to the substrate in the coastal shallow marine, but also lift themselves upward, both of which can make these cyanobacteria get more sunlight for photosynthysis. Polybessurus-like fossils are the key contributors to the PTBMs. With different growth patterns of Polybessurus-like fossils, different morphotype PTBMs formed, including stromatolites, thrombolites and dentrolites. This study revealed the main microbe contributors to the PTBMs of South China, as well as formation mechanisms of different morphotype PTBMs. The results also present us a picture of the microbial biota in the coastal marine environments on carbonate platforms near the equator during the Permian-Triassic interval, which has great significance to our knowledge about the marine ecosystem after the end-Permian mass extinction. This work was supported by the Key Research Program of Frontier Sciences of the Chinese Academy of Sciences, the Strategic Priority Research Program of Chinese Academy of Sciences and the National Natural Science Foundation of China. Reference: Zhang, X.Y., Zheng, Q.F.*, Li, Y., Yang, H.Q.*, Zhang, H., Wang, W.Q., Shen, S.Z., 2020. Polybessurus-like fossils as key contributors to Permian-Triassic boundary microbialites in South China. Palaeogeography, Palaeoclimatology, Palaeoecology, 552: https://doi.org/10.1016/j.palaeo.2020.109770. Lithological columns of the studied sections Outcrop photos of the studied Permian–Triassic boundary sections Polished slabs of microbe-bearing microbialites in the studied sections Microphotographs and line drawings of microbe fossils in the PTBMs of the South China SEM photos of microfossils in the PTBMs of the South China SEM images and EDS analysis results of microbe fossils in the PTBMs of South China
As one of the five major extinction events in Earth history, the Frasnian-Famennian boundary (FFB) crisis caused dramatic reductions in marine and terrestrial diversity. The effects of this event on terrestrial ecosystems are not well understood due to the limited preservation of terrestrial sedimentary rocks and the relative scarcity of plant fossils. Besides, the stratigraphic position of the FFB remains tentative. As one of the five major extinction events in Earth history, the Frasnian-Famennian boundary (FFB) crisis caused dramatic reductions in marine and terrestrial diversity. The effects of this event on terrestrial ecosystems are not well understood due to the limited preservation of terrestrial sedimentary rocks and the relative scarcity of plant fossils. Besides, the stratigraphic position of the FFB remains tentative. In the past years, and Prof. XU Honghe, the group members of from the ‘Modern terrestrial ecosystem origin and early evolution’ of Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, and Dr. ZHENG Daran from The University of Hong Kong, has made detailed investigations for several Devonian terrestrial outcrops in West Junggar, northwestern China. Related results were published online in the international geoscience journal Palaeogeography, Palaeoclimatology, Palaeoecology. They provide a robust zircon U-Pb age (371.5 ± 0.9 Ma; earliest Famennian) for a new fossil assemblage containing Lycopsida, Archaeopteridales, and Cladoxylopsida from the upper Zhulumute Formation of the West Junggar Basin, NW China. These taxa are typical arborescent plants of the Late Devonian and represent the oldest-known forest in China, documenting afforestation in West Junggar coevally with or just after the Upper Kellwasser event (~372 Ma). The new U-Pb ages generated in this study refine the placement of the FFB in West Junggar to within the Zhulumute Formation, instead of the Hongguleleng Formation as previously thought. In the study area, the Upper Devonian Zhulumute Formation contains at least three types of potentially forest-forming plants: the arborescent lycopsid L. rhombicum, the archaeopteridalean progymnosperms C. trifilievii and C. newberryi, and the cladoxylopsid X. lignescens. Although the floral assemblages of the lower Famennian Zhulumute Formation do not represent in-situ growth, the presence of abundant arborescent taxa is inferred to represent the earliest known forest in the West Junggar region. These fossil assemblages show the same taxonomic composition as those confidently ascribed to Late Devonian forest ecosystems elsewhere globally. It is significant that the early Frasnian Hujiersite and early Famennian Zhulumute floras contain no duplicate members. The elevation differences probably cause the different components of two floras. The present radiometric results constrain this floral transition to a ~9 to 11-Myr window between the Hujiersite Flora (maximum depositional ages 382.4 ± 1.0 Ma to 380.4 ± 1.1 Ma and the Zhulumute Flora (maximum depositional age 371.5 ± 0.9 Ma). Thus, our results are permissive of the possibility that this transition, although not tightly age-constrained, coincided with the Upper Kellwasser Event (~372-374 Ma). In West Junggar, the stratigraphic position of the FFB remains tentative. The FFB was controversially interpreted to occur in the lower part of the marine Hongguleleng Formation. Numerous studies have debated the age of the Hongguleleng Formation. Its conodont biostratigraphy has been interpreted as Famennian, late Frasnian–Famennian, or Famennnian–Tournaisian in age. At Bulongguoer, the FFB was placed 2.7 m above the base of the marine Hongguleleng Formation, but not without controversy. At Saerba, the 371.5 U-Pb ages of the present study favor FFB placement within the Zhulumute Formation. Strata of the upper Zhulumute Formation at Bulongguoer and Saerba are considered to be correlative based on similar lithologies and finds of Leptophloeum rhombicum and Callixylon newberryi. This interpretation differs from long-held interpretations regarding placement of the FFB in NW China. Specifically, our age data indicate that the FFB is present in the terrestrial Zhulumute Formation and not within the marine Hongguleleng Formation. Together with paleontological evidence, this new chronostratigraphic constraint indicates that forest development occurred synchronously with or immediately following the Upper Kellwasser crisis in West Junggar. These findings are consistent with the possibility of a major floral turnover at the FFB, although further investigation will be required to test this hypothesis. This research was supported by the Strategic Priority Research Program of Chinese Academy of Sciences, the HKU Seed Fund for Basic Research, and National Natural Science Foundation of China. Reference: Zheng, D.R., Chang, S.C. *, Algeo, T., Zhang H.C., Wang, B., Wang, H., Wang, J., Feng, C.Q., Xu, H.H.*, 2020. Age constraint for an earliest Famennian forest and its implications for Frasnian-Famennian boundary in West Junggar, Northwest China. Palaeogeography, Palaeoclimatology, Palaeoecology, 552, 109749. https://doi.org/10.1016/j.palaeo.2020.109749 Figure 1. Field photo of the Saerba Section of the Zhulumute Formation in West Junggar, Xinjiang, China Figure 2. The turn-over and the geological ages of the Middle to Late Devonian flora of West Junggar, Xinjiang, China Figure 3. Representative Frasnian-Famennian fossil plants in West Junggar, Xinjiang, China
Between two phases of the Late Ordovician mass extinction, Hirnantia Fauna developed globally, and world widely reported except that from Sibumasu Terrane, which now consists of Myanmar, peninsular Malaysia, western Thailand, Sumatra and parts of western Yunnan of China. The Terrane is geographically important, however, the features of Hirnantia Fauna from which and its relationship to South China have long been unclear. Since Reed firstly reported fossils from northern Shan State, Myanmar in 1915, there has been only one relevant paper (with only 9 brachiopods), and the information about western Yunnan is only recorded in one abstract. Between two phases of the Late Ordovician mass extinction, Hirnantia Fauna developed globally, and world widely reported except that from Sibumasu Terrane, which now consists of Myanmar, peninsular Malaysia, western Thailand, Sumatra and parts of western Yunnan of China. The Terrane is geographically important, however, the features of Hirnantia Fauna from which and its relationship to South China have long been unclear. Since Reed firstly reported fossils from northern Shan State, Myanmar in 1915, there has been only one relevant paper (with only 9 brachiopods), and the information about western Yunnan is only recorded in one abstract. Recently, Academician RONG Jiayu, Prof. ZHAN Renbin, Prof. HUANG Bing and CHEN Di (RA) from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, collaborated with Dr. Kyi Pyar Aung from Taunggyi University, Myanmar and Prof. David Harper from Durham University, Britain, studied Hirnantia Faunas from Hwe Mawng purple shale Member, Naungkangyi Group, Mandalay of Myanmar, Wanyaoshu Formation, Mangshi of western Yunnan, and Kuanyinqiao Bed, Meitan, of Guizhou (South China). A series of papers have been published, with 23 genera and 23 species of brachiopods from Mandalay, Myanmar, 22 species of 22 genera from western Yunnan, and 13 species of 13 genera from northern Guizhou were identified. Among them, Hirnantia itself was recorded from Myanmar for the first time, and a new systematical argument to some key taxa was put forward. In addition, Xenocrania, a new genus of Craniid brachiopod was established, and the synonyms for some core taxa of the fauna were revised. These systematic works provide a real basis for global summary in the future. More importantly, based on the classification information, with data from global relevant literatures and fossil materials, the studies revealed some facts in paleobiogeography, community ecology, and population ecology and variation as follows. Paleobiogeography: Based on the comparison of common and core taxa of the Hirnantia Fauna in Sibumasu Terrane and South China, the network analysis method is adopted to prove close relationship between them. The comparative study of Hirnantia Faunas from the Sibumasu Terrane and its adjacent blocks shows that the former was not far away from the south China plate and the Lhasa terrains, and they were all in the shallow tropical waters during the latest Ordovician. The Hirnantia Faunas from Sibumasu and South China with such a high diversity at the end of the Ordovician are very rare, shows their global importance. Brachiopod studies revealed the complex climatic differentiation from low latitude to high latitude during global cooling process in the late Ordovician. The origin and extinction of this global benthic fauna dominated by opportunistic is the important signal of the first and second phases of the major event respectively. Community ecology: The kinella-Paromalomena Association, which lived in deeper water (lower part of BA3, closer to BA4), was recognized based on the information of bathymetric indicator taxa together with data of both diversity and abundance of the Hirnantia Fauna in the Mandalay Division, Myanmar. However, The Hirnantia-Eostropheodonta Association in Meitan, Guizhou province lived in a relatively shallow water environment (BA2 to upper part of BA3). These two assemblages showed obvious differences in many features, as key taxa, composition and diversity. The materials in western Yunnan collected from the Wanshuyao Formation, which was significantly thicker than most of the Kuanyinqiao bed. Studies on brachiopods from 7 bottom up layers, two sets of associations (both including key taxa of Hirnantia Fauna, such as Hirnantia), the Fardenia-Hirnantia association (lower) and the Aegiromena-Anisopleurella association (upper). They belong to the typical shallow-water and deep-water Hirnantia Fauna respectively. There were significant differences in diversity, abundance and body size distribution between the two associations. The ecological succession of community from shallow water to deep water reflected the complexity and evolution of global glacial climate and Marine environment. The deglaciation process of the second pulse of the end-Ordovician mass extinction, was confirmed by the succession of brachiopod community. Population ecology and variation: Hirnantia, nominated the Fauna, is the most important taxon in the Hirnantia fauna, but its species assignment has been controversial. Based ondata from South China and other regions in the world for H. sagittifera, the type species of the genus from representative, the measurements and statistics of the key characters confirmed the significant and extensive variation in H. sagittifera. Six species (including two morpho-types) published previously were all proved to be the synonym of H. sagittifera. Based on materials difficult to identify from Myanmar, South China and other regions, a new genus Xenocrania was established, with its type species Palaeocyclus? haimei Reed (originally described as a coral) from the Hirnantia Fauna in northern Shan State, Myanmar. They found drastic variation of ornamentation of this genus. Three types of ornamentation are recognized within the same population of this species, and even on the same individual. This significant phenotypic pleiotropy was considered may be the response to the strong ecological pressure during the bio-event, in order to improve its probability of survival from the deteriorating environment. Financial supports for this work were provided by the Strategic Priority Research Program of Chinese Academy of Sciences, and the National Natural Science Foundation of China. The research results have been published recently in the journals Palaeoworld, Papers in Palaeontology, Journal of Paleontology, Lethaia and others. Publications information: Rong Jiayu, Aung K P, Zhan Renbin, Huang Bing, Harper D A T, Chen Di, Zhou Hanghang, Zhang Xiaole, 2020. The latest Ordovician Hirnantia brachiopod Fauna of Myanmar: Significance of new data from the Mandalay Region. Palaeoworld, 29: 1–30. Huang Bing, Zhou Hanghang, Harper D.A.T., Zhan Renbin, Zhang Xiaole, Chen Di, Rong Jiayu. 2020a. A latest Ordovician Hirnantia brachiopod fauna from western Yunnan, Southwest China and its paleobiogeographic significance. Palaeoworld, 29: 31–46. Huang Bing, Rong Jiayu, Harper D.A.T., Zhou Hanghang. 2020b. A nearshore Hirnantian brachiopod fauna from South China and its ecological significance. Journal of Paleontology, 94(2): 239–254. Huang Bing, Harper D.A.T., Zhou Hanghang, Rong Jiayu. 2020c. From shallow to deep-water: an ecological study of the Hirnantia brachiopod Fauna (Late Ordovician) and its global implications. Lethaia, doi.org/10.1111/LET.12360. Chen Di，Rong Jiayu. 2019. A new craniid brachiopod genus from the terminal Ordovician Hirnantia fauna of Myanmar and South China. Papers in Palaeontology, 5(3): 521-535. Fig. 1. Paleogeographic map displaying the positions of Sibumasu Terrane and other blocks; Network Analysis for Hirnantia Fauna demonstrates the close relationship between these blocks Fig. 2. Diversity and abundance curves for the Hirnantia Fauna from western Yunnan Fig. 3. Phenotypic pleiotropy of new genus Xenocrania, all are the same species Fig. 4. PCA shows significant variation of the type species of Hirnantia; 6 species were revised Fig. 5. Representative brachiopods of the Hirnantia Fauna of Myanmar (left) and western Yunnan (right)
The Mesoproterozoic interval postdates the Great Oxidation Event, and is considered to be an interval of relative stasis in terms of global tectonics, climate states, and marine geochemical conditions, particularly with regard to the low variance of carbon isotopes. As a result, this interval is referred to as the “boring billion”, although the biosphere changed considerably during this time with the evolution of red and green algae, fungi, and calcifying cyanobacteria. In addition, stromatolite abundance and diversity in the oceans more than doubled in the Mesoproterozoic. The “boring billion” may be, in fact, not “boring”, which attracts persistent studies. The Mesoproterozoic interval postdates the Great Oxidation Event, and is considered to be an interval of relative stasis in terms of global tectonics, climate states, and marine geochemical conditions, particularly with regard to the low variance of carbon isotopes. As a result, this interval is referred to as the “boring billion”, although the biosphere changed considerably during this time with the evolution of red and green algae, fungi, and calcifying cyanobacteria. In addition, stromatolite abundance and diversity in the oceans more than doubled in the Mesoproterozoic. The “boring billion” may be, in fact, not “boring”, which attracts persistent studies. Prof. CHEN Jitao from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS) started working on Mesoproterozoic from 2014 when he was invited twice by A. Knoll and J. Grotzinger toattend the Agouron Field School of Geobiology and collaborative research in Van Horn area, Texas. Recently, CHEN Jitao together with his colleagues from NIGPAS and US have been working on the well-preserved Mesoproterozoic strata of the Helan Mountains in the western margin of the North China Block (NCB). Based on their integrated works, they (1) reconstruct of the depositional history of a coarse redbed succession, (2) analyze a diverse suite of carbonate facies that include remarkably well preserved stromatolitic assemblages, (3) provide carbon and oxygen isotopic profiles for these strata, (4) present the first recovery of trilobites from Cambrian strata at this site that demonstrate the very specific age of the overlying strata, and (5) provide detrital zircon geochronological data for a suite of samples collected from Paleoproterozoic basement, Mesoproterozoic strata, and overlying Cambrian rocks. The study suggests the significant spatial distribution of approximately age-equivalent strata of the Mesoproterozoic Wangquankou carbonate in the NCB were most likely deposited on stable carbonate platform, rather than in an aulacogen. Carbonate carbon isotopes and detrital zircon ages provide a maximum depositional age of ~1610 Ma and prior to 1000–1200 Ma for the Wangquankou Formation. Detrital zircon geochronologic data also show a consistent provenance throughout the Mesoproterozoic section, and for both Middle Cambrian and Middle Ordovician strata, which could suggest a remarkable paucity of major igneous events in this western part of the NCB over a considerable time span (approximately 1000 Ma). The work provides fundamental basis for future studies on diverse stromatolites and biogeochemistry of the Mesoproterozoic. The study was recently published in the international journal Precambrian Research. This research was supported by the Strategic Priority Research Program of Chinese Academy of Sciences and the National Natural Science Foundation of China, and National Aeronautics and Space Administration and National Science Foundation of US. Reference: Zhang, T., Myrow, P.M., Fike, D.A., McKenzie, N.R. Yuan, J., Zhu, X., Li, W., Chen, J.*, 2020. Sedimentology, stratigraphy, and detrital zircon geochronology of Mesoproterozoic strata in the northern Helan Mountains, western margin of the North China Block. Precambrian Research, 343, 105730. https://doi.org/10.1016/j.precamres.2020.105730 Detailed sedimentary logs of the Mesoproterozoic redbeds of the Huangqikou Formation and the overlying carbonate succession of the Wangquankou Formation in the Helan Mountains, North China. Representative facies of the Mesoproterozoic redbeds of the Huangqikou Formation. Diverse Mesoproterozoic stromatolites of the Wangquankou Formation. Detrital zircon geochronologic results in the western margin of the North China Block.
Carbonate carbon and oxygen isotopes of the Wangquankou Formation.
The Steptoean Positive Carbon Isotope Excursion (SPICE) is a large excursion (by ~5‰) in marine carbon isotope (δ13C) records during the middle-late Cambrian transition, which is documented worldwide. The SPICE is hypothesized to be caused by a global carbon cycle perturbation (enhanced global carbon burial), which is accompanied with dramatic marine anoxia and euxinia. The SPICE event is coincident with and ascribed to, most likely the second phase of, the Dresbachian (or end-Marjuman) extinction event that slashed approximately 40% of marine genera during the early stage of life evolution. Recent studies imply that the synchroneity and magnitude of the SPICE may be controversial, which hampers proper interpretation on stratigraphic correlation and biogeochemical cycling. The Steptoean Positive Carbon Isotope Excursion (SPICE) is a large excursion (by ~5‰) in marine carbon isotope (δ13C) records during the middle-late Cambrian transition, which is documented worldwide. The SPICE is hypothesized to be caused by a global carbon cycle perturbation (enhanced global carbon burial), which is accompanied with dramatic marine anoxia and euxinia. The SPICE event is coincident with and ascribed to, most likely the second phase of, the Dresbachian (or end-Marjuman) extinction event that slashed approximately 40% of marine genera during the early stage of life evolution. Recent studies imply that the synchroneity and magnitude of the SPICE may be controversial, which hampers proper interpretation on stratigraphic correlation and biogeochemical cycling. In order to test the spatial variation of the SPICE, Prof. CHEN Jitao from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, in collaboration with his colleagues, studied six outcrop sections across a ~700 km transect along the eastern North China Platform by using sedimentology, trilobite biostratigraphy and carbon isotopes methods in recent years. The research results have been published in the international journals Palaeogeography, Palaeoclimatology, Palaeoecology. Their study found that the SPICE is present in all the studied sections, but showing different features regarding the duration and magnitude. An abrupt increase in δ13C from ~1.5‰ to 3.5‰ occurs in three Shandong sections, with maximum value present only in a thin (0.5-1.2 m thick) transgressive lag deposit (crudely wave stratified, bioclastic grainstone). In contrast, the δ13C record of the Baijiashan and Shashan sections in the Liaoning region displays a gradual increase (~20 m thick) from ~1.5‰ to the maximum value of 4.7‰. Both facies analysis and trilobite collections suggest that the spatial variation of the SPICE in the North China Platform most likely resulted from missing of sedimentary record (with high δ13C values) in the Shandong sections as a result of erosion and non-deposition during sea-level lowstand, a possible coeval hiatus prior to the Sauk III transgression in the Laurentian basins. This is a case study that utilizes an interdisciplinary approach involving sedimentology, stratigraphy, and geochemistry to better understand geological issues. This study reports the complete record of SPICE from the North China Platform, and provides fundamental basis for future global correlation of SPICE. The study was supported by the Strategic Priority Research Program of Chinese Academy of Sciences and the National Natural Science Foundation of China. Reference: Wang, Z., Chen, J.*, Liang, T., Yuan, J., Han, C., Liu, J., Zhu, C., Zhu, D., Han, Z.*, 2020. Spatial variation in carbonate carbon isotope during the Cambrian SPICE event across the North China Platform. Palaeogeography, Palaeoclimatology, Palaeoecology, 546, 109669. https://doi.org/10.1016/j.palaeo.2020.109669 Detailed sedimentary loggings of the Miaolingian-Furongian boundary successions in the eastern part of the North China Platform Representative facies of the Miaolingian-Furongian boundary successions in the eastern part of the North China Platform Representative trilobites of the Miaolingian-Furongian boundary successions in the eastern part of the North China Platform Correlation of carbonate δ13C records of the upper Miaolingian to the lower Furongian succession from the eastern part of the North China Platform
The end-Permian marine extinction (EPME) eliminated >80% of species globally, making it the most severe extinction of the Phanerozoic. Anoxia and euxinia are potential kill mechanisms that may have contributed to this biotic crisis. However, redox changes in the atmosphere-ocean system are likely to have been complex, with both the vertical location of the oxic-anoxic boundary (in the water column or sediments), and the total area or volume of anoxic and euxinic water in the global ocean changing over time. The end-Permian marine extinction (EPME) eliminated >80% of species globally, making it the most severe extinction of the Phanerozoic. Anoxia and euxinia are potential kill mechanisms that may have contributed to this biotic crisis. However, redox changes in the atmosphere-ocean system are likely to have been complex, with both the vertical location of the oxic-anoxic boundary (in the water column or sediments), and the total area or volume of anoxic and euxinic water in the global ocean changing over time. Recently, an international research team from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences, Western Carolina University and Nanjing University reported a series of geochemical analyses on iron speciation and major and trace element data from 141 samples of the Meishan-1 core, which was drilled at a site 550 m to the west of the Meishan D section. The research results have been published online in Palaeogeography Palaeoclimatology Palaeoecology. Iron speciation results, in combination with authigenic concentrations and enrichment factors of redox-sensitive metals (Mo, V, and U), and previously published macrofossil, trace fossil, and bioturbation evidence, suggest that: 1) Beds 21-24d were deposited beneath a predominantly oxic water column, 2) Beds 24e-28 were deposited under a persistently anoxic watermass with intermittently euxinic bottom water, and 3) Beds 29-34 were deposited under primarily ferruginous conditions. Excess fractions and enrichment factors of U, V and Mo in the anoxic and euxinic intervals of the Meishan-1 core suggest that authigenic precipitation of redox-sensitive trace metals mainly occurred before and during the EPME, with nearly no detectable authigenic U, V, or Mo accumulating after the EPME. The new results, along with published U, V and Mo concentrations from across the Neotethys, Paleotethys, and Panthalassic Ocean basins, indicate that oceanic trace metal reservoirs were depleted before and during the main extinction interval. This depletion of oceanic trace elements suggest a spatial expansion of both anoxic and euxinic watermasses prior to and during the EPME. The apparent coincidence in timing between the mass extinction and the areal expansion of anoxic and euxinic watermasses suggests that these factors played important roles in the loss of marine biota around the PTB, through oxygen deprivation and H2S toxicity. This work was supported by the Strategic Priority Research Program of Chinese Academy of Sciences, the National Natural Science Foundation of China and the Key Research Program of Frontier Sciences of the Chinese Academy of Sciences. Reference: Xiang, L., Zhang, H.*, Schoepfer, S.D., Zheng, Q.F., Yuan, D.X., Cai, Y.F., Cao, C.Q., Shen, S.Z., 2020. Oceanic redox evolution around the end-Permian mass extinction at Meishan, South China. Paleogeogr. Paleoclimatol. Paleoecol. 544, 109626. https://doi.org/10.1016/j.palaeo.2020.109626 Stratigraphic distributions of selected redox proxies around Permian-Triassic boundary in the Meishan section
Recent studies indicate increasing numbers of fossil organisms have been found in the Amber inclusions. However, few fossils have been documented for fossil liverworts in amber. Recently, a research team of the Mesozoic plants led by Prof. WANG Yongdong and Dr. LI Ya from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), cooperated with Prof. Harald Schneider from Xishuangbanna Tropical Botanical Garden, CAS and Prof. WU Pengcheng from Institute of Botany, CAS, have investigated the liverwort inclusions from the mid-Cretaceous Burmese amber. Recent studies indicate increasing numbers of fossil organisms have been found in the Amber inclusions. However, few fossils have been documented for fossil liverworts in amber. Recently, a research team of the Mesozoic plants led by Prof. WANG Yongdong and Dr. LI Ya from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), cooperated with Prof. Harald Schneider from Xishuangbanna Tropical Botanical Garden, CAS and Prof. WU Pengcheng from Institute of Botany, CAS, have investigated the liverwort inclusions from the mid-Cretaceous Burmese amber. They found a distinctive and anatomically preserved sterile branch of Frullania (Frullaniaceae, Porellales), and described it as F. partita sp. nov. after detailed comparisons with related extant and fossil species of Frullania. This research results have recently been published in the international geoscience journal Cretaceous Research. This new species is mainly characterized by apically apiculate leaf lobes, helmet-shaped to campanulate water sacs situated in some distance to stem, lanceolate styli, and apically deeply bilobed underleaves carrying rhizoid bundles in their basal parts. Recent molecular based studies introduced the hypothesis that the diversity of the predominantly epiphytic liverworts Porellales expanded during the Cretaceous Terrestrial Revolution (KTR) period around 125–80 Ma. Until now, the fossil record provides only insufficient support to elucidate this hypothesis. Porellales comprise seven families, viz. Porellaceae, Goebeliellaceae, Lepidolaenaceae, Radulaceae, Frullaniaceae, Jubulaceae, Lejeuneaceae. Representatives of the Porellales are most common in Cenozoic amber, however, these liverwort inclusions in Cretaceous amber are relatively rare and usually consist of small fragments, rather than complete plants. So far, only a few taxa (3 families 4 genera 6 species) of Porellales have been described from the mid-Cretaceous Burmese amber.This new discovery contributes our understandings for the diversity aspects of Frullaniaceae (Porellales) of Burmese amber inclusions. The bark fragments connected to the branch provide the evidence that the fossil is an epiphyte. This study was supported by the National Natural Science Foundation of China, and the Strategic Priority Research Program of the Chinese Academy of Sciences. Reference:Li, Y., Wang, Y.-D.*, Schneider, H., Wu, P.-C., 2020. Frullania partita sp. nov. (Frullaniaceae, Porellales), a new leafy liverwort from the mid-Cretaceous of Myanmar. Cretaceous Research 108, 104341. https://doi.org/10.1016/j.cretres.2019.104341 Morphology and anatomy of the sterile branch of Frullania partita sp. nov. from the mid-Cretaceous of Burmese amber Reconstruction of Frullania partita sp. nov. (drawn by Ding-Hua Yang)
As a predominant category in the Paleozoic evolutionary fauna, grapholites increased rapidly in the Ordovician and evolved rapidly. Late Ordovician graptolites from the Mandalay Region, Myanmar were first collected and reported by Reed in 1915, and then there were few reports after that. Recently Academician CHEN Xu and Dr. CHEN Qing from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS) cooperated with Dr. Kyi Pyar AUNG from Taunggyi University in Myanmar and Dr. Lucy A. MUIR from the National Museum of Wales to work on the graptolite fauna and the biostratigraphy of the Upper Ordovician Naungkangyi Group and Panghsa-pye Formation in this area. Related research results were published in Palaeoworld magazine. Based on detailed systematic paleontological description and identification, 13 species in 5 genera (Avitograptus, Korenograptus, Metabolograptus, Neodiplograptus and Normalograptus) were described from the Mandalay Region. Two of these species, Korenograptus selectus X. Chen n. sp. and Neodiplograptus mandalayensis X. Chen n. sp., were new. On the basis of the community analysis and international correlation, a biostratigraphic scheme for the uppermost Ordovician (Hirnantian: Metabolograptus extraordinarius Biozone and Metabolograptus? persculptus Biozone) strata was erected in this area. This research was supported by the Strategic Priority Research Program of Chinese Academy of Sciences, National Science and Technology Major Project of China, Ministry of Nature and Resources of China and the National Natural Science Foundation of China. Reference: Chen Xu*, Chen Qing, Kyi Pyar Aung, Lucy A. Muir. 2020. Latest Ordovician graptolites from the Mandalay Region, Myanmar. Palaeoworld, 29: 47–65. https://doi.org/10.1016/j.palwor.2019.09.003 Graptolite species range chart of the Upper Ordovician interval in the Shwethin Village–Yebyantaung waterfall section, Mandalay, Myanmar Typical graptolites pictures
The end-Ordovician mass extinction (EOME) was the first of the “Big Five” extinctions of the Phanerozoic. However, there is still uncertainty concerning the exact timing of the Silurian biotic recovery following this extinction event due to the lack of reliable age constraints of fossil records during this interval. The end-Ordovician mass extinction (EOME) was the first of the “Big Five” extinctions of the Phanerozoic. However, there is still uncertainty concerning the exact timing of the Silurian biotic recovery following this extinction event due to the lack of reliable age constraints of fossil records during this interval. Of particular interest is the richly fossiliferous succession from the Wulipo Formation in the Huangjiaba area near Meitan in northern Guizhou, SW China, which represents one of the very rare records of shelly fauna across the Ordovician and Silurian transition worldwide, and is therefore crucial for understanding the pattern and dynamics of the end-Ordovician mass extinction (EOME). Recently, Dr. WANG Guangxu from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences and his colleagues present for the first time, chemostratigraphic data from the Wulipo Formation which confirm the presence of the Hirnantian Isotope Carbon Excursion (HICE). The research results have been published online in the international geoscience journal Geological Journal. Historically, the Wulipo Formation was dated as middle Rhuddanian (early Silurian). However, its fauna shows a close affinity with Transitional Benthic Fauna 3 (TBF 3), now known to be confined within the late Hirnantian (latest Ordovician) in well-constrained successions globally. A critical review of faunal evidence further indicates a late Hirnantian age for this formation, and thus the hitherto only known anomalous TBF 3 record documented from South China is convincingly redated. The important implication is that the substantial biotic recovery after the EOME commenced globally at the very beginning of the Silurian with an overall amelioration of physical conditions. The new findings also suggest a much wider distribution of postglacial warm-water benthic faunas on the Yangtze Platform during the late Hirnantian than previously envisaged. This research was jointly funded by the National Natural Science Foundation of China, the Strategic Priority Research Program (B) of Chinese Academy of Sciences and the State Key Laboratory of Palaeobiology and Stratigraphy. Related information on this paper: Wang, G.X.*, Wei, X., Luan, X.C., Wu, R.C., Percival, I.G. & Zhan R.B. 2020. Constraining the biotic transitions across the end-Ordovician mass extinction in South China: Bio- and chemostratigraphy of the Wulipo Formation in the Meitan area of northern Guizhou. Geological Journal, https://onlinelibrary.wiley.com/doi/full/10.1002/gj.3816.
δ13Ccarb curves from Yanping (a) Gaojiang (b) of the study area, in comparison with that from Tunping (c) of the Shiqian area, indicating the presence of HICE in the Wulipo Formation. An updated chronostratigraphic classification of the Ordovician–Silurian boundary shelly rocks on the Yangtze Platform of South China.
The early land plant fossils of the group zosterophyllopsid are widely recorded in global Silurian to Devonian sediments and acts as a dominant group in the Early Devonian flora of South China. Demersatheca contigua is an endemic zosterophyllopsid of the Early Devonian flora in South China and its paleophytogeographic implication to southern China Early Devonian is discussed. The early land plant fossils of the group zosterophyllopsid are widely recorded in global Silurian to Devonian sediments and acts as a dominant group in the Early Devonian flora of South China. Demersatheca contigua is an endemic zosterophyllopsid of the Early Devonian flora in South China and its paleophytogeographic implication to southern China Early Devonian is discussed. Previous studies have suggested that the overall shape of the D. contigua is flat fern, while the new research changed this perception. In addition, the publication of D. contigua was effective but invalid because a holotype was not assigned in its initial description. Therefore, there are still many problems in the research of D. contigua. Recently, the Devonian Investigation Group (DIG) of Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, led by Professors XU Honghe and WANG Yi and PhD student WANG Yao, researched the same species from the Lower Devonian layers from Guangxi and Yunnan. The plant fossils described in this study include 6 specimens previously attributed to Zosterophyllum contiguum or Z. australianum by Li and Cai from the Lower Devonian Posongchong Formation of Wenshan, Yunnan and 11 specimens newly collected from the Lower Devonian Cangwu Formation of Cangwu, Guangxi. A better understanding to the morphology of the zosterophyllopsid group is achieved with the examination of new specimens collected from these localities and the specimens previously reported. The study was online published recently in Review of Palaeobotany and Palynology. The structure of the D. contigua strobilus is reconstructed and the diagnosis of the plant is emended in the aspect of four-row decussate sporangium arrangement. The nomenclature of D. contigua is summarized and the lectotype of the species is formally proposed.The strobilus of Demersatheca contigua is consists of four rows of lateral sporangia decussately arranged biconvex sporangia with marginal dehiscence bending towards the strobilus to make the strobilus a cylindrical-shape. In this study, we according to the International Code of Nomenclature for Algae, Fungi, and Plants (Shenzhen Code), here propose to select the specimen from original materials as the lectotype of D. contigua. The lectotype in this case equates to the holotype. For a long time, the southern China flora was thought to be a distinctive composition of the Early Devonian flora of China. However, recently accumulated study indicated that the Early Devonian flora of southern China can be subdivided into three phytogeographic zones, Yunnan, Guangxi and Sichuan, every flora of these three has its exclusive plant members, whilst a few shared members can be found among them. In generic level, Adoketophyton and Guangnania occur in both Yunnan and Sichuan; Demersatheca in Yunnan and Guangxi; Zosterophyllum in Guangxi, Yunnan and Sichuan. In specific level, only Demersatheca contigua occurs in Yunnan and Guangxi. These plant records, though being sparse and limited, seem to suggest similarities and potential relationships between these floras. A detailed flora comparison is highly expected and undoubtedly needed in the further study. Reference: Wang Yao, Xu Hong-He*, Wang Yi, 2020. Morphology, nomenclature and potential paleophytogeographic implication of Demersatheca contigua (Zosterophyllopsida) from the Lower Devonian of Yunnan and Guangxi, southwestern China. Review of Palaeobotany and Palynology.104209. https://doi.org/10.1016/j.revpalbo.2020.104209 Fig. 1. Specimens of Demersatheca contigua (Zosterophyllopsida) from the Lower Devonian of Yunnan (A, B and E) and Guangxi (C and D), southwestern China. Fig. 2. Three-dimensional diagram of the strobilus, the fertile structure of the Lower Devonian Demersatheca contigua (Zosterophyllopsida).
