This study provides new secondary carbonate (microcodium) 87Sr/86Sr record and integrates multi-proxy records from the central CLP to reinterpret the response of the EAWM to insolation and ice-sheet forcing during glacial inceptions. Microcodium 87Sr/86Sr record, which captures the global cooling trend at the transition zones between the paleosol layer and the overlying loess layer, provides an independent age control for comparing loess records with other paleoclimatic records during glacial inceptions. The East Asian winter monsoon (EAWM), a major component of the East Asian monsoon circulation, is characterized by prevailing low-level northwesterly winds tightly linked to the high-northern-latitude climate via the Siberian-Mongolian High. Our current understanding of the EAWM dynamics during the glacial-interglacial cycles is mostly based on loess records on the Chinese Loess Plateau (CLP), which suggest that the EAWM intensity is closely linked to the volume of the Northern Hemisphere ice sheets (NHIS) on orbital timescale. However, unlike the "sawtooth" pattern of global ice volume that shows a gradual build-up of the ice sheets (in ~90000 years) followed by rapid deglaciation (in ~10000 years) since the middle Pleistocene transition as documented by the benthic δ18O records, the loess records of EAWM show distinct glacial and interglacial modes, with the transitions between them generally being quick. This dissimilar evolution pattern between the EAWM and the global ice volume (and NHIS) at the interglacial-glacial transitions means that some key information is missing regarding the dynamics of the EAWM during the glacial inceptions. Recently, Associate Professor LI Tao from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), in collaboration with Profs. LI Gaojun, CHEN Tianyu, ZHAO Liang, JI Junfeng, CHEN Jun, and Dr. LI Le from Nanjing University, Prof. SUN Youbin and Dr. ZHANG Zeke from the Institute of Earth Environment (CAS), Prof. YIN Qiuzhen and Dr. WU Zhipeng from Université catholique de Louvain, Dr. MENG Xianqiang from Nanjing Institute of Geography and Limnology (CAS), and Prof. Robinson F. Laura from University of Bristol, carried out a high-resolution secondary carbonate (microcodium) Sr isotope (87Sr/86Sr) study from two loess-paleosol sequences on the central CLP, yielding an independent chronology framework for assessing the evolution and potential forcing mechanisms of the EAWM during glacial inceptions over the last 550,000 years (Fig. 1). The research results were published in the internationally recognized journal Geophysical Research Letters. Building upon this independent chronology and integrating multi-proxy records, the results offer new insights into the dynamics of the EAWM during glacial inceptions and provide compelling evidence for the millennial-scale teleconnections between the high- and middle-latitudes in terminating the interglacial period in the Northern Hemisphere. This study provides new secondary carbonate (microcodium) 87Sr/86Sr record and integrates multi-proxy records from the central CLP to reinterpret the response of the EAWM to insolation and ice-sheet forcing during glacial inceptions. Microcodium 87Sr/86Sr record, which captures the global cooling trend at the transition zones between the paleosol layer and the overlying loess layer, provides an independent age control for comparing loess records with other paleoclimatic records during glacial inceptions. At the mid-way of glacial cooling, abrupt coarsening occurred synchronously with rapid positive shifts in the hydrogen and oxygen isotopic compositions of precipitation, indicating concurrent abrupt shifts in the EAWM and EASM during glacial inceptions (Fig. 2). The gradual declining summer insolation in Northern Hemisphere high-latitudes during glacial inceptions may trigger an abrupt weakening of Atlantic meridional overturning circulation (AMOC) and thus cooling in the northern North Atlantic, which strengthens the Siberian–Mongolian High cell and the EAWM but weakens the EASM. Nevertheless, the insolation-triggered abrupt weakening of AMOC alone cannot account for the mode shift in the EAWM during glacial inceptions. For example, the δ18O record from the Iberian Margin and the modeling results both indicate a sharp weakening of AMOC at the Marine Isotope Stage (MIS) 5e/5d transition while the loess records show no significant changes in the EAWM from MIS 5e to MIS 5a. This indicates that the gradual build-up of the NHIS may have played an important role in preconditioning the rapid, coupled shifts in the EAWM and EASM at during the glacial inceptions. The key role of NHIS in modulating the insolation-triggered abrupt changes in the EAWM at the end of interglacial is further supported by the absence of an abrupt shift in the EAWM at the MIS 11/10 transition when the build-up of NHIS is delayed due to the eccentricity minima. "Our results thus provide compelling evidence for the nonlinear response of the EAWM to ice volume and insolation forcing during the interglacial-glacial transitions", says LI. This research was supported by the National Natural Science Foundation of China, the Strategic Priority Research Program of the Chinese Academy of Sciences. Reference: Li, T., Li, G.*, Chen, T., Sun, Y., Yin, Q., Wu, Z., Robinson, L.F., Li, L., Zhang, Z., Meng, X., Zhao, L., Ji, J., Chen, J., 2023. Ice Volume and Insolation Forcing of Abrupt Strengthening of East Asian Winter Monsoon During Glacial Inceptions. Geophysical Research Letters 50. https://doi.org/10.1029/2022GL102404. Fig. 1 Proxy variations of Xifeng and Zhenyuan loess sequences compared to the LR04 benthic δ18O stack.
Fig. 2 Comparison of loess proxy records with other paleoclimatic records over the last 550,000 years.
Contact: LIU Yun, Propagandist Email: yunliu@nigpas.ac.cn Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences Nanjing, Jiangsu 210008, China
Recently, Quaternary Geochronology published the first systematic investigation on the U-series isotope geochemistry as well as the early diagenetic imprints of fossil land snail shells (Cathaica sp.) from the Mangshan loess-paleosol sequence in Henan province, central China. Recently, Quaternary Geochronology published the first systematic investigation on the U-series isotope geochemistry as well as the early diagenetic imprints of fossil land snail shells (Cathaica sp.) from the Mangshan loess-paleosol sequence in Henan province, central China. This study was conducted by Associate Professor LI Tao from the Nanjing Institute of Geology and Paleontology, Chinese Academy of Sciences (NIGPAS), in collaboration with Profs. CHEN Tianyu, LI Gaojun, LIU Yuanyuan, and Dr. WANG Maoyu from Nanjing University, and Prof. Robinson F. Laura and Dr. Knowles Tim from University of Bristol. Several geochemical techniques, including Raman microscopy, SEM, LA-ICPMS, LA-MC-ICPMS, solution-MC-ICPMS, and AMS 14C dating, were employed to investigate the mineralogy, chemical and isotopic compositions of both modern and fossil snail shells to micrometer level. Terrestrial mollusks, which have been considered as typical "index animals" due to their sensitivity to climate change, are widely distributed in the semi-arid to arid region of China, such as Chinese Loess Plateau (CLP). So far, the assemblages of land snail fossils on the CLP have been used to prove the wind-blown origin of the Neogene loess sequences and red clay, and to reconstruct monsoonal environmental change in East Asia ranging from tectonic to orbital, and even millennial timescales. Growing studies have focused on the geochemical proxies recorded by their calcium carbonate shells, mainly including stable carbon (δ13C) and oxygen (δ18O) isotopes and clumped isotopes (Δ47). Despite the wide application of these geochemical proxies of fossil snail shells in paleoclimatic reconstruction, it remains elusive to what extent they were influenced by the diagenetic alteration. No investigation has been conducted regarding the early diagenetic pathways which could alter the geochemical compositions of fossil land snail shells. Another key advantage of land snail shells is that they can be absolutely dated by several methods, including 14C dating, electron spin resonance (ESR) dating, amino acid racemization (AAR) dating, and, potentially, U-Th dating, which helps to provide age constraints on loess deposits on the CLP. Among those geochronological approaches, U-Th dating is a very powerful technique due to its wide age coverage (0 to 640,000 years) and solid theoretical foundation. However, obtaining accurate U-series dates from both marine and terrestrial mollusk shells has remained an outstanding issue for more than 50 years. A major challenge faced is that a significant amount of U in the shell is incorporated during the diagenetic episode after the burial of the shell into the sediment, suggesting apparent "open-system" behavior concerning the U-series disequilibrium. On the CLP where fossil snail shells can be buried and isolated quickly from the influence of meteoric water due to the relatively high sedimentation rate of eolian dust and the semi-arid to the arid climate, it is possible that diagenesis might occur only in the very early stage when pore-water is still able to alter the composition and structure of the snail shells. Therefore, land snail shells on the CLP may serve as a datable archive that can be used for U-Th dating. In turn, a clear understanding on the U-Th systematics of land snail shells would also help to constrain the reliability of shell-based geochemical proxies in paleoclimatic reconstructions. Based on the Raman and SEM observations, it is clear that the fossil shell is characterized by an elevated degree of porosity and a higher content of organic matter. The trace elemental composition of the fossil Cathaica sp. shell has also been largely reset, which is linked to the diffusion and adsorption of organic matter into the fossil shell during the early diagenetic alternation of fossil Cathaica sp. shells. U-series data acquired via LA-MC-ICPMS show that [234U/238U] and [230Th/238U] values are relatively homogeneous throughout the shell and the calculated apparent U-Th dates are within analytical error consistent with corresponding solution MC-ICPMS results, demonstrating the homogeneous distribution of [234U/238U] and [230Th/238U] within the fossil Cathaica sp. shells. However, the apparent closed system U-Th ages of fossil Cathaica sp. shells are found to be systematically younger (~6,000 to 13,000 years) than their paired shell 14C ages. By evaluating possible U uptake scenarios, this study suggests that this apparent age discrepancy is related to the early diagenetic uptake of U and later close system behavior likely due to the isolation of fossil shell from the influence of pore waters. This research was supported by the National Natural Science Foundation of China, the Strategic Priority Research Program of the Chinese Academy of Sciences. Reference: Li, T.*, Chen, T.*, Robinson, L.F., Wang, M., Li, G., Liu, Y., Knowles, T.D.J., 2023. Early diagenetic imprints and U-Th isotope systematics of fossil land snail shells from the Chinese Loess Plateau. Quaternary Geochronology 74, 101417. https://doi.org/10.1016/j.quageo.2022.101417.
Fig. 1 Raman fluorescence and elemental mapping across the aperture part of both modern and fossil Cathaica sp. shells.
Fig. 2 The depth profiles of (a) U concentration, (b) Th concentration and (c) apparent U-Th age and 14C age compared with published quartz SAR chronology for the Mangshan section.
Contact: LIU Yun, Propagandist Email: yunliu@nigpas.ac.cn Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences Nanjing, Jiangsu 210008, China
Stromatoporoids are hypercalcified sponges that first became important in shallow-marine reefal systems in the Middle Ordovician, continuing as dominant reef components until Late Devonian time. The labechiid group has been regarded as the earliest stromatoporoid-type sponge based on its occurrence in the Floian Stage of the Lower Ordovician in South China. This group diversified substantially in the late Darriwilian of the Middle Ordovician, reaching a total of 12 genera that contributed to the Great Ordovician Biodiversification Event. Stromatoporoids are hypercalcified sponges that first became important in shallow-marine reefal systems in the Middle Ordovician, continuing as dominant reef components until Late Devonian time. The labechiid group has been regarded as the earliest stromatoporoid-type sponge based on its occurrence in the Floian Stage of the Lower Ordovician in South China. This group diversified substantially in the late Darriwilian of the Middle Ordovician, reaching a total of 12 genera that contributed to the Great Ordovician Biodiversification Event. Recently, doctoral student Juwan Jeon, Associate Professor LI Qijian, Professor ZHANG Yuandong et al. from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS) and their collaborator from Brunel University report stromatoporoid fossils, which occur sporadically throughout the Xiaonanhai section, located on a hill close to the Xiaonanhai Reservoir near Anyang City in Henan Province, China. The results were published in Alcheringa on Jan. 8. Four labechiid species from the Machiakou Formation are systematically described. These species are major constituents of the Middle Ordovician endemic labechiid assemblage in North China. The Darriwilian labechiid stromatoporoid assemblage of North China represents the highest generic diversity of the Middle Ordovician stromatoporoids globally. A microbioherm is recognised in the Xiaonanhai section, constructed by mutual encrustations of Labechia variabilis and Labechiella mingshankouensis, and is comparable to other microbioherms found in the Middle Ordovician Yeongheung Formation of South Korea. Different stratigraphic ranges, migration pathways and palaeogeographic distributions amongst the Darriwilian labechiid species of North China indicate that their environmental tolerance and migration dispersal behaviour were variable. This study was jointly supported by the Youth Innovation Promotion Association of CAS, grants from the Strategic Priority Research Program (B) of CAS. Reference:Jeon, J., Li, Q.J.*, Chen, Z.Y., Liang, K., Stephen, K. & Zhang, Y.D., 2022. Labechiid stromatoporoids from the Middle Ordovician Machiakou Formation of North China and their implications for the early development of stromatoporoids. Alcheringa, 46 (03-04): 219–236. https://doi.org/10.1080/03115518.2022.2130978. Figure 1 Labechiella mingshankouensis (Ozaki 1938) from the Middle Ordovician Machiakou Formation at the Xiaonanhai section, Anyang County, Anyang, Henan Province, China.
Figure 2 Four contiguous thin sections showing the microbioherm from the Middle Ordovician Machiakou Formation in the Xiaonanhai section, Anyang County, Anyang, Henan Province, China, together with an interpretive drawing of the microbioherm.
Contact: LIU Yun, Propagandist Email: yunliu@nigpas.ac.cn Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences Nanjing, Jiangsu 210008, China
Scientists from China, Germany and the UK led by Prof. LIU Feng from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences (NIGPAS) have revealed that pollen preserved in 250-million-year-old rocks contains abundant compounds that function like sunscreen but are produced by plants to protect themselves from harmful ultraviolet (UV-B) radiation. Scientists from China, Germany and the UK led by Prof. LIU Feng from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences (NIGPAS) have revealed that pollen preserved in 250-million-year-old rocks contains abundant compounds that function like sunscreen but are produced by plants to protect themselves from harmful ultraviolet (UV-B) radiation. The presence of these compounds suggests that a pulse of UV-B played an essential role in the end-Permian mass extinction event. The study was published in Science Advances on Jan. 6. The end-Permian mass extinction event (250 million years ago) is the most severe of the big five mass extinction events, with the loss of ~80% of marine and terrestrial species. This catastrophic loss of biodiversity resulted from a palaeoclimate emergency triggered by continental-scale volcanism that covers much of modern-day Siberia. The volcanic activity drove the release into the atmosphere of massive amounts of carbon that had been locked up in Earth's interior, thus generating large-scale greenhouse warming. Accompanying this global warming event was a collapse of the Earth’s ozone layer. Support for this theory comes from the abundant occurrence of malformed spores and pollen grains that testify to an influx of mutagenic UV irradiation. Plants require sunlight for photosynthesis but need to protect themselves and particularly their pollen from the harmful effects of UV-B radiation. "To do so, plants load the outer walls of pollen grains with compounds that function like sunscreen to protect vulnerable cells to ensure successful reproduction. Without the 'sunscreen' compounds, forests could have been sterilized, leading to the collapse of the terrestrial ecosystem," said Prof. Barry Lomax from the University of Nottingham. "We have developed a method to detect these phenolic compounds in fossil pollen grains (Alisporites-type) recovered from southern Tibet and detected much higher concentrations in those grains that were produced during the end-Permian mass extinction and peak phase of volcanic activity," said Prof. LIU. The researchers found an increase in UV-B-absorbing compounds (UACs) that coincided with a spike in mercury concentration and a decrease in carbon isotopes in the latest Permian deposits, suggesting a close temporal link between large-scale volcanic eruptions, global carbon- and mercury-cycle perturbations, and ozone-layer disruption. Elevated UV-B levels exerted far-reaching and long-lasting impacts on the entire Earth system. Recent modelling studies have demonstrated that elevated UV-B stress reduced plant biomass and terrestrial carbon storage, thus exacerbating global warming. In addition, increased concentration of phenolic compounds also makes plant tissue less easily digestible, making a hostile environment even more challenging for herbivores. "Volcanism on such a cataclysmic scale influences all aspects of the Earth system, from direct chemical changes in the atmosphere, through changes in carbon sequestration rates, to reducing the volume of nutritious food sources available for animals," said Dr. Wes Fraser from Oxford Brookes University.
Fig. 1 Alisporites-type fossil pollen recovered from Permian-Triassic transitional deposits in the Qubu section (Image by NIGPAS)
Fig. 2 The impacts of ozone depletion and elevated UV-B levels on the terrestrial ecosystem (Credit byConor Haynes-Mannering)
Contact: LIU Yun, Propagandist Email: yunliu@nigpas.ac.cn Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences Nanjing, Jiangsu 210008, China
Recently, Dr. NA Lin and Dr. LI Qi-jian from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS) and his collaborators from University of Erlangen-Nuremberg outline time-traceable provinces for marine invertebrates across the Cambrian period using a compositional network based on species-level fossil occurrence data. The Cambrian witnessed a noteworthy radiation in biodiversity and a remarkable divergence in Bau plans of marine metazoans. Although the temporal and spatial patterns of Cambrian biodiversity have been widely documented, less attention has been paid to the fundamental biogeographic structure and its changes through time. And it remains unclear how these changes scale up to first-order biogeographic patterns, which may provide insights into evolutionary processes during large-scale diversifications at different temporal scales. Recently, Dr. NA Lin and Dr. LI Qi-jian from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS) and his collaborators from University of Erlangen-Nuremberg outline time-traceable provinces for marine invertebrates across the Cambrian period using a compositional network based on species-level fossil occurrence data. The results have been published online in the Paleobiology, the official publication of the Paleontological Society. The study confirms an increase in regional differences (Fig. 1) of faunal composition and a decrease in by-species geographic distribution during the first three stages. The results also show that general biogeography tends to be reshaped after global extinction pulses (Fig. 2). The authors suggest that the abrupt biogeographic differentiation during the Cambrian radiation was controlled by a combination of tectonics, paleoclimate, and dispersal capacity changes. So this study provides further evidence for the evolution of biogeographic patterns during and after the Cambrian radiation. This study was jointly supported by the Youth Innovation Promotion Association of CAS, grants from the Strategic Priority Research Program (B) of CAS and the State Key Laboratory of Palaeobiology and Stratigraphy (NIGAPS). Reference: Na, L., Kocsis, á, Li, Q.*, & Kiessling, W. (2022). Coupling of geographic range and provincialism in Cambrian marine invertebrates. Paleobiology, 1-12. https://doi.org/10.1017/pab.2022.36. Figure 1 Trajectory of provinciality from the Fortunian to Stage 10 of the Cambrian, based on Hurlbert's probability of interspecific encounter (PIE). Figure 2 Paleogeographic positions of sampled bioregions for the ten 10 Cambrian stages. Numbers and colors indicate time-traceable bioregions.
Contact: LIU Yun, Propagandist Email: yunliu@nigpas.ac.cn Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences Nanjing, Jiangsu 210008, China
Acoustic communication has played a key role in the evolution of animals especially vertebrates and insects, ranging from mating to warning calls and even including social learning. On December 13, 2022 PNAS published the novel insight from an international team of paleoentomologists on acoustic evolution of Mesozoic katydids and evolution of the Mesozoic soundscape. Acoustic communication is commonly used in behaviors such as courtship, mating, predation, and avoidance of natural predators. The result is an amazingly diverse and complex modern soundscape. The reconstruction of ancient acoustic signals is challenging, however, due to the extreme rarity of fossilized organs. Insects were the first terrestrial animals to use air-borne sound signals for long-distance communication. Among acoustically signaling insects, katydids stand out as an ideal source to investigate the evolution of acoustic organs and behavior. PhD student XU Chunpeng from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences (NIGPAS), under the supervision of Profs. WANG Bo and ZHANG Haichun from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences (NIGPAS), carried out a detailed and global investigation of fossil katydids from the Mesozoic Era (commonly referred to as the age of the dinosaurs). We research team reported the earliest tympanal ears and sound-producing system (stridulatory apparatus) in exceptionally preserved Mesozoic katydids. We also studied the stridulatory apparatus and wing morphology of Mesozoic katydids, calculating their probable singing frequencies and analyzed the evolution of their acoustic communication. “The newly found tympanal ears in prophalangopsids katydids from the Middle Jurassic Daohugou Konservat-Lagerst？tte represent the earliest-known insect ears, extending the age range of the modern-type auditory tympana by 100 million years to the Middle Jurassic, some 160 million years ago”, says XU Chunpeng. The reconstruction of singing frequencies of Mesozoic katydids and oldest tympanal ears demonstrate that katydids had evolved complex acoustic communication, including mating signals, inter-male communication, and directional hearing, at least by the Middle Jurassic. Also, katydids had evolved a high diversity of singing frequencies, including high-frequency musical calls, accompanied by acoustic niche partitioning—all at least by the Late Triassic (200 million years ago). WANG Bo says that “we suggest that acoustic communication could have been an important evolutionary driver already in the early radiation of terrestrial insects after the Permo-Triassic mass extinction.” The Early and Middle Jurassic katydid transition from extinct haglid- to extant prophalangopsid-dominated insect faunas coincided with the diversification of derived mammalian groups (clades) and improvement of hearing in early mammals, supporting the hypothesis of acoustic co-evolution of mammals and katydids. The high-frequency songs of Mesozoic katydids could even have driven the evolution of intricate hearing systems in early mammals, and conversely, mammals with progressive hearing ability could have exerted selective pressure on the evolution of katydids, including faunal turnover. Our findings demonstrate that insects, especially katydids, dominated the choruses during the Triassic, which is different from the modern soundscape. After the appearance of birds and frogs in the Jurassic, the forest soundscape became almost the same as the modern one in the Cretaceous, except lacking the sound of cicadas (which have less musical calls). And all of these results also highlight the ecological significance of insects in the Mesozoic soundscape, which has hitherto been largely unknown in the palaeontological record. This research was supported by the National Natural Science Foundation of China, Strategic Priority Research Program of the Chinese Academy of Sciences, and the Deep-time Digital Earth (DDE) Big Science Program. Reference: Xu Chunpeng, Wang Bo*, Wappler T., Chen Jun, Kopylov D., Fang Yan, Jarzembowski E.A., Zhang Haichun, Michael S.E. (2022) High acoustic diversity and behavioral complexity of katydids in the Mesozoic soundscape. PNAS, https://doi.org/10.1073/pnas.2210601119. Figure 1 Stridulatory files of Triassic katydids (A–C) and tympanal ears of Jurassic katydids (D–E). Figure 2 Frequency range of hearing in vertebrates (above) and frequency range of tones used by extant crickets and fossil katydids (below). Figure 3 The origins of some key acoustic evolutionary events according to the fossil evidence. Figure 4 Ecological restoration of singing katydids from the Middle Jurassic Daohugou Konservat-Lagerst？tte of China. Contact: LIU Yun, Propagandist Email: yunliu@nigpas.ac.cn Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences Nanjing, Jiangsu 210008, China A record of enhanced water cycle in the late Paleozoic icehouse
This study investigated two Mid-Ordovician shale-dominated successions from the intra-shelf basin (Zhenjin section) and slope (Anye-1 core) settings of the Yangtze Sea in South China, with a novel combination of iron speciation, trace metals, bulk δ15N and pyrite δ34S (Fig. 1). And, for the first time, δ98Mo profile was produced for the Mid-Ordovician black shale in South China. The Ordovician is a critical transition for the coevolution of life and environments, as it witnessed stepwise rise of atmospheric O2 and secular decline of CO2, as well as the blooming of marine fauna and the colonization of early land plants. Herein the rapid increase in diversity and complexity of ecosystem was defined as “Great Ordovician Biodiversification Event” (GOBE), for which several triggers have been proposed including climatic cooling, atmospheric oxygenation, sea level rise and even asteroid breakup. However, the biotic overturn following the peak of GOBE and its causes warrant further investigation. Recent literature by Dr. ZHANG Junpeng and Prof. ZHANG Yuandong from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), Prof. Timothy W. Lyons from University of Calofornia (Riverside) and Prof. Thomas J. Algeo from University of Cincinnati proposes that remarkable expansion of seafloor anoxia during the climatic cooling accounted for such profound biotic change, which has been published on the journal of Earth and Planetary Science Letters. This study investigated two Mid-Ordovician shale-dominated successions from the intra-shelf basin (Zhenjin section) and slope (Anye-1 core) settings of the Yangtze Sea in South China, with a novel combination of iron speciation, trace metals, bulk δ15N and pyrite δ34S (Fig. 1). And, for the first time, δ98Mo profile was produced for the Mid-Ordovician black shale in South China. The Anye-1 core yields a negative shift in δ15Nbulk upwards and low values ~ 1-2‰ (same for Zhenjin section) across the Darriwilian to Sandbian boundary, implying a gradual dominance of microbial N-fixation in the oceans (Fig. 1 and 2A). That consists with the moderate-high primary productivity and dysoxic-anoxic bottom-water conditions. While the iron proxy and δ34S reveal a progressive evolution of bottom-water redox conditions from oxic, ferruginous to euxinic in the slope of Yangtze Sea (Fig. 1, Interval I~IV). Similarly, the co-variation of enriched Mo and U indicates predominantly euxinic bottom-waters for the late Darriwilian to early Sandbian (Fig. 2B). Moreover, moderate Mo/TOC (~18 ppm/%) suggests semi-restricted watermass conditions for the Yangtze Sea (Fig. 2C). Thus, if the euxinic sediments of Ningkuo shale captured global seawater compositions, modeling reconstructed δ98MoSW of ~0.8-1.1‰, which is close to previous estimates for Ordovician seawater (1.1-1.3‰) and suggests that the oceans were less oxygenated, at least for Mid-Late Ordovician, than previously assumed. Notably, equivalent black shales of wide distribution on other continents include Saergan Formation in Tarim, Wulalike Formation in North China, Roadriver Group in Northwestern Laurentia and Alum Shale in Baltica. Those shales formed in the low-latitude continental basins that were easily influenced by upwelling. Similar to modern, during the climatic cooling, high-latitude deep and cold currents would have gotten strengthened and brought more nutrients into low-latitude shelves via upwelling. Under such scenario, more efficient nutrient cycling would stimulate primary production in the ocean surface and export massive organic carbon downwards to the seafloor, where the organic matter would get decomposed largely consuming dissolved oxygen and thus cause bottom-water anoxia. In pace with those environmental changes, the biodiversity yields a ~50% decline of species (South China, Fig. 3). Although the timing for the peak of GOBE is different for several continents, the overturn is considered to have appeared before the late Darriwilian. Therefore, climatic cooling and concurrent expansion of seafloor anoxia can be proposed as a fundamental trigger for the biotic crisis, which provides important evidence for the biotic overturn following the peak of GOBE and valuable implications for the link between icehouse ages and biotic extinctions in Earth history. This work is financially supported by Chinese Academy of Sciences, National Natural Science Foundation of China, Natural Science Foundation of Jiangsu Province, Ministry of Science and Technology of China, NASA Astrobiology Institute of USA. Analyses involved with this study were completed with the help of the State Key Lab, China University of Geosciences (Wuhan), Guiyang Institute of Geochemistry, Chinese Academy of Sciences and University of California (Riverside). Reference: Zhang, J.P.*, Li, C., Fang, X., Li, W.J., Deng, Y.Y., Tu, C.Y., Algeo, T.J., Lyons, T.W. and Zhang, Y.D., 2022. Progressive expansion of seafloor anoxia in the Middle to Late Ordovician Yangtze Sea: Implications for concurrent decline of invertebrate diversity. Earth and Planetary Science Letters, 598, p.117858. https://doi.org/10.1016/j.epsl.2022.117858. Fig.1 Geochemical profiles for Zhenjin section and Anye-1 core. Fig.2 Cross plots of proxies (A, B and C) and modeling results for seawater δ98Mo (D). Fig.3 Integrated framework of the change in climate, marine environment and biodiversity during Mid-Late Ordovician.
Contact: LIU Yun, Propagandist Email: yunliu@nigpas.ac.cn Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences Nanjing, Jiangsu 210008, China
How precipitation in the paleotropical belt would react to changes in paleoclimate during the late Paleozoic is not well understood. The late Paleozoic Ice Age (LPIA) was the longest-lived icehouse of the Phanerozoic and the only geological archive that recorded a permanent icehouse-to-greenhouse turnover on a planet with complex terrestrial ecosystems and metazoan life. Recently, the LPIA has been widely studied especially regarding the temporal and spatial distribution of glaciers on high-latitude regions, the causes for the onset and demise of glaciation, correlations and feedbacks among various components of the Earth system, and influences on biodiversity variations. The water cycle in response to the evolution of LPIA is, however, rarely studied, except for numerical modeling Paleoclimate simulations suggested a coupled relationship between Gandwanan ice volume and paleotropical climate dynamics on a multitude of timescales. General circulation models of the LPIA show that increased ice volume would intensify the Intertropical Convergence Zone (ITCZ) and resultant paleotropical precipitation. In contrast, climate simulations also indicate that increased precipitation in the tropical region would come along with atmospheric pCO2 and temperature rise. How precipitation in the paleotropical belt would react to changes in paleoclimate during the late Paleozoic is not well understood. The South China Block was dominated by a stable carbonate platform environment during the middle to late Paleozoic (Fig. 1). In addition, the South China Block was situated near the paleoequator in isolation during the late Paleozoic until it collided with the North China Block in the Late Permian to Early Triassic. Hence, the South China Block was free of significant tectonic activities during the late Paleozoic Recently, an integrated sedimentological and biostratigraphic study on a late Carboniferous mixed carbonate-siliciclastic succession (Fig. 2) from the southeastern South China Block is conducted by Dr. GAO Biao, Prof. CHEN Jitao, Prof. ZHENG Quanfeng, Dr. HUANG Xing, and Ph.D. student XIN Hao from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), in collaboration with Dr. HU Keyi from Nanjing University. The study established a high-precision biostratigraphic framework and recovered the sedimentary environment and its evolution based on sedimentary petrographic analysis, and identified an enhanced water cycle event due to climate changes during the Middle-Late Moscovian. The research achievements were published in the international journal Global and Planetary Change. The conodont and fusulinid biostratigraphy indicate that the Outangdi succession formed during the middle to late Moscovian. Twelve facies and five facies associations have been recognized in the Outangdi section, which suggest an overall carbonate ramp environment episodically interrupted by siliciclastic influx of braid delta (Fig. 3). An anomalous siliciclastic deposit (with thickness of ca. 5 m) around the Podolskian substage has been recognized in the Outangdi succession. Such an abrupt siliciclastic influx event has also been recorded in the Madiyi succession in central South China, as well as other sections in the tropical peri-Paleotethys regions in the late Moscovian. This abrupt increase of siliciclastic influx reflects an enhanced water cycle in the paleotropical zone due to climate changes responding to the demise of C4 glacial interval in the late Moscovian (Fig. 4). The research is supported by the National Natural Science Foundation of China, the Strategic Priority Research Program of the Chinese Academy of Sciences. Reference: Gao, B., Xin, H., Huang, X., Hu, K.Y., Zheng, Q.F., and Chen, J.T.* (2022), A record of enhanced water cycle in the late Paleozoic icehouse, Global and Planetary Change. 218, 103957. https://doi.org/10.1016/j.gloplacha.2022.103957. Figure 1. Tectonic framework and paleogeographic map of the Cathaysia Block during the late Carboniferous and location of the study area. Figure 2. Detailed sedimentologic logging of the Outangdi section. Figure 3. Depositional model. (A) Lower Outangdi succession (from -15.9 m to -3.8 m). (B) Upper Outangdi succession (from -3.8 m to 34.0 m). Figure 4. Global correlation of stratigraphy and inferred paleoclimate events during the Moscovian. (A) Synthesis of late Moscovian sedimentary and paleoclimate records in the paleotropical zone. (B) Paleogeographic map marked with paleoclimate belts in the late Carboniferous.
Contact: LIU Yun, Propagandist Email: yunliu@nigpas.ac.cn Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences Nanjing, Jiangsu 210008, China A record of enhanced water cycle in the late Paleozoic icehouse
PtilozamitesNathorst 1878 is a seed fern genus widely documented from the Early Mesozoic with over 140 years long history; but the systematic position of Ptilozamites was debated for decades. Ptilozamites Nathorst 1878 is a seed fern genus widely documented from the Early Mesozoic with over 140 years long history; but the systematic position of Ptilozamites was debated for decades. The investigation of Ptilozamitesin China had started in 1950 due to the first discovery of Ptilozamiteschinensisby Hsü in Hunan Province. However, the systematic affinity of this plant was once transferred to the genus Pseudoctenis because of the preservation of specimens with lack of cuticular structures. Recently, a new report was published in the international journal Review of Palaeobotany and Palynology by a research team led by Prof. WANG Yongdong from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Science (NIGPAS). The team members include Prof. Mihai E. Popa (University of Bucharest of Romania), Prof. Evelyn Kustatscher (Ludwig Maximulian University of Munich, Germany), Ph.D. student and palaeobotanists from NIGPAS XU Yuanyuan, Dr. ZHANG Xiaoqing, Dr. LU Ning, Dr. LI Liqin, as well as Prof. ZHANG Tingshan’s team from Southwest Petroleum University of China. The well-preserved fossil material belonging to Ptilozamiteschinensis was recently collected from the Upper Triassic Xujiahe Formation in Guangyuan City of northern Sichuan Basin and the Upper Triassic Xiaoping Formation in central Guangdong Province. The detailed morphology and anatomy of these materials were studied and a neotype and an emended diagnosis for Ptilozamiteschinensis were proposed. The pinnule apex of Ptilozamiteschinensis are truncate or tipped with 2–4 mucrones, which is regarded as a kind of intraspecific morphological variability (Figs. 1-2). The stomata are haplocheilic, with obviously sunken guard cells surrounded by 4–7 subsidiary cells (Fig. 3). The systematic investigation of the cuticular and the macro-morphological characters supports the assignment of the species to the genus Ptilozamites rather than to the previous proposal to genus Pseudoctenis. A comparison with the previously documented specimens of Ptilozamiteschinensis suggests a different overall morphology during the developmental process of this plant. The palaeogeographic distribution of Ptilozamiteschinensis indicates a preference for hot and humid habitats during the Late Triassic of the Southern Floristic Province, and can be considered as an important marker for the Rhaetian (Fig. 4). Its short stratigraphic range in the Southern Floristic Province (with no fossil record in the Northern Floristic Province) indicate that this taxon most likely lived in humid and hot environments and its final extinction after the Triassic/Jurassic boundary may represents an ecological response to the regional climate change. This study was co-sponsored by the National Natural Science Foundation of China, Strategic Priority Research Program (B) of the Chinese Academy of Sciences, the State Key Laboratory of Palaeobiology and Stratigraphy and Natural Science Foundation of Jiangsu Province, China. Reference: Yuanyuan Xu, Mihai E. Popa*, Xiaoqing Zhang, Evelyn Kustatscher, Ning Lu, Liqin Li, Jianli Zeng, Tingshan Zhang, Yongdong Wang*, 2022. Ptilozamiteschinensis (Pteridospermopsida) from the Late Triassic of South China with considerations on its intraspecific variability and palaeoenvironmental preferences. Review of Palaeobotany and Palynology, 304: 104727. https://doi.org/10.1016/j.revpalbo.2022.104727. Fig. 1.New material and cuticles of Ptilozamiteschinensis Hsu, 1950 from the Upper Triassic of South China. Fig. 2.Representative material of Ptilozamiteschinensis Hsu, 1950 from the Upper Triassic of South China, showing denticulate and rounded apices of pinnules. Fig. 3.Cuticles of Ptilozamiteschinensis Hsu, 1950 from the Upper Triassic of China, showing details of stomatal apparatus. Fig. 4.Palaeogeographic and geographical distribution of the outcrops yielding Ptilozamiteschinensis during the Late Triassic in China. Contact: LIU Yun, Propagandist Email: yunliu@nigpas.ac.cn Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences Nanjing, Jiangsu 210008, China
An international research team led by Dr. ZHANG Huaqiao from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences (NIGPAS) has used hundreds of new fossil specimens to clarify the anatomy and evolutionary affinity of Saccorhytus, originally thought to be a deuterostome. An international research team led by Dr. ZHANG Huaqiao from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences (NIGPAS) has used hundreds of new fossil specimens to clarify the anatomy and evolutionary affinity of Saccorhytus, originally thought to be a deuterostome. The study was published in Nature on Aug. 17. Dr. LIU Yunhuan from Chang'an University, Dr. XIAO Shuhai from Virginia Tech, Dr. Philip C. J. Donoghue and Miss Emily Carlisle from the University of Bristol, and Dr. Michael Steiner from Shandong University of Science and Technology were also involved in the study. Saccorhytus, which was originally described in 2017, was discovered from the Cambrian Fortunian Zhangjiagou section of southern Shaanxi Province, China. It was interpreted to be an ancestral deuterostome. It is microscopic in size—about a millimetre in diameter—and resembles a spiky, wrinkly sack. Its mouth is surrounded by radial folds, nodes, and holes that were originally interpreted as pharyngeal openings—a primitive feature of deuterostomes. However, the evidence supporting Saccorhytus being a deuterostome was always very weak. Were those holes around the mouth really pharyngeal openings? To address this question, the research team collected hundreds of new Saccorhytus specimens from the Cambrian Fortunian Zhangjiagou and Shizhonggou sections of southern Shaanxi Province. Many of the specimens were much better preserved than any seen before, thus providing new information about the anatomy and evolutionary affinity of Saccorhytus. Based on these discoveries, the anatomy of Saccorhytus is now clear. Saccorhytus has a millimetric, ellipsoidal body, with one half slightly wider than the other half. Its integument is two-layered and non-ciliated. The mouth is situated terminally, and is surrounded by radial folds, one circlet of circumoral protuberances, and one to five large protuberances on one side of the body; all protuberances have a central main spine flanked by two lateral spines with a closed tip. Four to eight pairs of body cones are bilaterally arranged around the oral-aboral axis, each with an expanded conical base that is ornamented with longitudinal folds and supports an apical spine with a closed tip. Many nodes occur on the same side of the body as the large protuberances. In addition, many small, sharp-tipped spines are positioned on the aboral side of the body. No internal biological structures are preserved and the anus is absent. The team interpreted the integument as cuticle rather than epidermis. This is because cuticle contains multiple sub-layers (i.e., epicuticle, exocuticle, and endocuticle), whereas epidermis contains a single, very thin layer of epithelial cells. Furthermore, cuticle is decay-resistant and has relatively high fossilization potential, whereas epidermis is soft and decays quickly after death. This interpretation is consistent with the abundance of Saccorhytus specimens in the studied rocks, indicating that they have relatively high preservation potential. It is also consistent with experimental taphonomy on ecdysozoans, which shows that ecdysozoan epidermis, muscles, and visceral organs decay very quickly after death, leaving only cuticular structures and intestines. The researchers found that the circumoral/large protuberances, body cones, and small spines are all spinose structures with closed, sharp tips. Since the body cones have no openings, they cannot be interpreted as possible pharyngeal openings. The integument represents cuticle, with no trace of cilia, implying that the underlying epidermis is non-ciliated. The mouth has now been reinterpreted as terminal rather than ventral. Saccorhytus has three body axes. The terminal mouth defines the oral-aboral axis; the distribution of body cones defines the left-right axis; whereas the polarized distribution of nodes and large protuberances defines the third axis. Thus, Saccorhytus belongs to Bilateria and the three body axes represent the anterior-posterior axis, left-right axis, and dorsal-ventral axis, respectively. Saccorhytus is different from any known bilaterians in general morphology and body plan, but the research team have been able to find four key characteristics that help address the affinity of Saccorhytus, including a terminal mouth, the presence of cuticle, non-ciliated epidermis, and the presence of radially arranged circumoral structures. This suite of characteristics generally occurs in ecdysozoans. In particular, radially arranged circumoral structures are common to Cambrian and extant ecdysozoans. In other words, evidence pointed to Saccorhytus being an ecdysozoan. In order to test the ecdysozoan hypothesis, the research team conducted a comprehensive morphology-based phylogenetic analysis along with several experiments to test different possibilities. In all tests, results supported the hypothesis that Saccorhytus belongs to the total-group Ecdysozoa; conversely, the deuterostome and cnidarian hypotheses were not supported. Saccorhytus now represents one of the earliest known ecdysozoans. Although the exact position of Saccorhytus within the total-group Ecdysozoa is unclear, the sac-like body of Saccorhytus challenges the traditional worm-like body of ecdysozoans. It also implies that the ancestor of the ecdysozoans may not be worm-like. All in all, the origin of the ecdysozoan body plan awaits further study of the interrelationships among the earliest known ecdysozoans in the Cambrian Fortunian Age. SEM images of Saccorhytus coronarius Artistic reconstructions and phylogenetic position of Saccorhytus coronarius. A, anterior view; B, left view; C, posterior view; D, Saccorhytus is a total-group ecdysozoan Contact: LIU Yun, Propagandist Email: yunliu@nigpas.ac.cn Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences Nanjing, Jiangsu 210008, China
