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  • 1.
    Danise, Silvia
    et al.
    Dipartimento di Scienze della Terra, Università degli Studi di Firenze, Florence, Italy.
    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.
    Twitchett, Richard J.
    cDepartment of Earth Sciences, The Natural History Museum, London, SW7 5BD, UK.
    Land-sea ecological connectivity during a Jurassic warming event2022In: Earth and Planetary Science Letters, ISSN 0012-821X, E-ISSN 1385-013X, Vol. 578, p. 117290-117290, article id 117290Article in journal (Refereed)
    Abstract [en]

    Knowledge on how climate change affects land-sea ecological connectivity in deep time is scarce. To fill this knowledge gap we have assembled a unique dataset through a Jurassic (early Toarcian) warming event that includes quantitative abundance data from pollen and spores, organic-walled marine plankton and benthic macro-invertebrates, in association with geochemical data derived from the same sampled horizons, from the Cleveland Basin, UK. Using this dataset we: (i) reconstruct the timing of degradation and recovery of land-plants, marine primary producers and benthic fauna in response to this event, and (ii) test for connectivity between changes in land and marine ecosystems. We find a discrepancy between the timing of the response of land-plant and marine ecosystems to the event. Land-plants were the first to be affected by initial warming, but also recovered relatively quickly after the peak of warmth to return to pre-event levels of richness and diversity. Plankton and benthic fauna instead experienced a delayed response to initial warming, but as warming peaked, they suffered a rapid and extreme turnover. Recovery in the shelf sea was also delayed (particularly for the benthos) compared to the vegetation. Ecological connectivity analyses show a strong link between changes in terrestrial and marine ecosystems. The loss of large trees on land contributed to changes in marine plankton, from dinoflagellate-to prasinophyte algal-dominated communities, by enhancing erosion, runoff and nutrient-supply into shallow seas. Eutrophication and changes in primary productivity contributed to the decrease of dissolved oxygen in the water column and in bottom waters, which in turn affected benthic communities. Such cause-effect mechanisms observed in the Cleveland Basin are likely to have occurred in other basins of the Boreal Realm, and in part also in basins of the Sub-Boreal and Tethyan realms. Although palaeolatitudinal and palaeoceanographic gradients may have controlled local and regional changes in land-plants and marine ecosystems during the Early Jurassic, the main climatic and environmental changes linked to rapid global warming, enhanced weathering and high primary productivity, are shared among all the examined realms.

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  • 2.
    Danise, Silvia
    et al.
    Dipartimento di Scienze della Terra, Università degli Studi di Firenze, Florence, Italy.
    Slater, Sam M
    Swedish Museum of Natural History, Department of Paleobiology.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology.
    Twitchett, Richard J.
    Department of Earth Sciences, The Natural History Museum, London, SW7 5BD, UK.
    Land-sea ecological connectivity during a Jurassic warming event2021In: Earth and Planetary Science Letters, ISSN 0012-821X, E-ISSN 1385-013X, p. 117290-117290, article id 117290Article in journal (Refereed)
    Abstract [en]

    Knowledge on how climate change affects land-sea ecological connectivity in deep time is scarce. To fill this knowledge gap we have assembled a unique dataset through a Jurassic (early Toarcian) warming event that includes quantitative abundance data from pollen and spores, organic-walled marine plankton and benthic macro-invertebrates, in association with geochemical data derived from the same sampled horizons, from the Cleveland Basin, UK. Using this dataset we: (i) reconstruct the timing of degradation and recovery of land-plants, marine primary producers and benthic fauna in response to this event, and (ii) test for connectivity between changes in land and marine ecosystems. We find a discrepancy between the timing of the response of land-plant and marine ecosystems to the event. Land-plants were the first to be affected by initial warming, but also recovered relatively quickly after the peak of warmth to return to pre-event levels of richness and diversity. Plankton and benthic fauna instead experienced a delayed response to initial warming, but as warming peaked, they suffered a rapid and extreme turnover. Recovery in the shelf sea was also delayed (particularly for the benthos) compared to the vegetation. Ecological connectivity analyses show a strong link between changes in terrestrial and marine ecosystems. The loss of large trees on land contributed to changes in marine plankton, from dinoflagellate- to prasinophyte algal-dominated communities, by enhancing erosion, runoff and nutrient-supply into shallow seas. Eutrophication and changes in primary productivity contributed to the decrease of dissolved oxygen in the water column and in bottom waters, which in turn affected benthic communities. Such cause-effect mechanisms observed in the Cleveland Basin are likely to have occurred in other basins of the Boreal Realm, and in part also in basins of the Sub-Boreal and Tethyan realms. Although palaeolatitudinal and palaeoceanographic gradients may have controlled local and regional changes in land-plants and marine ecosystems during the Early Jurassic, the main climatic and environmental changes linked to rapid global warming, enhanced weathering and high primary productivity, are shared among all the examined realms.

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  • 3.
    Krüger, Ashley
    et al.
    Swedish Museum of Natural History, Department of Paleobiology. Swedish Museum of Natural History.
    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.
    3D imaging of shark egg cases (Palaeoxyris) from Sweden with new insights into Early Jurassic shark ecology2021In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 143, no 2-3, p. 229-247Article in journal (Refereed)
    Abstract [en]

    Several shark species produce egg cases as protective casings in which their embryos develop. These casings are composed of multiple layers of collagen and are extremely durable, making them prone to fossilisation. Here we document Palaeoxyris (Spirangium) ‒ fossil shark egg cases from Lower Jurassic successions of southern Sweden. We present high-resolution 3D images of Palaeoxyris based on microfocus X-ray computed tomography (μCT) of seven specimens, including fossils that were embedded within a sandstone matrix. Our examination of the internal structure of the egg cases revealed the possible remnants of a yolk and foetus in one specimen. The cases were most likely produced by hybodont sharks, as outlined in previous studies, and the occurrence of hybodont teeth from Lower Jurassic successions of Sweden support this. Palynological analysis of the matrix from one of the specimens hosting Palaeoxyris, indicates an early Hettangian age. The high percentage of spores (c. 60%) reveals that the egg cases were laid during the Transitional Spore Spike Interval following the end-Triassic mass extinction. The egg cases are found in conjunction with fossil horsetails; with the broader palynological and sedimentological evidence, this suggests an estuarine depositional setting, and potentially indicates that newborn sharks were living in habitats comparable to modern mangroves, as is often the case today.

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  • 4.
    Mays, Chris
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    McLoughlin, Stephen
    Swedish Museum of Natural History, Department of Paleobiology.
    Frank, Tracy D.
    Department of Earth & Atmospheric Sciences, University of Nebraska-Lincoln.
    Fielding, Christopher R.
    Department of Earth & Atmospheric Sciences, University of Nebraska-Lincoln.
    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.
    Lethal microbial blooms delayed freshwater ecosystem recovery following the end-Permian extinction2021In: Nature Communications, E-ISSN 2041-1723, Vol. 12, no 1, article id 5511Article in journal (Refereed)
    Abstract [en]

    Harmful algal and bacterial blooms linked to deforestation, soil loss and global warming are increasingly frequent in lakes and rivers. We demonstrate that climate changes and deforestation can drive recurrent microbial blooms, inhibiting the recovery of freshwater ecosystems for hundreds of millennia. From the stratigraphic successions of the Sydney Basin, Australia, our fossil, sedimentary and geochemical data reveal bloom events following forest ecosystem collapse during the most severe mass extinction in Earth’s history, the end-Permian event (EPE; c. 252.2 Ma). Microbial communities proliferated in lowland fresh and brackish waterbodies, with algal concentrations typical of modern blooms. These initiated before any trace of post-extinction recovery vegetation but recurred episodically for >100 kyrs. During the following 3 Myrs, algae and bacteria thrived within short-lived, poorly-oxygenated, and likely toxic lakes and rivers. Comparisons to global deep-time records indicate that microbial blooms are persistent freshwater ecological stressors during warming driven extinction events.

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  • 5.
    Peng, Jungang
    et al.
    Nanjing Institute of Geology and Palaeontology.
    Li, Jianguo
    Nanjing Institute of Geology and Palaeontology.
    Slater, Sam M
    Swedish Museum of Natural History, Department of Paleobiology.
    Zhang, Qianqi
    Nanjing Institute of Geology and Palaeontology.
    Zhu, Huaicheng
    Nanjing Institute of Geology and Palaeontology.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    Triassic vegetation and climate evolution on the northern margin of Gondwana: a palynological study from Tulong, southern Xizang (Tibet), China2019In: Journal of Asian Earth Sciences, ISSN 1367-9120, E-ISSN 1878-5786, Vol. 175, p. 74-82Article in journal (Refereed)
    Abstract [en]

    We present vegetation reconstructions based on an almost complete succession through the Triassic of Tulong, Nyalam County, southern Xizang (Tibet), China. The Permian and earliest Triassic samples were barren of palynomorphs, however, in overlying strata we identified well-preserved and diverse miospore assemblages. Seven pollen and spore zones spanning the Olenekian to the Rhaetian were recognized. These palynological zones were amalgamated into three floral stages that comprise distinct vegetation types: (1) an early Olenekian lycophyte dominated flora with common pteridosperms, indicative of a warm and dry climate; (2) a late Olenekian transitional flora composed of abundant conifers with low abundances of lycophytes, signifying a decrease in temperature and increase in humidity; (3) a Middle to Late Triassic mature conifer-dominated flora with diverse sphenophytes, ferns and cycadophytes, indicative of a stable, temperate and humid climate. The changes in vegetation and climate tentatively correlate with the rifting of northern Gondwana, suggesting that regional tectonics was a contributive driving factor to local floral community change.

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  • 6.
    Peng, Jungang
    et al.
    Swedish Museum of Natural History, Department of Paleobiology. 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.
    Slater, Sam M
    Swedish Museum of Natural History, Department of Paleobiology.
    McLoughlin, Stephen
    Swedish Museum of Natural History, Department of Paleobiology.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology.
    New species of Kuqaia from the Lower Jurassic of Sweden indicates a possible water flea (Crustacea: Branchiopoda) affinity2023In: PLOS ONE, E-ISSN 1932-6203, Vol. 18, no 6, article id e0282247Article in journal (Refereed)
    Abstract [en]

    The enigmatic acid-resistant mesofossil genus Kuqaia isemended, anew species (Kuqaia scanicus) isinstituted, and three established species are described from the Lower Jurassic (lower Pliensbachian) ofthe Ka ̈ vlinge BH-928 core, insouthern Sweden. Kuqaia has adistribution across the middle northern latitudes ofPangaea and isrestricted toLower tolower Middle Jurassic strata. Morphological characters support Kuqaia being the ephippia (resting egg/embryo cases) ofCladocera (Crustacea: Branchiopoda), and aprobable early stemgroup taxon ofthe Daphnia lineage. The paleoecology ofthe small planktonic crustaceans indicate purely fresh-water environments, such as lakes orponds, all occurrences being in continental deposits, and the Kuqaia specimens possibly represent dry-season resting eggs. Chemical analyses ofthese and similar fossils, and ofextant invertebrate eggs and egg cases are recommended toimprove resolution ofthe biological affiliations ofsuch mesofossil groups.

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    Peng et al_2023_New species of Kuqaia from the Lower Jurassic of Sweden indicates a possible
  • 7.
    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. Department of Palaeobiology, Swedish Museum of Natural History, Stockholm, Sweden.
    A Late Triassic vegetation record from the Huangshanjie Formation, Junggar Basin, China: possible evidence for the Carnian Pluvial Episode2022In: Geological Society Special Publication, ISSN 0305-8719, E-ISSN 2041-4927, Vol. 521, no 1, p. 95-108Article in journal (Refereed)
    Abstract [en]

    The Carnian Pluvial Episode (CPE; c. 234–232 million years ago) is characterized by an accelerated hydrological cycle, global warming and a period of elevated biotic turnover. Using spores and pollen, we reconstruct vegetation and climate changes through a Carnian–Norian (Upper Triassic) interval of the Huangshanjie Formation from the Junggar Basin, China. Four palynofloras were identified, representing distinct vegetation communities. Among these palynofloras, we observed a prominent shift from a conifer-dominated climax forest community, with common ginkgophytes and bennettites, to a fern-dominated community, suggestive of an environmental perturbation. We interpret this change as a regional shift in vegetation, likely caused by increased humidity, consistent with the CPE. Our records represent the first indication of a possible CPE-induced vegetation response in the Junggar Basin and highlight how this event likely affected floral communities of inland Laurasia.

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  • 8.
    Peng, Jungang
    et al.
    Swedish Museum of Natural History, Department of Paleobiology. aState 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.
    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.
    A review of the Triassic pollen Staurosaccites: systematic and phytogeographical implications2021In: Grana, ISSN 0017-3134, E-ISSN 1651-2049, Vol. 60, no 6, p. 407-423Article in journal (Refereed)
    Abstract [en]

    Staurosaccites, a highly distinctive pollen genus, ranges from the late Anisian (Pelsonian; Middle Triassic) to the Norian, at low tomid latitudes, globally. Here we review the systematic taxonomy and spatial and temporal ranges of Staurosaccites. We provide anemendation to S. tharipatharensis, synonymise S. minutus with the type species S. quadrifidus, and retain the species S. quadrifidus, S. tharipatharensis, S. densus and S. marginalis. Following comparison with morphologically similar pollen and environmental reconstructions of the habitat of its parent plant, we hypothesise that Staurosaccites was produced by a conifer that was likely adapted to warm and humid conditions. Based on occurrences of diagnostic taxa for the Onslow and Ipswich microfloral provinces in the Southern Hemisphere (Staurosaccites, Camerosporites, Enzonalasporites, Infernopollenites and Ovalipollis), we show that these palynofloras were established in the Middle Triassic. Our findings further suggest that, based on the presence of diagnostic taxa in western Laurasia and their absence in eastern Laurasia, western and eastern Laurasia represent different palynofloral provinces in the Middle Triassic.

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  • 9.
    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.
    A review of the Triassic pollen Staurosaccites: systematic and phytogeographical implications2021In: Grana, ISSN 0017-3134, E-ISSN 1651-2049, Vol. 60, no 6, p. 407-423Article in journal (Refereed)
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  • 10.
    Peng, Jungang
    et al.
    State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology and Centre for Excellence in Life and Palaeoenvironment, 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.
    Floral and faunal biostratigraphy of the Middle–Upper Triassic Karamay and Huangshanjie formations from the southern Junggar Basin, China2024In: Geological Society Special Publication, ISSN 0305-8719, E-ISSN 2041-4927, Vol. 538, no 1Article in journal (Refereed)
    Abstract [en]

    In the Junggar Basin, northwestern China, the biostratigraphy and vegetation patterns of the Middle–Late Triassic sediments are comparatively poorly resolved. Here we investigate Middle–Late Triassic successions of the Dalongkou Section in the southern Junggar Basin for palynostratigraphy and vegetation patterns. Three palynological abundance zones are proposed here: the Aratrisporites Abundance Zone (Middle Triassic), the Dictyophyllidites–Aratrisporites Abundance Zone (latest Middle to early Late Triassic) and the Lycopodiacidites–Stereisporites informal abundance zone (Late Triassic). A review of previous records of the Fukangichthys Fauna indicates that this vertebrate fossil assemblage is stratigraphically located within the uppermost part of the Karamay Formation and is Middle Triassic in age. The revised dating of this and other faunas are further used to constrain the palynological zones in the Junggar Basin. Although the palynoflora is consistently dominated by non-striate bisaccate pollen (produced by seed ferns and/or conifers) in the studied section, spores record a distinctive abundance increase during the late Middle Triassic. Spore taxon abundance changes indicate a vegetational shift from a Middle Triassic–early Late Triassic community characterized by abundant lycophytes (likely Annalepis and Pleuromeia) to a Late Triassic ecosystem with abundant dipteridaceous ferns (e.g. Dictyophyllum) in the Junggar Basin and across North China. This study updates the Triassic biostratigraphy in the Junggar Basin, and sheds light on temporal floral changes in this basin and elsewhere in North China during the Middle to Late Triassic.

  • 11.
    Peng, Jungang
    et al.
    Swedish Museum of Natural History, Department of Paleobiology. aState 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.
    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.
    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)
    Abstract [en]

    Here we investigate megaspores from 10 Triassic‒Jurassic localities of southern Sweden and Bornholm, Denmark, based on collections housed in the Swedish Museum of Natural History. We identify and describe 19 megaspore taxa belonging to three stratigraphically constrained assemblages, representing the Rhaetian, Hettangian and Pliensbachian, respectively. Megaspores are abundant and diverse (12 taxa) in the Rhaetian assemblage. Diversity markedly decreases across the Triassic–Jurassic boundary (TJB), with species richness reducing from 12 to two taxa. The Hettangian assemblage is well-preserved but depauperate, and is overwhelmingly dominated by Nathorstisporites hopliticus. A subsequent recovery of lycopsid diversity followed, recorded by an increase in richness to six taxa in the Pliensbachian assemblage. The disappearance of the hygrophilous and diverse heterosporous lycophyte communities acrossthe TJB, suggests a shift to drier conditions in the earliest Jurassic. This is supported by lithological changes from coal-forming environments in the Rhaetian to sandstone-dominated fluvial-estuarine facies in the Hettangian. Throughout this study, we analysed the megaspores using fluorescence microscopy, which revealed detailed morphological features on specimens that were otherwise opaque under visible light. This non-destructive technique is particularly useful for examining opaque megaspores embedded in permanent mounting media, such as epoxy resin, and may provide new insights into historical megaspore collections elsewhere.

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  • 12.
    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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  • 13.
    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.

  • 14.
    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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  • 15.
    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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  • 16.
    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
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