The Cretaceous–Paleogene boundary (K–Pg boundary) marks the beginning of the Cenozoic, and is one of the most important geological boundaries. Charophytes are usually very abundant in the non-marine strata near the K–Pg boundary, and the significant changes of charophyte flora can help to recognize the K–Pg boundary. The “SK-1” scientific drilling project in the Songliao Basin is the first continental Cretaceous scientific drilling under the framework of the International Continental Scientific Drilling Program, which provides a rich source of fossils for this research. Recent investigation conducted by the assistant researcher Sha LI, Professor Qifei WANG, Professor Haichun ZHAMG from “Modern terrestrial ecosystems origin and early evolution research team” at the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, cooperated with Xiaoqiao WAN from the China University of Geosciences and Carles MARTíN-CLOSAS from the University of Barcelona, studied the change of charophyte floras from the Cretaceous–Paleogene transition in the Songliao Basin. Four charophyte biozones and one superzone are defined in the Sifangtai and Mingshui formations from the SK-1(North) borehole in the Songliao Basin (NE China) and correlated to the Geomagnetic Polarity Time Scale. These include a mid–late Campanian Atopochara trivolvis ulanensis Zone, a latest Campanian–early Maastrichtian Microchara gobica Zone, a late Maastrichtian Microchara prolixa Zone, and an earliest Danian Peckichara sinuolata Zone. The latter three zones are grouped within the Microchara cristata Superzone, which allows intra- and intercontinental correlation with other basins in China and Europe. Peckichara sinuolata first appears in chron C29r (upper Mingshui Formation) and is proposed as the basal marker of the Paleocene. The biozonation of the K–Pg interval proposed for the Songliao Basin differs from a previous biozonation proposed in the Pingyi Basin since it represents a different biogeographical and palaeoecological context. In the mid-Campanian to Maastrichtian, the flora was limited to freshwater lakes in northern China and Mongolia, whereas in the Pingyi Basin, brackish water dominated. In the Paleocene, the Songliao Basin contained a diverse flora consisting of nine species that thrived in terrigenous and temporary lakes, whereas the flora in the Pingyi Basin was dominated by one species inhabiting permanent alkaline lakes. The species common to the two basins are widely distributed in Eurasia and constitute a useful tool for long-distance correlations, but serve as a less-precise tool for detailed biostratigraphical subdivision within one specific basin. Reference: Li, S.*, Wang, Q.F., Zhang, H.C., Wan, X.Q., Martín-Closas, C.*, 2018. Charophytes from the Cretaceous–Paleocene boundary in the Songliao Basin (north-eastern China): a Chinese biozonation and its calibration to the Geomagnetic Polarity Time Scale. Papers in Palaeontology, DOI: 10.1002/spp1002.1225. Charophytes from the Songliao Basin. Stratigraphic log of the SK-1(N) borehole showing position of samples and of charophytes, calibrated to the GPTS (Deng et al. 2013).
Numerous well-preserved fossils have already been discovered in mid-Cretaceous (late Albian to earliest Cenomanian, ≈100 Ma) amber from northern Myanmar, including new species, genera, and even families of plants and invertebrates. Compared to many new discoveries on insects, researches of the botanical inclusions stay faraway behind, so far only a few derived ferns (polypods) described from the Myanmar ambers. However, the polypod fossils are significant not only in recovering the polypod ferns’ diversity changes in history, but also in bridging the gap between the Cretaceous records of polypod ferns and divergence time estimates obtained based on the DNA sequence variation. For ferns, amber inclusions are scientifically valuable because of their preservation of micro-structures, especially sporangia, which are usually poorly preserved in sedimentary fossils. Two new fern fossils with beautifully preserved sporangia were reported by Prof. LI Chunxiang from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences and her colleagues, from the mid-Cretaceous amber of Myanmar. Thyrsopteris cretacea represents the first fossil occurrence of Thyrsopteris in the Myanmar tropical forest. Today only one species is known in Thyrsopteris and Thyrsopteridaceae from temperate southern hemisphere and the new fossil species adds much needed data on the evolutive history of this group of ferns. It adds to the diversity previously ascribed to the Thyrsopteridaceae, which has been based on Eocene fossils, and it extends the fossil record of the family further back to the mid-Cretaceous. Most previous fossils of Thyrsopteridaceae have been from the Southern Hemisphere and are therefore considered Gondwanan. Thyrsopteris cretacea represents one of the few occurrences of the family in Laurasia. Researchers also described another new fossil belonging to the Lindsaeaceae as Proodontosoria myanmarensis gen. et sp. nov.. This new fossil probably scrambled with scandent leaves and spiny axes on other plants. The increasing inventory of the Lindsaeaceae in amber has important implications for the phylogenetic reconstruction of extant Lindsaeaceae lineages and subsequent interpretation of their classification. The morphology of Proodontosoria myanmarensis does not concur with any crown group lineage of Lindsaeaceae, but rather display a character state mosaic of several extant lineages. As a result, the fossil might be a Lindsaeaceae stem group representative, rather than a crown group element. These researches were supported by Project of State Key Laboratory of Palaeobiology and Stratigraphy (Nanjing Institute of geology and Palaeontology, CAS) (Grant No. Y626040108), and Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDB26000000). References: 1) Chunxiang Li, Robbin C. Moran, Junye Ma, Bo Wang, Jiasheng Hao (2018). A new fossil record of Lindsaeaceae (Polypodiales) from the mid-Cretaceous amber of Myanmar. Cretaceous Research. https://doi.org/10.1016/j.cretres.2018.12.010 2) Chunxiang Li, Robbin C. Moran, Junye Ma, Bo Wang, Jiasheng Hao, Qun Yang (2019). A mid-Cretaceous tree fern of Thyrsopteridaceae (Cyatheales) preserved in Myanmar amber. Cretaceous Research. https://doi.org/10.1016/j.cretres.2019.01.002 Fossil and extant Thyrsopteris. (A–E) Holotype of Thyrsopteris cretacea. (F-I) Extant Thyrsopteris elegans. Proodontosoria myanmarensis gen. et sp. nov. (Lindsaeaceae, Polypodiales).
Silicified and phosphatized microfossils preserved in the Ediacaran Doushantuo Formation in South China provide key evidence for the early radiation of eukaryotes after the Neoproterozoic global glaciations. Two microfossil biozones (the Tianzhushania spinosa biozone from the lower Doushantuo Formation, and the Hocosphaeridium anozos biozone from the upper Doushantuo Formation) have been proposed on the basis of acanthomorphic acritarchs preserved in the Doushantuo Formation chert nodules in the Yangtze Gorges area. However, their correlation with the stratigraphic horizons yielding Weng’an biota, a well-known phosphatized microfossil assemblage, has long been an issue of debate, which hinders our understanding of the radiation pattern of microscopic eukaryotes after the Marinoan glaciation, as well as their biostratigraphic significance in the subdivision and correlation of the Ediacaran successions. OUYANG Qing from Nanjing Institute of Geology and Palaeontology Chinese Academy of Sciences and her colleagues carried out litho-, bio-, and chemostratigraphic studies on the Ediacaran Doushantuo Formation in the Zhangcunping area of the western Hubei Province, South China. They found that both the lithostratigraphic sequence and microfossil assemblage at Zhangcunping resemble those at Weng’an, indicating a straightforward correlation between fossiliferous strata in these two areas. Litho- and chemostratigraphic correlations suggest that the microfossil-bearing strata at Zhangcunping could be correlated with the upper part of the lower acritarch biozone in the Yangtze Gorges area, thus supporting the stratigraphic correlation between the stratigraphic units yielding the Weng’an biota at Weng’an and the upper part of the lower acritarch biozone in the Yangtze Gorges area. This correlation scenario supports the idea that the Weng’an biota is biostratigraphically transitional between the lower and upper acritarch biozones, suggesting a stepwise evolutionary pattern of the Ediacaran acanthomorphic acritarchs after the Cryogenian global glaciation, and calls for more detailed investigation on the taxonomical composition and biostratigraphic ranges of acanthomorphs in the T. spinosa biozone in the Yangtze Gorges area, and re-consideration of acanthomorphic biozonation of the Doushantuo Formation in the Yangtze Gorges area. Reference: Ouyang, Q., Zhou, C.*, Xiao, S., Chen, Z., Shao, Y., 2019, Acanthomorphic acritarchs from the Ediacaran Doushantuo Formation at Zhangcunping in South China, with implications for the evolution of early Ediacaran eukaryotes. Precambrian Research, 320: 171–192. Correlation of the Weng’an biota at Weng’an, Guizhou Province and the Zhangcunping microfossil assemblage at Zhangcunping
Some acanthomorphic acritarchs from the Doushantuo Formation at Zhangcunping, Hubei Province, South China
The Late Devonian Frasnian-Famennian (F-F) mass extinction is traditionally known as one of the “Big Five” faunal crises during the Phanerozoic. Ostracods are microcrustacea that first appeared in the Ordovician (Cambrian?) and are still developing today. Ostracods offer special insights into the characteristics of the Devonian bio-environmental events. So far, it is still ambiguous that how benthic ostracods from shallow to deep waters responded to the crisis. Moreover, pelagic ostracods are relatively rare in the F-F transitional interval and their responses to the F-F event are not clear as well. Recently, Dr. SONG Junjun from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, together with her colleagues studied the Late Devonian ostracods from South China and Europe. The study showed that ostracods in varied environments responded to the F-F event differently. Namely, from the carbonate platform, slope, to basinal settings, the extinction rate of benthic ostracods at the F-F transition decreased with increasing water depth. Nevertheless, the F-F event caused substantial loss among pelagic entomozooidea lineages. The extinction pattern of benthic and pelagic ostracods in F-F event in South China is similar to the situation in Europe. But the extinction rates of benthic ostracods in shallow water and slope in Europe seems to be higher than that in the same situation in South China. The abundance and diversity of ostracods decreased and some species even disappeared in anoxic environments across the F-F boundary in South China, when there were rapid changes in the palaeotemperature of surface sea water. Article information: Song, J. J., Huang, C. & Gong, Y. M. *, Response of Ostracods (Crustacea) to the Devonian F—F event: Evidence from the Yangdi and Nandong sections in Guangxi, South China. 2019, Global and Planetary Change 173: 109-120. https://doi.org/10.1016/j.gloplacha.2018.12.015 Extinction pattern of the Devonian F-F transitional ostracods from South China Ostracod assemblages and extinction rates of benthic and pelagic species from shallow marine to deep marine setting in the F-F event. The relationship between variations in the abundance and diversity of benthic ostracods and changes of the marine
As one of the major groups in the Great Ordovician Biodiversification Event, cephalopods may have played a critical role in the marine environment. Their origins and radiations indicate the expansion of the marine ecosystem from the water bottom to open sea. However, the morphologic characteristic and diversity of the early cephalopods during the Cambrian–Ordovician transition have been poorly known. Recently, Dr. Fang Xiang and Prof. Zhang Yuandong from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, and Dr. Bj？rn Kr？ger from University of Helsinki, Finland, conducted a research on the cephalopods from the latest Cambrian. In the study, all the published Cambrian cephalopod occurrences were analyzed using several quantitative methods, including cluster analysis (CA) and non-metric multidimensional scaling (NMDS). The results showed that the cephalopods first appeared during the late Cambrian in North China, and rapidly dispersed to South China, North America, and probably also to Siberia and Kazakhstan, showing their first evolutionary radiation. However, shortly afterwards, nearly 95% of these existing cephalopods disappeared abruptly in the Cambrian–Ordovician transition, with only several elements of two families surviving into the earliest Ordovician, which became the ancestors of the Ordovician and subsequent cephalopods. In addition, the rapid diversification of cephalopods during the late Cambrian approximately coincides with the origination and diversification of several other groups, e.g., graptolites and radiolarians, while the mass extinction of cephalopods in the Cambrian–Ordovician transition coincides with those of trilobites and brachiopods, and temporally with a major late Cambrian sea-level regression. This study was financially supported by the National Science Foundation of China, Chinese Academy of Sciences. This study is a contribution to the IGCP653 ‘The onset of the Great Ordovician Biodiversity Event’. Reference: Fang, X., Kroger, B., Zhang, Y.D., Zhang, Y.B., Chen, T.E., 2018. Palaeogeographic distribution and diversity of cephalopods during the Cambrian–Ordovician transition. Palaeoworld, DOI: https://doi.org/10.1016/j.palwor.2018.08.007. Range chart of early cephalopod faunas through the Cambrian and Ordovician transition and the diversity of some other major marine organisms. Palaeobiogeographic distribution of cephalopods during the latest Cambrian.
Representative palynomorphs from the Miocene Shengxian Formation in eastern Zhejiang Province (scale bar=20μm)The Miocene was a period in which significant environmental and climatic changes occurred. Global temperature began to rise since the late Early Miocene, then significantly decreased after the Mid-Miocene Climatic Optimum, which was accompanied by frequent fluctuations. In China, the zonal climate pattern linked to the planetary circulation system was transformed to a monsoon-dominated pattern similar to the present-day one, which had occurred at least by the early Miocene, giving rise to great environment and vegetation changes in this region. The Neogene Shengxian Formation is a set of strata consisting of basaltic rocks of multi-volcanic cycles and fluvial–lacustrine deposits, the latter is one of the most renowned localities of Neogene fossil plants in China. Isotope chronology studies show the volcanic activities related to the Shengxian Formation occurred during the Late Miocene to the earliest Quaternary, while the fossiliferous horizons are generally assigned to the Miocene which is mainly based on the fossil flora comparisons. Research progress on the palynoflora of the formation is still limited because these deposits either occurred as the intercalations or were formed in small rifted basins and intermontane basins with scattered distribution and small thickness, greatly preventing the accurate correlation among different sections. As sporopollen is an important palaeoenvironmental and palaeoclimatic proxy, it is necessary to establish a possible palynological succession for the in-depth study of the evolution of palaeovegetation and palaeoenvironment in east China. Recently, a group led by Prof. Wang Weiming from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences provides a new insight into the palynoflora of the Shengxian Formation and its palaeovegetational and palaeoenvironmental implications. The result was published in “Review of Palaeobotany and Palynology” lately. According to the division of the volcanic belt within the distribution range of the Shengxian Formation, the research group carried out systematic pollen sampling and analysis. On the basis of compilation of previous studies and extensive correlation with existing sporopollen data, a Miocene palynological succession was established, including the late Early–early Middle Miocene Quercus E.–Liquidambar–Carya assemblage, the late Middle–early Late Miocene Quercus E.–Pinus–(Poaceae)–Trapa assemblage, and the late Late Miocene Quercus E.–Fagus–Artemisia assemblage. This palynological succession indicates that along with the changes of climate, the vegetation of the study area went through three periods, i.e., thermophilous arbors–dominated stage under the warm and humid climate, conifers–increased and aquatic plants Trapa–flourished stage, forests–shrunk and grassland–expanded stage, which were largely related to the global climate change at that time. Combining with fossil plants records, the zonal vegetation of eastern Zhejiang Province during the late Early–Late Miocene was similar to its modern type but with more distinct altitudinal zonality because of the occurrence of Larix. This study was financially supported by the National Natural Science Foundation of China, and the Strategic Priority Research Program of Chinese Academy of Sciences. Reference: Yi Yang, Wei-Ming Wang*, Jun-Wu Shu, Wei Chen, 2018. Miocene palynoflora from Shengxian Formation, Zhejiang Province, southeast China and its palaeovegetational and palaeoenvironmental implications. Review of Palaeobotany and Palynology. 259, 185-197.
Paleozoic stromatoporoids have long been considered to have emerged during the late Middle Ordovician. Five of seven families in the Order Labechiida appeared nearly contemporaneously during the Darriwilian throughout the low-paleolatitude regions of Laurentia, Siberia and Gondwana. This rather sudden and almost simultaneous widespread Darriwilian appearance of diverse early stromatoporoids has been explained by two different hypotheses: the conventional view states that the early stromatoporoids arose from one or two basic skeletonized rosenellids such as Cystostroma or Pseudostylodictyon, whereas the alternative hypothesis suggests that stromatoporoids rose from ‘a simple, non-calcifying sponge root stock’ that acquired the ability to secrete a mineralized skeleton during the Darriwilian. Recently, Dr. LI Qijian from Nanjing Institute of Geology and Palaeontology and his collaborators from South Korea have reported a new species of the most primitive rosenellid stromatoporoid Cystostroma (C. primordia sp. nov.) from the Hunghuayuan Formation (Lower Ordovician, Floian) of Guizhou Province in the South China Block (Figure 1) and the Duwibong Formation (Middle Ordovician, Darriwilian) of the Taebaeksan Basin in mid-eastern Korea (North China Block) (Figure 2). This species is the first representative of the genus found in both the North and South China blocks. Cystostroma primordia sp. nov. is characterized by the absence of denticles and distinctively smaller cyst plates than any other known species of Cystostroma. The presence of this new species in Lower to Middle Ordovician strata of western Gondwana challenges the long-held view of the late Middle Ordovician emergence of Paleozoic stromatoporoids. The simple internal morphological features of this new species and its occurrence in the Lower Ordovician of South China strongly indicate that an Early Ordovician Cystostroma-type precursor from western Gondwana is located near the base of the stromatoporoid stock. This occurrence greatly preceded the late Middle Ordovician (late Darriwilian) stromatoporoid diversification in circum-equatorial regions worldwide. Reference: Juwan Jeon, Qijian Li, Jae-Ryong Oh, Suk-Joo Choh, Dong-Jin Lee. 2018. A new species of primitive stromatoporoid Cystostroma from the Ordovician of East Asia. Geosciences Journal, DOI: https://doi.org/10.1007/s12303-018-0063-7 Photomicrographs of the labechiid stromatoporoid Cystostroma from South China. Field photographs of a stromatoporoid-bryozoan skeletal reef in the Duwibong Formation. Scale bars in Figures 2b and c = 1 cm.
The uplift of Tibetan Plateau had a significant impact on the evolution of regional and global climate during the Cenozoic including the origin and evolution of the Asian monsoon system and the aridification in northwestern China. The Lhasa terrane has been considered a key region for understanding the elevation history of the southern Tibetan Plateau after collision of continental India and Asia in early Paleocene. Stable isotopic studies consistently suggest that the Lhasa terrane had reached its near-present elevation before the Miocene. In a recent collaborative study by Dr. Gongle Shi, Professor Shuangxing Guo, and the research group of Professor Kexin Zhang from China University of Geosciences, Wuhan, a plant megafossil assemblage from the Kailas Formation of the Kailas Basin in western part of the southern Lhasa terrane was reported. The U-Pb dating and magnetostratigraphic correlation show that the studied section of the Kailas Formation ranges from 25.1 Ma to 21.8 Ma in age, and that the fossil flora occurred at 23.3 Ma (latest Oligocene). The uppermost Oligocene Kailas fossil flora is low in diversity and dominated by Populus, Betulaceae and legume. It most likely represents a deciduous, broad-leaf vegetation and suggests a temperate, humid environment with a low to moderate palaeoelevation of 1500–2900 m in the Kailas Basin during the latest Oligocene, based on the co-existing range of the living analogues of the fossil plants. This conflicts with the existence of a continuous, high Gangdese Mountains stretching across the whole southern Lhasa terrane in the late Oligocene. Available evidence appears to suggest strong uplift of the southern Lhasa terrane after the latest Oligocene. The research was recently published in “Palaeogeography, Palaeoclimatology, Palaeoecology”. This work is funded by the Foundation of the Geological Survey of China, the National Natural Science Foundation of China, and the Youth Innovation Promotion Association, CAS. Reference: Ai K., Shi G.*, Zhang K.*, Ji J., Song B., Shen T., Guo S., 2018. The uppermost Oligocene Kailas flora from southern Tibetan Plateau and its implications for the uplift history of the southern Lhasa terrane. Palaeogeography, Palaeoclimatology, Palaeoecology. DOI: 10.1016/j.palaeo.2018.04.017.https://www.sciencedirect.com/science/article/pii/S0031018217307496 Populus from the uppermost Oligocene of the Kailas Basin
During late Cretaceous to Palaeogene, there were many terrestrial salty basins in Eastern China. Many of the basins are the main oilfields in Eastern China, and salt rocks in the basins formed good cap rocks for gas and oil. Since 1970s, it has been debated that these basins were terrestrial salt lakes or transgressed by sea. The Palaeogene Shahejie Formation in the Shulu Sag of Huabei Oilfield developed a great thickness of sediments of evaporate rocks, among which layers of mudstones also occurred. Dr. Cheng Jinhui and Dr. Meng Fanwei of Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences and Dr. Zhao Yanjun of Chinese Academy of Geological Sciences discovered some well-preserved fossils of dinoflagellate cysts in this formation. Salt rocks and assemblage of fossil dinoflagellate cysts indicate a palaeoenvironment of salt lake. The discovery not only indicates the palaeoenvironment of late Palaeogene, but also is helpful for the evaluation of oil source rocks in this set of salt-bearing strata. Reference: Cheng, J., Zhao, Y. & Meng, F. 2018. Paleogene organic-walled dinoflagellate cysts in the Shulu Sag, Hebei Province, China. Carbonates and Evaporites. DOI: https://doi.org/10.1007/s13146-018-0456-8 Mudstones interweaved with salt in core NY3 in the Shulu Sag. Dinoflagellate cysts from Core NY3 in the Shulu Sag.
Based on multivariate morphometric analysis, Halysites catenularius is identified from the Rumba Formation (Telychian) and Jaagarahu Formation (Sheinwoodian) of Estonia; H. priscus is confirmed as a junior synonym. Halysites catenularius, H. junior and H. senior are shown to be closely related; H. catenularius is morphologically intermediate. Cyclomorphism in H. catenularius, recorded by fluctuations of corallite tabularial area, indicates an average annual growth rate of 6.0 mm, which is typical for halysitids. Tubules in H. catenularius, generated from small intramural openings between adjacent corallites, were involved in two types of interstitial increase. The intramural openings, three types of lateral increase, temporary agglutinated patches of corallites, and axial increase documented in H. catenularius resemble features in some species of Catenipora. These similarities are consistent with the interpretation that Halysites evolved from Catenipora. Evaluation of the possibility that both genera are polyphyletic will require further detailed analysis of additional species. Reference: Liang, K., Elias, R.J., Lee, D.-J. 2018. Morphometrics, growth characteristics and phylogenetic implications of Halysites catenularius (Tabulata, Silurian, Estonia). Journal of Paleontology. https://doi.org/10.1017/jpa.2018.73 Growth cycles detected from fluctuations of corallite tabularial area base on serial peels A new offset developed by interstitial increase and formation of new tubules (arrows) in Halysites catenularius New offsets developed by lateral increase (arrows) in Halysites catenularius
