Trace fossils, as behavioural records of organisms in the geological past, have been proved useful in deciphering the mechanisms and timing of biotic recovery after mass extinctions. In many cases, trace fossils record the behaviours of soft-bodied organisms that have null to very limited preservation potential in the fossil record. They often provide significant ecologic information on ancient communities not available from the study of body fossils. Trace fossils, as behavioural records of organisms in the geological past, have been proved useful in deciphering the mechanisms and timing of biotic recovery after mass extinctions. In many cases, trace fossils record the behaviours of soft-bodied organisms that have null to very limited preservation potential in the fossil record. They often provide significant ecologic information on ancient communities not available from the study of body fossils. More and more ichnologists focused on ichnological records during mass extinctions and subsequent biotic recovery intervals, with numerous studies emphasizing ichnological proxies as indicators of biotic recovery process after the latest Permian, when the the end-Permian mass extinction (EPME) has caused the highest biodiversity loss coupled with the most profound ecological impact in Phanerozoic Earth history. The vast majority of ichnological studies have focused on elucidating the timing and patterns of ecosystem recovery after the EPME, leading to the establishment of various ichnological parameters (e.g., ichnodiversity, bioturbation indices, bedding plane bioturbation indices, burrow sizes, tiering, trace-fossil complexity) as proxies for unraveling the pacing and processes of biotic recovery in the Early Triassic. However, some recognitions derived from ichnological studies seem to be inconsistent with those from body fossil observations (prolonged, stepwise recovery versus fast recovery). In addition, there are also cases whereby different ichnologists choose to use different parameters (e.g., ichnofabric indices and bioturbation indices) for documenting the same ichnological features. These discrepancies pose a need to critically evaluate current and popular ichnological parameters and the scopes of their applicability. Recently, Dr. LUO Mao from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS) in collaboration with Prof. SHI Guangrong from University of Wollongong (Australia), Prof. Buatois from University of Saskatchewan (Canada), and Prof. CHEN Zhongqiang from China University of Geoscience (Wuhan) presented a critical review on the use of various ichnological parameters as relative proxies for unravelling ecosystem recovery after the EPME in order to place them on more solid theoretical grounds. In their study, the significance and caveats of various ichnological parameters and their limitations are clarified and discussed in detail, in the hope that these proxies will be more appropriately used in the future studies dealing with mass extinctions and biotic recoveries. Related research results has been published online in the comprehensive geology journal Earth-Science Reviews. According to Dr. LUO Mao, ichnodiversity, ichnodisparity, burrow sizes are good indicators of biotic recovery, while bedding plane bioturbation indices remain to be explored further as various studies suggest that on bedding planes, trace-fossil distribution can be heterogeneous on a scale of meters to decimeters. In terms of tiering, the composition of the different tiers (e.g., shallow, intermediate, and deep tier) should be reconstructed rather than only considering the penetration depth of burrows. Further, it is worth noting that evaluating the benthic ecospace occupation and ecosystem engineering through the analysis of trace fossils would be a promising approach. Based on current ichnological studies from the Permian-Triassic interval and researchers own observations, Dr. LUO Mao and his collaborators have reached several main recognitions for biotic recovery after the end-Permian mass extinction. These are: (1) Distribution of varying oxic conditions results in the disparate patterns of benthic macrofaunal recovery (including trace-making organisms) in the Early Triassic. Such oxic conditions in the shallow-marine ‘habitable zone’ possibly aid a faster recovery of trace-making organisms in the earliest Triassic. (2) The widespread matground-dominated ecosystems could have inhabited a variety of metazoans (including trace makers) during the Earl Triassic recovery interval. (3) Low bioturbation intensities in the Lower Triassic strata may be a reason leading to enhanced pyrite burial and prolonged low sulfate concentrations in the Early Triassic ocean. This research has been supported by the Strategic Priority Research Program of the Chinese Academy of Sciences, the CAS Pioneer Hundred Talents Program, and by grants from NSFC. Reference: Luo, M*., Shi, G.R., Buatois, L.A., Chen, Z.Q., 2020. Trace fossils as proxy for biotic recovery after the end-Permian mass extinction: A critical review. Earth-Science Reviews, Volume 203, 103059. Trend of ichnodiversity along a depositional profile (modified from Buatois and Mángano, 2013)
Trend of burrow-size changes for typical ichnotaxa (Planolites, Rhizocorallium, Thalassinoides) from Permian to Middle Triassic (global data) Tiering structure as expressed by the maximum penetration depth and ichnological composition at different sediment depths
Integrated marine geochemical variations and general bioturbation intensity during the Permian-Triassic interval, with geochemical cycling models established for the Late Permian, Early Triassic, and Middle Triassic respectively
Ordovician corals in eastern Australia are mostly confined to the Upper Ordovician series, with the earliest tabulates occurring in strata which span the uppermost Darriwilian (upper Middle Ordovician) to basal Sandbian (lower Upper Ordovician) interval. Recognition of the biostratigraphic utility of coral faunas in the field as an adjunct to mapping Ordovician limestones in NSW led previous authors to propose a series of four coral/stromatoporoid faunas: C/S I–IV from oldest (Eastonian 1, equivalent to latest Sandbian–earliest Katian) to youngest (Bolindian 1–2, or latest Katian). Such a local biostratigraphic framework permits an accurate means of dating field collections in the region, and has also enhanced our understanding of the evolutionary history of corals and stromatoporoids during this time interval. Ordovician corals in eastern Australia are mostly confined to the Upper Ordovician series, with the earliest tabulates occurring in strata which span the uppermost Darriwilian (upper Middle Ordovician) to basal Sandbian (lower Upper Ordovician) interval. Recognition of the biostratigraphic utility of coral faunas in the field as an adjunct to mapping Ordovician limestones in NSW led previous authors to propose a series of four coral/stromatoporoid faunas: C/S I–IV from oldest (Eastonian 1, equivalent to latest Sandbian–earliest Katian) to youngest (Bolindian 1–2, or latest Katian). Such a local biostratigraphic framework permits an accurate means of dating field collections in the region, and has also enhanced our understanding of the evolutionary history of corals and stromatoporoids during this time interval. Corals representing the sole occurrence of C/S Fauna IV of the regional biostratigraphic scheme occur in limestone in the uppermost Malachis Hill Formation of the Bowan Park area, central New South Wales. Though this coral fauna is restricted to a relatively thin limestone band, exposed intermittently for approximately 1.5 km, its significance greatly outweighs this in terms of completing the coral biostratigraphic scheme and also in contributing to the knowledge of the biogeographic relationships of the region in the Late Ordovician. Recently, Dr. WANG Guangxu from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS) and his colleagues Ian. G. Percival and ZHEN Yong Yi from Geological Survey of New South Wales described corals from the uppermost Malachis Hill Formation in central NSW. Related research results have been published online in the international geoscience journal Alcheringa. New species described and illustrated from this fauna include the rugosan Bowanophyllum ramosum and tabulate Hemiagetiolites longiseptatus. Also three other distinct species of Hemiagetiolites, H. spinimarginatus (Hall, 1975), H. cf. H. palaeofavositoides (Lin & Chow, 1977) and H. sp., an unnamed species of Paleofavosites, and three heliolitine corals, Heliolites waicunensis Lin & Chow, 1977, Navoites cargoensis (Hill, 1957) and Plasmoporella sp. were documented. These descriptions, which complete knowledge of the entire fauna collected over 50 years, enable interesting conclusions to be drawn regarding palaeogeographic affinities of this youngest in situ Ordovician coral fauna known from eastern Australia. Its remarkable similarities to contemporaneous coral faunas from South Tien Shan and the Chu-Ili Terrane indicate strong connections between eastern Australia and the latter two terranes, supporting their positioning in equatorial latitudes of eastern peri-Gondwana. However, it is puzzling that fewer similarities exist between the eastern Australian coral fauna and those from rocks of Katian age in SE China, which may be due to either a slightly younger age of the former fauna or a relatively higher palaeolatitudinal position of South China. This research was jointly supported by the National Science Foundation of China, the Strategic Priority Research Program (B) of the Chinese Academy of Sciences. Reference: Wang, G. X., Percival, I. G. & Zhen, Y. Y., 2020. The youngest Ordovician (latest Katian) coral fauna from eastern Australia, in the uppermost Malachis Hill Formation of central New South Wales. Alcheringa (https://doi.org/10.1080/03115518.2020.1747540) A new rugose coral Bowanophyllum ramosum documented from the Malachis Hill Formation of central New South Wales, eastern Australia
Cordaitaleans, as close relatives of modern conifers, had a long geological history in the Cathaysia from the Visean (Mississippian, lower Carboniferous) to the end of Permian. They became prominent since the late Pennsylvanian, and best developed during the Cisuralian (early Permian) in North China, serving as the volumetrically dominant to subdominant elements of wetland floras. Architecture and ecology of the Cathaysian cordaitaleans from non-peat-forming environments are poorly known. Cordaitaleans, as close relatives of modern conifers, had a long geological history in the Cathaysia from the Visean (Mississippian, lower Carboniferous) to the end of Permian. They became prominent since the late Pennsylvanian, and best developed during the Cisuralian (early Permian) in North China, serving as the volumetrically dominant to subdominant elements of wetland floras. Architecture and ecology of the Cathaysian cordaitaleans from non-peat-forming environments are poorly known. Dr. WANG Mingli and other researchers from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), recently found 211 giant cordaitalean trunks and described their morphology and brief anatomical features from the Cisuralian Taiyuan Formation in Yangquan, Shanxi Province, North China. This results have been published online in Palaeoworld. It is reported that the discovery of the giant cordaitalean trunks has attracted great attention from the local government, and has been listed as a key protection object by the Yangquan City Planning and Natural Resources Bureau. It is planned to build a fossil remains park and museum on this basis. These trunks are characterized by the Artisia-like pith and pycnoxylic xylem. Absence of growth rings in the logs suggests they grew under non-seasonal humid tropical conditions. They are preserved in sandstone bodies interpreted as deposits of distributary river channels on the delta plain. Several trunks with attached rooting systems indicate that these trees may have been growing on channel levees or delta plains and brought into the channels by lateral bank erosion. Allometric estimates of tree height suggests that the largest trees were up to approximately 43.5 m tall. Mature cordaitaleans with straight trunks were probably the tallest trees and formed the canopy of the riparian forest in North China during the Cisuralian. This study was supported by the Strategic Priority Research Program (B) of the Chinese Academy of Sciences, the National Natural Science Foundation of China, Youth Innovation Promotion Association CAS and the National Science Foundation. Reference: Wan, M.L., Yang, W., Wan, S., Li, D.D., Zhou, W.M., He, X.Z., Wang, J., 2020. Giant cordaitalean trees in early Permian riparian canopies in North China: Evidence from anatomically preserved trunks in Yangquan, Shanxi Province. Palaeoworld, https://doi.org/10.1016/j.palwor.2020.04.008
Chrono- and lithostratigraphy of the Taiyuan Formation in Yangquan, Qinshui Basin, Shanxi Province, North China(A), in addition to the gross morphology (B-D) and anatomical features (E-H) of the trunks.
Reefs are important marine ecosystems in marine, and an excellent tool for tracking marine ecosystem changes, especially through mass extinction transitions. During the geological history, the earliest marine reef ecosystems were formed of stromatolites and flourished during the Precambrian before declining in the Phanerozoic. Metazoan reefs first appeared in the late Ediacaran and proliferated during the Phanerozoic, albeit with time gaps after mass extinction events, which are often marked by microbial reef proliferation. During the Middle-Late Devonian, the largest area of metazoan (stromatoporoid-coral) reefs of the Phanerozoic occurred, which covered about five million square kilometres (10 times the surface area of modern reef ecosystems). The Late Devonian Frasnian-Famennian (F-F) Kellwasser and the end-Devonian Hangenberg extinctions caused the collapse and disappearance of stromatoporoid-coral ecosystems, respectively. The succeeding Mississippian has long been assumed to be an interval dominated by microbial reefs, and lack of metazoan reefs. Small-sized metazoan reefs gradually reappeared during the middle-late Mississippian (Visean Stage). However, due to low-resolution and limited data available in previous studies, the timing and style of metazoan reef recovery in the Mississippian are unclear. Recently, Dr. YAO Le from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), Dr. Markus Aretz from the University of Toulouse 3, and Prof. Paul, B. Wignall from the University of Leeds, systematically reviewed and documented the reef composition, distribution and evolutionary process from the Late Devonian to Mississippian, and uncovered the re-emergence of the Mississippian coral reef ecosystems after the Late Devonian mass extinctions. Relevant findings were published online on 16th December, 2019 in Earth-Science Reviews. Previous reports of the late Visean coral bioconstructions from the Western Europe and North Africa (western Palaeotethys Ocean), may mark the first metazoan reef proliferation after the Hangenberg extinction. In this study, abundant coral reefs, coral frameworks and coral biostromes were described from the late Visean strata on the South China Block (eastern Palaeotethys Ocean). The occurrence of these coral bioconstructions further suggests that the late Visean coral reef recovery may have been a widespread phenomenon. Based on the high-resolution reef database constructed in this study, three sub-intervals of the Mississippian metazoan reef recovery were distinguished, which are (1) metazoan “reef gap” phase (MRG) without metazoan reefs during the Tournaisian; (2) metazoan reef re-establishment phase (MRR) containing a few metazoan reefs from early Visean to early part of the late Visean; and (3) metazoan reef proliferation phase (MRP) with global coral reef flourishment during the middle part of the late Visean (late Asbian to early Brigantian substages). Coral reef proliferation at this time showed that the Mississippian was not solely a period dominated by microbial reefs. Late Visean coral reef development coincided with increased nektonic and benthic diversity, showing that stable marine ecosystems developed during this time. Even compared with other slow reef-recovery intervals, such as the middle-late Cambrian and Early-Middle Triassic with the intervals until the MRR and MRP of 5 Ma and 2 Ma, and 15 and 9 Ma respectively, the Mississippian metazoan reef recovery was the longest in reef history with about 12 Ma and 23 Ma until the MRR and MRP, respectively. Harsh climatic and oceanic conditions were present during the Mississippian, mainly including the widespread marine anoxia during the middle part of Tournaisian and the following recurrent glacial and interglacial climatic episodes with frequent changes in sea level, sedimentary facies and sea-water surface temperature, which may have stymied metazoan reef recovery during this time. During the late Visean, marine communities flourished during a phase of relative warm conditions and high sea level, and coincided with the long-delayed re-emergence of coral reef ecosystems after the Late Devonian extinctions. This research was supported by the Strategic Priority Research Program (B) of the Chinese Academy of Sciences, the National Natural Science Foundation of China, and the Natural Science Foundation of Jiangsu Province. Article information：Yao, L*., Aretz, M., Wignall, P.B., Chen, J.T., Vachard, D., Qi, Y.P., Shen S.Z., Wang, X.D., 2019. The longest delay: Re-emergence of coral reef ecosystems after the Late Devonian extinctions. Earth-Science Reviews. DOI: https://doi.org/10.1016/j.earscirev.2019.103060. Composition and evolutionary pattern of the Late Devonian to Mississippian reefs, and their relations to coeval changes in reef builders and palaeoenvironments Field (A-E), polished-slab (F-G) and thin-section photographs of the late Visean (Mississippian) coral reefs in South China
Field photographs of the late Visean coral reefs from other areas, e.g., Morocco (A), England (B-D), Australia (E) and Japan (F)
Taxaceae, commonly known as yews, is widely cultivated all over the world and has been loved by most people. Taxaceae sensu stricto includes Taxus (yew), Pseudotaxus (whiteberry yew), Amentotaxus (catkin-yew), Austrotaxus (New Caledonia yew), and Torreya. Many species of yews are endangered in the wild. Extant Amentotaxus comprises five to six species, which all are the endangered species on the IUCN list. The Taxaceae has a long history as the earliest group in the fossil record appeared in the earliest Jurassic, and probably had a certain diversity during the Jurassic and the Cretaceous. However, well-preserved fossil yews carrying important information have been extremely limited, especially absence of fossils preserved with reproductive organs, which result in the insufficient of our understanding of the origin and early evolution of the Taxaceae. Recently, Dr. DONG Chong, Dr. SHI Gongle, and Professor WANG Yongdong of the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Science (NIGPAS), and other members from the Chicago Botanic Garden, the Oak Spring Gardens Foundation and School of Forestry and Environmental Studies, Yale University, collaborated with a research focusing on the Middle？Late Jurassic yew fossils from the Daohugou Biota in northeastern China. Comparative morphological evidence and morphological phylogenic analysis both support that the fossils can be assigned to the genus Amentotaxus. The results show that, like Ginkgo, the catkin-yew is another living fossil dating back to the Middle？Late Jurassic that have undergone little morphological change over at least ~ 160 million years. This study was published online on June 2020 in the National Science Review, a high-level comprehensive academic journal. The fossils were collected from the Daohugou Bed in the Daohugou village in Ningcheng County, Inner Mongolia. Well-preserved catkin-yew fossil shoots have linear-lanceolate leaves borne in opposite pairs that are decussately inserted, and opposite ultimate shoots that spread in more or less a single plane. Attached seed-bearing structures arise singly from the axil of a normal vegetative leaf and consist of a short, naked axis bearing a single terminal seed that is enclosed by up to five pairs of opposite and decussate bracts. These features closely resemble those of the extant catkin-yew Amentotauxs. A close relationship of the Daohugou fossils to extant catkin-yews is consistent with the results of a phylogenetic analysis based on 13 groups scored for three Jurassic Taxaceae fossil species, and six extant species representing Cephalotaxus and the five genera Taxaceae. Both an unconstrained analysis and an analysis with the relationships of extant Taxaceae constrained to the topology of the molecular phylogeny support that it would be reasonable to assign to the Daohugou fossils to the catkin-yew Amentotauxs. The Middle？Late Jurassic Daohugou fossils confirm that the origin of the catkin-yew was at least 160 million years ago. “Living fossil” firstly appeared in Darwin’s book on the Origin of Species in 1859. The morphological stasis reflected by the “Living fossil” is one of the most interesting scientific topics in evolutionary biology. China is rich in plant diversity, including a large number of ancient families or genera and relict groups. The credible fossil record of relictual genera such as Craigia, Davidia, Cyclocarya and Metasequoia extend back to the early Cenozoic, and Taiwania and Hedyosmum extend back into the Cretaceous. However, the extent of morphological stasis between Daohugou fossils and extant Amentotaxus highlights that, like Ginkgo, Amentotaxus is a living fossil and its earliest record extends back into the Jurassic. This research was jointly supported by the National Science Foundation of China, the Strategic Priority Research Program (B) of the Chinese Academy of Sciences, the U. S. National Science Foundation, and Youth Innovation Promotion Association, CAS. Article reference: Dong Chong, Shi Gongle*, Herrera F., Wang Yongdong, Herendeen P. S., Crane P. R., Middle-Late Jurassic fossils from northeastern China reveal morphological stasis in the catkin-yew. National Science Review. https://doi.org/10.1093/nsr/nwaa138 (a, b) cf. Amentotaxus from the Middle-Late Jurassic Daohugou Bed in eastern Inner Mongolia; (c, d) Extant Amentotaxus; (e, f) Reconstructive drawings of the cf. Amentotaxus from the Daohugou biota.
Nature is full of colors, from the radiant shine of a peacock’s feathers or the bright warning coloration of toxic frogs to the pearl-white camouflage of polar bears. Nature is full of colors, from the radiant shine of a peacock’s feathers or the bright warning coloration of toxic frogs to the pearl-white camouflage of polar bears. Usually, fine structural detail necessary for the conservation of color is rarely preserved in the fossil record, making most reconstructions of the fossil based on artists’ imagination. A research team from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences (NIGPAS) has now unlocked the secrets of true coloration in the 99-million-year-old insects. Colors offer many clues about the behaviour and ecology of animals. They function to keep organisms safe from predators, at the right temperature, or attractive to potential mates. Understanding the coloration of long-extinct animals can help us shed light on ecosystems in the deep geological past. The study, published in Proceedings of the Royal Society B on July 1, offers a new perspective on the often overlooked, but by no means dull, lives of insects that co-existed alongside dinosaurs in Cretaceous rainforests. Researchers gathered a treasure trove of 35 amber pieces with exquisitely preserved insects from an amber mine in northern Myanmar. “The amber is mid-Cretaceous, approximately 99 million years old, dating back to the golden age of dinosaurs. It is essentially resin produced by ancient coniferous trees that grew in a tropical rainforest environment. Animals and plants trapped in the thick resin got preserved, some with life-like fidelity,” said Dr. CAI Chenyang, associate professor at NIGPAS who lead the study. The rare set of amber fossils includes cuckoo wasps with metallic bluish-green, yellowish-green, purplish-blue or green colors on the head, thorax, abdomen, and legs. In terms of color, they are almost the same as cuckoo wasps that live today, said Dr. CAI. The researchers also discovered blue and purple beetle specimens and a metallic dark-green soldier fly. “We have seen thousands of amber fossils but the preservation of color in these specimens is extraordinary,” said Prof. HUANG Diying from NIGPAS, a co-author of the study. “The type of color preserved in the amber fossils is called structural color. It is caused by microscopic structure of the animal’s surface. The surface nanostructure scatters light of specific wavelengths and produces very intense colors. This mechanism is responsible for many of the colors we know from our everyday lives,” explained Prof. PAN Yanhong from NIGPAS, a specialist on palaeocolor reconstruction. To understand how and why color is preserved in some amber fossils but not in others, and whether the colors seen in fossils are the same as the ones insects paraded more than 99 million years ago, the researchers used a diamond knife blades to cut through the exoskeleton of two of the colorful amber wasps and a sample of normal dull cuticle. Using electron microscopy, they were able to show that colorful amber fossils have a well-preserved exoskeleton nanostructure that scatters light. The unaltered nanostructure of colored insects suggested that the colors preserved in amber may be the same as the ones displayed by them in the Cretaceous. But in fossils that do not preserve color, the cuticular structures are badly damaged, explaining their brown-black appearance. What kind of information can we learn about the lives of ancient insects from their color? Extant cuckoo wasps are, as their name suggests, parasites that lay their eggs into the nests of unrelated bees and wasps. Structural coloration has been shown to serve as camouflage in insects, and so it is probable that the color of Cretaceous cuckoo wasps represented an adaptation to avoid detection. “At the moment we also cannot rule out the possibility that the colors played other roles besides camouflage, such as thermoregulation,” adds Dr. CAI. This research was supported by the National Natural Science Foundation of China, Chinese Academy of Sciences, and the Youth Innovation Promotion Association, CAS. Reference: Cai C*, Tihelka E, Pan Y*, Yin Z, Jiang R, Xia F, Huang D. (2020) Structural colours in diverse Mesozoic insects. Proc. R. Soc. B 287: 20200301. doi:10.1098/rspb.2020.0301 Fig. 1. Diverse structural-colored insects in mid-Cretaceous amber from northern Myanmar (Image by NIGPAS) Fig. 2. Comparisons between original and altered metallic colors in cleptine wasps (Image by NIGPAS)
Macroalgae, which are usually multicellular or coenocytic eukaryotes, play an important role, both ecologically and biogeochemically, in modern marine ecosystems. Molecular clock studies suggest that eukaryotic algae have an evolutionary deep history tracing back to the Paleoproterozoic to Mesoproterozoic. However, fossil biomarkers indicate that prokaryotes were the only notable primary producers in pre-Cryogenian oceans and it was not until the Cryogenian that eukaryotic algae rose to ecological prominence. The fossil record of macroalgae during the Tonian Period is poorly documented, hampering our ability to evaluate the potential ecological and geobiological importance of early macroalgae. Moreover, compared with Ediacaran macroalga assemblages, the taxonomic diversities of Tonian macroalga assemblages are usually considered much lower and their morphology relatively simple. Macroalgae, which are usually multicellular or coenocytic eukaryotes, play an important role, both ecologically and biogeochemically, in modern marine ecosystems. Molecular clock studies suggest that eukaryotic algae have an evolutionary deep history tracing back to the Paleoproterozoic to Mesoproterozoic. However, fossil biomarkers indicate that prokaryotes were the only notable primary producers in pre-Cryogenian oceans and it was not until the Cryogenian that eukaryotic algae rose to ecological prominence. The fossil record of macroalgae during the Tonian Period is poorly documented, hampering our ability to evaluate the potential ecological and geobiological importance of early macroalgae. Moreover, compared with Ediacaran macroalga assemblages, the taxonomic diversities of Tonian macroalga assemblages are usually considered much lower and their morphology relatively simple. A team of scientists led by Dr. PANG Ke from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), and Drs. LI Guangjin and CHEN Lei from Shandong University of Science and Technology collected thousands of specimens from a fossiliferous horizon in the ca.~910 Ma to ~720 Myr rocks (Shiwangzhuang Formation, Tumen Group) from western Shandong Province, North China. Related results have recently been published in the Precambrian Research. The Shiwangzhuang assemblage consists of macroscopic and diversified carbonaceous compression fossils. In total, the Shiwangzhuang assemblage consists of twelve genera, sixteen species and one type of unnamed filaments, including a new genus and six new species: Anqiutrichoides constrictus n. gen. and sp.; Eosolena magna n. sp.; Protoarenicola baishicunensis n. sp.; Protoarenicola shijiacunensis n. sp.; Pararenicola gejiazhuangensis n. sp.; Sinosabellidites huangshanensis n. sp. The taxonomic diversity of the Shiwangzhuang assemblageis remarkable. It is more diverse than many other Tonian macrofossil assemblages all over the world. Indeed, the Shiwangzhuang assemblage nearly matches the Ediacaran Lantian and Miaohe biotas in terms of taxonomic diversity. Eleven taxa of the Shiwangzhuang assemblage are likely eukaryotic organisms on the basis of morphological features and sub-millimetric to millimetric size, whereas four taxa of the Shiwangzhuang assemblage are likely of cyanobacterial origin and two taxa are left undetermined in terms of biological affinity. Three taxa, including Anqiutrichoides constrictus, Eosolena magna, and Chuaria colony, show evidence of simple multicellularity with delicately preserved cellular structure. Among them, Anqiutrichoides constrictus and Eosolena magna consist of submillimetric to millimetric giant cells and comparable to giant-celled green algae. Seven tubulartaxa, including Protoarenicola baiguashanensis, Protoarenicola baishicunensis, Protoarenicola shijiacunensis, Pararenicola huaiyuanensis, Pararenicola gejiazhuangensis, Sinosabellidites huainanensis, and Sinosabellidites huangshanensis, are likely coenocyticalgae with diagnostic transverse annulations. Among them, Protoarenicolais characterized byannulated tubes with a bulbous terminal structure at one end, Pararenicola is characterized by annulated tubes with a constricted opening at one end and a round and closed termination at the other end, and Sinosabellidites is characterized by annulated tubes with two round and closed ends. The new Shiwangzhuang assemblage provides an important window onto the evolution of pre-Cryogenian macroalgae. It indicates that some eukaryotic clades had achieved macroscopic growth through simple multicellularity or coenocytism, paving the way, either ecologically or phylogenetically, for the eventual appearance of complex multicellularity. The abundant occurrence of diverse macroalgae in the Shiwangzhuang Formation also implies that the Tonian diversity of multicellular or coenocytic macroalgae is probably underestimated and macroscopic photoautotrophs may have played important roles, both ecologically and geobiologically, at least at a local scale in the Tonian. In addition, there are some biostratigraphically significant genera, including the Chuaria-Tawuia and Sinosabellidites-Protoarenicola-Pararenicola assemblages, indicating a Tonian age for the Shiwangzhuang Formation. This research was supported by the National Key Research and Development Program of China, National Natural Science Foundation of China, Chinese Academy of Sciences, Shandong University of Science and Technology Research Fund, Taishan Scholars Project, and State Key Laboratory of Palaeobiology and Stratigraphy. Reference: Li, G#., Chen, L.#*, Pang, K.*, Zhou, G., Han, C., Yang, L., Lv, W., Wu, C., Wang, W., Yang, F. An assemblage of macroscopic and diversified carbonaceous compression fossils from the Tonian Shiwangzhuang Formation in western Shandong, North China. Precambrian Research,2020, 346: 105801. Fig.1 Chuariacircularis and Chuaria colonies (A-C), Tawuia dalensis (E-G), Vendotaenia sp. (H-I), Mucoplagum primitivum (J), Glomulus filamentum (K), Unnamed filaments (L) and Beltina danai (M) from the Shiwangzhuang assemblage Fig.2. Protoarenicola baiguashanensis (A-B), Protoarenicola baishicunensis n. sp. (C-E), Protoarenicola shijiacunensis n. sp. (F-G), Pararenicola huaiyuanensis (H-I), Pararenicola gejiazhuangensis n. sp. (J–K), Sinosabellidites huainanensis (L), Sinosabellidites huangshanensis n. sp. (M) from the Shiwangzhuang assemblage Fig.3 Anqiutrichoides constrictus n. gen. and sp. (A-E) and Eosolena magna n. sp. (F-J) from the Shiwangzhuang assemblage
The Ediacara biota (580–541 Ma) documents an important evolutionary episode just before the Cambrian explosion and marks the first appearance of macroscopic and complex multi-cellular life. Most Ediacara-type fossils were preserved as casts and molds in sandstone successions, but several recent studies have shown that some taxa of the Ediacara biota can also be preserved as casts and molds in carbonate successions or as carbonaceous. The Ediacara biota (580–541 Ma) documents an important evolutionary episode just before the Cambrian explosion and marks the first appearance of macroscopic and complex multi-cellular life. Most Ediacara-type fossils were preserved as casts and molds in sandstone successions, but several recent studies have shown that some taxa of the Ediacara biota can also be preserved as casts and molds in carbonate successions or as carbonaceous. In addition, and some of these taxa also extend to the early Ediacaran Period. Various Ediacaran strata in South China, including black shales in the Doushantuo/Lantian Formation and limestones in the Shibantan Member of the Dengying Formation, are known to preserve Ediacara-type fossils and they offer an opportunity to broaden our view of the stratigraphic, environmental, and taphonomic distributions of the Ediacaran macrofossils. Recently, Dr. WAN Bin, and other members of the Innovative Research Group on ‘Origin and early evolution of multi-cellular life from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), collaborated with researchers from Virginia Tech and University of California at Riverside of USA, and Birbal Sahni Institute of Palaeosciences of India discovered a common Ediacara-type fossil Flabellophyton among the Lantian and Shibantan biotas form South China and Ediacara biota form South Australia. This study was recently published as Focus review on the Gondwana Research, Flabellophyton was the representative genus of early Ediacaran Lantian biota (635-580 Ma) preserved as carbonaceous compressions in black shales of the Lantian Formation, and later was founded from the Ediacara biota (560-550 Ma) form South Australia preserved as casts and molds in the Ediacara Sandstone. Recently, it was discovered from the Shibantan biota (550-539 Ma), and preserved as casts and molds in the Shibantan Limestone of the Dengying Formation. This discover makes Flabellophytonthe only genus that occurs in all three taphonomic modes. In this study, they provided a systematic description of Flabellophyton based on material from the Lantian and Dengying formations in South China, recognizing three morphospecies—F. lantianense, F. typicum sp. nov., and F. obesum sp. nov. Based on morphological and structural characters, Flabellophyton is reconstructed as an erect epibenthic marine organism attached to sandy, carbonate, and muddy substrates. Its phylogenetic affinity remains ambiguous though it was historically interpreted as an algal fossil. Flabellophyton occured in all three taphonomic modes, allowing comparative ecological and taphonomic analyses. First, taphonomic analysis of Flabellophyton indicates that multiple taphonomic pathways can facilitate the preservation of Ediacaran macrofossils. In particular, the precipitation of authigenic minerals such as pyrite, clay minerals, calcite, and possibly silica may have contributed to the preservation of Flabellophyton in a certain degree of three-dimensionality. Second, environmental factors such as water depth, sediment substrates and redox conditions exert a strong control through taphonomic and/or paleoecological processes of Flabellophyton. The wide geographicand environmental distribution of Flabellophyton points to an unusual capability of Flabellophyton to evolutionarily adapt to different environments. Third, as a window into Ediacaran paleoecology, Flabellophyton and other Ediacaran fossils played a crucial role in the construction of epibenthic communities in Ediacaran oceans, and helps to understand the ecologicalmigration and evolutionary expansion from deeper to shallower oceans during the Ediacaran Period. This research was jointly supported by the the National Natural Science Foundation of China, Strategic Priority Research Program (B) and Major program of the Chinese Academy of Sciences, China and SKLPS State Key Lab Funding of NIGPAS, and National Geographic Society of USA. Article reference：Bin Wan, Zhe Chen, Xunlai Yuan, Ke Pang, Qing Tang, Chengguo Guan, Xiaopeng Wang, S. K. Pandey, Mary L. Droser and Shuhai Xiao. 2020. A Tale of Three Taphonomic Modes: The Ediacaran Fossil Flabellophyton Preserved in Limestone, Black Shale, and Sandstone. Gondwana Research 84: 296-314. https://doi.org/10.1016/j.gr.2020.04.003 Stratigraphic columns, representative specimens, and morphological reconstruction of Flabelloophyton from the early Ediacaran Lantian biota（635-580 Ma）and late Ediacaran Shibantan biota（551-539 Ma）of South China, and Middle-late Ediacaran Ediacara biota (560-550 Ma) of Australia Paleoecological reconstruction of Flabellophyton from the early Ediacaran Lantian biota, showing a Flabellophyton community on early Ediacaran ocean floor
The increase of atmospheric carbon dioxide concentration (pCO2) is widely regarded as the main factor leading to global warming. Therefore, reconstructing the atmospheric CO2 concentration during the geological history has important reference significance for humans to predict the future global climate trend. The inverse relationship between concentrations of CO2 in the atmosphere (pCO2) and the stomatal index of vascular plant has been widely used to estimate ancient levels of atmospheric CO2. However, some atmospheric concentration of CO2 in the geological past (paleo-CO2) estimates show little congruence because they are derived using different correlative methods, or from different fossil plant species with different calibration approaches. The increase of atmospheric carbon dioxide concentration (pCO2) is widely regarded as the main factor leading to global warming. Therefore, reconstructing the atmospheric CO2 concentration during the geological history has important reference significance for humans to predict the future global climate trend. The inverse relationship between concentrations of CO2 in the atmosphere (pCO2) and the stomatal index of vascular plant has been widely used to estimate ancient levels of atmospheric CO2. However, some atmospheric concentration of CO2 in the geological past (paleo-CO2) estimates show little congruence because they are derived using different correlative methods, or from different fossil plant species with different calibration approaches. Recently, an international research team leading by Prof. WANG Yongdong from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), Dr. ZHOU Ning from the Department of Geology of Northwest University, China and Prof. Jennifer McElwain from the Trinity College Dublin, the University of Dublin, Ireland published a new report in the international journal Palaeogeography, Palaeoclimatology, Palaeoecology about inter-comparison study of three stomatal-proxy methods for CO2 reconstruction applied to early Jurassic Ginkgoales plants. Researchers applied three methods, including the empirical method of McElwain (1998), the empirical method of Barclay and Wing (2016) and the mechanistic method of Franks et al., (2014) to a single fossil Ginkgo species (Ginkgoites marginatus) to track and assess their consistency of pCO2 estimates for the Early Jurassic. By using an inter-comparison of three methods, a high degree of consistency in pCO2 estimates and trends had been observed in two empirical proxy methods. In addition, the mechanistic method and both the empirical methods also showed generally good consistent paleo-CO2 estimates at the bed-level. To test the congruence of paleo-CO2 estimates, they also applied all three methods to one additional Ginkgoalean fossil species (Sphenobaiera huangii). All three methods showed species-dependent uncertainty in paleo-CO2 estimates when applied to different Ginkgalean fossil species collected from the same fossiliferous bed. Moreover, considering the potential effect of guard cell size to the mechanistic method, the genome size of fossil and living Ginkgo taxa was analyzed based on the significant positive relationship between genome size and guard cell size. In addition, the continuous variation curve of pCO2 in the early Jurassic in southern China was reconstructed by the three models, it showed that the CO2 concentration is 900–1400 ppm. This result agreed with the values of the early Jurassic pCO2 using the other plant stomatal parameter method and the geochemical models. It is thus demonstrated that the late Early Jurassic (dated about 180 Ma) was characterized by a greenhouse climate condition with global warming and oceanic anoxic events. This study was jointly supported by the Strategic Priority Research Program (B) of the Chinese Academy of Sciences, the National Natural Science Foundation of China, State Key Programme of Basic Research of Ministry of Science and Technology, China and SKLPS State Key Lab Funding of NIGPAS. Article reference：Zhou Ning, Wang Yongdong*, Li Ya, Porter Amanda, Kürschner Wolfram, Li Liqin, Lu Ning, McElwain Jennifer*, 2020. An inter-comparison study of three stomatal-proxy methods for CO2 reconstruction applied to early Jurassic Ginkgoales plants. Palaeogeography, Palaeoclimatology, Palaeoecology, 542, 109547. https://doi.org/10.1016/j.palaeo.2019.109547 Two fossil ginkgoalean plants from the Early Jurassic in western Hubei and their epidermal structures and stomatal distribution（left, Ginkgoites; right, Sphenobaiera) Comparisons of paleo-CO2 estimates using three stomatal-proxy methods. (Red indicates empirical method of Barclay and Wing (2016) ; Blue indicates empirical method of McElwain (1998); and Blue indicates mechanistic method of Franks et al., (2014)) The estimated genome size from guard cell data of fossil Ginkgoites and Sphenobaira and living Ginkgo from South China and East Greenland Estimated paleo-CO2 values during Early Jurassic obtained from three methods (blue, red and green box), and comparison with other paleo-CO2 estimates based on the stomatal ratios of plant fossils and geochemical models
The majority of the deep ocean was likely under ferruginous conditions during the first four billion years of Earth’s history. As the atmosphere was gradually oxygenated, the sources, sinks, redox cycling, and reservoir size of dissolved iron in the deep ocean are likely to have changed dramatically. Whether deep water was thoroughly oxygenated by the time of the Ediacaran-Cambrian transition, and the relationship of this oxygenation to the Cambrian explosion, remains debated. To explore the degree of oceanic oxygenation and its effect on Cambrian explosion, a research team, composed of Dr. XIANG Lei, Prof. ZHANG Hua and Prof. CAO Changqun from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, and collaborators from the University of West Carolina, the University of Science and Technology of China and Nanjing University, measured the iron isotopic composition (δ56Fe) of bulk rock (i.e., cherts and mudstones/shales) through the Piyuancun and Hetang formations, using samples collected from the Chunye-1 core, on the Lower Yangtze Block in western Zhejiang. The limited variation in δ56Fe values (<0.7‰) and low FeT/Al ratios (<0.77) in euxinic samples show that the deep-water Fe2+ reservoir was quite limited, and likely similar to that of the modern ocean, during the latest Ediacaran and Cambrian Stages 1-3. Iron isotope results, combined with published data from sections on the Middle and Upper Yangtze Block, record a general decline in seawater δ56Fe values from >0.55‰ during the end-Ediacaran and Cambrian Stages 1-3 to <0‰ during Cambrian Stage 4. Seawater δ56Fe values in the lower and middle Hetang Formation range between 0 and 0.2‰, suggesting that the riverine dissolved and suspended flux and/or aeolian dust was the predominant source of highly reactive iron to the deep basin. Positive deep-water δ56Fe values, above 0.55‰ during the terminal Ediacaran and Cambrian Stages 1-3, likely reflect a basin where pyritization, rather than oxidation, was the predominant sink for deep-water ferrous Fe. Thus, researchers infer that only the shallow water was sufficiently oxygenated to support complex metazoans and the evolutions of skeletons, and that atmospheric oxygen levels were not high enough to directly oxygenate deep water environments during the Cambrian explosion.The research results have been published online in the international geology journal Chemical Geology. And this research was supported by by the Strategic Priority Research Program (B) of the Chinese Academy of Sciences and the National Natural Science Foundation of China. Reference: Xiang, L., Schoepfer, S.D., Zhang, H., Chen, Z.W., Cao, C.Q., Shen, S.Z., 2020. Deep-water dissolved iron cycling and reservoir size across the Ediacaran-Cambrian transition. Chemical Geology, 541: 119575. https://doi.org/10.1016/j.chemgeo.2020.119575 Iron isotope and iron composition data in Chunye 1 core
