Chemostratigraphic profiles of the Lantian Formation The coevolution of life and environment is highlighted in the recent debate on the possible relationship between ocean oxygenation and animal evolution in the Neoproterozoic. Some argue that the progressive oxygenation of the Earth’s surface in the late Neoproterozoic removed the final environmental hurdle to animal evolution, whereas others counter that atmospheric pO2 levels were sufficiently high to support basal animal metabolism in the Mesoproterozoic, long before the rise of animals themselves. Building upon previous work, Dr. WANG Wei from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences and her colleagues recent attempts to test these competing hypotheses are focused on the compilations and meta-analyses of redox proxies. While these meta-analyses offer a critical view of the big-picture redox trend through the Neoproterozoic, they omit the more nuanced picture of spatial heterogeneity and often lack the stratigraphic resolution to appreciate the temporal dynamics of Neoproterozoic redox evolution. Ediacaran successions in South China, particularly the Doushantuo Formation, are highly fossiliferous. They are ideal targets for focused and integrated geochemical analysis at high resolution to infer the impact of redox conditions on evolution, ecology, and taphonomy. Previous studies of the Doushantuo Formation have been focused on shelf sections in the Yangtze Gorges and surrounding areas. To fully understand the Ediacaran redox structure of South China, it is necessary to gain insights from sections in deep-water slope and basinal facies. High-resolution chemostratigraphic analysis of integrated geochemical data—including δ13Ccarb, δ13Corg, δ34Spyr, δ34SCAS, and δ15Nsed—from the Lantian Formation deposited in deep-water environments in South China allows a better resolution of the spatial patterns and temporal variations of Ediacaran oceanic redox conditions. A large spatial gradient of δ13Ccarb, with a magnitude of >10‰, is confirmed to be present in the lower Doushantuo/Lantian Formation. It is proposed that this gradient is largely due to the influence of 13C-depleted authigenic/diagenetic calcite cements in organic-rich and carbonate-poor sediments deposited in deep-water facies. A pronounced negative δ13Ccarb excursion in the upper Doushantuo/Lantian Formation, however, is spatially consistent and does not display a > 10‰ depth gradient. This negative excursion has been previously described as EN3 (Ediacaran Negative excursion 3) in South China and regarded as equivalent to the Shuram excursion in Oman. The δ34Spyr record seems to show a spatial pattern, with more negative δ34Spyr values in deeper-water facies. The spatial pattern of δ34Spyr is interpreted as evidence for a chemically stratified basin, with predominantly euxinic deep waters where pyrite precipitated in the water column has lower δ34Spyr values. The δ15Nsed record of the Lantian and Doushantuo formations is consistent. The δ15Nsed data suggest nitrate limitation and denitrification is often quantitative. The Lantian and Doushantuo formations do not preserve highly positive δ15Nsed values characteristic of partial denitrification in suboxic environments of modern oxygen-minimum zone. Integrated TOC, TN, δ34Spyr, and Fe speciation data suggest that oscillation between oxic and euxinic conditions is characteristic of the Lantian Formation. Macrofossils in the Lantian Formation include morphologically complex macroalgae and putative animals. Stratigraphic distribution of these fossils is largely restricted to euxinic black shales.The euxinic environments were punctuated by brief oxygenation events when macroalgae and putative animals thrived, but were subsequently decimated and preserved when local environment switched to euxinic conditions. Reference: Wang W, Guan C, Zhou C, Peng Y, Pratt L M, Chen X, Chen L, Chen Z, Yuan X, Xiao S. Integrated carbon, sulfur, and nitrogen isotope chemostratigraphy of the Ediacaran Lantian Formation in South China: Spatial gradient, ocean redox oscillation, and fossil distribution. Geobiology. 2017. doi: 10.1111/gbi.12226
Hyphae with clamp connections within tracheids of the primary xylem of the fossil stem Shanxioxylon sp. Widespread coal deposits during the Carboniferous and Permian Periods of the late Paleozoic. A widely accepted explanation for this peak in coal production is a temporal lag between the evolution of abundant lignin production in woody plants and the subsequent evolution of lignin-degrading Agaricomycetes fungi, resulting in amounts of lignin-rich plant material accumulated. Recently, Dr. WAN Mingli and Prof. WANG Jun from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences reported the occurrence of fossil fungi in silicified cordaitalean stems from the Cisuralian (Permian) Taiyuan Formation of Yangquan City, Shanxi Province, North China. Fungi occur within parenchymatous cells of the pith and tracheids of the primary xylem. The fossil fungal hyphae consist of branching, septate hyphae with clamp connections and, therefore, are assigned to Basidiomycetes. The clamp-bearing hyphae from the Asselian–Sakmarian of North China are the first evidence for unequivocal basidiomycete body fossils in the Cathaysia. This discovery provides the first evidence of cordaitalean stems colonized by basidiomycetous fungi. Although the lower systematic affinities of the fungi currently remain unsolved, their existence sheds light on the multiple levels of biological association and interaction that had shaped the Permian terrestrial ecosystems. Their work also deny the fungal evolutionary lag hypothesis by the direct palaeontological evidence. This work is supported by Chinese Academy of Sciences, State Key Laboratory of Palaeobiology and Stratigraphy, and the National Natural Science Foundation of China. Related information: Wan, M., Yang, W., He, X., Liu, L., Wang, J., 2017. First record of fossil basidiomycete clamp connections in cordaitalean stems from the Asselian–Sakmarian (lower Permian) of Shanxi Province, North China. Palaeogeography Palaeoclimatology Palaeoecology, 466, 353-260. doi: 10.1016/j.palaeo.2016.11.050
The same specimen photographed in transmitted white light and infared light microscope A collection of low-grade metamorphosed rocks from Lvchun, Yunnan, Southwest China were found to contain a variety of highly mature microfossils comprising cryptospores, trilete spores, and dispersed plant fragments (tubular structures) as well as a small number of marine palynomorphs (acritarchs and scolecodonts), by Dr. LIU Feng from Nanjing Institute of Geology and palaeontology, Chinese Academy of Sciences and his colleagues. Infrared microscopic examination enabled the recognition and description of 38 species. Based on its correlation with previously established palynozonations and independent age evidence from acritarchs and graptolites, the palynomorph assemblage from Lvchun is attributed to the early Ludlow age. This new age constraint suggests that at least the upper level of these presumably Llandovery rocks in Lvchun belongs to the early Ludlow age. The palynomorph assemblage of Lvchun from Indo-China terrane share many taxonomic similarities with coeval findings from Tunisia and Saudi Arabia (i.e., southern Gondwana), hence reflecting the early geographical proximity of the two palaeocontinents. The increasing quantity and diversity of trilete spores point to the rapid evolution of early vascular plants in Indo-China terrane during the early Ludlow. This work was funded by Strategic Priority Research Program (B) of the Chinese Academy of Sciences and the National Natural Science Foundation of China. Article information: Liu, F., Wang Y., Zhu, H.C., Ouyang, S. (2016): Palynomorphs from massive metamorphosed rocks in Lvchun, Yunnan, Southwest China: evidence from the Ludlow Age and its geological implications. Review of Palaeobotany and Palynology, 233. 146-160.
Pollen fossils extracted from Huguangyan Maar Lake sediment The Earth’s climate changed from cold to warm through a succession of abrupt climate fluctuations over the past 30 000 years, including three important periods, i.e. the Last Glaciation, the Last Deglaciation and the Holocene, which casted great influence on the formation of human civilization and the development of early agriculture. Huguangyan Maar Lake in Zhanjiang, Guangdong Province is rarely affected by the outside disturbance because its supply is limited to a volcano formed ring dyke. The long time of water retention, simple lake system, and deep underground dyke make the Maar Lake sediments one of the valuable sites in the past global change study, which is comparable with deep sea sediments, polar ice cores and loess deposits. Huguangyan is located in the Leizhou Peninsula at the southernmost tip of Chinese Mainland, and adjacent to the South China Sea. It is under the inference of East Asian summer monsoon and southwest India monsoon, becoming a most important link between the South China Sea, the water vapor sources for the summer monsoon rainfall and the inland area. It is also a connection of the low latitude tropical climate system and the mid latitude monsoon climate. In recent years, a research team combined by Prof. WANG Weiming and his postgraduate students MENG Yuting et al. from Nanjing Institute of Geology and palaeontology, Chinese Academy of Sciences, and Prof. HU Jianfang from Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, carried out a systematic study of a drilling core from Huguangyan Maar Lake in Guangdong Province, South China. They reconstructed vegetation and climate changes over the last 30 000 years based on a relatively high-resolution pollen record. Pollen assemblages are well comparable with the results from ice-core, loess, stalagmites, lake and deep sea sediment records, reflecting that the tropical land system is very sensitive to both climate change on the solar orbit scale, and rapid climate events on the non solar orbit scales. This results provide a new scientific evidence for a better understanding of the interaction among the sea, the land and the plateau snow cover, the evolution of the monsoon, and the regional response of the global climate change in the low latitude region. The pollen assemblages show a succession of vegetation and climate changes from 30 cal. ka BP. During the Last Glaciations, 30-15.8 cal. ka BP, the Huguangyan area was dominated by subtropical evergreen-deciduous forest with grassland surrounding the lake, reflecting a colder and drier climate than today. During the Last Deglaciation, 15.8–11 cal. ka BP, the content of evergreen and deciduous broad-leaved plants displayed a mutual growth and decline, indicating the study area was experiencing several climatic fluctuations. In the Holocene from 11 cal. ka BP, the tropical rain forest was common with the climate shifted to warmer and wetter conditions.
A comparison of the pollen assemblage with summer mean insolation, NGRIP ice-core, EPICA Dome C ice-core and Guliya ice-core records During the Last glacial maximum (LGM), pollen assemblage showed no distinct millennial climate change recorded in some East Asia and high latitude regions. A clear warming event in about 21-18.5 cal. ka BP, might indicate a gradually warming climate in the Huguangyan area which was earlier than the high latitude area, but similar to the warming pattern revealed by the oxygen isotope records from the Antarctic and the Guliya Ice cores. In addition, the climate warming was synchronous with the increasing amount of sunshine at 33 ° north latitude, reflecting a highly responsible terrestrial vegetation system in the tropical area to the solar orbital scale changes. Frequent climate fluctuations were recognized in the pollen assemblages during the Last Deglaciation, with a changing process from warm, to colder, warmer and cold climate. The evergreen broad-leaved forest expanded during 15.8-14 cal. ka BP, corresponding to B？lling-early Aller？d warm period, while the subtropical deciduous broadleaved trees and grassland became re-established during 14-11 cal. ka BP, implying a cold period, possibly including the Younger Dryas. The tropical rain forest got rapidly expanded during 11-6 cal. ka BP, which was consistent with that the arrival of Holocene climatic optimum with warm and humid climate condition. Tropical rain forest had a rapid decline in 8.5 cal. ka BP, implying a strong cooling event. The ratio of woody and herbaceous plants decreased in the middle and late Holocene, indicating a possible climate decay, which may be related to a weakening summer monsoon. The sediment record of the last 2 cal. ka BP cannot be used to interpret natural palaeoclimate changes due to the intense anthropogenic influences. The article was published online on February 15, 2017 in Boreas. This research was funded by the CAS Strategic Priority Research Program and National Natural Science Foundation of China. Article information: Yuting Meng, Weiming Wang*, Jianfang Hu, Jixiao Zhang, Yangjun Lai, 2017. Vegetation and climate changes over the last 30 000 years on the Leizhou Peninsula, southern China, inferred from the pollen record of Huguangyan Maar Lake. Boreas, doi/10.1111/bor.12229.
A research team led by NIGPAS reported the oldest, morphologically specialized, and obligate termitophiles from mid-Cretaceous Burmese amber, which represent the oldest known termitophiles, and reveal that ancient termite societies were quickly invaded by beetles about 99 million years ago. The result has been published in Current Biology on April 13th, 2017.
The oldest termitophile from 99-million-year-old Burmese amber, Cretotrichopsenius burmiticus (Image by Cai et al., 2017) Eusocial insects, such as ants, social wasps and bees, and termites, include some of the most ecologically ubiquitous of terrestrial animals. The nests of these insects are well protected and provide a safe, communal space for the storing of resources and production of brood, so the nests are often cohabited by various highly specialized symbionts that take advantage of the abundant resources and protection inside the nests. Termitophiles, symbionts that live in termite nests, include a wide range of morphologically and behaviorally specialized organisms. Understanding of the early evolution of termitophily is challenging due to a scarcity of fossil termitophiles, with all known reliable records occurring from the Miocene Dominican and Mexican ambers (approximately 19 million years ago). Mesozoic termitophiles are of great significance for understanding the origin of eusocial societies of termites and the early evolution of specialized termitophily. Recently, a research team led by Dr. CAI Chenyang and Prof. HUANG Diying from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences reported the oldest, morphologically specialized, and obligate termitophiles from mid-Cretaceous Burmese amber (approximately 99 million years ago), which represent the oldest known termitophiles. The result has been published in Current Biology on April 13th, 2017. To integrate into the hosts’ societies, termitophilous beetles have repeatedly evolved physogastry (swollen abdomens) and limuloid (horseshoe-crab-shaped) body shapes, representing the two principal forms. Both morphological adaptations have arisen convergently many times in beetles (Coleoptera) as well as in flies (Diptera). The peculiar fossil rove beetles, named as Cretotrichopsenius burmiticus Cai et al., 2017, exhibits the characteristic features of the modern aleocharine tribe Trichopseniini, including the articulation of the hind leg whereby the coxae are fully fused and incorporated into the metaventrite.
Ecological reconstruction of the mid-Cretaceous termitophille (Image by Cai et al., 2017) Cretotrichopsenius burmiticus has a protective horseshoe-crab-shaped body form typical of many modern termitophiles, with concealed head and antennae and strong posteriorly directed abdominal setae. The discovery represents the earliest definitive termitophiles, pushing back the fossil record of termitophiles by 80 million years. Recent species of Trichopseniini are usually associated with derived neoisopteran termites of Rhinotermitidae, and less frequently with Termitidae. Interestingly, some trichopseniines are known to live within nests of the basal-most termites (Mastotermitidae) and drywood termites (Kalotermitidae). Because host specificity is rather low in extant trichopseniines, it is certainly likely that Cretotrichopsenius may have been associated with the variety of termite groups known from Burmese amber. The fossils reveal that ancient termite societies were quickly invaded by beetles about 99 million years ago. This study was jointly supported by the Chinese Academy of Sciences, the National Natural Science Foundation, the Natural Sciences Foundation of Jiangsu Province, and the Ministry of Science and Technology of China. Reference: Chenyang Cai, Diying Huang, A. F. Newton, K. T. Eldredge, M. S. Engel, 2017. Early evolution of specialized termitophily in Cretaceous rove beetles. Current Biology doi: 10.1016/j.cub.2017.03.009
Courtship behaviours, frequent among modern insects, have left extremely rare fossil traces. Recently, Scientists described three male damselflies showing ancient courtship behaviour from mid-Cretaceous Burmese amber. The new findings provide suggestive evidence of damselfly courtship behaviour as far back as the mid-Cretaceous. Embargo: 10am UK time, the 20th of March 2017 photograph and line drawing of specimen Yijenplatycnemis huangi (Image by ZHENG Daran) Courtship behaviours, frequent among modern insects, have left extremely rare fossil traces. In odonates, the male must persuade the female to mate in tandem and the female should be willing to engage her genitalia with the male’s. Many territorial odonatans display their courtship by high-frequency wing-beats towards an approaching female. Most courtship, mating and parenting (social-sexual) behaviour cannot be preserved and fossil reports are few and ambiguous. No courtship behavious were previously recorded for fossil odonatans. Recently, Dr. ZHENG Daran and Prof. WANG Bo from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences described three male damselflies showing ancient courtship behaviour from mid-Cretaceous Burmese amber. These fossils were named Yijenplatycnemis huangi after Mr. Huang Yijen from Taiwan, for his generously donation of the type specimen. Y. huangi has spectacular extremely expanded, pod-like tibiae, helping to fend off other suitors as well as attract mating females, increasing the chances of successful mating. The new findings provide suggestive evidence of damselfly courtship behaviour as far back as the dinosaur age. Modern Platycnemidinae and Chlorocyphidae convergently acquired similar but less developed structures. During courtship, male Platycypha caligata waves the white anterior surface of all six laterally enlarged tibiae at the females, but uses the posterior surface of the tibiae for intra-sexual signaling during territorial defense. Similarly, male East Asian Platycnemis species with expanded, feather-like tibiae well differentiated from the females, exhibit a strong sexual dimorphism. The males display their white legs in a fluttering flight in front of females before mating. By morphological inference, the six extremely expanded tibiae of Y. huangi could also have a signaling function for courtship displays. Platycypha has all six tibiae expanded, but all less so than Y. huangi in size. Platycnemis has more expanded mid and hind tibiae, but is still smaller than Y. huangi. These more expanded fossil tibiae suggest an extreme adaptation for courtship behaviour. More importantly, unlike Platycypha and Platycnemis, the tibiae of Y. huangi are asymmetric and pod-shaped, especially the hindleg tibia with a semi-circular outline. This pod-like shape would make waving slower due to air resistance. Y. huangi waving its giant pod-like tibiae would make males more easily noticed and attract female attention, increasing mating opportunities and implying sexual selection. Reconstruction showing the courtship behavior (Image by YANG Dinghua) The tibial shape of Y. huangi also resembles the wings of some members of the extinct neuropteran families. The tibiae of Y. huangi are hyaline and partly covered with two narrow brown bands, making them even more like pigmented wings. In addition, there is an eye-shaped spot in the middle of the hindleg, quite like the wing spots in Kalligrammatidae and some recent butterfly eyespots. These well-developed eyespots were and are used to make a conspicuous and contrasting display to intimidate vertebrate predators or protect the body by deflecting an attack to the wings. Deflective eyespots in butterflies and fossil lacewings are smaller than deimatic ones and both are never on the legs, but dragonflies are predators with good eyesight, and the tiny ones in Y. huangi may have less to do with paralleling fossil lacewings in deflecting nearby predators and more to do with raising the interest of females (cf. peacock eyespots). That none of the pigmented tibiae in Y. huangi are damaged, however, suggests they did not precipitate an aggressive response. This research was recently published in Scientific Reports, and supported by the National Natural Science Foundation of China, the Chinese Academy of Sciences, and the HKU Seed Funding Program for Basic Research. Reference: Daran Zheng, André Nel, Edmund A. Jarzembowski, Su-Chin Chang, Haichun Zhang, Fangyuan Xia, Haoying Liu, Bo Wang, 2017. Extreme adaptations for probable visual courtship behaviour in a Cretaceous dancing damselfly, Scientific Reports, 7:44932; doi: 10.1038/srep44932. WANG Bo bowang@nigpas.ac.cn Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences Related News: https://www.eurekalert.org/pub_releases/2017-03/caos-cbt031717.php http://www.dailymail.co.uk/sciencetech/article-4330808/Damselflies-trapped-100-million-year-old-amber.html http://www.ibtimes.co.uk/extremely-rare-amber-fossils-capture-100-million-year-long-flirt-1612578 https://phys.org/news/2017-03-courtship-behavior-million-year-old-amber.html http://gizmodo.com/this-poor-cretaceous-damselfly-has-been-waiting-100-mil-1793438939 http://www.telegraph.co.uk/science/2017/03/20/coitus-interruptus-frisky-insect-trapped-100-million-year-old/ https://www.aol.com/article/news/2017/03/20/100-million-year-old-courtship-behavior-preserved-in-amber/21903624/
Recently, a research team led by Prof. HUANG Diying from Nanjing Institute of Geology and Palaeontology reported a diversity of gilled mushrooms and mycophagous rove beetles from Burmese amber, the latter belonging to Oxyporinae, modern members of which exhibit an obligate association with soft-textured mushrooms. Their finding displays an ancient ecological community assembling diverse mushrooms and beetles and established on specialized trophic interaction by this early date. The results have been published in Nature Communications on 16th March, 2017. Mushrooms, or Agaricomycetes, are common, conspicuous and morphologically diverse fungi. Most agaricomycete fruiting bodies are ephemeral, so they are extremely rare in fossils. Up to now, all described species of gilled mushrooms, or Agaricales, have been known exclusively from amber. Among them, two forms are from the Mesozoic, including the earliest mushrooms, Palaeoagaracites antiquus from 99-million-year-old Burmese amber, and the slightly younger Archaeomarasmius leggetti from New Jersey amber (about 90 million year old). The remaining three species are known from early Miocene Dominican amber, some 20-million-year-old. Evidence indicating the origin and early diversification of Agaricomycetes is very limited. Recently, a research team led by Prof. HUANG Diying from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS) reported a diversity of gilled mushrooms and mycophagous rove beetles from Burmese amber, the latter belonging to Oxyporinae, modern members of which exhibit an obligate association with soft-textured mushrooms. The results have been published in Nature Communications on 16th March, 2017. All the mushrooms they studied are very well-preserved and can be grouped in four forms. A stalk and a complete intact cap containing distinct gills are visible in most of these amber mushrooms. The new discovery suggests a long-term evolutionary stasis of body form for at least 99 million years and highlights the palaeodiversity of mushrooms, pushing back the presence of agarics by at least 25 million years. More interestingly, the mouthparts of these early oxyporine rove beetles, including enlarged mandibles and greatly enlarged apical labial palpomeres with dense specialized sensory organs, match those of modern taxa and indicate a mushroom feeding habit of these beetles. The diverse and morphologically specialized oxyporine beetles had also been appeared by the Early Cretaceous, some 125 million years ago. Their finding displays an ancient ecological community assembling diverse mushrooms and beetles and established on specialized trophic interaction by this early date. This study was jointly supported by the Chinese Academy of Sciences, the National Natural Science Foundation, the Natural Sciences Foundation of Jiangsu Province, and the Ministry of Science and Technology of China. Reference: Chenyang Cai, R. A. B. Leschen, D. S. Hibbett, Fangyuan Xia, Huang Diying, 2017: Mycophagous rove beetles highlight diverse mushrooms in the Cretaceous. Nature Communications doi: 10.1038/ncomms14894
Diverse mushrooms in 99-million-year-old Burmese amber (Image by Cai et al.)
Diverse mycophagous oxyporine rove beetles (Image by Cai et al.)
Details of mouthparts of extinct and extant mycophagous oxyporine rove beetles (Image by Cai et al.)
Ecological reconstructions of Cretaceous mushrooms and mycophagous beetles (Image by Cai et al.) HUANG Diying dyhuang@nigpas.ac.cn Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences
Recently, a research team has found a new morphologically specialized beetle, Cascomastigus monstrabilis, from the mid-Cretaceous Burmese amber, shedding new light on the predator–prey associations in the late Mesozoic terrestrial ecosystem. Recently, a research team led by researchers from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS) has found a new morphologically specialized beetle from the mid-Cretaceous Burmese amber, shedding new light on the predator–prey associations in the late Mesozoic terrestrial ecosystem. Insects exhibit various morphological specializations specific to particular behaviors, and these permit the reconstruction of palaeobiological traits. Dr. CAI Chenyang at NIGPAS and Dr. YIN Ziwei at the Shanghai Normal University discovered three exceptionally well-preserved fossils of highly specialized ant-like stone beetles (Staphylinidae, Scydmaeninae) from mid-Cretaceous Burmese amber, some 99 million years ago. These fossils, named as Cascomastigus monstrabilis Yin & Cai, 2017, are represented by both male and female, and belong to a small tribe called Mastigini. These early beetles display morphological modifications on the antennae unknown among living ant-like stone beetles and associated with predation on springtails (Collembola), a widespread and abundant group of significantly greater geological age. Cascomastigus has an extremely large body size, elongate clubbed maxillary palpi, toothed mandibles, and more importantly, slender and highly modified antennae that functioned as an antennal setal trap. Such an antennal modification is analogous to that of the modern ground beetle genus Loricera (Carabidae, Loricerinae), a group possessing a specialized antennal setal trap exclusively for the capture of springtails. Springtails, usually only a few millimeters long, are one of the most widespread and abundant of terrestrial arthropods, and is the most diverse group of Entognatha, the sister group to insects. The earliest known springtails, Rhyniella praecursor, are from the Early Devonian Rhynie chert (Scotland, approximately 400 million years ago), and Mesozoic and Cenozoic ambers have witnessed the explosive radiation of this usually overlooked group. Burmese amber also harbors abundant and diverse springtails, which sometimes occur in groups. Therefore, the springtails are potential ideal food resource for these litter-dwelling beetles. The tribe Mastigini display a disjunctive distribution, occurring in South Africa and southern Europe. The new discovery of Cascomastigus from northern Myanmar further highlights the once broader distribution of Mastigini. All previously known specialist predators of springtails are confined to the middle Eocene. Cascomastigus from about 99 million years ago represents the earliest known predators specialized for capturing springtails, pushing back the age of such predation by at least 54 million years. This study is jointly supported by the Chinese Academy of Sciences, the National Natural Science Foundation, the Natural Sciences Foundation of Jiangsu Province, and the Ministry of Science and Technology of China. Reference: Zi-Wei Yin, Chen-Yang Cai*, Di-Ying Huang & Li-Zhen Li, 2017. Specialized adaptations for springtail predation in Mesozoic beetles. Scientific Reports, DOI: 10.1038/s41598-017-00187-8 (*corresponding author) CAI Chenyang cycai@ nigpas.ac.cn Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences Cascomastigus monstrabilis, Image by YIN Ziwei
A severe mass extinction event happened during the Devonian-Carboniferous transition (about 359 Ma heretofore), which causes the extinction of >45% genera and ~21% of marine invertebrate families. Typical sedimentary rocks from the Rhenish Massif, western German, are global distributed (Hangenberg black shale, Hangenberg shale and Hangenberg sandstone in ascending order), resulted from the prominent marine anoxia and global sea-level changes. Hence, this end-Devonian mass extinction event is also named as Hangenberg mass extinction event. Recent comprehensive analyses show that the Hangenberg event lasted from the latest Devonian to the earliest Carboniferous (e.g., ~100-300 kyr; uppermost Lower Siphonodella praesulcata Zone to lowest Siphonodella sulcate Zone). Microbial carbonates usually flourished after the mass extinction events, taking the end-Permian mass extinction event for example. Proliferation of microbial carbonates was generally attributed to the reduced competition from multicellular organisms after mass extinctions, resulted in lower levels of grazing and/or bioturbation of microbial communities. In addition to metazoan competition, flourishing microbial carbonates were also supported by a high seawater calcite saturation state (SCSS), which must have enhanced microbial calcification and carbonate production. The decline of marine metazoans and the SCSS in that time is much higher than those in the Early Triassic during the Hangenberg extinction transition. Therefore, microbial carbonates should have thrived in the early Tournaisian. However, the documented bioconstructions dominated by stromatolites and/or thrombolites to date are rare, and can only be founded in Australia. Skeletal and microbial reef ecosystems are two opposite elements of the marine biosphere, which could be used to unravel the marine ecosystem evolution during the mass extinctions. In order to unravel the changes in the marine biosphere across the Hangenberg extinction transition, Dr. YAO Le, Prof. WANG Xiangdong, and Dr. CHEN Jitao from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Prof. ARETZ Markus from the University of Toulouse Ⅲ, and Prof. WEBB Gregory E. from the University of Queensland, recently studied the stromatolites from Northwest China in great detail. Their materials came from the Qianheishan Formation at the Dashuigou section in Ciyao area, Pingchuan County, Gansu Province, China, containing volume of rock 200 m in width and 16 m in thickness. The age of the stromatolites is constrained to the earliest Carboniferous, which is equal to the conodont zone of Lower Siphonodella sulcate, based on the comprehensive analysis of ammonoid, ostracod and palynological biostratigraphy. In addition, the bryozoan and brachiopod fossils, the fine-scale laminations and the fenestral structures in the Qianheishan stromatolites suggest that they formed in the normal marine environment. Hence, the stromatolites described in this study are the production of marine microbial proliferation after the Hangenberg event. The Qianheishan stromatolites are mainly composed of micrite, peloids, small oncoids, and sparry calcite, which are formed by the microbial baffling, binding and calcification. Three stromatolite morphology types are distinguished, including laminar, wavy-laminar and domal forms. With other early Tournaisian microbe-dominated bioconstructions extensively distributed on shelves, the Qianheishan stromatolites support an event of microbial carbonate proliferation after the Hangenberg extinction. In order to confirm this hypothesis, a lot of quantified study of the microbe-dominated has been taken systematically. The result embraced the hypothesis that the marine biosphere has been significantlymodified, changing from the stromatoporoid-coral reef ecosystem to microbial ecosystem. In the early Tournaisian, the microbe-dominated bioconstructions were globally distributed in western America, eastern Russia, eastern Australia, northern India and northwestern and southern China (between 40° latitude on both sides of the palaeoequator) and that their abundance increased more than ten-fold in the early Tournaisian compared to the latest Devonian (Strunian). This result indicates that the microbial carbonate proliferation occurred after the Hangenberg mass extinction event. The proliferation of the microbial carbonates following the Hangenberg extinction event is related to the declined metazoan diversity and the increased calcification rates. However, it remains unclear that which of the two controlling factors is dominant. Reconstruction of the relative abundance of skeleton- and microbe-dominated bioconstructions is a new insight to solve this problem. For this purpose, the changes in the relative abundance of skeleton- and microbe-dominated bioconstructions during the Hangenberg and “Big Five” mass extinction transitions, respectively, are constructed. Comparing them to the reality, we found that the increase of the abundance of microbe-dominated bioconstructions is consistent with the decline of skeleton-dominated bioconstruction abundance after mass extinctions, implying that the abundance of skeletal bioconstructors plays a crucial role in regulating the proliferation of microbial carbonates in the aftermath of mass extinctions. This paper was published in Scientific Reports and financially supported by the National Natural Science Foundation of China, the Strategic Priority Research Program (B) of the Chinese Academy of Sciences and the Ministry of Science and Technology Foundation Project and the Centre national de la recherche scientifique (CNRS) Project. Reference: Yao, L., Aretz, M., Chen, J.T., Webb, G.E., Wang, X.D., 2016. Global microbial carbonate proliferation after the end-Devonian mass extinction: Mainly controlled by demise of skeletal bioconstructors. Scientific Reports 6, 39694; doi: 10.1038/srep39694.
Field (a, b and c), polished-slab (d) and thin-section (e and f) photographs of the Qianheishan stromatolites at the Dashuigou section, Gansu Province, northwestern China.
Comparison of the variations in the relative abundance between skeleton- and microbe-dominated bioconstructions across the Hangenberg and ‘Big Five’ mass extinction transitions.
Stromatoporoid-coral reef ecosystems have collapsed and disappeared during the Frasnian-Famennian and Hangenberg mass extinction events during the late Devonian and Devonian-Carboniferous transition, respectively. In addition, prominent glacial and interglacial events accompanied by frequent sea-level fluctuations occurred during the Carboniferous. They all have an important influence on the evolution of the Carboniferous reefs. The Devonian and Permian are periods of global reef expansion, while the Carboniferous is a period of global low reef abundance, with a few reef cases documented. To date, it is still unclear about the composition and evolutionary process of the Carboniferous reefs. Reefs are complex ecosystems and their growth and demise are closely related to changes in the abundance of potential reef-builders, temperature, relative sea level, and palaeogeography. During the Carboniferous, the South China Block was located near the equator, with warm climate and extensively successive carbonate sequence which provide suitable conditions for the development of reefs, and then for the studies on the reef composition and evolution and their relationships to the palaeoenvironmental changes during this time interval. The published and new data on reefs, main reef-builders (corals, bryozoans, calcareous algae etc.), and palaeoenvironmental proxies (glacial records, sea-level changes etc.) during the Carboniferous were systematically reviewed by Dr. YAO Le and Prof. WANG Xiangdong from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences. The types, abundance, and distribution of Carboniferous reefs in South China were relatively simple, low and limited, respectively. The reef types mainly include metazoan reef (coral reef/biostrome and bryozoan-coral reef), algal reef (red algal and phylloid algal reefs), microbial reef (stromatolite and Tubiphytes reefs) and carbonate mud mound (Waulsortian carbonate mud bank), which were distributed mainly at the platform or isolated platform margins and slopes in Qian-Gui areas. In South China, the Carboniferous reefs underwent the evolutionary episodes of the recovery, decline and turnover, which were controlled mainly by reef-builders abundance, sedimentary facies, and relative sea-level changes. Metazoan flourishing, carbonate facies development with relative sea-level rise are in favour of developing metazoan reefs, such as during the Viséan and late Bashkirian-middle Kasimovian times. On the contrary, metazoan decline, non-carbonate facies formation due to relative sea-level fall leads to metazoan reef decrease, as in the Tournaisian and Serpukhovian times. From the Mississippian to Pennsylvanian, the changes from metazoan reefs into algal reefs are caused primarily by the development of shallow-water carbonate facies that resulted from relative sea-level fall. Although some differences can be recognized in the different time scales, the reef evolution in South China is consistent with that of globe during the Carboniferous. Besides, the transgressive and regressive events in South China correspond to the growing and retreating of Gondwana glaciation. They all suggest that global climate cooling and warming may also influence the reef evolution in South China during this time. This paper was published in Palaeoworld and financially supported by the National Natural Science Foundation of China and the Ministry of Science and Technology Foundation Project. Reference: Yao, L., Wang, X.D., 2016. Distribution and evolution of Carboniferous reefs in South China. Palaeoworld, 25: 362-376.
Main reef types of the Carboniferous reefs in South China (A) Carbonate mud mound (Waulsortian carbonate mud bank); (B) Coral reef; (C) Microbial reef (Stromatolite reef mound); (D) Algal reef (Phylloid algae reef) Overview of lithostratigraphical column with indications of reef intervals, shelf geometry, and climate A: Carbonate mud mound; B: Metazoan reef; B1: Coral reef; B2: Bryozoan-coral reef; B3: Coral biostrome; C1: Red algae reef; C2: Phylloid algae reef; D1: Stromatolite mound; D2: Tubiphytes reef
