The Steptoean Positive Carbon Isotope Excursion (SPICE) is a large excursion (by ~5‰) in marine carbon isotope (δ13C) records during the middle-late Cambrian transition, which is documented worldwide. The SPICE is hypothesized to be caused by a global carbon cycle perturbation (enhanced global carbon burial), which is accompanied with dramatic marine anoxia and euxinia. The SPICE event is coincident with and ascribed to, most likely the second phase of, the Dresbachian (or end-Marjuman) extinction event that slashed approximately 40% of marine genera during the early stage of life evolution. Recent studies imply that the synchroneity and magnitude of the SPICE may be controversial, which hampers proper interpretation on stratigraphic correlation and biogeochemical cycling. The Steptoean Positive Carbon Isotope Excursion (SPICE) is a large excursion (by ~5‰) in marine carbon isotope (δ13C) records during the middle-late Cambrian transition, which is documented worldwide. The SPICE is hypothesized to be caused by a global carbon cycle perturbation (enhanced global carbon burial), which is accompanied with dramatic marine anoxia and euxinia. The SPICE event is coincident with and ascribed to, most likely the second phase of, the Dresbachian (or end-Marjuman) extinction event that slashed approximately 40% of marine genera during the early stage of life evolution. Recent studies imply that the synchroneity and magnitude of the SPICE may be controversial, which hampers proper interpretation on stratigraphic correlation and biogeochemical cycling. In order to test the spatial variation of the SPICE, Prof. CHEN Jitao from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, in collaboration with his colleagues, studied six outcrop sections across a ~700 km transect along the eastern North China Platform by using sedimentology, trilobite biostratigraphy and carbon isotopes methods in recent years. The research results have been published in the international journals Palaeogeography, Palaeoclimatology, Palaeoecology. Their study found that the SPICE is present in all the studied sections, but showing different features regarding the duration and magnitude. An abrupt increase in δ13C from ~1.5‰ to 3.5‰ occurs in three Shandong sections, with maximum value present only in a thin (0.5-1.2 m thick) transgressive lag deposit (crudely wave stratified, bioclastic grainstone). In contrast, the δ13C record of the Baijiashan and Shashan sections in the Liaoning region displays a gradual increase (~20 m thick) from ~1.5‰ to the maximum value of 4.7‰. Both facies analysis and trilobite collections suggest that the spatial variation of the SPICE in the North China Platform most likely resulted from missing of sedimentary record (with high δ13C values) in the Shandong sections as a result of erosion and non-deposition during sea-level lowstand, a possible coeval hiatus prior to the Sauk III transgression in the Laurentian basins. This is a case study that utilizes an interdisciplinary approach involving sedimentology, stratigraphy, and geochemistry to better understand geological issues. This study reports the complete record of SPICE from the North China Platform, and provides fundamental basis for future global correlation of SPICE. The study was supported by the Strategic Priority Research Program of Chinese Academy of Sciences and the National Natural Science Foundation of China. Reference: Wang, Z., Chen, J.*, Liang, T., Yuan, J., Han, C., Liu, J., Zhu, C., Zhu, D., Han, Z.*, 2020. Spatial variation in carbonate carbon isotope during the Cambrian SPICE event across the North China Platform. Palaeogeography, Palaeoclimatology, Palaeoecology, 546, 109669. https://doi.org/10.1016/j.palaeo.2020.109669 Detailed sedimentary loggings of the Miaolingian-Furongian boundary successions in the eastern part of the North China Platform Representative facies of the Miaolingian-Furongian boundary successions in the eastern part of the North China Platform Representative trilobites of the Miaolingian-Furongian boundary successions in the eastern part of the North China Platform Correlation of carbonate δ13C records of the upper Miaolingian to the lower Furongian succession from the eastern part of the North China Platform
The end-Permian marine extinction (EPME) eliminated >80% of species globally, making it the most severe extinction of the Phanerozoic. Anoxia and euxinia are potential kill mechanisms that may have contributed to this biotic crisis. However, redox changes in the atmosphere-ocean system are likely to have been complex, with both the vertical location of the oxic-anoxic boundary (in the water column or sediments), and the total area or volume of anoxic and euxinic water in the global ocean changing over time. The end-Permian marine extinction (EPME) eliminated >80% of species globally, making it the most severe extinction of the Phanerozoic. Anoxia and euxinia are potential kill mechanisms that may have contributed to this biotic crisis. However, redox changes in the atmosphere-ocean system are likely to have been complex, with both the vertical location of the oxic-anoxic boundary (in the water column or sediments), and the total area or volume of anoxic and euxinic water in the global ocean changing over time. Recently, an international research team from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences, Western Carolina University and Nanjing University reported a series of geochemical analyses on iron speciation and major and trace element data from 141 samples of the Meishan-1 core, which was drilled at a site 550 m to the west of the Meishan D section. The research results have been published online in Palaeogeography Palaeoclimatology Palaeoecology. Iron speciation results, in combination with authigenic concentrations and enrichment factors of redox-sensitive metals (Mo, V, and U), and previously published macrofossil, trace fossil, and bioturbation evidence, suggest that: 1) Beds 21-24d were deposited beneath a predominantly oxic water column, 2) Beds 24e-28 were deposited under a persistently anoxic watermass with intermittently euxinic bottom water, and 3) Beds 29-34 were deposited under primarily ferruginous conditions. Excess fractions and enrichment factors of U, V and Mo in the anoxic and euxinic intervals of the Meishan-1 core suggest that authigenic precipitation of redox-sensitive trace metals mainly occurred before and during the EPME, with nearly no detectable authigenic U, V, or Mo accumulating after the EPME. The new results, along with published U, V and Mo concentrations from across the Neotethys, Paleotethys, and Panthalassic Ocean basins, indicate that oceanic trace metal reservoirs were depleted before and during the main extinction interval. This depletion of oceanic trace elements suggest a spatial expansion of both anoxic and euxinic watermasses prior to and during the EPME. The apparent coincidence in timing between the mass extinction and the areal expansion of anoxic and euxinic watermasses suggests that these factors played important roles in the loss of marine biota around the PTB, through oxygen deprivation and H2S toxicity. This work was supported by the Strategic Priority Research Program of Chinese Academy of Sciences, the National Natural Science Foundation of China and the Key Research Program of Frontier Sciences of the Chinese Academy of Sciences. Reference: Xiang, L., Zhang, H.*, Schoepfer, S.D., Zheng, Q.F., Yuan, D.X., Cai, Y.F., Cao, C.Q., Shen, S.Z., 2020. Oceanic redox evolution around the end-Permian mass extinction at Meishan, South China. Paleogeogr. Paleoclimatol. Paleoecol. 544, 109626. https://doi.org/10.1016/j.palaeo.2020.109626 Stratigraphic distributions of selected redox proxies around Permian-Triassic boundary in the Meishan section
Recent studies indicate increasing numbers of fossil organisms have been found in the Amber inclusions. However, few fossils have been documented for fossil liverworts in amber. Recently, a research team of the Mesozoic plants led by Prof. WANG Yongdong and Dr. LI Ya from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), cooperated with Prof. Harald Schneider from Xishuangbanna Tropical Botanical Garden, CAS and Prof. WU Pengcheng from Institute of Botany, CAS, have investigated the liverwort inclusions from the mid-Cretaceous Burmese amber. Recent studies indicate increasing numbers of fossil organisms have been found in the Amber inclusions. However, few fossils have been documented for fossil liverworts in amber. Recently, a research team of the Mesozoic plants led by Prof. WANG Yongdong and Dr. LI Ya from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), cooperated with Prof. Harald Schneider from Xishuangbanna Tropical Botanical Garden, CAS and Prof. WU Pengcheng from Institute of Botany, CAS, have investigated the liverwort inclusions from the mid-Cretaceous Burmese amber. They found a distinctive and anatomically preserved sterile branch of Frullania (Frullaniaceae, Porellales), and described it as F. partita sp. nov. after detailed comparisons with related extant and fossil species of Frullania. This research results have recently been published in the international geoscience journal Cretaceous Research. This new species is mainly characterized by apically apiculate leaf lobes, helmet-shaped to campanulate water sacs situated in some distance to stem, lanceolate styli, and apically deeply bilobed underleaves carrying rhizoid bundles in their basal parts. Recent molecular based studies introduced the hypothesis that the diversity of the predominantly epiphytic liverworts Porellales expanded during the Cretaceous Terrestrial Revolution (KTR) period around 125–80 Ma. Until now, the fossil record provides only insufficient support to elucidate this hypothesis. Porellales comprise seven families, viz. Porellaceae, Goebeliellaceae, Lepidolaenaceae, Radulaceae, Frullaniaceae, Jubulaceae, Lejeuneaceae. Representatives of the Porellales are most common in Cenozoic amber, however, these liverwort inclusions in Cretaceous amber are relatively rare and usually consist of small fragments, rather than complete plants. So far, only a few taxa (3 families 4 genera 6 species) of Porellales have been described from the mid-Cretaceous Burmese amber.This new discovery contributes our understandings for the diversity aspects of Frullaniaceae (Porellales) of Burmese amber inclusions. The bark fragments connected to the branch provide the evidence that the fossil is an epiphyte. This study was supported by the National Natural Science Foundation of China, and the Strategic Priority Research Program of the Chinese Academy of Sciences. Reference:Li, Y., Wang, Y.-D.*, Schneider, H., Wu, P.-C., 2020. Frullania partita sp. nov. (Frullaniaceae, Porellales), a new leafy liverwort from the mid-Cretaceous of Myanmar. Cretaceous Research 108, 104341. https://doi.org/10.1016/j.cretres.2019.104341 Morphology and anatomy of the sterile branch of Frullania partita sp. nov. from the mid-Cretaceous of Burmese amber Reconstruction of Frullania partita sp. nov. (drawn by Ding-Hua Yang)
As a predominant category in the Paleozoic evolutionary fauna, grapholites increased rapidly in the Ordovician and evolved rapidly. Late Ordovician graptolites from the Mandalay Region, Myanmar were first collected and reported by Reed in 1915, and then there were few reports after that. Recently Academician CHEN Xu and Dr. CHEN Qing from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS) cooperated with Dr. Kyi Pyar AUNG from Taunggyi University in Myanmar and Dr. Lucy A. MUIR from the National Museum of Wales to work on the graptolite fauna and the biostratigraphy of the Upper Ordovician Naungkangyi Group and Panghsa-pye Formation in this area. Related research results were published in Palaeoworld magazine. Based on detailed systematic paleontological description and identification, 13 species in 5 genera (Avitograptus, Korenograptus, Metabolograptus, Neodiplograptus and Normalograptus) were described from the Mandalay Region. Two of these species, Korenograptus selectus X. Chen n. sp. and Neodiplograptus mandalayensis X. Chen n. sp., were new. On the basis of the community analysis and international correlation, a biostratigraphic scheme for the uppermost Ordovician (Hirnantian: Metabolograptus extraordinarius Biozone and Metabolograptus? persculptus Biozone) strata was erected in this area. This research was supported by the Strategic Priority Research Program of Chinese Academy of Sciences, National Science and Technology Major Project of China, Ministry of Nature and Resources of China and the National Natural Science Foundation of China. Reference: Chen Xu*, Chen Qing, Kyi Pyar Aung, Lucy A. Muir. 2020. Latest Ordovician graptolites from the Mandalay Region, Myanmar. Palaeoworld, 29: 47–65. https://doi.org/10.1016/j.palwor.2019.09.003 Graptolite species range chart of the Upper Ordovician interval in the Shwethin Village–Yebyantaung waterfall section, Mandalay, Myanmar Typical graptolites pictures
The end-Ordovician mass extinction (EOME) was the first of the “Big Five” extinctions of the Phanerozoic. However, there is still uncertainty concerning the exact timing of the Silurian biotic recovery following this extinction event due to the lack of reliable age constraints of fossil records during this interval. The end-Ordovician mass extinction (EOME) was the first of the “Big Five” extinctions of the Phanerozoic. However, there is still uncertainty concerning the exact timing of the Silurian biotic recovery following this extinction event due to the lack of reliable age constraints of fossil records during this interval. Of particular interest is the richly fossiliferous succession from the Wulipo Formation in the Huangjiaba area near Meitan in northern Guizhou, SW China, which represents one of the very rare records of shelly fauna across the Ordovician and Silurian transition worldwide, and is therefore crucial for understanding the pattern and dynamics of the end-Ordovician mass extinction (EOME). Recently, Dr. WANG Guangxu from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences and his colleagues present for the first time, chemostratigraphic data from the Wulipo Formation which confirm the presence of the Hirnantian Isotope Carbon Excursion (HICE). The research results have been published online in the international geoscience journal Geological Journal. Historically, the Wulipo Formation was dated as middle Rhuddanian (early Silurian). However, its fauna shows a close affinity with Transitional Benthic Fauna 3 (TBF 3), now known to be confined within the late Hirnantian (latest Ordovician) in well-constrained successions globally. A critical review of faunal evidence further indicates a late Hirnantian age for this formation, and thus the hitherto only known anomalous TBF 3 record documented from South China is convincingly redated. The important implication is that the substantial biotic recovery after the EOME commenced globally at the very beginning of the Silurian with an overall amelioration of physical conditions. The new findings also suggest a much wider distribution of postglacial warm-water benthic faunas on the Yangtze Platform during the late Hirnantian than previously envisaged. This research was jointly funded by the National Natural Science Foundation of China, the Strategic Priority Research Program (B) of Chinese Academy of Sciences and the State Key Laboratory of Palaeobiology and Stratigraphy. Related information on this paper: Wang, G.X.*, Wei, X., Luan, X.C., Wu, R.C., Percival, I.G. & Zhan R.B. 2020. Constraining the biotic transitions across the end-Ordovician mass extinction in South China: Bio- and chemostratigraphy of the Wulipo Formation in the Meitan area of northern Guizhou. Geological Journal, https://onlinelibrary.wiley.com/doi/full/10.1002/gj.3816.
δ13Ccarb curves from Yanping (a) Gaojiang (b) of the study area, in comparison with that from Tunping (c) of the Shiqian area, indicating the presence of HICE in the Wulipo Formation. An updated chronostratigraphic classification of the Ordovician–Silurian boundary shelly rocks on the Yangtze Platform of South China.
The early land plant fossils of the group zosterophyllopsid are widely recorded in global Silurian to Devonian sediments and acts as a dominant group in the Early Devonian flora of South China. Demersatheca contigua is an endemic zosterophyllopsid of the Early Devonian flora in South China and its paleophytogeographic implication to southern China Early Devonian is discussed. The early land plant fossils of the group zosterophyllopsid are widely recorded in global Silurian to Devonian sediments and acts as a dominant group in the Early Devonian flora of South China. Demersatheca contigua is an endemic zosterophyllopsid of the Early Devonian flora in South China and its paleophytogeographic implication to southern China Early Devonian is discussed. Previous studies have suggested that the overall shape of the D. contigua is flat fern, while the new research changed this perception. In addition, the publication of D. contigua was effective but invalid because a holotype was not assigned in its initial description. Therefore, there are still many problems in the research of D. contigua. Recently, the Devonian Investigation Group (DIG) of Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, led by Professors XU Honghe and WANG Yi and PhD student WANG Yao, researched the same species from the Lower Devonian layers from Guangxi and Yunnan. The plant fossils described in this study include 6 specimens previously attributed to Zosterophyllum contiguum or Z. australianum by Li and Cai from the Lower Devonian Posongchong Formation of Wenshan, Yunnan and 11 specimens newly collected from the Lower Devonian Cangwu Formation of Cangwu, Guangxi. A better understanding to the morphology of the zosterophyllopsid group is achieved with the examination of new specimens collected from these localities and the specimens previously reported. The study was online published recently in Review of Palaeobotany and Palynology. The structure of the D. contigua strobilus is reconstructed and the diagnosis of the plant is emended in the aspect of four-row decussate sporangium arrangement. The nomenclature of D. contigua is summarized and the lectotype of the species is formally proposed.The strobilus of Demersatheca contigua is consists of four rows of lateral sporangia decussately arranged biconvex sporangia with marginal dehiscence bending towards the strobilus to make the strobilus a cylindrical-shape. In this study, we according to the International Code of Nomenclature for Algae, Fungi, and Plants (Shenzhen Code), here propose to select the specimen from original materials as the lectotype of D. contigua. The lectotype in this case equates to the holotype. For a long time, the southern China flora was thought to be a distinctive composition of the Early Devonian flora of China. However, recently accumulated study indicated that the Early Devonian flora of southern China can be subdivided into three phytogeographic zones, Yunnan, Guangxi and Sichuan, every flora of these three has its exclusive plant members, whilst a few shared members can be found among them. In generic level, Adoketophyton and Guangnania occur in both Yunnan and Sichuan; Demersatheca in Yunnan and Guangxi; Zosterophyllum in Guangxi, Yunnan and Sichuan. In specific level, only Demersatheca contigua occurs in Yunnan and Guangxi. These plant records, though being sparse and limited, seem to suggest similarities and potential relationships between these floras. A detailed flora comparison is highly expected and undoubtedly needed in the further study. Reference: Wang Yao, Xu Hong-He*, Wang Yi, 2020. Morphology, nomenclature and potential paleophytogeographic implication of Demersatheca contigua (Zosterophyllopsida) from the Lower Devonian of Yunnan and Guangxi, southwestern China. Review of Palaeobotany and Palynology.104209. https://doi.org/10.1016/j.revpalbo.2020.104209 Fig. 1. Specimens of Demersatheca contigua (Zosterophyllopsida) from the Lower Devonian of Yunnan (A, B and E) and Guangxi (C and D), southwestern China. Fig. 2. Three-dimensional diagram of the strobilus, the fertile structure of the Lower Devonian Demersatheca contigua (Zosterophyllopsida).
With a prominent disparity in the morphology and the microfabric, stromatolites occur widely in the fossil record of the Precambrian. Noticeably, they show a long-term decline in abundance throughout the Proterozoic. The decline tendency continued in the Phanerozoic, while the Cambrian and Early Ordovician record a resurgence of microbialites. It has long been known that the Ordovician marks a changeover from microbial to metazoan-dominated reefs. However, by the Early Ordovician, the abundance of stromatolites achieved Neoproterozoic- to Mesoproterozoic- like prevalence, based on the latest rock record–normalized occurrence analyses. With a prominent disparity in the morphology and the microfabric, stromatolites occur widely in the fossil record of the Precambrian. Noticeably, they show a long-term decline in abundance throughout the Proterozoic. The decline tendency continued in the Phanerozoic, while the Cambrian and Early Ordovician record a resurgence of microbialites. It has long been known that the Ordovician marks a changeover from microbial to metazoan-dominated reefs. However, by the Early Ordovician, the abundance of stromatolites achieved Neoproterozoic- to Mesoproterozoic- like prevalence, based on the latest rock record–normalized occurrence analyses. Cooperated with Dr. Stephen Kershaw of the Brunel University, Dr. LI Qijian from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences（NIGPAS） leaded and conducted a study on the microbial reefs of the Lunshan Formation in southern Anhui Province. The team systematically collected stromatolite samples from the Lunshan Formation of various sections and conducted in-depth studies through microscopic slices. Related results have been published online in the international journal Facies. In the eastern Yangtze Platform of South China Block, Tremadocian (Early Ordovician) stromatolites occur along a palaeoenvironmental transect from the shallowest intra-platform setting through to deeper platform margin. The intra-platform and platform margin belts of Tremadocian rocks in the eastern platform are carbonate-dominated marine environments favourable for calcimicrobes. However, stromatolites are absent in siliciclastic-dominated slope facies. Shallower carbonate facies are represented by the upper member of the Lunshan Formation, composed of a hundred metres thickness of stromatolite-bearing carbonates. Such stromatolites at the Beigong section of Jinxian county are characterized by stratiform and dome-shaped laminations. Girvanella filaments are ubiquitous in thin sections (Fig 1). Crinoids grew on the surfaces of the microbialites. In contrast, towards the deeper carbonate platform margin, stromatolites in massive-bedded limestones of the upper member of Lunshan Formation of the Ma’anshan section at Shitai occur as dense columns of bindstones; macrofossils and bioclasts are rare in those stromatolites, indicating a lower energy and deeper marine setting. Water depth at the platform margin of the Ma’anshan section is interpreted as being above the base of the euphotic zone (Fig 2); however, benthic fauna notably declined. In contrast to shallower settings, in clastic-dominated locations interpreted as deposited in deeper water, stromatolites are absent, represented by the middle member of Dawuqian Formation at the Ziliqian section. This work, therefore, supports that Early Ordovician reef systems were still microbial-dominated, representing the last golden age of stromatolites. This study was financially supported by the Youth Innovation Promotion Association, the National Natural Science Foundation of China, and the Chinese Academy of Science. This study is a contribution to the IGCP-653‘The onset of the Great Ordovician Biodiversity Event’ and the IGCP Project 668 ‘The stratigraphic and magmatic history of Early Palaeozoic equatorial Gondwana and its associated evolutionary Dynamics’. Reference: Yu, Shenyang., Li, Qijian*., Kershaw, Stephen. et al. Microbial reefs in eastern Yangtze Platform, South China Block: the last golden age of stromatolites in the Ordovician. Facies 66, 12 (2020). (DOI: https://doi.org/10.1007/s10347-020-0596-x) Fig 1．Microfacies of the lithological types of the stromatolitic units, upper member of the Lunshan Formation at Beigong section of Jinxian. A) Tangled filaments of Girvanella (Gi); B) Linear and tangled filaments of Girvanella (Gi) and crinoidal fragment (Cr); C) tangled filaments of Girvanella, some filaments are recrystallized as spars, BG-3; D) calcimicrobial(Cm) encrusts on the borings of crinoid (Cr) fragments. Fig 2．Environmental reconstruction interpreting the biotic and lithological facies changes controlled by bathymetric deeping and decreased photosynthesis of marine-floor along the transition between the Lunshan and Dawuqian formations in the Tremadocian, southern Anhui.
The end-Permian mass extinction (EPME), approximately 252 million years ago (Ma), was the greatest biological and ecological crisis of the Phanerozoic Eon on Earth, which caused a serious marine and terrestrial ecosystem crisis, and about 75% of terrestrial biological species disappeared. But how long does it take for terrestrial ecosystems to recover? The end-Permian mass extinction (EPME), approximately 252 million years ago (Ma), was the greatest biological and ecological crisis of the Phanerozoic Eon on Earth, which caused a serious marine and terrestrial ecosystem crisis, and about 75% of terrestrial biological species disappeared. But how long does it take for terrestrial ecosystems to recover? Recently, the research team led by Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS) found that both lake and peat-forming forest ecosystems probably took as long as 10 million years to recover after EPME. Related results were published online in Geology on March 30, 2020. Because the subsequent Early Triassic interval was characterized by recurrent, rapid global warming, harsh marine and terrestrial conditions, marine ecosystems are thought to have recovered substantially by the middle to late Anisian, 8？10 million years and their restoration was still ongoing in the latest Triassic. However, the pattern of recovery of lacustrine ecosystems is still unclear due to the highly fragmentary freshwater fossil record. Recently, a systematic study of the Middle Triassic lacustrine sediments in the Ordos Basin by an international research group led by Prof. WANG Bo from NIGPAS, and the engineer Xie Guwei from Changqing Oilfield. The fossil-bearing horizons are also important oil-producing strata in the Changqing Oilfield. The results of isotope chronology and stratigraphy also provide new dating and fossil evidence for fine-time stratigraphic comparison and petroleum resource exploration. The research group performed high-resolution work involving stratigraphy, sedimentology, and palaeontology in three outcrops (Bawangzhuang, Mazhuang, and Yishicun) on the southern edge of the Ordos Basin. U-Pb isotopic ages of tuffaceous layers in three outcrops dated the Triassic organic-rich shale to 242 Ma in the Middle Triassic Tongchuan Formation. The organic-rich shale in the lower part of the Tongchuan Formation represents the first known appearance of a deep perennial lake after the EPME and is 5 million years earlier than any previous record. The shales have yielded abundant fossils, including microalgae, macroalgae, notostracans, ostracods, insects, fishes, and fish coprolites. The largest fish coprolites was 77 mm long in length, indicating that large predatory fish already existed in the lake at that time. The chitinous mandibles of predatory dipteran larvae were found in phosphatized coprolites. The results provide data on the earliest known Triassic complex lacustrine ecosystem. Primary producers included various micro- and macroalgae, together with some notostracans, ostracods and insects that fed on algae as primary consumers. Second-level consumers included some predatory insects, with higher order trophic levels being represented by predatory fish. Such an ecosystem is a key component of Mesozoic lakes, which were different from pre-Mesozoic lakes in which dipteran larvae were absent and aquatic beetles were rare. The restoration of a complex lacustrine ecosystem was coincident with the termination of the ‘coal gap’, which was an interval of approximately10 million years when no coals were deposited worldwide. It is generally believed that the reoccurrence of the Middle Triassic coal seam represents a significant restoration of the forest ecosystem after EPME. In the Ordos Basin, the oldest known Triassic coal seam occurs in the uppermost part of the Ermaying Formation, the age of which is slightly greater than that of the organic-rich shale in the bottom of the Tongchuan Formation. The appearance of Triassic coal seams is generally considered to represent the substantial recovery of peat-forming forests following the mass extinction, suggesting that lakes and forest ecosystems may be tightly linked through biological, physical, and chemical interactions. Therefore, both lake and peat-forming forest ecosystems probably took up to 10 million years to recover, much longer than the period of recovery of plant communities inferred from palynological data. The hot Early Triassic climate would have limited dissolved oxygen in lakes, potentially hindering ecosystem recovery. A subsequent major increase in marine carbon burial in the Anisian could, however, have caused CO2 drawdown and global cooling, improving lacustrine conditions. In addition, the abundant volcanic ash likely transferred nutrients into the water and probably significantly increased the efficiency of primary productivity in the Ordos Basin. Therefore, both the climatic cooling and high volcanic nutrient input most likely facilitated development of this complex lake community. Relevant research work was jointly funded by the Chinese Academy of Sciences and the National Natural Science Foundation of China. Reference: Zhao Xiangdong, Zheng Daran, Xie Guwei, Jenkyns H.C., Guan Chengguo, Fang Yanan, He Jing, Yuan Xiaoqi, Xue Naihua, Wang He, Li Sha, Jarzembowski E.A., Zhang Haichun, Wang Bo* (2020) Recovery of lacustrine ecosystems after the end-Permian mass extinction. Geology, doi:10.1130/G47502.1.
Figure 1: Field photographs of study area (Imaged by NIGPAS) Figure 2: Photographs showing representative lithologies and collected samples for U-Pb dating (Imaged by NIGPAS) Figure 3: Stratigraphic column showing lithologies, fossiliferous horizons, sample points and age results (Imaged by NIGPAS) Figure 4: Representative fossils from the organic-rich shale and mudstone of the Tongchuan Formation. (A-C) Fish coprolites. (D and E) Sliced photomicrographs of fish coprolite. (F and G) Beetles. (H) Fish. (I) Ostracoda. (J) Tadpole shrimp (Imaged by NIGPAS)
Mesopsychoid scorpionflies are peculiar Mesozoic insects with a distinctly elongate mouthpart and are considered to be a critical group of pollinators prior to the rise of angiosperms. A new genus found from 99-million-year-old Burmese amber reveals the origin of scorpionflies’ long mouthpart. This discovery was reported in Science Advances on March 4.
Mesopsychoid scorpionflies are peculiar Mesozoic insects with a distinctly elongate mouthpart and are considered to be a critical group of pollinators prior to the rise of angiosperms. A new genus found from 99-million-year-old Burmese amber reveals the origin of scorpionflies’ long mouthpart. This discovery was reported in Science Advances on March 4. Aneuretopsychidae is a family of mecopteran insects with a long siphonate mouthpart. In particular, this family is the key to understanding both the early evolution of highly modified mouthparts in Mesopsychoidea and arguably the origin of fleas. Previously, all known aneuretopsychids were from compression fossils, and the detailed structure of their mouthparts was still unclear. Now, however, an international research group led by Prof. WANG Bo from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences (NIGPAS) has found a new genus, including two new aneuretopsychid species from early Late Cretaceous (99 million years ago) Burmese amber, which reveals new anatomically significant details of the elongate mouthpart elements. The aneuretopsychid mouthpart in the new amber fossils consists of one pair of galeae and one unpaired central hypopharynx. During feeding, the galeae would come together temporarily and enclose the hypopharynx thus forming a functional tube. The structures of the new three-dimensionally preserved fossils thus reveal that the aneuretopsychid mouthpart is not labial but maxillary in origin. The phylogenetic results based on 38 taxa and 54 discrete characters support the monophyly of Mesopsychoidea and demonstrate that an elongate mouthpart is one of its key synapomorphies, challenging the view that the long-proboscid condition independently originated two or three times in this clade. In addition, the mouthpart of Mesopsychoidea differs structurally from the highly modified piercing mouthparts of Siphonaptera. So, neither Aneuretopsychidae nor Mesopsychoidea is a sister group to Siphonaptera. In the Burmese amber forest, at least five families of long-proboscid insects have been discovered, further revealing the variety and complexity of mid-Cretaceous pollinating insects. This study provides new insights into the separate origin of the long mouthpart of Mesopsychoidea and fleas, and the evolution of Cretaceous pollinating insects. Reference: Zhao Xiangdong, Wang Bo*, Bashkuev A.S., Aria C., Zhang Qingqing, Zhang Haichun, Tang Wentao, Engel M.S. (2020) Mouthpart homologies and life habits of Mesozoic long-proboscid scorpionflies. Science Advances, 6: eaay1259. Aneuretopsychidae from Late Cretaceous Burmese amber（Image by NIGPAS） Ecological reconstruction of Mesozoic Aneuretopsychidae (Image by NIGPAS)
When and how animal ancestors made the transition from single-celled microbes to complex multicellular organisms is unclear. But a new scientific study suggests animal-like embryological traits developed long before animals themselves. Proposed life cycle of Caveasphaera (Image by NIGPAS) Animals evolved from single-celled ancestors before diversifying into 30-40 distinct anatomical designs. When and how animal ancestors made the transition from single-celled microbes to complex multicellular organisms is unclear. But a new scientific study suggests animal-like embryological traits developed long before animals themselves. The research – by an international research team led by scientists from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences (NIGPAS) and the University of Bristol – focused on ancient fossils of Caveasphaera, a multicellular organism found in 609-million-year-old rocks in South China’s Guizhou Province that defies easy definition as animal or non-animal. Using X-ray microscopy, the researchers analyzed the tiny fossils, which measure about a half-millimeter in diameter and were preserved down to their component cells. Various fossils displayed different stages of Caveasphaera development – from a single cell to a multicellular organism. “We were able to sort the fossils into growth stages, reconstructing the embryology of Caveasphaera,” said Kelly Vargas from the University of Bristol. YIN Zongjun of NIGPAS interpreted the discovery: “Our results show that Caveasphaera sorted its cells during embryo development in just the same way as living animals, including humans.” YIN emphasized, however, there is “no evidence that these embryos developed into more complex organisms.” Still, the discovery offers the earliest evidence of a key step in the evolution of animals – the capacity to develop distinct tissue layers and organs. The verdict still seems to be out on whether Caveasphaera was itself an animal or just an important step in animal evolution, even as researchers search for more fossils. Co-author ZHU Maoyan of NIGPAS said, “Caveasphaera looks a lot like the embryos of some starfish and corals – we don’t find the adult stages simply because they are harder to fossilize.” Whatever Caveasphaera turns out to be, its fossils tell us that animal-like embryonic development evolved long before the oldest definitive animals appeared in the fossil record. This research was funded through the Biosphere Evolution, Transitions and Resilience (BETR) programme, which is co-funded by the UK’s Natural Environment Research Council (NERC) and the Natural Science Foundation of China (NSFC). Reference: The early Ediacaran Caveasphaera foreshadows the evolutionary origin of animal-like embryology’ by Z. Yin, K. Vargas, J. Cunningham, S. Bengtson, M. Zhu, F. Marone and P. Donoghue, Current Biology. https://doi.org/10.1016/j.cub.2019.10.057
