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  • 51.
    Peng, Jungang
    et al.
    State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology and Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Nanjing, China;Department of Palaeobiology, Swedish Museum of Natural History, Stockholm, Sweden.
    Slater, Sam M.
    Swedish Museum of Natural History, Department of Paleobiology.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology.
    Megaspores from the Late Triassic‒Early Jurassic of southern Scandinavia: taxonomic and biostratigraphic implications2021In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 143, no 2-3, p. 202-228Article in journal (Refereed)
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  • 52.
    Peng, Yungang
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Li, Jianguo
    Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China.
    Li, Wenben
    Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China.
    Slater, Sam M
    Swedish Museum of Natural History, Department of Paleobiology.
    Zhu, Huaicheng
    State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    The Triassic to Early Jurassic palynological record of the Tarim Basin, China2018In: Palaeobiodiversity and Palaeoenvironments, ISSN 1867-1594, E-ISSN 1867-1608, Vol. 98, p. 7-28Article in journal (Refereed)
    Abstract [en]

    The Tarim Basin, located in northwestern China, is an important oil-bearing region, and the extensive non-marine Mesozoic successions make this a key location for understanding environmental changes through the Triassic and Jurassic. Palynological analyses on samples from Lunnan-1 and Tazhong-1 drill cores from the northern and central part of the Tarim Basin reveal wellpreserved spore–pollen assemblages. Five palynological assemblages, i.e. Tarim Triassic 1 (TT1)–Tarim Triassic 4 (TT4) and Tarim Jurassic 1 (TJ1), spanning the Early Triassic to Early Jurassic were identified based on compositional changes, which are supported by ordination of samples using non-metric multidimensional scaling (NMDS). The Early Triassic assemblages possess abundant bryophytes and Densoisporites spp.-producers, which potentially represent a recovery succession following the end-Permian event. The Late Triassic spore–pollen assemblages are more similar to those of the North China Palynofloral Province compared to the South China Province. Based on our phytogeographic analysis, we propose that the western section of the boundary between the North and South China palynofloras should be placed at the southern margin of the Tarim Basin.

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  • 53.
    Peterffy, Olof
    et al.
    Department of Geology, Lund University.
    Calner, Michael
    Department of Geology, Lund University.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    Early Jurassic microbial mats—A potential response to reduced biotic activity in the aftermath of the end-Triassic mass extinction event2016In: Palaeogeography, Palaeoclimatology, Palaeoecology, ISSN 0031-0182, E-ISSN 1872-616X, Vol. 464, p. 76-85Article in journal (Refereed)
    Abstract [en]

    Wrinkle structures are microbially induced sedimentary structures (MISS) formed by cyanobacteria and are common in pre-Cambrian and Cambrian siltstones and sandstones but are otherwise rare in the Phanerozoic geological record. This paper reports the first discovery of Mesozoic wrinkle structures from Sweden. These are preserved in fine-grained and organic-rich heterolithic strata of the Lower Jurassic (Hettangian) Höganäs Formation in Skåne, southern Sweden. The strata formed in a low-energy, shallowsubtidal setting in themarginal parts of the Danish rift-basin. Palynological analyses of fine-grained sandstones hosting the wrinkle structures show that the local terrestrial environment probably consisted of a wetland hosting ferns, cypress and the extinct conifer family Cheirolepidaceae. Palynostratigraphy indicates a Hettangian age, stillwithin the floral recovery phase following the end-Triassic mass extinction event. The finding of wrinkle structures is significant as the presence of microbial mats in the shallow subtidal zone, (in a deeper setting compared to where modern epibenthic microbial mats grow) suggests decreased benthic biodiversity and suppressed grazing in shallow marine environments in the early aftermath of the end-Triassic mass extinction event.

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  • 54.
    Qu, Yuangao
    et al.
    Institute of Deep-Sea Science and Engineering, Chinese Academy of Sciences.
    McLoughlin, Nicola
    Rhodes University.
    van Zuilen, Mark A.
    Sorbonne Paris Cité.
    Whitehouse, Martin
    Swedish Museum of Natural History, Department of Geology.
    Engdahl, Anders
    MAX IV Laboratory, Lund University.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    Evidence for molecular structural variations in the cytoarchitectures of a Jurassic plant2019In: Geology, ISSN 0091-7613, E-ISSN 1943-2682, Vol. 47, p. 325-329Article in journal (Refereed)
    Abstract [en]

     

    In this study, we investigate the molecular structural characteristics of organic remains in various cellular organelles from a 180 Ma Jurassic royal fern belonging to the Osmundaceae family of ferns, and compare their carbon isotopic compositions to a now-living species of royal fern (Osmunda regalis). We discovered molecular structural variations indicated by Raman and infrared spectral parameters obtained from various fossilized cellular organelles. The organic remains preserved in the chromosomes and cell nuclei show marked structural heterogeneities compared to the cell walls during different stages of the cell cycle. The fossil and extant fern have similar δ13C values obtained from bulk samples, supporting evolutionary stasis in this plant lineage and an unchanged metabolic pathway of carbon assimilation since the Jurassic. The organic remains in the cellular organelles of the fossil seem to be less heterogeneous than those in the extant fern, likely due to the preferential preservation of certain cellular compounds during fossilization. Taphonomic processes appear to have diminished the subcellular isotopic heterogeneities. Our research sheds light on the functioning of ancient plant cellular organelles during mitosis, provides insights to the taphonomic processes operating at molecular and isotopic levels, and shows the practicability of in situ techniques in studying the evolution and behaviors of ancient cells.

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  • 55.
    Qu, Yuangao
    et al.
    Institute of Deep-Sea Science and Engineering, Chinese Academy of Sciences, Sanya, China..
    Yin, Zongjun
    State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, China..
    Kustatscher, Evelyn
    Museum of Nature South Tyrol, Bozen/Bolzano, Italy.;Department für Geo- und Umweltwissenschaften, Paläontologie und Geobiologie, Ludwig-Maximilians-Universität, München, Germany.;SNSB-Bayerische Staatssammlung für Paläontologie und Geobiologie, München, Germany..
    Nützel, Alexander
    Department für Geo- und Umweltwissenschaften, Paläontologie und Geobiologie, Ludwig-Maximilians-Universität, München, Germany.;SNSB-Bayerische Staatssammlung für Paläontologie und Geobiologie, München, Germany.;GeoBio-Center, Ludwig-Maximilians-Universität München, München, Germany..
    Peckmann, Jörn
    Institute für Geologie, Centrum für Erdsystemforschung und Nachhaltigkeit, Universität Hamburg, Hamburg, Germany..
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology.
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology.
    Traces of Ancient Life in Oceanic Basalt Preserved as Iron-Mineralized Ultrastructures: Implications for Detecting Extraterrestrial Biosignatures2023In: Astrobiology, ISSN 1531-1074, E-ISSN 1557-8070, Vol. 23, no 7, p. 769-785Article in journal (Refereed)
    Abstract [en]

    Benefiting from their adaptability to extreme environments, subsurface microorganisms have been discovered in sedimentary and igneous rock environments on Earth and have been advocated as candidates in the search for extraterrestrial life. In this article, we study iron-mineralized microstructures in calcite-filled veins within basaltic pillows of the late Ladinian Fernazza group (Middle Triassic, 239 Ma) in Italy. These microstructures represent diverse morphologies, including filaments, globules, nodules, and micro-digitate stromatolites, which are similar to extant iron-oxidizing bacterial communities. In situ analyses including Raman spectroscopy have been used to investigate the morphological, elemental, mineralogical, and bond-vibrational modes of the microstructures. According to the Raman spectral parameters, iron minerals preserve heterogeneous ultrastructures and crystallinities, coinciding with the morphologies and precursor microbial activities. The degree of crystallinity usually represents a microscale gradient decreasing toward previously existing microbial cells, revealing a decline of mineralization due to microbial activities. This study provides an analog of possible rock-dwelling subsurface life on Mars or icy moons and advocates Raman spectroscopy as an efficient tool for in situ analyses. We put forward the concept that ultrastructural characteristics of minerals described by Raman spectral parameters corresponding to microscale morphologies could be employed as carbon-lean biosignatures in future space missions. Key Words: Ultrastructures—Iron minerals—Oceanic basalt—Subsurface biosignatures.

  • 56.
    Qvarnström, Martin
    et al.
    Uppsala University.
    Anagnostakis, Stavros
    Nikolaou Plastira 3, Kardia, 57500 Thessaloniki, Greece.
    Lindskog, Anders
    Lund University.
    Scheer, Udo
    Jud. Dâmboviţa, Sat. Mătăsaru 93, RO-137295 Com. Mătăsaru, Romania.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    Rasmussen, Bo W.
    Geomuseum Faxe.
    Lindgren, Johan
    Lund University.
    Eriksson, Mats E.
    Lund University.
    Multi‐proxy analyses of Late Cretaceous coprolites from Germany2019In: Lethaia: an international journal of palaeontology and stratigraphy, ISSN 0024-1164, E-ISSN 1502-3931, Vol. 52, p. 550-569Article in journal (Refereed)
    Abstract [en]

    A total of 462 coprolites from three localities exposing Upper Cretaceous deposits in the Münster Basin, northwestern Germany, have been subjected to an array of analytical techniques, with the aim of elucidating ancient trophic structures and predator–prey interactions. The phosphatic composition, frequent bone inclusions, size and morphology collectively suggest that most, if not all, coprolites were produced by carnivorous (predatory or scavenging) vertebrates. The bone inclusions further indicate that the coprolite producers preyed principally upon fish. Putative host animals include bony fish, sharks and marine reptiles – all of which have been previously recorded from the Münster Basin. The presence of borings and other traces on several coprolites implies handling by coprophagous organisms. Remains of epibionts are also common, most of which have been identified as the encrusting bivalve Atreta. Palynological analyses of both the coprolites and host rocks reveal a sparse assemblage dominated by typical Late Cretaceous dinoflagellates, and with sub‐ordinate fern spores, conifer pollen grains and angiosperm pollen grains. The dinoflagellate key taxon Exochosphaeridium cenomaniense corroborates a Cenomanian age for the Plenus Marl, from which most studied coprolites derive. The findings of this study highlight the potential of a multiproxy approach when it comes to unravelling the origin, composition and importance of coprolites in palaeoecosystem analyses.

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  • 57.
    Renne, Paul R
    et al.
    Berkeley Geochronology Center, Berkeley, California 94709, USA.
    Arenillas, Ignacio
    Departamento de Ciencias de la Tierra, and Instituto Universitario de Investigación en Ciencias Ambientales de Aragón, Universidad de Zaragoza, E-50009 Zaragoza, Spain.
    Arz, José A.
    Departamento de Ciencias de la Tierra, and Instituto Universitario de Investigación en Ciencias Ambientales de Aragón, Universidad de Zaragoza, E-50009 Zaragoza, Spain.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    Gilabert, Vicente
    Departamento de Ciencias de la Tierra, and Instituto Universitario de Investigación en Ciencias Ambientales de Aragón, Universidad de Zaragoza, E-50009 Zaragoza, Spain.
    Bermúdez, Hermann D
    Grupo de Investigación Paleoexplorer, St. George, Vermont 05495, USA.
    Multi-proxy record of the Chicxulub impact at the Cretaceous-Paleogene boundary from Gorgonilla Island, Colombia2018In: Geology, ISSN 0091-7613, E-ISSN 1943-2682, Vol. 46, p. 547-550Article in journal (Refereed)
    Abstract [en]

    A 40 m stratigraphic section at Gorgonilla Island, Colombia, provides a unique deepmarine, low-latitude, Southern Hemisphere record of events related to the end-Cretaceous Chicxulub impact and the global Cretaceous/Paleogene boundary (KPB). The KPB is marked by a 20-mm-thick, densely packed spherule bed as defined by planktic foraminifera, in contrast to complex relationships found in high-energy, impact-proximal sites in the Gulf of Mexico and Caribbean basins. The absence of basal Danian foraminiferal Zone P0 may indicate a possible hiatus of <10 ka immediately above the spherule bed, but is most probably an artifact of deposition below the calcite compensation depth as suggested by the nearly complete absence of calcareous fossils for 20 m below the Zone Pα. A weighted mean 40Ar/39Ar age of 66.051 ± 0.031 Ma for 25 fresh glassy spherules unequivocally establishes both their derivation from Chicxulub, and the association between the impact and the KPB. The spherule bed, and Maastrichtian strata below it, display soft-sediment deformation features consistent with strong seismic motion, suggesting that seismic activity in the immediate aftermath of the Chicxulub impact continued for weeks. We discovered a fern-spike immediately above the spherule bed, representing the first record of this pioneer vegetation from the South American continent, and from a low-latitude (tropical) environment.

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  • 58.
    Rich, Tom
    et al.
    Museums Victoria, Melbourne, Victoria, Australia.
    Kaufman, J.
    Museums Victoria, Melbourne, Victoria, Australia.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology.
    Shevchuk, Olena
    Swedish Museum of Natural History, Department of Paleobiology. Ukrainian Academy of Sciences; Stockholm University.
    Shepherd, L.
    Museums Victoria, Melbourne, Victoria, Australia.
    Kool, L.
    Museums Victoria, Melbourne, Victoria, Australia.
    Poropat, S.
    Curtin University.
    Duddy, I.
    Museums Victoria, Melbourne, Victoria, Australia.
    Vickers-Rich, P.
    Museums Victoria, Melbourne, Victoria, Australia.
    McLees, D.
    Museums Victoria, Melbourne, Victoria, Australia.
    The Koonwarra Fossil Fish Beds Konservat-Lagerstätte: an Update2023In: Program and Abstracts: 18th Conference on Australasian VertebrateEvolution, Palaeontology and Systematics, Melbourne: CAVEPS Melbourne 2023 Executive Committee , 2023, , p. 124p. 124-124Conference paper (Other academic)
    Abstract [en]

    The Koonwarra Fossil Fish Beds located in South Gippsland, Victoria, Australia is renowned for the quality and quantity of the Early Cretaceous fossil plants, arthropods and fish recovered from this ancient lake deposit.

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  • 59.
    Rubinstein, C V
    et al.
    Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales, CCT CONICETa Mendoza, A. Ruiz Leal s/n, Parque General San Martín, M5502IRA Mendoza, Argentina.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology.
    Middle–Late Ordovician organic-walled phytoplankton from Sweden: diversity and early radiation2023In: Estonian journal of earth sciences, ISSN 1736-4728, E-ISSN 1736-7557, Vol. 72, no 1, p. 158-158Article in journal (Other academic)
    Abstract [en]

    The Borenshult-1 core, drilled in the vicinity of Motala, east of Lake Vättern in south centralSweden, comprises a well-dated and nearly complete succession of marine marly carbonatesdeposited relatively close to land. The 34 core samples analyzed for palynology encompass theupper part of the Darriwilian (Furudal Limestone), the entire Sandbian (Dalby Limestone, theKinnekulle K-bentonite and the lower Skagen Limestone) and the lower part of the Katian (SkagenLimestone). The age of this interval is well-constrained to the late Darriwilian (Stage slice Dw3)–early Katian (Stage slice Ka1), based on conodonts and 206Pb/238U dating of volcanic ashdeposits.

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    Rubinstein_Vajda_2023_Middle–Late Ordovician organicwalled phytoplankton from Sweden
  • 60.
    Rubinstein, Claudia V.
    et al.
    IANIGLA, CCT CONICET Mendoza, M5502IRA Mendoza, Argentina.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology.
    High diversity and early radiation of organic-walled phytoplankton in southern Baltica during the Middle-Late Ordovician – evidence from the Borenshult-1 drillcore of southern Sweden2023In: GFF, ISSN 1103-5897, E-ISSN 2000-0863Article in journal (Refereed)
    Abstract [en]

    Highly diverse and well preserved organic-walled phytoplankton were recorded from the Darriwilian–early Katian interval of the Borenshult-1 drillcore. We identified 154 species in 53 genera, and three assemblages were distinguished; Assemblage A of a late Darriwilian age, Assemblage B of a Sandbian age (further subdivided into sub-assemblages B1 and B2), and Assemblage C dated as Katian. Taxa with “Silurian affinities” with previous first appearance datum in the early Silurian, Hirnantian, such as Metaleiofusa and Visbysphaera, are here recorded from the late Darriwilian and Sandbian respectively. These occurrences question the relationship between the appearance of pioneering phytoplankton morphotypes and the Hirnantian glaciation. Other taxa with no pre-Silurian records such as Visbysphaera pirifera subsp. minor, Petaloferidium cazurrum and Dorsennidium cf. D. estrellitae are here present in the Sandbian, where bentonite beds are intercalated. The diversity curve of acritarchs shows similarities with those proposed for the Darriwilian-Katian of Baltica with main differences in the interval with bentonite beds representing an intense volcanic activity. The species Metaleiofusa arcuata Wall is here emended and a new combination is proposed: Petaloferidium cazurrum (Cramer) comb. nov. The genus Fankea is recorded for the first time from Swedish strata, suggesting a dominant high- to middle latitudinal distribution instead of a Perigondwanan distribution. We contend that the location of paleo-southern Sweden contributed to the great diversity seen, since a middle-low latitude provided a suitable habitat with warm, shallow water, rich in nutrients.

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    High diversity and early radiation of organic-walled phytoplankton in southern Baltica during the Middle-Late Ordovician – evidence from the Borenshult-1 drillcore of southern Sweden
  • 61.
    Rubinstein, Claudia
    et al.
    Department of Paleopalynology, IANIGLA, CCT CONICET Mendoza.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    Baltica cradle of early land plants? Oldest record of trilete spores and diversecryptospore assemblages; evidence from Ordovician successions of Sweden2019In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 141, p. 181-190Article in journal (Refereed)
    Abstract [en]

    The origin of land plants is one of the most important evolutionary events in Earth’s history. The mode and timing of the terrestrialization of plants remains debated and previous data indicate Gondwana to be the center of land-plant radiation at ~ 470–460 Ma. Here we present the oldest occurrences of trilete spores, probably the earliest traces of vascular land plants yet recorded. The spores occur in Ordovician, Sandbian (455 million years old) successions in central Sweden, once part of the paleocontinent Baltica. These strata are independently dated by marine microfossils (conodonts) and 206Pb/238U dating of volcanic ash deposits. Our discovery extends the record of trilete spores globally by ~8 million years, and for Baltica by ~25 million years. Additionally, cryptospore assemblages are identified revealing a diverse and stable mid-Ordovician (Darriwilian: ~ 460 Ma) vegetation of free-sporing plants. The formation of regolith substrates on land as a consequence of permanent plant cover must in turn have affected the marine biota. We link these early land plant spore occurrences to the extensive, nutrient-rich volcanic ash deposits and propose Baltica as the possible original region of the radiation of early land plants.

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  • 62.
    Schaefer, Bettina
    et al.
    Curtin University.
    Grice, Kliti
    Curtin University.
    Coolen, Marco
    Curtin University.
    Summons, Roger
    Massachusetts Institute of Technology.
    Vui, Xingqian
    Massachusetts Institute of Technology.
    Bauersachs, Thorsten
    Christian-Albrechts-University.
    Schwark, Lorenz
    Curtin University.
    Böttcher4, Michael
    University of Greifswald.
    Bralowe, Timothy
    Pennsylvania State University.
    Lyons, Shelby
    Pennsylvania State University.
    Freeman, Katherine
    Pennsylvania State University.
    Cockell, Charles
    University of Edinburgh.
    Gulick, Sean
    University of Texas at Austin.
    Morgan, Joanna
    Imperial College, London.
    Whalen, Michael
    University of Alaska.
    Lowery, Christopher
    University of Texas at Austin.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    Microbial life in the nascent Chicxulub crater2020In: Geology, ISSN 0091-7613, E-ISSN 1943-2682, Vol. 48, p. 328-332Article in journal (Refereed)
    Abstract [en]

    The Chicxulub crater was formed by an asteroid impact at ca. 66 Ma. The impact is considered to have contributed to the end-Cretaceous mass extinction and reduced productivity in the world’s oceans due to a transient cessation of photosynthesis. Here, biomarker profiles extracted from crater core material reveal exceptional insights into the post-impact upheaval and rapid recovery of microbial life. In the immediate hours to days after the impact, ocean resurge flooded the crater and a subsequent tsunami delivered debris from the surrounding carbonate ramp. Deposited material, including biomarkers diagnostic for land plants, cyanobacteria, and photosynthetic sulfur bacteria, appears to have been mobilized by wave energy from coastal microbial mats. As that energy subsided, days to months later, blooms of unicellular cyanobacteria were fueled by terrigenous nutrients. Approximately 200 k.y. later, the nutrient supply waned and the basin returned to oligotrophic conditions, as evident from N2-fixing cyanobacteria biomarkers. At 1 m.y. after impact, the abundance of photosynthetic sulfur bacteria supported the development of water-column photic zone euxinia within the crater.

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  • 63.
    Sha, J.
    et al.
    Chinese Academy of Sciences, China.
    Slater, Sam M
    Swedish Museum of Natural History, Department of Paleobiology.
    Vajda, V.
    Swedish Museum of Natural History, Department of Paleobiology.
    Olsen, P. E.
    Lamont-Doherty Earth Observatory of Columbia University, USA.
    Zhang, H.
    Chinese Academy of Sciences, China.
    The Triassic and Jurassic of the Junggar Basin, China: Advances in Palaeontology and Environments2024In: Geological Society Special Publication, ISSN 0305-8719, E-ISSN 2041-4927, Vol. 538, no 1Article in journal (Refereed)
    Abstract [en]

    This volume presents recent advances in our understanding of Mesozoic palaeontology, sedimentology and geochemistry of the Junggar Basin, China. This basin is of particular interest because it provides rare insights into life on the continents from a region that was at high latitudes during the Triassic and Jurassic.

  • 64.
    Sha, Jingeng
    et al.
    LPS, Nanjing Institute of Geology & Paleontology, Nanjing 210008, China.
    Pan, Yanhong
    LPS, Nanjing Institute of Geology & Paleontology, Nanjing 210008, China.
    Gong, Enpu
    Northeastern University, Shenyang 110004, China.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    IGCP 632, The Jurassic–Cretaceous transition in North Eastern China (westernLiaoning and Inner Mongolia): An IGCP meeting and field excursion on the continentalJurassic2017In: Episodes, ISSN 0705-3797, Vol. 40, no 1, p. 79-84Article in journal (Refereed)
    Abstract [en]

    Exposures of strata spanning the Jurassic–Cretaceous boundary occur within several basins in western Liaoning and adjacent Inner Mongolia. These continental successions host world-renowned plant and animal fossils including feathered dinosaurs and the oldest flowering plant, Archaeofructus.

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  • 65.
    Shevchuk, Olena
    et al.
    Institute of Geological Sciences, NAS of Ukraine.
    McLoughlin, Stephen
    Swedish Museum of Natural History, Department of Paleobiology.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    The first Cretaceous megaspores from Ukraine2021In: Cretaceous research (Print), ISSN 0195-6671, E-ISSN 1095-998X, Vol. 118, p. 104649-104649, article id 104649Article in journal (Refereed)
    Abstract [en]

    The first megaspores recovered from Ukrainian Lower Cretaceous strata are described and illustrated by reflected light and scanning electron micrography. Four lycopsid megaspore taxa are identified in core samples from north of Kherson (Khersons'ka Oblast), in the Black Sea Basin, southern Ukraine. Miospore assemblages recovered from the same samples reveal a slightly higher diversity of lycopsid microspores and, in conjunction with previous foraminiferal biostratigraphy, indicate an Aptian-Albian age for the strata. The megaspore suite shares genera with mid-Mesozoic assemblages from widely distributed parts of the world, but most of the Ukrainian specimens have subtle morphological differences from congeneric forms established in other regions. The megaspores accumulated in fluvial floodplain facies and highlight the potential of this region for investigating other Cretaceous mesofossils including early flowers.

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  • 66.
    Shevchuk, Olena
    et al.
    Institute of Geological Sciences, National Academy of Sciences of Ukraine, Kyiv, Ukraine.
    Slater, Sam M
    Swedish Museum of Natural History, Department of Paleobiology.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    Palynology of Jurassic (Bathonian) sediments from Donbas, northeast Ukraine2018In: Palaeobiodiversity and Palaeoenvironments, ISSN 1867-1594, E-ISSN 1867-1608, Vol. 98, no 1, p. 153-164Article in journal (Refereed)
    Abstract [en]

    A palynological and sedimentological study of an outcrop succession adjacent to the village of Kamyanka within the Kharkiv region of northeast Ukraine was carried out. The successions occur within the Dnieper–Donets Basin, which hosts vast successions (> 20 km) of post mid- Devonian strata and is one of the main hydrocarbonproducing basins in Europe. Middle Jurassic sandstones, siltstones and claystones represent the sedimentary successions at the Kamyanska locality. Few palynological studies have been performed on the Jurassic of Ukraine and even fewer presented in the international literature. Thirty spore taxa and 21 pollen taxa were identified, together with taxa kept in open nomenclature (e.g. bisaccate pollen). Two palynological assemblages were identified within the Kamyanska succession (assemblages A and B) dated as Bathonian. Assemblage A is dominated by the fern spores (Cyathidites and Osmundacidites) and gymnosperm pollen produced by Cupressaceae Perinopollenites elatoides), ginkgophytes/Cycadales/Bennettitales (monosulcates) and Cheirolepidiaceae (Classopollis). Assemblage B differs in also comprising high abundances of Gleicheniidites and higher percentages of Pinuspollenites and Araucariacites compared to assemblage A. Another difference between the two units is the high relative abundance of seed fern pollen (Alisporites) in the upper part of assemblage B. The thermal alteration index (TAI) of the palynomorphs is estimated to range from 3 to 3.5, indicating a burial depth corresponding to the mature main phase of liquid petroleum and, to some extent, gas generation. Comparisons between the miospore and macrofloral assemblages show that the palynoflora and macroflora are strongly similar at broad taxonomic levels. Importantly, the miospore assemblages described here compare well with European Middle Jurassic assemblages indicating limited provincialism, with similar vegetation extending from eastern Ukraine and across most of Western Europe.

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  • 67.
    Skovsted, Christian
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Topper, Timothy, P.
    Swedish Museum of Natural History, Department of Paleobiology.
    McLoughlin, Stephen
    Swedish Museum of Natural History, Department of Paleobiology.
    Johansson, Ove
    Swedish Museum of Natural History, Department of Paleobiology. Department of Palaeobiology, Swedish Museum of Natural History, Stockholm, Sweden.
    Liu, Fan
    Swedish Museum of Natural History, Department of Paleobiology. Department of Palaeobiology, Swedish Museum of Natural History, Stockholm, Sweden;State Key Laboratory of Continental Dynamics, Shaanxi Key Laboratory of Early Life and Environments and Department of Geology, Northwest University, Xi’an, China.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    First discovery of Small Shelly Fossils and new occurrences of brachiopods and trilobites from the early Cambrian (Stage 4) of the Swedish Caledonides, Lapland2021In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 143, no 2-3, p. 134-150Article in journal (Refereed)
    Abstract [en]

    New fossil discoveries are reported from the Grammajukku Formation at Luobákte south of Lake Torneträsk in northern Swedish Lapland, including a fauna of Small Shelly Fossils (SSF) from a limestone bed in the uppermost part of the formation and new occurrences of brachiopods and trilobites in siltstones of the lower part of the formation. The moderately diverse SSF fauna is the first of its kind reported from the Swedish Caledonides and includes the first record of the tommotiid Lapworthella schodackensis and the bradoriid spine Mongolitubulus spinosus from Baltica, together with fragmentary specimens of Bradoria sp. and remains of one additional bradoriid arthropod, a protoconodont and a helcionelloid mollusc. In addition, the limestone bed yields abundant specimens of the brachiopods Botsfordia cf. caelata and Eoobolus cf. priscus and an unidentified ellipsocephalid trilobite. Lower down in the Grammajukku Formation, specimens of both brachiopod taxa, orthothecid hyoliths, the trilobite Ellipsocephalus cf. gripi and an unidentified holmiid trilobite were found at several levels in a siltstone, previously regarded as unfossiliferous. These discoveries markedly increase the known diversity of the palaeobiota from the Grammajukku Formation in northern Lapland and provide new insights into the biostratigraphy and palaeoenvironment of the lower Cambrian in Scandinavia and the palaeobiogeography of Cambrian faunas in general.

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  • 68.
    Slater, Sam M
    Swedish Museum of Natural History, Department of Paleobiology.
    Twitchett, Richard (Contributor)
    Department of Earth Sciences, The Natural History Museum, London.
    Danise, Silvia (Contributor)
    4Dipartimento di Scienze della Terra, Università degli Studi di Firenze, Firenze, Italy..
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    Global record of “ghost” nannofossils reveals plankton resilience to high CO2 and warming2022In: Science, ISSN 0036-8075, Vol. 376, no 6595, p. 853-856Article in journal (Refereed)
    Abstract [en]

    Predictions of how marine calcifying organisms will respond to climate change rely heavily on the fossilrecord of nannoplankton. Declines in calcium carbonate (CaCO3) and nannofossil abundance throughseveral past global warming events have been interpreted as biocalcification crises caused by oceanacidification and related factors. We present a global record of imprint—or“ghost”—nannofossils thatcontradicts this view, revealing exquisitely preserved nannoplankton throughout an inferred Jurassicbiocalcification crisis. Imprints from two further Cretaceous warming events confirm that the fossilrecords of these intervals have been strongly distorted by CaCO3dissolution. Although the rapidity ofpresent-day climate change exceeds the temporal resolution of most fossil records, complicatingdirect comparison with past warming events, our findings demonstrate that nannoplankton were moreresilient to past events than traditional fossil evidence suggests.

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  • 69.
    Slater, Sam M
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Kustatscher, Evelyn
    Museum of Nature South Tyrol, Bindergasse/via Bottai 1, 39100 Bozen/Bolzano, Italy.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    An introduction to Jurassic biodiversity and terrestrial environments2018In: Palaeobiodiversity and Palaeoenvironments, ISSN 1867-1594, E-ISSN 1867-1608, Vol. 98, p. 1-5Article in journal (Refereed)
    Abstract [en]

    This special issue of Palaeobiodiversity and Palaeoenvironments is devoted to studies of Jurassic terrestrial floras. The special issue Jurassic biodiversity and terrestrial environments includes nine contributions that investigate plant fossils and their spores and pollen from a range of localities across the globe that stratigraphically span the Jurassic (Fig. 1). These papers are a collective contribution to the IGCP project 632: Continental crises of the Jurassic: Major extinction events and environmental changes within lacustrine ecosystems.

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  • 70.
    Slater, Sam M
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Twitchett, Richard J.
    The Natural History Museum, London.
    Danise, Silvia
    Università degli Studi di Firenze.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    Substantial vegetation response to Early Jurassicglobal warming with impacts on oceanic anoxia2019In: Nature Geoscience, ISSN 1752-0894, E-ISSN 1752-0908, Vol. 12, p. 462-467Article in journal (Refereed)
    Abstract [en]

    Rapid global warming and oceanic oxygen deficiency during the Early Jurassic Toarcian Oceanic Anoxic Event at around 183 Ma is associated with a major turnover of marine biota linked to volcanic activity. The impact of the event on land-based ecosystems and the processes that led to oceanic anoxia remain poorly understood. Here we present analyses of spore–pollen assemblages from Pliensbachian–Toarcian rock samples that record marked changes on land during the Toarcian Oceanic Anoxic Event. Vegetation shifted from a high-diversity mixture of conifers, seed ferns, wet-adapted ferns and lycophytes to a low-diversity assemblage dominated by cheirolepid conifers, cycads and Cerebropollenites-producers, which were able to survive in warm, drought-like conditions. Despite the rapid recovery of floras after Toarcian global warming, the overall community composition remained notably different after the event. In shelf seas, eutrophication continued throughout the Toarcian event. This is reflected in the overwhelming dominance of algae, which contributed to reduced oxygen conditions and to a marked decline in dinoflagellates. The substantial initial vegetation response across the Pliensbachian/Toarcian boundary compared with the relatively minor marine response highlights that the impacts of the early stages of volcanogenic global warming were more severe for continental ecosystems than marine ecosystems.

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  • 71.
    Slater, Sam M
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Wellman, Charles H
    Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK.
    Romano, Michael
    Sheffield, UK.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    Dinosaur-plant interactions within a Middle Jurassic ecosystem—palynology of the Burniston Bay dinosaur footprint locality, Yorkshire, UK2018In: Palaeobiodiversity and Palaeoenvironments, ISSN 1867-1594, E-ISSN 1867-1608, Vol. 98, p. 139-151Article in journal (Refereed)
    Abstract [en]

    Dinosaur footprints are abundant in the Middle Jurassic Ravenscar Group of North Yorkshire, UK. Footprints are particularly common within the Bathonian Long Nab Member of the Scalby Formation and more so within the so called ‘Burniston footprint bed’ at Burniston Bay. The Yorkshire Jurassic is also famous for its exceptional plant macrofossil and spore-pollen assemblages. Here we investigate the spore-pollen record from the dinosaur footprint-bearing successions in order to reconstruct the vegetation and assess possible dinosaur-plant interactions. We also compare the spore-pollen assemblages with the macroflora of the Scalby Ness Plant Bed, which occurs within the same geological member as the Burniston succession. The spore-pollen assemblages are dominated by Deltoidospora spp., the majority of which were probably produced by Coniopteris. Lycophyte spores (including megaspores) are common in the Yorkshire Jurassic, but lycophyte parent plants are extremely poorly represented in the macroflora. Seed ferns, represented by Alisporites spp., are moderately abundant. Conifer pollen assemblages are dominated by Araucariacites australis (probably produced by Brachyphyllum mamillare), Perinopollenites elatoides and Classopollis spp., with additional bisaccate pollen taxa. Abundant Ginkgo huttonii in themacroflora suggests that much of the monosulcate pollen was produced by ginkgoes. The diverse vegetation of the Cleveland Basin presumably represented an attractive food source for herbivorous dinosaurs. The dinosaurs probably gathered at the flood plains for fresh-water and also used the non-vegetated plains and coastline as pathways. Although assigning specific makers to footprints is difficult, it is clear that a range of theropod, ornithopod and sauropod dinosaurs inhabited the area.

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  • 72.
    Slater, Sam
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    McKie, Tom
    Shell UK Ltd., 1 Altens Farm Road, Nigg, Aberdeen AB12 3FY, UK.
    Vieira, Manuel
    UK Ltd., 1 Altens Farm Road, Nigg, Aberdeen AB12 3FY, UK.
    Wellmann, Charles
    Department of Animal and Plant Sciences, University of Sheffield, Alfred Denny Building,Western Bank, Sheffield S10 2TN, UK.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    Episodic river flooding events revealed by palynological assemblages inJurassic deposits of the Brent Group, North Sea2017In: Palaeogeography, Palaeoclimatology, Palaeoecology, ISSN 0031-0182, E-ISSN 1872-616X, Vol. 485, p. 389-400Article in journal (Refereed)
    Abstract [en]

    Spore and pollen (sporomorph) assemblages from Middle Jurassic marine deposits of the Brent Group in the northern North Sea are investigated to assess temporal and spatial variations in vegetation and depositional processes. Four wells were sampled for palynology from the Penguins Cluster and the Don North East fields through the Rannoch Formation shoreface succession. Hyperpycnite deposits occur throughout, but are concentrated within the lower part of the section. These are expressed by sand-prone beds displaying waxing and waning current motifs, normally graded muddy beds and structureless mudstones. Hyperpycnal/hypopycnal deposits resulting from episodic river flooding represent important sedimentary features as they may be preserved below fair weather wave base in more offshore settings and potentially be the only record of the former presence of a nearby river mouth. The hyperpycnites typically contain abundant Botryoccocus spp., Amorphous Organic Matter (AOM) and hinterland sporomorph taxa with relatively few marine components compared to associated marine shoreface facies. Variations in palynofacies assemblages and Botryococcus spp. abundances indicate frequent river mouth avulsion. Ordination of samples using non-metric multidimensional scaling (NMDS) indicates that shoreface samples of the sampled wells are relatively distinct, but hyperpycnite samples are highly similar regardless of their sampled well. This suggests that depositional processes and spore/pollen sources (i.e. catchment zones) were similar among hyperpycnite events across different wells. Abundant bisaccate pollen, Botryococcus spp. and AOM within interpreted hyperpycnites suggest sediment mixing along the fluvial drainage path during flooding events. The terrestrial signature of hyperpycnite sporomorph assemblages demonstrates that underflows remained coherent as they descended the shoreface profile with little turbulent mixing with ambient marine waters. Sporomorph assemblages display few large changes through time suggesting vegetation on the adjacent coastal plain was relatively static through the studied interval.

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  • 73.
    Slodownik, Miriam
    et al.
    Swedish Museum of Natural History, Department of Paleobiology. Department of Ecology and Evolutionary Biology, University of Adelaide.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    Steinthorsdottir, Margret
    Swedish Museum of Natural History, Department of Paleobiology. Bolin Centre for Climate Research, Stockholm University.
    Fossil seed fern Lepidopteris ottonis from Sweden records increasing CO2 concentration during the end-Triassic extinction event2021In: Palaeogeography, Palaeoclimatology, Palaeoecology, ISSN 0031-0182, E-ISSN 1872-616X, Vol. 564, article id 110157Article in journal (Refereed)
    Abstract [en]

    The end-Triassic event (ETE), a short global interval occurring at the end of the Triassic Period (~201.5 Ma), was characterized by climate change, environmental upheaval, as well as widespread extinctions in both the marine and terrestrial realms. It was associated with extensive perturbations of the carbon cycle, principally caused by the volcanic emplacement of the Central Atlantic Magmatic Province in relation to the break-up of Pangea. The correlated change in atmospheric CO2 concentrations (pCO2) can be reconstructed with the stomatal proxy, which utilizes the inverse relationship between stomatal densities of plant leaves (here stomatal index (SI), which is the percentage of stomata relative to epidermal cells) and pCO2. Fossilized Lepidopteris leaves are common and widespread in Triassic strata, thus offering great potential for high-resolution pCO2 reconstructions. A dataset of leaf cuticle specimens belonging to the seed fern species Lepidopteris ottonis from sedimentary successions in Skåne (Scania), southern Sweden, provided the possibility of pCO2 reconstruction at the onset of the ETE. Here, we tested the intra- and interleaf variability of L. ottonis SI, and estimated the pCO2 during the onset of the ETE. Our findings confirm L. ottonis as a valid proxy for palaeo-pCO2, also when using smaller leaf fragments. Importantly, the statistical analyses showed that the SI values of abaxial and adaxial cuticles are significantly different, providing a tool to distinguish between the two sides and select cuticles for analysis. Reconstructed pCO2 increased from ~1000 pre ETE to ~1300 ppm at the onset of the event, a significant increase of ~30% over a relatively short time period. The pCO2 recorded here is similar to previously published estimates, and strongly supports the observed pattern of elevated pCO2 at the onset of the ETE.

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  • 74.
    Smith, Vann
    et al.
    Louisiana State University.
    Warny, Sophie
    Louisiana State University.
    Jarzen, David
    Cleveland Museum of Natural History.
    Demchuk, Thomas
    Louisiana State University.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    Palaeocene–Eocene miospores from the Chicxulub impact crater, Mexico. Part 1:spores and gymnosperm pollen2020In: Palynology, ISSN 0191-6122, E-ISSN 1558-9188, Vol. 44, p. 473-487Article in journal (Refereed)
    Abstract [en]

    In the summer of 2016, the International Ocean Discovery Program (IODP) Expedition 364 coredthrough the post-impact strata of the end-Cretaceous Chicxulub impact crater, Mexico. Core sampleswere collected from the post-impact successions for terrestrial palynological analysis, yielding a rareDanian to Ypresian high-resolution palynological assemblage. This record constitutes one of the firstPalaeocene and Ypresian palynological assemblages from Central America or Mexico, representing amore coastal lowland palaeoenvironment than previous studies from mainland Mexico. Although theabundance of pollen and spores is very low in the Palaeocene carbonates, abundance increases in themore organic-rich shale layers representing the Palaeocene–Eocene Thermal Maximum (PETM) andlater Ypresian. The spores and gymnosperm pollen identified from IODP 364, although rare comparedto the angiosperm pollen, are a diverse mix of cosmopolitan taxa, as well as some characteristic of fossilCentral American assemblages (e.g. Selaginellaceae), and others previously identified from thePaleogene northern Gulf of Mexico coastal plain. The assemblage generally indicates the presence ofnearby moist to seasonally dry lowland tropical forest, with some taxa suggestive of higher elevationforests. Ephedroid pollen grains may be indicative of the presence of more arid conditions.

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  • 75.
    Smith, Vann
    et al.
    Louisiana State University.
    Warny, Sophie
    Louisiana State University.
    Jarzen, David M.
    Cleveland Museum of Natural History.
    Demchuk, Thomas
    Louisiana State University.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    Gulick, Sean P.S.
    University of Texas at Austin.
    Paleocene–Eocene palynomorphs from the Chicxulub impact crater, Mexico.Part 2: angiosperm pollen2020In: Palynology, ISSN 0191-6122, E-ISSN 1558-9188, Vol. 44, p. 489-519Article in journal (Refereed)
    Abstract [en]

    At the end of the Cretaceous Period, an asteroid collided with the Earth and formed the Chicxulub impact structure on the Yucatan Platform. International Ocean Discovery Program (IODP) Expedition 364 drilled into the peak ring of the Chicxulub impact crater. The post-impact section of the core was sampled for terrestrial palynological analysis, yielding a high-resolution record ranging from the early Paleocene to the earliest Eocene (Ypresian), including a black shale deposited during the Paleocene–Eocene Thermal Maximum (PETM). The IODP 364 core provides the first record of floral recovery following the K–Pg mass extinction from inside the Chicxulub impact crater. The systematic taxonomy of the angiosperm pollen provided here follows a separate publication describing the systematic paleontology of the plant spores and gymnosperm pollen from the IODP 364 core (Smith et al. 2019). The Paleocene section of the core is nearly barren, but with unusually high relative abundances of the angiosperm pollen Chenopodipollis sp. A (comparable to the Amaranthaceae), possibly indicating an estuarine pollen source. Pollen recovery is higher in the PETM section, and variable but generally increasing in the later Ypresian section, with excellent preservation in several samples. Estimated absolute ages of several potentially useful regional biostratigraphic events are provided. One new genus (Scabrastephanoporites) and five new species (Brosipollis reticulatus, Echimonocolpites chicxulubensis, Psilastephanocolporites hammenii, Scabrastephanoporites variabilis, and Striatopollisgrahamii) are formally described.

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  • 76.
    Smith, Vann
    et al.
    Department of Geology and Geophysics, Louisiana State University, Baton Rouge, LA, USA;Museum of Natural Science, Louisiana State University, Baton Rouge, LA, USA.
    Warny, Sophie
    Department of Geology and Geophysics, Louisiana State University, Baton Rouge, LA, USA;Museum of Natural Science, Louisiana State University, Baton Rouge, LA, USA.
    Vellekoop, Johan
    Department of Earth and Environmental Sciences, Division of Geology, KU Leuven, Heverlee, Belgium;Analytical, Environmental and Geochemistry (AMGC), Vrije Universiteit Brussel, Brussels, Belgium.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    Escarguel, Gilles
    Université Lyon, UMR5023 Ecologie des Hydrosystèmes Naturels et Anthropisés, ENTPE, CNRS, Université Lyon 1, Lyon, France.
    Jarzen, David M.
    Paleobotany and Paleoecology Department, Cleveland Museum of Natural History, Cleveland, OH, USA.
    Palynology from ground zero of the Chicxulub impact, southern Gulf of Mexico2021In: Palynology, ISSN 0191-6122, E-ISSN 1558-9188, Vol. 45, no 2, p. 283-299Article in journal (Refereed)
    Abstract [en]

    Palynological analysis of Site M0077A in the Chicxulub impact crater has yielded a record of the immediate Cretaceous/Paleogene (K/Pg) recovery from ground zero of the end-Cretaceous mass extinction, followed by a record of the Paleocene–Eocene Thermal Maximum (PETM) and later Ypresian (Eocene), including the Early Eocene Climatic Optimum (EECO). Eight specimens of the dinoflagellate cyst Trithyrodinium evittii have been observed near the base of the K/Pg transitional unit; these likely representa post-impact dinoflagellate disaster recovery assemblage deposited within several days following the impact, although the possibility that some or all of the T. evittii specimens are reworked Maastrichtian cysts cannot be fully excluded. Despite high-resolution sampling of the lowermost Paleocene successions, the oldest identifiable terrestrial palynomorphs observed in the Site M0077A core, two specimens of Deltoidospora fern spores, occur at least c. 200,000 years after the impact. Other than these occurrences, the Paleocene section is nearly barren in terms of palynomorphs, likely a result of poor preservation of organic material combined with a long recovery time for vegetation in the vicinity of the crater. Pollen and fungal spore concentrations spike in an anoxic dark shale deposited during the PETM around 56 Ma, with a diverse pollen assemblage indicating the presence of a coastal shrubby tropical forest in the geographic vicinity, likely in the Yucatan Peninsula to the south. In the marine realm, this interval is characterized by thermophilic assemblages of dinoflagellate cysts. Stratigraphically constrained cluster analysis identified four statistically robust sample clusters in the lower Eocene successions, with Malvacipollis spp. and Milfordia spp. abundances driving the highest average dissimilarity between clusters. A second notable spike in palynological concentrations above the PETM section may represent another early Eocene hyperthermal event. Pollen and plant spore concentrations generally increased during the EECO, associated with increases in terrestrial input during basin infilling.

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  • 77.
    Steinthorsdottir, Margret
    Department of Geological Sciences and Bolin Centre for Climate Research, Stockholm University.
    Pole, Mike
    Nanjing Institute of Geology and Palaeontology, The Chinese Academy of Sciences.
    Global trends of pCO2 across the Cretaceous-Paleogene boundary supported by the first Southern Hemisphere stomatal proxy-based pCO2 reconstruction2016In: Palaeogeography, Palaeoclimatology, Palaeoecology, ISSN 0031-0182, E-ISSN 1872-616X, Vol. 464, p. 143-152Article in journal (Refereed)
    Abstract [en]

    Reliable reconstructions of atmospheric carbon dioxide concentrations (pCO2) are required at higher resolution than currently available to help resolve the relationship between mass extinctions and changes in palaeo-pCO2 levels. Such reconstructions are needed: 1, at a high temporal resolution for constraining the pre- and post-extinction atmospheres; and 2, at a sufficient spatial resolution to constrain potential inter-hemispheric differences. Here we estimate pCO2 based on fossil Lauraceae leaf cuticle specimens derived from three localities with strata spanning the latest Cretaceous to the mid-Paleocene, including a new Cretaceous–Paleogene boundary (K–Pg) locality, in New Zealand. We use two independent methods of stomatal density-based pCO2 reconstructions; a transfer function calibrated using herbarium material and the stomatal ratio method, producing three calibration sets. Our results based on the mean values of each of the three calibration methods indicate pCO2 ranging between ca. 460 and 650 ppm during the latest Cretaceous, falling precipitously to average values between ca. 360 and 430 ppm across the K–Pg boundary, and further to ca. 305–320 ppm in the mid-Paleocene. A ‘spike’ of extremely high pCO2 at the K–Pg could not be confirmed, but our results are, nonetheless, consistent with previously published pCO2 records from the Northern Hemisphere, and show that stomatal density worldwide was responding to significant changes in pCO2 across the K–Pg.

  • 78. Steinthorsdottir, Margret
    et al.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    Early Jurassic (late Pliensbachian) CO2 concentrations based on stomatalanalysis of fossil conifer leaves from eastern Australia2015In: Gondwana Research, ISSN 1342-937X, E-ISSN 1878-0571, Vol. 27, p. 932-939Article in journal (Refereed)
    Abstract [en]

    The stomatal index (a measure of stomatal density) of an extinct Australian Early Jurassic araucariacean conifer species, Allocladus helgei Jansson, is used to reconstruct the atmospheric carbon dioxide concentration (pCO2) in the Early Jurassic. The fossil leaves are preserved in a single bed, palynologically dated to late Pliensbachian (~185–183 Mya). Atmospheric pCO2 is estimated from the ratios between the stomatal index of A. helgei and the stomatal indices of three modern analogs (nearest living equivalent plants). CO2 concentration in the range of ~750–975 ppm was calibrated from the fossil material, with a best-estimated mean of ~900 ppm. The new average pCO2 determined for the late Pliensbachian is thus similar to, although ~10% lower, than previously inferred minimum concentrations of ~1000, based on data from the Northern Hemisphere, but may help constrain pCO2 during this period. Our results are the first pCO2 estimates produced using Jurassic leaves from the Southern Hemisphere and showthat i) paleo-atmospheric pCO2 estimates are consistent at a global scale, though more investigations of Southern Hemisphere material are required, and ii) the stomatal proxy method can now be used without the context of relative change in pCO2 when applying the correct methodology.

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  • 79.
    Steinthorsdottir, Margret
    et al.
    Swedish Museum of Natural History, Department of Paleobiology. Bolin Centre for Climate Research, Stockholm University.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    Pole, Mike
    Queensland Herbarium, Brisbane Botanic Gardens, Mt. Coot-tha, Mt. Coot-tha Rd., Toowong, QLD 4066, Australia.
    Global trends of pCO2 across the Cretaceous–Paleogene boundary supported by the first Southern Hemisphere stomatal proxy-based pCO2 reconstruction2016In: Palaeogeography, Palaeoclimatology, Palaeoecology, ISSN 0031-0182, E-ISSN 1872-616X, Vol. 464, p. 143-152Article in journal (Refereed)
    Abstract [en]

    Reliable reconstructions of atmospheric carbon dioxide concentrations (pCO2) are required at higher resolution than currently available to help resolve the relationship between mass extinctions and changes in palaeo-pCO2 levels. Such reconstructions are needed: 1, at a high temporal resolution for constraining the pre- and post- extinction atmospheres; and 2, at a sufficient spatial resolution to constrain potential inter-hemispheric differ- ences. Here we estimate pCO2 based on fossil Lauraceae leaf cuticle specimens derived from three localities with strata spanning the latest Cretaceous to the mid-Paleocene, including a new Cretaceous–Paleogene bound- ary (K–Pg) locality, in New Zealand. We use two independent methods of stomatal density-based pCO2 recon- structions; a transfer function calibrated using herbarium material and the stomatal ratio method, producing three calibration sets. Our results based on the mean values of each of the three calibration methods indicate pCO2 ranging between ca. 460 and 650 ppm during the latest Cretaceous, falling precipitously to average values between ca. 360 and 430 ppm across the K–Pg boundary, and further to ca. 305–320 ppm in the mid-Paleocene. A ‘spike’ of extremely high pCO2 at the K–Pg could not be confirmed, but our results are, nonetheless, consistent with previously published pCO2 records from the Northern Hemisphere, and show that stomatal density world- wide was responding to significant changes in pCO2 across the K–Pg. 

  • 80.
    Steinthorsdottir, Margret
    et al.
    Swedish Museum of Natural History, Department of Paleobiology. Bolin Centre for Climate Research, Stockholm University.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    Pole, Mike
    Significant transient pCO2 perturbation at the New Zealand Oligocene- Miocene transition recorded by fossil plant stomata2018In: Palaeogeography, Palaeoclimatology, Palaeoecology, ISSN 0031-0182, E-ISSN 1872-616X, Vol. 515, p. 152-161Article in journal (Refereed)
    Abstract [en]

    The reorganisation of Earth's climate system from the Oligocene to the Miocene was influenced by complex interactions between Tethyan tectonics, orbital parameters, oceanographic changes, and carbon cycle feedbacks, with climate modelling indicating that pCO2 was an important factor. Oscillating episodes of climate change during the Oligocene–Miocene transition (OMT) have however been difficult to reconcile with existing pCO2 records. Here we present a new pCO2 record from the OMT into the early Miocene, reconstructed using the stomatal proxy method with a database of fossil Lauraceae leaves from New Zealand. The leaf database derives from three relatively well-dated sites located in the South Island of New Zealand; Foulden Maar, Mataura River and Grey Lake. Atmospheric pCO2 values were obtained based on four separate calibrations with three nearest living equivalents, using the stomatal ratio method as well as transfer functions. Our results, based on the mean values of each of the four calibrations, indicate pCO2 ranging ~582–732 ppm (average 650 ppm) at the OMT, falling precipitously to mean values of ~430–538ppm (average 492ppm) for the earliest Miocene and ~454–542 ppm (average 502 ppm) in the early Miocene. The much higher values of pCO2 at the OMT indicate that pCO played an important role in climate dynamics during this time, potentially including the abrupt ter- mination of glaciations. 

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  • 81.
    Steinthorsdottir, Margret
    et al.
    Swedish Museum of Natural History, Department of Paleobiology. Bolin Centre for Climate Research, Stockholm University.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    Pole, Mike
    Queensland Herbarium, Brisbane Botanic Gardens.
    Significant transient pCO2 perturbation at the New Zealand Oligocene-Miocene transition recorded by fossil plant stomata2019In: Palaeogeography, Palaeoclimatology, Palaeoecology, ISSN 0031-0182, E-ISSN 1872-616X, Vol. 515, p. 152-161Article in journal (Refereed)
    Abstract [en]

    The reorganisation of Earth's climate system from the Oligocene to the Miocene was in fluenced by complex interactions between Tethyan tectonics, orbital parameters, oceanographic changes, and carbon cycle feedbacks, with climate modelling indicating that pCO2 was an important factor. Oscillating episodes of climate change during the Oligocene-Miocene transition (OMT) have however been difficult to reconcile with existing pCO2 records. Here we present a new pCO2 record from the OMT into the early Miocene, reconstructed using the stomatal proxy method with a database of fossil Lauraceae leaves from New Zealand. The leaf database derives from three relatively well-dated sites located in the South Island of New Zealand; Foulden Maar, Mataura River and Grey Lake. Atmospheric pCO2 values were obtained based on four separate calibrations with three nearest living equivalents, using the stomatal ratio method as well as transfer functions. Our results, based on the mean values of each of the four calibrations, indicate pCO2 ranging ~582–732 ppm (average 650 ppm) at the OMT, falling precipitously to mean values of ~430–538 ppm (average 492 ppm) for the earliest Miocene and ~454–542 ppm (average 502 ppm) in the early Miocene. The much higher values of pCO2 at the OMT indicate that pCO played an important role in climate dynamics during this time, potentially including the abrupt termination of glaciations.

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  • 82.
    Steinthorsdottir, Margret
    et al.
    Swedish Museum of Natural History, Department of Paleobiology. Bolin Centre for Climate Research, Stockholm University.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    Pole, Mike
    3Queensland Herbarium, Brisbane Botanic Gardens.
    Holdgate, Guy
    4School of Earth Sciences, University of Melbourne.
    Moderate levels of Eocene pCO2 indicated by Southern Hemisphere fossil plant stomata2019In: Geology, ISSN 0091-7613, E-ISSN 1943-2682, Vol. 47, p. 914-918Article in journal (Refereed)
    Abstract [en]

    Reducing the uncertainty in predictions of future climate change is one of today’s greatest scientific challenges, with many significant problems unsolved, including the relationship between pCO2 and global temperature. To better constrain these forecasts, it is meaningful to study past time intervals of global warmth, such as the Eocene (56.0–33.9 Ma), serving as climatic analogues for the future. Here we reconstructed pCO2 using the stomatal densities of a large fossil Lauraceae (laurel) leaf database from ten sites across the Eocene of Australia and New Zealand. We show that mostly moderate pCO2 levels of 450–600 ppm prevailed throughout the Eocene, levels that are considerably lower than the pCO2 forcing currently needed to recreate Eocene temperatures in climate models. Our data record significantly lower pCO2 than inferred from marine isotopes, but concur with previously published Northern Hemisphere Eocene stomatal proxy pCO2. We argue that the now globally consistent stomatal proxy pCO2 record for the Eocene is robust and that climate sensitivity was elevated and/or that additional climate forcings operated more powerfully than previously assumed.

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  • 83.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    Villanueva-Amadoz, Uxue
    ERNO, Instituto de Geología, UNAM, L.D. Colosio y Madrid.
    Lehsten, Veiko
    Dept of Physical Geography and Ecosystems Science, Lund University.
    Alcalá, Luis
    Fundación Conjunto Paleontológico de Teruel-Dinópolis/Museo Aragonés de Paleontología.
    Dietary and environmental implications of Early Cretaceous predatory dinosaur coprolites from Teruel, Spain2016In: Palaeogeography, Palaeoclimatology, Palaeoecology, ISSN 0031-0182, E-ISSN 1872-616X, Vol. 464, p. 134-142Article in journal (Refereed)
    Abstract [en]

    Coprolites from the Early Cretaceous vertebrate bone-bed at Ariño in Teruel, Spain, were analyzed geochemically and palynologically. They contain various inclusions, such as small bone fragments, abundant plant remains, pollen, and spores. We attribute the coprolites to carnivorous dinosaurs based partly on their morphology together with the presence of bone fragments, and a high content of calcium phosphate (hydroxylapatite) with calcite.Well-preserved pollen and spore assemblages were identified in all coprolite samples and a slightly poorer assemblage was obtained from the adjacent sediments, both indicating an Early Cretaceous (Albian) age. This shows that the coprolites are in situ and also confirms previous age determinations for the host strata. The depositional environment is interpreted as a continental wetland based on the palynoflora, which includes several hydrophilic taxa, together with sparse occurrences of fresh-water algae, such as Ovoidites, and the absence of marine palynomorphs. Although the coprolites of Ariño samples generally are dominated by pollen produced by Taxodiaceae (cypress) and Cheirolepidiaceae (a family of extinct conifers), the sediment samples have a slightly higher relative abundance of fern spores. The distribution of major organic components varies between the coprolite and sediment samples, which is manifest by the considerably higher charcoal percentage within the coprolites. The high quantities of charcoal might be explained by a ground-dwelling species, feeding on smaller vertebrates that complemented its diet with plant material from a paleoenvironment were wild fires were a part of the ecosystem. The state of preservation of the spores and pollen is also more detailed in the coprolites, suggesting that encasement in calcium phosphate may inhibit degradation of sporopollenin.

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  • 84.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    Sha, Jingeng
    Nanjing Institute of Geology and Palaeontology, Academia Sinic.
    Mesozoic ecosystems – climate and biotas2016In: Palaeogeography, Palaeoclimatology, Palaeoecology, ISSN 0031-0182, E-ISSN 1872-616X, Vol. 464, p. 1-4Article in journal (Other academic)
    Abstract [en]

    This issue of Palaeogeography Palaeoclimatology Palaeoecology is devoted to papers on Mesozoic ecosystems and is an outcome of the International Geoscience Program (IGCP) 632. IGCP is a joint operation by UNESCO and the International Union of Geological Sciences (IUGS), which promote interdisciplinary Earth science research among scientists internationally. Since its formation in 1972, IGCP has supported over 500 projects in about 150 countries.

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  • 85.
    Vajda, Vivi
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Cavalcante, Larissa
    Swedish Museum of Natural History, Department of Paleobiology.
    Palmgren, Kristoffer
    Swedish Museum of Natural History, Department of Paleobiology.
    Krüger, Ashley
    Swedish Museum of Natural History, Department of Paleobiology.
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology.
    Prototaxites reinterpreted as mega-rhizomorphs, facilitating nutrient transport in early terrestrial ecosystems2023In: Canadian journal of microbiology (Print), ISSN 0008-4166, E-ISSN 1480-3275, Vol. 69, no 1, p. 17-31Article in journal (Refereed)
    Abstract [en]

    The enigmatic fossil Prototaxites found in successions ranging from the Middle Ordovician to the Upper Devonian was originally described as having conifer affinity. The current debate, however, suggests that they probably represent gigantic algal–fungal symbioses. Our re-investigation of permineralized Prototaxites specimens from two localities, the Heider quarry in Germany and the Bordeaux quarry in Canada, reveals striking anatomical similarities with modern fungal rhizomorphs Armillaria mellea. We analysed extant fungal rhizomorphs and fossil Prototaxites through light microscopy of their anatomy, Fouriertransform infrared spectroscopy, X-ray microscopy, and Raman spectroscopy. Based on these comparisons, we interpret thePrototaxites as fungi. The detailed preservation of cell walls and possible organelles seen in transverse sections of Prototaxites reveal that fossilization initiated while the organism was alive, inhibiting the collapse of delicate cellular structures. Prototaxites has been interpreted to grow vertically by many previous workers. Here we propose an alternative view that Prototaxites represents a complex hyphal aggregation (rhizomorph) that may have grown horizontally similar to modern complex aggregatedmycelial growth forms, such as cords and rhizomorphs. Their main function was possibly to redistribute water and nutritionfrom nutrient-rich to nutrient-poor areas facilitating the expansion for early land plant communities.

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    Vajda et al_2022_Prototaxites reinterpreted as mega-rhizomorphs, facilitating nutrient transport
  • 86.
    Vajda, Vivi
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Grice, Kliti
    WA-Organic and Isotope Geochemistry Centre, School of Earth and Planetary Sciences, Curtin University, GPO Box U1987, Perth, 6845, Australia.
    Krüger, Ashley
    Swedish Museum of Natural History, Department of Paleobiology.
    Lee, Sangmin
    School of Earth, Atmospheric and Life Sciences, University of Wollongong, NSW 2522, Australia.
    Shi, G.R.
    School of Earth, Atmospheric and Life Sciences, University of Wollongong, NSW 2522, Australia.
    End-Permian marine ecosystem collapse was a direct consequence of deforestation: Evidence from the Kockatea Shale of the Perth Basin, Western Australia2023In: Evolving Earth, ISSN 2950-1172, Vol. 1, article id 100027Article in journal (Refereed)
    Abstract [en]

    The end-Permian mass extinction event resulted in devastated continental biomes, desolated land, and toxic waters. Anoxia led to widespread extinctions in marine ecosystems, affecting most oceanic clades. In this paper, the palynofacies of the marine Kockatea Shale, Western Australia, was studied in drill cores Hovea-3 and Redback-2, with the aim of linking changes in the marine and continental realms across the Permian–Triassic boundary interval in Australia. We show that the post-extinction ‘Dead Zone’ of the Frazer Beach Member of the Sydney Basin, eastern Australia, whose base is dated to 252.10 ± 0.06 Ma, directly correlates to the lower part of the Kockatea Shale in the Perth Basin, the so-called Inertinitic Interval. We demonstrate that the extinction of Permian Glossopteris forests observed in the Perth Basin had an immediateimpact on the marine faunas due to the massive buildup of organic matter, leading to euxinia in the photic zone and ultimately pushing the marine faunas to an ecological extinction. The last lingering occurrence of marine invertebrates of Permian aspect occur in layers that may tentatively mark the Permian –Triassic boundary, positioned just below the appearance of Triassic floras of the Kraeuselisporites saeptatus Zone (equivalent to the Lunatisporites pellucidus Zone). A striking feature at the base of the Early Triassic Sapropelic Interval of the Hovea Member is the sudden and synchronous appearances of anomalously abundant acritarchs and lycophyte spores, alongside the mass occurrence of the bivalve Claraia, allowing correlation with the rise of the eastern Australian post-extinction pioneer floras in the Early Triassic. This demonstrates a significant lag time between the recovery of the terrestrial versus the marine pioneer biota in high-latitude Gondwana, with a significant delay for the faunal recovery.

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    Vajda et al_2023_End-Permian marine ecosystem
  • 87.
    Vajda, Vivi
    et al.
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    Linderson, Hans
    Geology Department, University of Lund.
    McLoughlin, Stephen
    Swedish Museum of Natural History, Department of Paleobiology.
    Disrupted vegetation as a response to Jurassic volcanism in southern Sweden2016In: Geological Society of London Special Publications, ISSN ISSN 0305-8719, Vol. 434, p. 127-147Article in journal (Refereed)
    Abstract [en]

    Central Skåne (Scania) in southern Sweden hosts evidence of extensive Jurassic volcanism in the form of mafic volcanic plugs and associated volcaniclastic deposits that entomb well preserved macro-plant and spore–pollen assemblages. Palynological assemblages recovered from the Höör Sandstone are of Hettangian–Pliensbachian age and those from the overlying lahar deposits are dated as Pliensbachian–early Toarcian (?). Palynomorph assemblages from these units reveal significantly different ecosystems, particularly with respect to the gymnospermous components that represented the main canopy plants. Both palynofloras are dominated by osmundacean, marattiacean and cyatheacean fern spore taxa but, whereas the Höör Sandstone hosts abundant Chasmatosporites spp. pollen produced by plants related to cycadophytes, the volcanogenic deposits are dominated by cypress family pollen (Perinopollenites) with an understorey component rich in putative Erdtmanithecales (or possibly Gnetales), and collectively representing vegetation of disturbed habitats. Permineralized conifer wood attributed to Protophyllocladoxylon sp., belonging to plants that probably produced the abundant Perinopollenites grains, is abundant in the volcanigenic strata, and shows sporadic intraseasonal and multi-year episodes of growth disruption. Together with the relatively narrow but marked annual growth rings, and the annual and mean sensitivity values that span the complacent–sensitive domains, these features suggest growth within Mediterranean-type biomes subject to episodic disturbance.

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  • 88.
    Vajda, Vivi
    et al.
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    McLoughlin, Stephen
    Swedish Museum of Natural History, Department of Paleobiology.
    Extinction and recovery patterns of the vegetation across the Cretaceous–Palaeogene boundary — a tool for unravelling the causes of the end-Permian mass-extinction2007In: Review of Palaeobotany and Palynology, ISSN 0034-6667, E-ISSN 1879-0615, Vol. 144, p. 99-112Article in journal (Refereed)
    Abstract [en]

    High-resolution palynofloral signatures through the Cretaceous–Palaeogene boundary succession show several features in common with the Permian–Triassic transition but there are also important differences. Southern Hemisphere Cretaceous–Palaeogene successions, to date studied at high resolution only in New Zealand, reveal a diverse palynoflora abruptly replaced by fungi-dominated assemblages that are in turn succeeded by low diversity suites dominated by fern spores, then gymnosperm- and angiosperm-dominated palynofloras of equivalent diversity to those of the Late Cretaceous. This palynofloral signature is interpreted to represent instantaneous (days to months) destruction of diverse forest communities associated with the Chicxulub impact event. The pattern of palynofloral change suggests wholesale collapse of vascular plant communities and short-term proliferation of saprotrophs followed by relatively rapid successional recovery of pteridophyte and seed–plant communities. The Permian–Triassic transition records global devastation of gymnosperm-dominated forests in a short zone synchronous with one or more peaks of the fungal/algal palynomorph Reduviasporonites. This zone is typically succeeded by assemblages rich in lycophyte spores and/or acritarchs. Higher in the succession, these assemblages give way to diverse palynofloras dominated by new groups of gymnosperms. Although different plant families were involved in the mass-extinctions, the general pattern of extinction and recovery is consistent between both events. The major difference is the longer duration for each phase of the Triassic recovery vegetation compared to that of the Paleocene. The protracted extinction-recovery succession at the Permian–Triassic boundary is incompatible with an instantaneous causal mechanism such as an impact of a celestial body but is consistent with hypotheses invoking extended environmental perturbations through flood-basalt volcanism and release of methane from continental shelf sediments.

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  • 89. Vajda, Vivi
    et al.
    McLoughlin, Stephen
    Swedish Museum of Natural History, Department of Paleobiology.
    Fungal proliferation at the Cretaceous-Tertiary boundary.2004In: Science, ISSN 0036-8075, E-ISSN 1095-9203, Vol. 303, no 5663, p. 1489-Article in journal (Refereed)
    Abstract [en]

    We have found that a fungal spike occurs between the diverse Late Cretaceous palynoflora and the low-diversity fern-dominated early Paleocene assemblages in a New Zealand section. The fungal layer is coincident with the Ir anomaly marking the extinction event.

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    K-Pg fungi
  • 90.
    Vajda, Vivi
    et al.
    Lund University.
    McLoughlin, Stephen
    Swedish Museum of Natural History, Department of Paleobiology.
    Bomfleur, Benjamin
    Swedish Museum of Natural History, Department of Paleobiology.
    Fossilfyndet i Korsaröd2014In: Geologiskt Forum, ISSN 1104-4721, Vol. 82, p. 24-29Article in journal (Other (popular science, discussion, etc.))
    Abstract [sv]

    Upptackten av ett extremt valbevarat ormbunksfossil, inkapslat i laharflodena vid Korsarod och Djupadalsmollan, vacker nu hopp hos forskarna om att hitta fler fynd. Dessutom ska ormbunken testas for fossilt DNA.

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  • 91.
    Vajda, Vivi
    et al.
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    McLoughlin, Stephen
    Swedish Museum of Natural History, Department of Paleobiology.
    Mays, Chris
    Swedish Museum of Natural History, Department of Paleobiology.
    Frank, Tracy
    University of Nebraska.
    Fielding, Christopher
    University of Nebraska.
    Tevyaw, Allen
    University of Nebraska.
    Lehsten, Veiko
    Lund University,.
    Bocking, Malcolm
    Bocking Associates.
    Nicoll, Robert
    Geoscience Australia.
    End-Permian (252 Mya) deforestation, wildfires and flooding—Anancient biotic crisis with lessons for the present2020In: Earth and Planetary Science Letters, ISSN 0012-821X, E-ISSN 1385-013X, Vol. 529, article id 115875Article in journal (Refereed)
    Abstract [en]

    Current large-scale deforestation poses a threat to ecosystems globally, and imposes substantial and prolonged changes on the hydrological and carbon cycles. The tropical forests of the Amazon and Indonesia are currently undergoing deforestation with catastrophic ecological consequences but widespread deforestation events have occurred several times in Earth’s history and these provide lessons for the future. The end-Permian mass-extinction event (EPE; ∼252Ma) provides a global, deep-time analogue for modern deforestation and diversity loss. We undertook centimeter-resolution palynological, sedimentological, carbon stable-isotope and paleobotanical investigations of strata spanning the end-Permian event at the Frazer Beach and Snapper Point localities, in the Sydney Basin, Australia. We show that the typical Permian temperate, coal-forming, forest communities disappeared abruptly, followed by the accumulation of a 1-m-thick mudstone poor in organic matter that, in effect, represents a ‘dead zone’ hosting degraded wood fragments, charcoal and fungal spores. This signals a catastrophic scenario of vegetation die-off and extinction in southern high-latitude terrestrial settings. Lake systems, expressed by laterally extensive but generally less than a few-metres-thick laminated siltstones, generally lacking bioturbation, hosting assemblages of algal cysts and freshwater acritarchs, developed soon after the vegetation die-off. The first traces of vascular plant recovery occur ∼1.6m above the extinction horizon. Based on analogies with modern deforestation, we propose that the global fungal and acritarch events of the Permo-Triassic transition resulted directly from inundation of basinal areas following water-table rise as a response to the abrupt disappearance of complex vegetation from the landscape. The δ13Corg values reveal a significant excursion toward low isotopic values, down to −31ppt (a shift of ∼4deg), across the end-Permian event. The magnitude of the shift at that time records a combination of changes in the global carbon cycle that were enhanced by the local increase in microbial activity, possibly also involving cyanobacterial proliferation. We envisage that elevated levels of organic and mineral nutrients delivered from inundated dead forests, enhanced weathering and erosion of extra-basinal areas, together with local contributions of volcanic ash, led to eutrophication and increased salinity of basinal lacustrine–lagoonal environments. We propose that the change in acritarch communities recorded globally in nearshore marine settings across the end-Permian event is to a great extent a consequence of the influx of freshwater algae and nutrients from the continents. Although this event coincides with the Siberian trap volcanic activity, we note that felsic–intermediate volcanism was extensively developed along the convergent Panthalassan margin of Pangea at that time and might also have contributed to environmental perturbations at the close of the Permian.

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  • 92.
    Vajda, Vivi
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    McLoughlin, Stephen
    Swedish Museum of Natural History, Department of Paleobiology.
    Shevchuk, Olena
    Swedish Museum of Natural History, Department of Paleobiology. Ukrainian Academy of Sciences.
    The war in Ukraine - Its impact on palaeobotany, palynology, herbaria and museums.2022In: 11th European Palaeobotany and Palynology Conference Abstracts, Program and Proceedings / [ed] Stephen McLoughlin, Stockholm, Sweden: Swedish Museum of Natural History , 2022, , p. 75-76p. 75-76Conference paper (Refereed)
    Abstract [en]

    Ukraine hosts extensive strata containing plant and algal fossils. Owing to their location on southern flank of Laurasia, Ukrainian fossiliferous deposits potentially play an important role, not only in local biostratigraphy, but also in understanding climate changes and biogeographic interchange between Europe, Africa, northern Asia, India and the Cimmerian terranes of the Mesozoic Tethys. However, much of the past work in Ukraine has been little recognized in western scientific literature, partly owing to language bariers and difficulties accessing provincial literature. Of particular note are past studies on the following fossil assemblages and regions: the Ediacaran biotas in the Dniester River area of western Ukraine; Silurian and Early Devonian plants and nematophytes from Podolia, western Ukraine; extensive Carboniferous floras associated with the coals of the Donbas region; the little-studied early Permian flora from the western Donets Basin; the rich but relatively little-known Triassic flora on the Donets Basin; Middle Jurassic palynofloras from the Dnieper–Donets Basin; Early Cretaceous megaspores and other sporomorphs from southern Ukraine; late Albian leaf and wood floras from the Kaniv area, central Ukraine; Late Cretaceous floras from western Ukraine and adjacent areas of Poland; Miocene–Pliocene macro- and palynofloras from shallow deposits of the Ukrainian Plain that are helping to build palaeoclimatic and marine incursion models for the Central and the Eastern Paratethys region; late Pliocene permineralized woods from Transcarpathian region in southwestern Ukraine; and extensive Quaternary palynofloras for studies of forest-steppe fluctuation over the past 2 million years.Ukraine has 21 major herbaria (78 in total) with >116 staff and about 4.8 million specimens. As of May, 2022, many of these are in conflict zones directly impacted by the Russian invasion. Of note, the CWU herbarium at Karazin University in Kharkiv has been damaged and the contents require urgent protection. Ukraine also hosts major palaeontological collections that are now threatened: particularly, the National Science and Natural History Museum of the National Academy of Sciences of Ukraine, Kyiv, and the National Museum of Natural History, Lviv. Staff at many of Ukraine’s museums have been busy hiding art and collections in basements, returning loans, loaning material abroad for safekeeping, and reopening the museums as bomb shelters. To support Ukrainian science and culture, funding was provided by the Swedish Royal Academy, Swedish Research Council, Swedish Strategic Fund and Collegium Palynologicum Scandinavicum for four Ukrainian palynologists to attend the 11th EPPC, and for several others to submit poster presentations. We welcome our Ukrainian colleagues to the conference.

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  • 93.
    Vajda, Vivi
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    McLoughlin, Stephen
    Swedish Museum of Natural History, Department of Paleobiology.
    Slater, Sam M
    Swedish Museum of Natural History, Department of Paleobiology.
    Gustafsson, Ola
    Department of Biology, Lund University, SE-223 62 Lund, Sweden.
    Rasmusson, Allan G.
    Department of Biology, Lund University, SE-223 62 Lund, Sweden.
    The ‘seed-fern’ Lepidopteris mass-produced the abnormal pollen Ricciisporites during the end-Triassic biotic crisis2023In: Palaeogeography, Palaeoclimatology, Palaeoecology, ISSN 0031-0182, E-ISSN 1872-616X, Vol. 627, article id 111723Article in journal (Refereed)
    Abstract [en]

    The end-Triassic mass extinction (ETE; ~201.6 million years ago) led to dramatic changes in terrestrial eco­ systems including the extinction of several seed-plant groups. Among the most intriguing features in the vege­ tation signal is the dominance of the peculiar pollen, Ricciisporites tuberculatus Lundblad, across large areas of the Northern Hemisphere immediately prior to and during the ETE. The parent plant of this pollen has remained unknown for 70 years. Here, we demonstrate that the ‘seed-fern’ Lepidopteris ottonis (Go¨ppert) Schimper (Pel­ taspermales) produced R. tuberculatus in permanent tetrads. We show that R. tuberculatus is a large, abnormal form of the small smooth-walled monosulcate pollen traditionally associated with L. ottonis, which disappeared at the ETE, when volcanism induced cold-spells followed by global warming. We argue that the production of aberrant R. tuberculatus resulted from ecological pressure in stressed environments that favoured asexual reproduction in peltasperms. The expansion of dry environments led to the dominance of drought-tolerant plants in the Early Jurassic of northern middle latitudes.

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    Vajda et al_2023_The ‘seed-fern’ Lepidopteris mass-produced the abnormal pollen Ricciisporites
  • 94.
    Vajda, Vivi
    et al.
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    Pucetaite, Milda
    Department of General Physics and Spectroscopy, Vilnius University, LT-102 57 Vilnius, Lithuania.
    McLoughlin, Stephen
    Swedish Museum of Natural History, Department of Paleobiology.
    Engdahl, Anders
    MAX-IV laboratory, Lund University, SE-221 00 Lund, Sweden.
    Heimdal, Jimmy
    MAX-IV laboratory, Lund University, SE-221 00 Lund, Sweden.
    Uvdal, Per
    Chemical Physics, Department of Chemistry, Lund University, SE-222 41 Lund, Sweden.
    Molecular signatures of fossil leaves provideunexpected new evidence for extinct plant relationships2017In: Nature Ecology and Evolution, E-ISSN ISSN 2397-334X, Vol. 1, p. 1093-1099Article in journal (Refereed)
    Abstract [en]

    Gene sequences form the primary basis for understanding the relationships among extant plant groups, but genetic data are unavailable from fossils to evaluate the affinities of extinct taxa. Here we show that geothermally resistant fossil cuticles of seed-bearing plants, analysed with Fourier transform infrared (FTIR) spectroscopy and hierarchical cluster analysis (HCA), retain biomolecular suites that consistently distinguish major taxa even after experiencing different diagenetic histories. Our results reveal that similarities between the cuticular biochemical signatures of major plant groups (extant and fossil) are mostly consistent with recent phylogenetic hypotheses based on molecular and morphological data. Our novel chemotaxonomic data also support the hypothesis that the extinct Nilssoniales and Bennettitales are closely allied, but only distantly related to Cycadales. The chemical signature of the cuticle of Czekanowskia (Leptostrobales) is strongly similar to that of Ginkgo leaves and supports a close evolutionary relationship between these groups. Finally, our results also reveal that the extinct putative araucariacean, Allocladus, when analysed through HCA, is grouped closer to Ginkgoales than to conifers. Thus, in the absence of modern relatives yielding molecular information, FTIR spectroscopy provides valuable proxy biochemical data complementing morphological characters to distinguish fossil taxa and to help elucidate extinct plant relationships.

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  • 95.
    Vajda, Vivi
    et al.
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    Pucetaite, Milda
    Centre for Environmental and Climate Science, Lund University.
    Steinthorsdottir, Margret
    Swedish Museum of Natural History, Department of Paleobiology. Bolin Centre for Climate Research, Stockholm University.
    Geochemical Fingerprints of Ginkgoales Across the Triassic-Jurassic Boundary of Greenland2021In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 182, no 7, p. 649-662Article in journal (Refereed)
    Abstract [en]

    Premise of research. Geochemical fingerprinting of fossil plants is a relatively new research field complementing morphological analyses and providing information for paleoenvironmental interpretations. Ginkgoales contains a single extant species but was diverse through the Mesozoic and is an excellent target for biochemical analyses.

    Methodology. Cuticles derived from fresh and fallen autumn leaves of extant Ginkgo biloba and seven fossil gink- goalean leaf taxa, one seed fern taxon, and two taxa with bennettitalean affinity were analyzed by infrared (IR) microspec- troscopy at the D7 beamline in the MAX IV synchrotron laboratory, Sweden. The fossil material derives from Triassic and Jurassic successions of Greenland. Spectral data sets were compared and evaluated by hierarchical cluster analysis (HCA) and principal component analysis performed on vector-normalized, first-derivative IR absorption spectra.

    Pivotal results. The IR absorption spectra of the fossil leaves all reveal signatures that clearly indicate the pres- ence of organic compounds. Spectra of the extant G. biloba leaves reveal the presence of aliphatic chains, aromatic and ester carbonyl functional groups from polymer cutin and other waxy compounds, and polysaccharides. Inter- estingly, both the extant autumn leaves and the fossil specimens reveal the presence of carboxyl/ketone molecules, suggesting that chemical alterations during the initial stages of decomposition are preserved through fossilization. Two major subclusters were identified through HCA of the fossil spectra.

    Conclusions. Consistent chemical IR signatures, specific for each fossil taxon are present in cuticles, and suf- ficient molecular content is preserved in key regions to reflect the plants’ original chemical signatures. The alter- ations of the organic compounds are initiated as soon as the leaves are shed, with loss of proteins and increased ester and carboxyl/ketone compound production in the fallen leaves. We further show that the groupings of taxa reflect a combination of phylogeny and environmental conditions related to the end-Triassic event.

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  • 96.
    Vajda, Vivi
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Sigfridsson Clauss, Kajsa G.V.
    MAX IV Laboratory, Lund University, PO Box 118, SE-221 00, Lund, Sweden.
    Krüger, Ashley
    Swedish Museum of Natural History, Department of Paleobiology.
    Nehzati, Susan
    Swedish Museum of Natural History, Department of Paleobiology. MAX IV Laboratory, Lund University, PO Box 118, SE-221 00, Lund, Sweden.
    Changes in Fe-redox and Fe-species across the end-Permian ‘Dead Zone’ in the Sydney Basin, Australia (252.10 ± 0.06 Ma): Evidence from X-ray absorption spectroscopy2023In: Evolving Earth, ISSN 2950-1172, Vol. 1, article id 100029Article in journal (Refereed)
    Abstract [en]

    The end-Permian mass extinction event is traceable across several non-marine basins in Australia. In the Sydney Basin, the lithological succession is characterized by a change from coal seams to mudstones and sandstones, recording a major environmental change following the disappearance of the Permian vegetation. A few millimeter-thick iron-rich ‘rusty’ layer occurs between the uppermost Permian coal seam and the mudstone, a layer that extends laterally across the basin and which has also been documented from coeval successions in Antarctica. This layer is overlain by the <1.5-m-thick Frazer Beach Member, whose basal 10-cm-thick microbreccia bed comprises 99% kaolinite and quartz, and is dated as 252.10 ± 0.06 Ma. The Frazer Beach Member corresponds to the so-called end-Permian ‘Dead Zone’ lacking fossil pollen and leaves. This distinctive member was deposited directly following the extinction of the Permian peat-forming forests.

    Here we identify, through X-ray absorption spectroscopy, a drastic redox shift across the extinction interval with increasing amount of reduced Fe-species followed by highly oxidized Fe-species, most resembling Fe(III) complexed with organic matter. Values subsequently normalise in younger samples through the ‘Dead Zone’, attaining only slightly higher redox-levels than before the event. The organically complexed Fe-species in the event bed is consistent with the standard Suwannee River fulvic acid, an acid Fe-complex with iron bound to organic matter, whereas the samples above and below the extinction layer yield spectra predominantly resembling magnetite (Fe3O4) mineral phase. We consider that the iron redox fluctuation marking the extinction interval is related to significant environmental changes with accumulation of organic matter following the mass extinction. The highly reduced iron in the extinction layer may relate to methane release from bacterial degradation, or emissions from clathrates. The presence of fulvic acid in the distinct iron-rich extinction layer indicates that an abrupt onset of the process of degradation of plant matter, lipids and calcium hydroxide (CaOH) took place, resulting in this ‘Death layer’. This was followed by millions of years of erosive conditions before new, complex vegetation could establish.

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    Vajda et al_2023_Changes in Fe-redox and Fe-species across the end-Permian ‘Dead Zone’ in the
  • 97.
    Vajda, Vivi
    et al.
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    Skovsted, Christian
    Swedish Museum of Natural History, Department of Paleobiology.
    Advances in Swedish palaeontology; the importance of fossils in natural history collections - The Department of Palaeobiology at the Swedish Museum of Natural History2021In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 143, no 2-3, p. 93-102Article in journal (Other academic)
    Abstract [en]

    This special issue aims to highlight the value of historical paleontological collections at museums in general, and at Swedish Museum of Natural History (NRM) in particular, providing a glimpse into our national fossil archives in the light of modern science and technology. Museums worldwide house fossil material collected over a time span of hundreds of years, in many cases from sedimentary successions that are no longer accessible. The paleontological collections at the NRM comprise over two million specimens that were contributed to the museum over the past 200 years, by pioneers, such as Nordenskiöld, Angelin, Holm, Stensiö, Nathorst, Halle and Lundblad. In more recent times, donations from other institutes and private persons have enriched our collections and a new generation of scientists and curators are continuously adding valuable material. For the purpose of this special issue, we focus mainly on our Swedish collections, focusing on scientifically important specimens not described previously, but also new material investigated with the latest technologies. Research highlighted in this issue covers most of the Phanerozoic eon incorporating macro- and microfossil data from marine and continental successions. We wish to show the reader that the collections represent an invaluable national resource and a great asset for both Swedish and international researchers long into the future.

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  • 98.
    Yuan, Qin
    et al.
    Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining, China.
    Barbolini, Natasha
    Department of Ecology, Environment and Plant Sciences and Bolin Centre for Climate Research, Stockholm University.
    Ashworth, Luisa
    School of Geography, Environment and Earth Sciences, Victoria University of Wellington.
    Rydin, Catarina
    Department of Ecology, Environment and Plant Sciences and Bolin Centre for Climate Research, Stockholm University.
    Gao, Dong-Lin
    Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining, China.
    Shan, Fa-Shou
    Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining, China.
    Zhong, Xiao-Yong
    University of China Mining and Technology, Beijing 100049, China.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    Palaeoenvironmental changes in Eocene Tibetan lake systems traced by geochemistry, sedimentology and palynofacies2021In: Journal of Asian Earth Sciences, ISSN 1367-9120, E-ISSN 1878-5786, Vol. 214, p. 104778-104778, article id 104778Article in journal (Refereed)
    Abstract [en]

    Ancient lake deposits preserve detailed records of Cenozoic environmental changes, providing information on past climate, vegetation, precipitation and lake chemistry. This study focuses on palaeoenvironmental changes recorded in Eocene limnic environments across what is today the modern Tibetan Plateau. We describe a section dated as late Eocene (~38–37 Ma) and integrate these findings within a regional context of similarly-aged Tibetan lake deposits across the plateau. These sedimentary archives of environmental change indicate a period of late Eocene aridification and cooling in the lead-up to the greenhouse-icehouse transition, which remains poorly understood in Central Asia. We show, based on geochemical, sedimentological, and palynofacies analyses, that a large saline lake existed within a semi-arid to arid steppe environment in the Nangqian Basin, east-central Tibet. The saline lake experienced cyclic drying intervals with shifts to a playa lake / mudflat system. Evidence of increased aridity is recorded in the upper part of the section, including a thinning of gypsum beds, decrease in palynomorph abundance, and concurrent increase in wood debris and amorphous organic matter. This is consistent with late Eocene aridity in Asia, drying of the playa lake, and an impoverished desert-steppe vegetation. Grain size data and geochemistry indicate a stable provenance of sedimentary material, suggesting that tectonic activity did not dominate sedimentation in east-central Tibet during deposition of these successions. Rather, palaeoenvironmental changes across the Tibetan region were most probably controlled by global climate oscillations and retreat of the proto-Paratethys Sea during the late Eocene: knowledge that is relevant for ecological interpretations through the Cenozoic, Quaternary and to the present.

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  • 99.
    Yuan, Qin
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Barbolini, Natasha
    Stockholm University.
    Rydin, Catarina
    Stockholm University.
    Gao, Dong-Lin
    Qinghai Institute of Salt Lakes, Chinese Academy of Sciences.
    Wei, Hai-Cheng
    Qinghai Institute of Salt Lakes, Chinese Academy of Sciences.
    Fan, Qi-Shun
    Qinghai Institute of Salt Lakes, Chinese Academy of Sciences.
    Qin, Zhan-Jie
    Qinghai Institute of Salt Lakes, Chinese Academy of Sciences.
    Du, Yong-Shen
    Qinghai Institute of Salt Lakes, Chinese Academy of Sciences.
    Shan, Jun-Jie
    Qinghai Institute of Salt Lakes, Chinese Academy of Sciences.
    Shan, Fa-Shou
    Qinghai Institute of Salt Lakes, Chinese Academy of Sciences.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    Aridification signatures from fossil pollen indicate a drying climate in east-central Tibet during the late Eocene2020In: Climate of the Past, ISSN 1744-9588, Vol. 16, p. 2255-2273Article in journal (Refereed)
    Abstract [en]

    Central Asia experienced a number of significant elevational and climatic changes during the Cenozoic, but much remains to be understood regarding the timing and driving mechanisms of these changes as well as their influence on ancient ecosystems. Here, we describe the palaeoecology and palaeoclimate of a new section from the Nangqian Basin in Tibet, north-western China, dated as Bartonian (41.2–37.8 Ma; late Eocene) based on our palynological analyses. Located on the east-central part of what is today the Tibetan Plateau, this section is excellently placed for better understanding the palaeoecological history of Tibet following the Indo-Asian collision. Our new palynological record reveals that a strongly seasonal steppe–desert ecosystem characterized by drought-tolerant shrubs, diverse ferns, and an underlying component of broad-leaved forests existed in east-central Tibet during the Eocene, influenced by a southern monsoon. A transient warming event, possibly the middle Eocene climatic optimum (MECO; 40 Ma), is reflected in our record by a temporary increase in regional tropical taxa and a concurrent decrease in steppe–desert vegetation. In the late Eocene, a drying signature in the palynological record is linked to proto-Paratethys Sea retreat, which caused widespread long-term aridification across the region. To better distinguish between local climatic variation and farther-reaching drivers of Central Asian palaeoclimate and elevation, we correlated key palynological sections across the Tibetan Plateau by means of established radioisotopic ages and biostratigraphy. This new palynozonation illustrates both intra- and inter-basinal floral response to Qinghai–Tibetan uplift and global climate change during the Paleogene, and it provides a framework for the age assignment of future palynological studies in Central Asia. Our work highlights the ongoing challenge of integrating various deep time records for the purpose of reconstructing palaeoelevation, indicating that a multi-proxy approach is vital for unravelling the complex uplift history of Tibet and its resulting influence on Asian climate.

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  • 100.
    Yuan, Qin
    et al.
    baKey Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining,Qinghai 810008, China.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    Li, Qing-Kuan
    University of Chinese Academy of Sciences, Beijing 100049, China.
    Fan, Qi-Shun
    Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining, China.
    Wei, Hai-Cheng
    Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining, China.
    Qin, Zhan-Jie
    Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, China.
    Zhang, Xiang-Ru
    University of Chinese Academy of Sciences, Beijing 100049, China.
    Shan, Fa-Shou
    Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining, China.
    A late Eocene palynological record from the Nangqian Basin, TibetanPlateau: Implications for stratigraphy and paleoclimate2017In: Palaeoworld, ISSN 1871-174X, E-ISSN 1875-5887, Vol. 26, p. 369-379Article in journal (Refereed)
    Abstract [en]

    With the uplifting, large-scale thrusting and striking of the Tibetan Plateau, several Paleogene intracontinental basins formed within the northernTibetan Plateau (TP). Stratigraphical and paleoenvironmental studies of the sedimentary successions within these basins are critical for understandingPaleogene climatological changes in Eurasia. The Nangqian Basin, one of such basins, formed in the Yushu area of the northeastern Tibetan Plateau.A set of lacustrine sediments, dominated by red clasolite, marlite, and gypsum, developed in the Yang Ala section in this basin. Paleontologicalrecords from the Nangqian Basin remain poorly known. Here, we investigate the palynological assemblages of one sedimentary succession at theYang Ala section that belongs to the Gongjue Formation, and their implications regarding the geological age and paleoclimate are discussed. Theresults reveal that the assemblages are dominated mainly by angiosperm pollen (tricolpates and tricolporate), including

    Nitrariadites (Pokrovskaja), Quercoidites, and Labitricolpites, followed by gymnosperm pollen taxa, such as Ephedripites and Taxodiaceaepollenites, and sparse pteridophytespores produced by ferns. A late Eocene age is inferred based on palynostratigraphy and comparison with other pollen assemblages in the TP. Arelatively dry climate with brief humid periods is indicated by the high abundance of xerophytic pollen taxa, such as Ephedripites and Nitrariadites,which are associated with broadleaved deciduous and evergreen plants. The characteristics of the pollen assemblages from the studied Yang Alasection are consistent with other Cenozoic palynofloras from the Mahalagou Formation in the Xining Basin and with those of the Yaxicuo Groupin the Hoh Xil Basin. These results provide an improved stratigraphical scheme for parts of the Cenozoic and enrich the current knowledge of thevegetation history of the northeastern Tibetan Plateau.

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