Change search
Refine search result
12 1 - 50 of 55
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1. BADAWY, AHMED SALAH
    et al.
    Mehlqvist, Kristina
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology.
    Ahlberg, Per
    Calner, Mikael
    Late Ordovician (Katian) spores in Sweden: oldest land plant remains from Baltica2014In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 136, no 1, p. 16-21Article in journal (Refereed)
    Abstract [en]

    A palynological study of the Ordovician–Silurian boundary (Katian–Rhuddanian) succession in the Röstaånga-1 drillcore, southern Sweden, has been performed. The lithology is dominated by mudstone and graptolitic shale, with subordinate limestone, formed in the deeper marine halo of southernBaltica. The palynological assemblages are dominated by marine microfossils, mainly chitinozoans and acritarchs. Sparse but well-preserved cryptospores, including Tetrahedraletes medinensis, Tetrahedraletes grayii and Pseudodyadospora sp., were encountered in the Lindegård Formation (late Katian–early Hirnantian), with the oldest record just above the first appearance of the graptolite species Dicellograptus complanatus. This represents the earliest record of early land plant spores from Sweden and possibly also from Baltica and implies that land plants had migrated to the palaeocontinent Baltica by at least the Late Ordovician.

  • 2.
    Bercovici, Antoine
    et al.
    Department of Geology, Lund University, Sölvegatan 12, SE-223 62 Lund, Sweden.
    Cui, Ying
    Department of Geosciences, 512 Deike Building, The Pennsylvania State University, University Park, PA 16802, USA.
    Forel, Marie-Béatrice
    State Key Laboratory of Biogeology and Environmental Geology of Ministry of Education, China University of Geosciences, Wuhan 430074, People’s Republic of China.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    Terrestrial paleoenvironment characterization across the Permian–Triassic boundary in South China2015In: Journal of Asian Earth Sciences, ISSN 1367-9120, Vol. 98, p. 225-246Article in journal (Refereed)
    Abstract [en]

    Well-preserved marine fossils in carbonate rocks permit detailed studies of the end-Permian extinction event in the marine realm. However, the rarity of fossils in terrestrial depositional environments makes it more challenging to attain a satisfactory degree of resolution to describe the biotic turnover on land. Here we present new sedimentological, paleontological and geochemical (X-ray fluorescence) analysis from the study of four terrestrial sections (Chahe, Zhejue, Mide and Jiucaichong) in Western Guizhou and Eastern Yunnan (Yangtze Platform, South China) to evaluate paleoenvironmental changes through the Permian–Triassic transition.

    Our results show major differences in the depositional environments between the Permian Xuanwei and the Triassic Kayitou formations with a change from fluvial–lacustrine to coastal marine settings. This change is associated with a drastic modification of the preservation mode of the fossil plants, from large compressions to small comminuted debris. Plant fossils spanning the Permian–Triassic boundary show the existence of two distinct assemblages: In the Xuanwei Formation, a Late Permian (Changhsingian) assemblage with characteristic Cathaysian wetland plants (mainly Gigantopteris dictyophylloides, Gigantonoclea guizhouensis, G. nicotianaefolia, G. plumosa, G. hallei, Lobatannularia heinanensis, L. cathaysiana, L. multifolia, Annularia pingloensis, A. shirakii, Paracalamites stenocostatus, Cordaites sp.) is identified. In the lowermost Kayitou Formation, an Early Triassic (Induan)Annalepis–Peltaspermum assemblage is shown, associated with very rare, relictual gigantopterids. Palynological samples are poor, and low yield samples show assemblages almost exclusively represented by spores. A 1 m thick zone enriched in putative fungal spores was identified near the top of the Xuanwei Formation, including diverse multicellular forms, such as Reduviasporonites sp. This interval likely corresponds to the PTB ‘‘fungal spike’’ conventionally associated with land denudation and ecosystem collapse. While the floral turnover is evident, further studies based on plant diversity would be required in order to assess contribution linked to the end-Permian mass extinction versus local paleoenvironmental changes associated with the transition between the Xuanwei and Kayitou formations.

  • 3.
    Bermúdez, Hermann
    et al.
    Grupo de Investigación Paleoexplorer.
    Arenillas, Ignacio
    Universidad de Zaragoza.
    Arz, José Antonio
    Universidad de Zaragoza.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    Renne, Paul
    University of California, Berkeley.
    Gilabert, Vicente
    Universidad de Zaragoza.
    Rodríguez, José Vicente
    Grupo de Investigación Paleoexplorer.
    The Cretaceous/Paleogene Boundary Deposits on Gorgonilla Island2019In: The Geology of Colombia, Volume 3 Paleogene – Neogene / [ed] Gómez, J. & Mateus–Zabala, D., Bogota: Servi­cio Geológico Colombiano , 2019, 1, p. 1-19Chapter in book (Refereed)
    Abstract [en]

    A ca. 20 mm thick spherule bed representing Chicxulub impact ejecta deposits and marking the Cretaceous/Paleogene (K/Pg) boundary was recently discovered on Gorgonilla Island (Gorgona National Natural Park, Pacific of Colombia). This discovery represents the first confirmed record of the K/Pg event in Colombia, South America and the eastern Pacific Ocean. The deposit consists of extraordinarily well–preserved glass spherules (microtektites and microkrystites) reaching 1.1 mm in diameter. Importantly, the Gorgonilla spherule bed is unique relative to other K/Pg boundary sites in that up to 90% of the spherules are intact and not devitrified, and the bed is virtually devoid of lithic fragments and microfossils. The spherules were deposited in a deep marine environment, possibly below the calcite compensation depth. The preservation, normal size–gradation, presence of fine textures within the spherules, and absence of bioturbation or traction transport indicate that the Gorgonilla spherules settled within a water column with minimal disturbance. The spherule bed may represent one of the first parautochthonous primary deposits of the Chicxulub impact known to date. 40Ar/39Ar dating and micropaleontological analysis reveal that the Gorgonilla spherule bed resulted from the Chicxulub impact. Intense soft–sediment deformation and bed disruption in Maastrichtian sediments of the Gorgonilla Island K/Pg section provide evidence for seismic activity triggered by the Chicxulub bolide impact, 66 million years ago. It is also notable that the basal deposits of the Danian in the Colombian locality present the first evidence of a recovery vegetation, characterized by ferns from a tropical habitat, shortly following the end–Cretaceous event.

  • 4. BERMÚDEZ,, Hermann Darío
    et al.
    ARENILLAS, Ignacio
    ARZ, José Antonio
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    RENNE, Paul R.
    GILABERT, Vicente
    RODRÍGUEZ, José Vicente
    The Cretaceous/Paleogene boundary deposits on Gorgonilla Island2018In: The Geology of Colombia: Volume  3   Paleogene – Neogene / [ed] Tapias, J.G. et al., Bogota: Servicio Geológico Colombiano , 2018, p. 1-34Chapter in book (Refereed)
    Abstract [en]

    A ~20 mm thick spherule bed representing Chicxulub impact ejecta deposits and marking the Cretaceous/Paleogene (K/Pg) boundary was recently discovered on Gorgonilla Island (Gorgona National Natural Park, Pacific of Colombia). This discovery represents the first confirmed record of the K/Pg event in Colombia, South America and the eastern Pacific Ocean. The deposit consists of extraordinarily well–preserved glass spherules (microtektites and microkrystites) reaching 1.1 mm in diameter. Importantly, the Gorgonilla spherule bed is unique relative to other K/Pg boundary sites in that up to 90% of the spherules are intact and not devitrified, and the bed is virtually devoid of lithic fragments and microfossils. The spherules were deposited in a deep marine environment, possibly below the calcite compensation depth. The preservation, normal size–gradation, presence of fine textures within the spherules, and absence of bioturbation or traction transport indicate that the Gorgonilla spherules settled within a water column with minimal disturbance. Thus, the spherule bed may represent one of the first parautochthonous primary deposits of the Chicxulub impact known to date. 40Ar/39Ar dating and micropaleontological analysis reveal that the Gorgonilla spherule bed resulted from the Chicxulub impact. Intense soft–sediment deformation and bed disruption in Maastrichtian sediments of the Gorgonilla Island K/Pg section provide evidence for seismic activity triggered by the Chicxulub bolide impact, 66 million years ago. It is also notable that the basal deposits of the Danian in the Colombian locality present the first evidence of a recovery vegetation, characterized by ferns from a tropical habitat, shortly following the end–Cretaceous event.

  • 5.
    Bomfleur, Benjamin
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    McLoughlin, Stephen
    Swedish Museum of Natural History, Department of Paleobiology.
    Vajda, Vivi
    Lund University.
    Fossilized nuclei and chromosomes reveal 180 millionyears of genomic stasis in Royal Ferns2014In: Science, ISSN ISSN 0036-8075, Vol. 343, p. 1376-1377Article in journal (Refereed)
    Abstract [en]

    Rapidly permineralized fossils can provide exceptional insights into the evolution of life over geological time. Here, we present an exquisitely preserved, calcified stem of a royal fern (Osmundaceae) from Early Jurassic lahar deposits of Sweden in which authigenic mineral precipitation from hydrothermal brines occurred so rapidly that it preserved cytoplasm, cytosol granules, nuclei, and even chromosomes in various stages of cell division. Morphometric parameters of interphase nuclei match those of extant Osmundaceae, indicating that the genome size of these reputed “living fossils” has remained unchanged over at least 180 million years—a paramount example of evolutionary stasis.

  • 6.
    Cui, Ying
    et al.
    Department of Geosciences, The Pennsylvania State University, University Park, PA, United States.
    Bercovici, Antoine
    Department of Geology, Lund University, Lund, Sweden.
    Yu, Jianxin
    State Key Laboratory of Biogeology and Environmental Geology of Ministry of Education, China University of Geosciences (Wuhan), People's Republic of China.
    Kump, Lee R.
    Department of Geosciences, The Pennsylvania State University, University Park, PA, United States.
    Freeman, Katherine
    Department of Geosciences, The Pennsylvania State University, University Park, PA, United States.
    Su, Shangguo
    School of Earth Sciences and Resources, China University of Geosciences (Beijing), People's Republic of China.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    Carbon cycle perturbation expressed in terrestrial Permian–Triassic boundary sections in South China2017In: Global and Planetary Change, ISSN 0921-8181, E-ISSN 1872-6364, Vol. 148, p. 272-285Article in journal (Refereed)
    Abstract [en]

    Stable isotopes of inorganic and organic carbon are commonly used in chemostratigraphy to correlatemarine andterrestrial sedimentary sequences based on the assumption that the carbon isotopic signature of the exogenic carbon pool dominates other sources of variability. Here, sediment samples fromfour Permian–Triassic boundary (PTB) sections ofwesternGuizhou and eastern Yunnan provinces in South China, representing a terrestrial tomarine transitional setting,were analyzed for δ13C of organic matter (δ13Corg). These valueswere subsequently compared to published δ13C values of carbonates (δ13Ccarb) from the Global Stratotype Section and Point at Meishan and many other marine and terrestrial sections. A similar isotopic trend evident through all four sections is characterized by a negative shift of 2–3‰ at the top of the Xuanwei Formation, where we tentatively place the PTB. This negative shift also corresponds to a turnover in the vegetation and the occurrence of fungal spores, which is generally interpreted as a proliferation of decomposers and collapse of complex ecosystems during the end-Permian mass extinction event. Moreover, the absolute values of δ13Corg are more extreme in the more distal (marine) deposits. The δ13Corg values for the studied sediments aremore variable compared to coeval δ13Ccarb records from marine records especially in the interval below the extinction horizon. We contend that the depositional environment influenced the δ13Corg values, but that the persisting geographic δ13Corg pattern through the extinction event across the four independent sections is an indication that the atmospheric δ13C signal left an indelible imprint on the geologic record related to the profound ecosystem change during the end-Permian extinction event.

  • 7. Cui, Ying
    et al.
    Bercovici, Antoine
    Yu, Yianxin
    Kump, Lee
    Freeman, Katherine
    Su, Shangguo
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology.
    Carbon cycle perturbation expressed in terrestrial Permian–Triassic boundary sections in South China2015In: Global and Planetary Change, ISSN 0921-8181, E-ISSN 1872-6364Article in journal (Refereed)
    Abstract [en]

    Stable isotopes of inorganic and organic carbon are commonly used in chemostratigraphy to correlate marine and terrestrial sedimentary sequences based on the assumption that the carbon isotopic signature of the exogenic carbon pool dominates other sources of variability. Here, sediment samples from four Permian–Triassic boundary (PTB) sections of western Guizhou and eastern Yunnan provinces in South China, representing a terrestrial to marine transitional setting, were analyzed for δ13C of organic matter (δ13Corg). These values were subsequently compared to published δ13C values of carbonates (δ13Ccarb) from the Global Stratotype Section and Point at Meishan and many other marine and terrestrial sections. A similar isotopic trend evident through all four sections is characterized by a negative shift of 2–3‰ at the top of the Xuanwei Formation, where we tentatively place the PTB. This negative shift also corresponds to a turnover in the vegetation and the occurrence of fungal spores, which is generally interpreted as a proliferation of decomposers and collapse of complex ecosystems during the end-Permian mass extinction event. Moreover, the absolute values of δ13Corg are more extreme in the more distal (marine) deposits. The δ13Corg values for the studied sediments are more variable compared to coeval δ13Ccarb records from marine records especially in the interval below the extinction horizon. We contend that the depositional environment influenced the δ13Corg values, but that the persisting geographic δ13Corg pattern through the extinction event across the four independent sections is an indication that the atmospheric δ13C signal left an indelible imprint on the geologic record related to the profound ecosystem change during the end-Permian extinction event.

  • 8.
    Einarsson, Elisabeth
    Department of Geology, Lund University.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    First evidence of the Cretaceous decapod crustacean Protocallianassa from Sweden2016In: Geological Society, London, Special Publications, ISSN ISSN 0305-8719, Vol. 434, p. 241-250Article in journal (Refereed)
    Abstract [en]

    An assemblage of the burrowing ghost shrimp, Protocallianassa faujasi, is described, providing the first evidence of this decapod species from Sweden. The fossils occur in successions of the informal earliest late Campanian Belemnellocamax balsvikensis Zone at Åsen and the latest early Campanian B. mammillatus zone at Ivö Klack, both in the Kristianstad Basin of NE Skåne. Numerous, heavily calcified chelipeds were found within a restricted bed at Åsen that was rich in carbonate-cemented nodules. Based on the burrowing lifestyle of modern mud shrimps, we interpret these nodules as infilled burrow chambers. The low abundance of molluscs within the Protocallianassa beds is also consistent with analogous extant communities, indicating that a similar ecologically exclusive relationship ruled within the Late Cretaceous shallow marine ecosystems.

  • 9.
    Field, Daniel J
    et al.
    Milner Centre for Evolution, Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, UK.
    Bercovici, Antoine
    2Department of Paleobiology MRC-121, National Museum of Natural History, Smithsonian Institution, 10th Street and Constitution Avenue, NW, Washington, DC 20560-0121, USA.
    Berv, Jacob S
    Department of Ecology & Evolutionary Biology, Cornell University, 215 Tower Road, Ithaca, NY 14853, USA.
    Dunn, Regan
    Integrated Research Center, Field Museum of Natural History, 1400 South Lake Shore Drive, Chicago, IL 60605, USA.
    Fastovsky, David E
    Department of Geosciences, University of Rhode Island, 9 East Alumni Avenue, Kingston, RI 02881, USA.
    Lyson, Tyler R
    6Department of Earth Sciences, Denver Museum of Nature and Science, 2001 Colorado Boulevard, Denver, CO 80205, USA.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    Gauthier, Jacques A
    Department of Geology & Geophysics, Yale University 210 Whitney Avenue, New Haven, CT 06511, USA.
    Early Evolution of Modern Birds Structured by Global Forest Collapse at the End-Cretaceous Mass Extinction2018In: Current Biology, ISSN 0960-9822, E-ISSN 1879-0445, Vol. 28, p. 1825-1831Article in journal (Refereed)
    Abstract [en]

    The fossil record and recent molecular phylogenies support an extraordinary early-Cenozoic radiation of crown birds (Neornithes) after the Cretaceous-Paleogene (K-Pg) mass extinction [1–3 ]. However, questions remain regarding the mechanisms underlying the survival of the deepest lineages within crown birds across the K-Pg boundary, particularly since this global catastrophe eliminated even the closest stem-group relatives of Neornithes [4 ]. Here, ancestral state reconstructions of neornithine ecology reveal a strong bias toward taxa exhibiting predominantly non-arboreal lifestyles across the K-Pg, with multiple convergent transitions toward predominantly arboreal ecologies later in the Paleocene and Eocene. By contrast, ecomorphological inferences indicate predominantly arboreal lifestyles among enantiornithines, the most diverse and widespread Mesozoic avialans [5–7 ]. Global paleobotanical and palynological data show that the K-Pg Chicxulub impact triggered widespread destruction of forests [8, 9 ]. We suggest that ecological filtering due to the temporary loss of significant plant cover across the K-Pg boundary selected against any flying dinosaurs (Avialae [10 ]) committed to arboreal ecologies, resulting in a predominantly non-arboreal postextinction neornithine avifauna composed of totalclade Palaeognathae, Galloanserae, and terrestrial total-clade Neoaves that rapidly diversified into the broad range of avian ecologies familiar today. The explanation proposed here provides a unifying hypothesis for the K-Pg-associated mass extinction of arboreal stem birds, as well as for the post-K-Pg radiation of arboreal crown birds. It also provides a baseline hypothesis to be further refined pending the discovery of additional neornithine fossils from the Latest Cretaceous and earliest Paleogene.

  • 10.
    Fielding, Christopher
    et al.
    University of Nebraska.
    Frank, Tracy
    University of Nebraska.
    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.
    Mays, Chris
    Swedish Museum of Natural History, Department of Paleobiology.
    Tevyaw, Allen
    University of Nebraska.
    Winguth, Arne
    University of Texas at Arlington.
    Winguth, Cornelia
    University of Texas at Arlington.
    Nicoll, Robert
    Geoscience Australia.
    Bocking, Malcolm
    Bocking Associates.
    Crowley, James
    Boise State University.
    Age and pattern of the southern high-latitude continental end-Permian extinction constrained by multiproxy analysis2019In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 10, no 385, p. 1-12Article in journal (Refereed)
    Abstract [en]

    Past studies of the end-Permian extinction (EPE), the largest biotic crisis of the Phanerozoic, have not resolved the timing of events in southern high-latitudes. Here we use palynology coupled with high-precision CA-ID-TIMS dating of euhedral zircons from continental sequences of the Sydney Basin, Australia, to show that the collapse of the austral Permian Glossopteris flora occurred prior to 252.3 Ma (~370 kyrs before the main marine extinction). Weathering proxies indicate that floristic changes occurred during a brief climate perturbation in a regional alluvial landscape that otherwise experienced insubstantial change in fluvial style, insignificant reorganization of the depositional surface, and no abrupt aridification. Palaeoclimate modelling suggests a moderate shift to warmer summer temperatures and amplified seasonality in temperature across the EPE, and warmer and wetter conditions for all seasons into the Early Triassic. The terrestrial EPE and a succeeding peak in Ni concentration in the Sydney Basin correlate, respectively, to the onset of the primary extrusive and intrusive phases of the Siberian Traps Large Igneous Province.

  • 11.
    Gulick, Sean, P.S.
    et al.
    University of Texas at Austin.
    Bralower, Timothy J.
    Pennsylvania State University.
    Ormö, Jens
    Instituto Nacional de Técnica Aeroespacial-Spanish National Research Council.
    Hall, Brendon
    Enthought, Inc..
    Grice, Kliti
    Curtin University.
    Schaefer, Bettina
    Curtin University.
    Lyons, Shelby
    Pennsylvania State University.
    Freeman, Katherine
    Pennsylvania State University.
    Morgan, Joahha
    Imperial College London.
    Artemieva, Natalia
    Planetary Science Institute, Tucson.
    Kaskes, Pim
    Vrije Universiteit Brussel.
    de Graaff, Sietze
    Vrije Universiteit Brussel.
    Whalen, Michael T.
    University of Alaska Fairbanks.
    Collins, Gareth S.
    Imperial College London.
    Tikoo, Sonia M.
    Rutgers University.
    Verhagen, Christina
    Rutgers University.
    Christeson, Gail L.
    University of Texas at Austin.
    Claeys, Philippe
    Vrije Universiteit Brussel.
    Coolen, Marco J. L.
    Curtin University.
    Goderis, Steven
    Imperial College London.
    Goto, Kazuhisa
    Tohoku University.
    Grieve, Richard A. F.
    University of Western Ontario.
    McCall, Naoma
    University of Texas at Austin.
    Osinski, Gordon R.
    University of Western Ontario.
    Rae, Auriol S. P.
    Imperial College London.
    Riller, Ulrich
    Universität Hamburg.
    Smit, Jan
    Vrije Universiteit Amsterdam.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    Wittmann, Axel
    Arizona State University.
    The first day of the Cenozoic2019In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 116, p. 19342-19351Article in journal (Refereed)
    Abstract [en]

    Highly expanded Cretaceous–Paleogene (K-Pg) boundary section from the Chicxulub peak ring, recovered by International Ocean Discovery Program (IODP) –International Continental Scientific Drilling Program (ICDP) Expedition 364, provides an unprecedented window into the immediate aftermath of the impact. Site M0077 includes ∼130 m of impact melt rock and suevite deposited the first day of the Cenozoic covered by <1 m of micrite-rich carbonate deposite over subsequent weeks to years. We present an interpreted series of events based on analyses of these drill cores. Within minutes of the impact, centrally uplifted basement rock collapsed outward to forma peak ring capped in melt rock. Within tens of minutes, the peak ring was covered in ∼40 m of brecciated impact melt rock and coarsegrained suevite, including clasts possibly generated by melt–water interactions during ocean resurge. Within an hour, resurge crested the peak ring, depositing a 10-m-thick layer of suevite with increased particle roundness and sorting. Within hours, the full resurge deposit formed through settling and seiches, resulting in an 80-m-thick fining-upward, sorted suevite in the flooded crater. Within a day, the reflected rim-wave tsunami reached the crater, depositing a cross-bedded sand-to-fine gravel layer enriched in polycyclic aromatic hydrocarbons overlain by charcoal fragments. Generation of a deep crater open to the ocean allowed rapid flooding and sediment accumulation rates among the highest known in the geologic record. The high-resolution section provides insight into the impact environmental effects, including charcoal as evidence for impactinduced wildfires and a paucity of sulfur-rich evaporites from the target supporting rapid global cooling and darkness as extinction mechanisms.

  • 12.
    Halamski, Adam
    Institute of Paleobiology, Polish Academy of Sciences.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    Late Cretaceous (Campanian) leaf and palynoflora from southern Sweden2016In: Geological Society of London Special Publications, ISSN 0305-8719, Vol. 434, p. 207-230Article in journal (Refereed)
    Abstract [en]

    A Late Cretaceous (Campanian) leaf megaflora from the Vomb Trough in southern Skåne, Sweden, has been investigated on the basis of collections held at the Swedish Museum of Natural History. The main plant-bearing locality is Köpinge, but single specimens originate from Högestad, Ingelstorp, Rödmölla, Svenstorps mölla and Tosterup. The fossil flora is dominated by the angiosperm (eudicot) Debeya (Dewalquea) haldemiana (Debey ex de Saporta & Marion) Halamski. Other dicots are cf. Dryophyllum sp., Ettingshausenia sp., Rarytkinia? sp., Dicotylophyllum friesii (Nilsson) comb. nov. and Salicites wahlbergii (Nilsson) Hisinger. Conifers are represented by cf. Aachenia sp. (cone scales), Pagiophyllum sp. and Cyparissidium sp. (leaves). Single poorly preserved specimens of ferns and monocots have also been identified. The terrestrial palynomorphs (the focus herein) clearly link to the megaflora, although with different relative abundances. The fern spore Cyathidites dominates along with the conifer pollen Perinopollenites elatoides and Classopollis. Angiosperm pollen comprise up to 15% of the assemblage, represented by monocolpate, tricolpate and periporate pollen and the extinct Normapolles group. The spores in the kerogen residue show a thermal alteration index (TAI) of 2+. The flora probably represents mainly a coastal lowland Debeya/conifer forest, and is similar to approximately coeval assemblages from analogous palaeo-communities described from eastern Poland, western Ukraine and Westphalia.

  • 13.
    Kear, Benjamin
    et al.
    Museum of Evolution, Uppsala University.
    Lindgren, Johan
    Department of Geology, Lund University.
    Jörn Hurum, Jörn
    Natural History Museum, University of Oslo.
    Milan, Jesper
    Geomuseum Faxe/Østsjællands Museum.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    An introduction to the Mesozoic biotas of Scandinavia and its Arctic territories2016In: Geological Society, London, Special Publications, ISSN ISSN 0305-8719, Vol. 434, p. 1-14Article in journal (Refereed)
    Abstract [en]

    The Mesozoic biotas of Scandinavia have been studied for nearly two centuries. However, the last 15 years have witnessed an explosive advance in research, most notably on the richly fossiliferous Triassic (Olenekian–Carnian) and Jurassic (Tithonian) Lagersta¨tten of the Norwegian Arctic Svalbard archipelago, Late Cretaceous (Campanian) Kristianstad Basin and Vomb Trough of Skåne in southern Sweden, and the UNESCO heritage site at Stevns Klint in Denmark – the latter constituting one of the most complete Cretaceous–Palaeogene (Maastrichtian–Danian) boundary sections known globally. Other internationally significant deposits include earliest (Induan) and latest Triassic (Norian–Rhaetian) strata from the Danish autonomous territory of Greenland, and the Early Jurassic (Sinemurian–Pliensbachian) to Early Cretaceous (Berriasian) rocks of southern Sweden and the Danish Baltic island of Bornholm, respectively. Marine palaeocommunities are especially well documented, and comprise prolific benthic macroinvertebrates, together with pelagic cephalopods, chondrichthyans, actinopterygians and aquatic amniotes (ichthyopterygians, sauropterygians and mosasauroids). Terrestrial plant remains (lycophytes, sphenophytes, ferns, pteridosperms, cycadophytes, bennettitaleans and ginkgoes), including exceptionally well-preserved carbonized flowers, are also world famous, and are occasionally associated with faunal traces such as temnospondyl amphibian bones and dinosaurian footprints. While this collective documented record is substantial, much still awaits discovery. Thus, Scandinavia and its Arctic territories represent some of the most exciting prospects for future insights into the spectacular history of Mesozoic life and environments.

  • 14.
    Kustatscher, Evelyn
    et al.
    Museum of Nature South Tyrol, Bindergasse 1, 39100 Bozen/Bolzano, Italy.
    Ash, Sidney
    Department of Earth and Planetary Sciences, Northrop Hall, University of New Mexico, Albuquerque, NM 87131, USA.
    Karasev, Eugeny
    Borissiak Paleontological Institute, Russian Academy of Sciences, Profsoyuznaya 123, Moscow 117647, Russia.
    Pott, Christian
    Swedish Museum of Natural History, Department of Paleobiology.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    Yu, Jianxin
    State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, P.O.Box 430074, P.R. China.
    McLoughlin, Stephen
    Swedish Museum of Natural History, Department of Paleobiology.
    Flora of The Late Triassic2017In: The Late Triassic World: Earth in a Time of Transition / [ed] Tanner, L.H., New York: Springer International Publishing , 2017, 1, p. 545-622Chapter in book (Refereed)
    Abstract [en]

    The Triassic was a crucial period of botanical evolutionary innovations and plant diversification. Key plant groups (Bennettitales, Czekanowskiales, Gnetales and several modern fern and conifer families) originated during this span of time, together with some taxa putatively related to angiosperms. The composition of the various plant assemblages shows a more homogeneous flora globally than during the Permian. Nonetheless two major floristic provinces are distinguishable during the Late Triassic (Gondwana and Laurussia) together with several subprovinces (two within Gondwana, nine within Laurussia), based on palyno- and macro-floras.The latter are differentiated by contrasting taxonomic composition and group abundances related to different climatic and regional environmental conditions. Many plant families and genera are widely distributed in the Late Triassic, at least in the respective hemispheres. Based on the array of preserved damage types on leaves and wood, insect faunas appear to have recovered from the end-Permian mass extinction by the Late Triassic, with a major expansion of herbivory in Gondwana. All modern functional feeding groups (FFG) were present by the Triassic, including external foliage feeding, piercing-and-sucking, galling, leaf mining and seed predation, with some evidence for the development of very specialized feeding traits and egg-laying strategies.

  • 15.
    Li, Liqin
    et al.
    State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China.
    Wang, Yongdong
    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.
    Liu, Zhaosheng
    State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China.
    Late Triassic ecosystem variations inferred by palynological records from Hechuan, southern Sichuan Basin, China2018In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 155, p. 1793-1810Article in journal (Refereed)
    Abstract [en]

    The Late Triassic deposits of the Sichuan Basin, southwestern China are significant for hosting abundant and diverse fossil assemblages including plants (containing spores and pollen), bivalves and insects. However, the Late Triassic palaeoecological variations are still poorly documented in this region. Here we present results from a palynological study from the Upper Triassic Xujiahe Formation in Hechuan of Chongqing, southern Sichuan Basin. The palynological analysis revealed a well-preserved terrestrial palynoflora of high diversity, comprising 184 species in 75 genera of spores and pollen. Three palynological assemblages were recognized, reflecting terrestrial successions throughout the entire interval with significant changes in the vegetation. Cycads/bennettites/ginkgophytes and conifers show an increasing trend into younger deposits, while ferns and lycopsids decrease in relative abundance. The Late Triassic vegetation underwent changes from lowland fern forest to a mixed forest with more canopy trees. We applied the Spore-pollen Morphological Group (SMG) method and Sporomorph EcoGroup (SEG) model to interpret the palaeoclimate features. The results reveal that the lower part of the Xujiahe Formation was deposited under relatively warm and humid conditions with an overall cooling and drying trend from latest Norian to Rhaetian time, accompanied by a general decrease of ferns and simultaneous increase of gymnosperms, and a decline in diversity of miospores. This study presents data on variations within the terrestrial ecosystem prior to the end-Triassic extinction event in the Sichuan Basin, and therefore provides important information for understanding the changes in the vegetation preceding the end-Triassic event.

  • 16.
    McLoughlin, Stephen
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Bomfleur, Benjamin
    Swedish Museum of Natural History, Department of Paleobiology.
    Vajda, Vivi
    Lund University.
    A phenomenal fossil fern, forgotten for forty years2014In: Deposits Magazine, ISSN 17749588, Vol. 40, p. 16-21Article in journal (Other (popular science, discussion, etc.))
    Abstract [en]

    On some occasions, it is the hard sweat and toil of palaeontologists labouring in the field at carefully planned excavation sites that yields the prize specimen on which careers are built. On other occasions, it is the chance discovery by an amateur collector that may yield that special fossil. We present an account of one such remarkable fossil discovery by an eccentric farmer in southern Sweden. However, more remarkable is that this exceptional fossil remained unstudied and largely unnoticed in a major museum for almost 40 years, before its true significance was realised.

  • 17.
    McLoughlin, Stephen
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Jansson, Ida-Maria
    Lund University.
    Vajda, Vivi
    Lund University.
    Megaspore and microfossil assemblages reveal diverse herbaceous lycophytes in the Australian Early Jurassic flora2014In: Grana, ISSN 0017-3134, Vol. 53, p. 22-53Article in journal (Refereed)
    Abstract [en]

    Here, we describe and illustrate by transmitted light and scanning electron microscopy the first Australian Jurassic megaspore assemblages. The megaspores and other mesofossils were isolated from terrestrial deposits of the Marburg Subgroup (late Pliensbachian) at Inverleigh Quarry, Clarence-Moreton Basin, eastern Australia. Nine megaspore taxa are identified including one new species: Paxillitriletes rainei. Miospore assemblages recovered from the same samples at Inverleigh reveal a slightly higher diversity of lycophyte microspores. The collective megaspore suite from Inverleigh shares several genera with mid-Mesozoic assemblages from widely distributed parts of the world, but most of the Inverleigh species have subtle morphological differences from congeneric forms elsewhere. The megaspores accumulated in fluvial floodplain facies and are associated with mostly dissociated isoetalean leaf debris. Other mesofossils in the sampled interval include annelid egg cases, dispersed seeds and charcoal. Invertebrate burrows and possible vertebrate tracks also occur in this succession. Lycophyte macrofossils are otherwise known from only two other Australian Jurassic deposits. The richness of the megaspore and microspore suites attest to a significant diversity of lycophytes in the Australian Jurassic floras not hitherto appreciated from described macrofloras

  • 18. Mehlqvist, Kristina
    et al.
    Larsson, Kent
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology.
    Linking upper Silurian terrestrial and marine successions—Palynologicalstudy from Skåne, Sweden2014In: Review of Palaeobotany and Palynology, ISSN 0034-6667, E-ISSN 1879-0615, Vol. 202, p. 1-14Article in journal (Refereed)
    Abstract [en]

    We have performed a palynostratigraphic study on miospore assemblages from near-shore marine Silurian sed-imentary rocks of Skåne, southern Sweden. The material includes both drillcore (from Klintaborrningen 1 and Bjärsjölagårdborrningen 2) and outcrop samples from various localities in Skåne. Well- preserved spore assemblages were identified. Long ranging species with a global distribution dominate the spore assemblages, including Ambitisporites sp., Dyadospora sp., Laevolancis sp., and Tetrahedraletes sp. and complemented with key taxa including Emphanisporites neglectus, Hispanaediscus lamontii, Hispanaediscus verrucatus, Scylaspora scripta, Synorisporites libycus and Synorisporites tripapillatus. Based on biostratigraphical schemes for early land plant spores, the studied sedimentary rocks of the cores Klintaborrningen 1 and Bjärsjölagårdborrningen 2 are interpreted as late Silurian in age, spanning Ludlow to Přídolí. The spore assemblages are compared and correlated to marine fossil schemes including those of conodonts, chitinozoans, graptolites and tentaculitids. Additionally, relative abundance data of specific spore taxa have been used for correlation between the drillcores and the outcrops.

  • 19.
    Mehlqvist, Kristina
    et al.
    Department of Geology, Lund University, Sölvegatan 12, SE-223 62 Lund, Sweden.
    Steemans, Philippe
    Palaeogeobiology–Palaeobotany–Palaeopalynology, University of Liège, Allée du 6 Août, Bât. B-18, parking 40, B-4000 Liège 1, Belgium.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    First evidence of Devonian strata in Sweden — A palynological investigation of Övedskloster drillcores 1 and 2, Skåne, Sweden2015In: Review of Palaeobotany and Palynology, ISSN 0034-6667, E-ISSN 1879-0615, Vol. 221, p. 144-159Article in journal (Refereed)
    Abstract [en]

    Palynological analyses were carried out on 50 samples from the Övedskloster 1 (Ö1) and 2 drillcores (Ö2), southern Sweden. The study revealed well-preserved palynological assemblages including 77 spore species in 28 genera, and some additional forms retained under open nomenclature. The spore assemblages are collectively dominated by trilete spores in terms of abundance and diversity and have been ascribed to two informal palynozones (Assemblage A and Assemblage B), based on the representation of spore taxa. The presence of the spore species Acinosporites salopiensis, Chelinohilates erraticus, Cymbohilates allenii, Cymbohilates allenii var. magnus, and Retusotriletes maccullockii indicates that the stratigraphic succession spans the Silurian–Devonian boundary (Přídolí–Lochkovian), and thus constitutes the first robust evidence of Devonian strata on the Swedish mainland. These results have implications for the age of fossil faunas (e.g. fish) from the samedeposits, previously dated as late Silurian. Palynofacies analyses reveal a shallowing-upward succession with nearshore marine marls at the base of the investigated core, grading into sandstones in conjunction with a decrease in the relative abundance of marine palynomorphs. The uppermost 70 m are mainly represented by red sandstones that are devoid of recognizable palynomorphs and host only phytodebris. We interpret this interval to represent predominantly paralic to fluvial deposits equivalent to facies represented in the Old Red Sandstone of Britain.

  • 20. Mehlqvist, Kristina
    et al.
    Wigforss-Lange, Jane
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology.
    A palynological study from Sweden reveals stable terrestrial environments during Late Silurian extreme marine conditions2015In: Earth and environmental science transactions of the Royal Society of Edinburgh, ISSN 1755-6910, E-ISSN 1755-6929, Vol. 105, p. 149-158Article in journal (Refereed)
    Abstract [en]

    A palynological study of the upper Silurian Öved–Ramsåsa Group in Skåne, Sweden yields a well preserved spore assemblage with low relative abundances of marine microfossils. In total, 26 spore taxa represented by 15 genera were identified. The spore assemblage is dominated by long-ranging cryptospore taxa, and the trilete spore Ambitisporites avitus-dilutus. However, key-species identified include Artemopyra radiata, Hispanaediscus lamontii, H. major, H. verrucatus, Scylaspora scripta and Synorisporites cf. libycus. Importantly, Scylaspora klintaensis was identified, allowing correlation with the Klinta 1 drillcore (Skåne). A Ludlow age is inferred for the exposed succession, which agrees well with previous conodont stratigraphy. The organic residue is dominated by phytodebris and spores, but with high relative abundances of acritarchs at two levels, possibly related to flooding surfaces. Based on the palynofacies analysis, a near-shore marine environment is proposed. The close proximity to land is inferred by the high proportions of spores, and the dispersed assemblage most likely represents the local flora growing on delta plains. The palynological signal also infers a stable terrestrial environment and vegetation, in contrast to unstable conditions in the marine environment characterised by ooid formation in an evaporitic environment. Comparisons with coeval spore assemblages from Gotland, Avalonia and Laurentia show relatively close similarities in taxonomic composition at the generic level.

  • 21.
    Peng, Jungang
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Li, Jianguo
    Key Laboratory of Economic Stratigraphy and Palaeogeography, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China.
    Slater, Sam M
    Swedish Museum of Natural History, Department of Paleobiology.
    Li, Wenben
    Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China.
    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.
    Triassic palynostratigraphy and palynofloral provinces: evidence from southern Xizang (Tibet), China2018In: Alcheringa, ISSN 0311-5518, E-ISSN 1752-0754, Vol. 42, p. 67-86Article in journal (Refereed)
    Abstract [en]

    Palynological analysis was carried out on Middle to Upper Triassic strata from Tulong, Nyalam County, southern Xizang (Tibet), China. Well-preserved miospore (pollen and spore) assemblages and sparse acritarch occurrences were identified. We recognized four formal and one informal biozones based on stratigraphically important taxa and compositional changes through the succession, in ascending order: the Triplexisporites Interval Zone (Anisian), the Staurosaccites quadrifidus Taxon-range Zone (upper Anisian to lower Norian), the Striatella Interval Zone (lower Norian), the Craterisporites rotundus Taxon-range Zone (middle to upper Norian) and the informal ‘Dictyophyllidites harrisii zone’ (Rhaetian). The zonation was supported by marine fossils (e.g., ammonoids and conodonts), and compositional similarity between the zones was examined using non-metric multidimensional scaling (NMDS). Correlation with other representative palynological sequences across Gondwana was also conducted. The presence of miospore taxa not previously recovered from the Late Triassic North and South China palynofloral provinces (e.g., Ashmoripollis reducta, Craterisporites rotundus, Enzonalasporites vigens, Minutosaccus crenulatus, Samaropollenites speciosus and Staurosaccites quadrifidus) calls for a new province in southwestern China, i.e., the Southern Xizang Province. It is proposed here that the modern expression of the northern boundary runs along the Yarlung Zangbo Suture, the remnant of the Tethys that separated the Indian Plate (southern Xizang) and the Lhasa Block during the Late Triassic. This new palynofloral province comprises typical elements of the Onslow Microflora, indicating the need for an extension of this microflora in southern Xizang, China.

  • 22.
    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.

  • 23.
    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.

  • 24.
    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.

  • 25.
    Qu, Yuangao
    et al.
    Department of Earth Science and Centre for Geobiology, University of Bergen, Norway.
    Engdahl, Anders
    MAX IV Laboratory, Lund University, Sweden.
    Zhu, Shixing
    Tianjin Institute of Geology and Mineral Resources, CGS, China.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    McLoughlin, Nicola
    Department of Geology, Lund University, Sweden.
    Ultrastructural heterogeneity of carbonaceous material in ancient cherts: investigating biosignature origin and preservation2015In: Astrobiology, ISSN 1531-1074, E-ISSN 1557-8070, Vol. 15, no 10, p. 825-842Article in journal (Refereed)
    Abstract [en]

    Opaline silica deposits on Mars may be good target sites where organic biosignatures could be preserved. Potential analogues on Earth are provided by ancient cherts containing carbonaceous material (CM) permineralized by silica. In this study, we investigated the ultrastructure and chemical characteristics of CM in the Rhynie chert (c. 410 Ma, UK), Bitter Springs Formation (c. 820 Ma, Australia), and Wumishan Formation (c. 1485 Ma, China). Raman spectroscopy indicates that the CM has experienced advanced diagenesis or lowgrade metamorphism at peak metamorphic temperatures of 150–350C. Raman mapping and micro-Fourier transform infrared (micro-FTIR) spectroscopy were used to document subcellular-scale variation in the CM of fossilized plants, fungi, prokaryotes, and carbonaceous stromatolites.

    In the Rhynie chert, ultrastructural variation in the CM was found within individual fossils, while in coccoidal and filamentous microfossils of the Bitter Springs and formless CM of the Wumishan stromatolites ultrastructural variation was found between, not within, different microfossils. This heterogeneity cannot be explained by secondary geological processes but supports diverse carbonaceous precursors that experienced differential graphitization. Micro-FTIR analysis found that CM with lower structural order contains more straight carbon chains (has a lower R3/2 branching index) and that the structural order of eukaryotic CM is more heterogeneous than prokaryotic CM.

    This study demonstrates how Raman spectroscopy combined with micro-FTIR can be used to investigate the origin and preservation of silica-permineralized organics. This approach has good capability for furthering our understanding of CM preserved in Precambrian cherts, and potential biosignatures in siliceous deposits on Mars. Key

  • 26.
    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.

  • 27.
    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.

  • 28.
    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.

  • 29.
    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.

  • 30.
    Sha, Jingeng
    et al.
    State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Paleontology, Nanjing 210008, China.
    Olsen, Paul E.
    Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10968.
    Pan, Yanhong
    State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Paleontology, Nanjing 210008, China.
    Xu, Daoyi
    Institute of Geology, China Earthquake Administration, Beijing 100029, China.
    Wang, Yaqiang
    State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Paleontology, Nanjing 210008, China.
    Zhang, Xiaolin
    Chinese Academy of Sciences Key Laboratory of Crust-Mantle Materials and Environments, School of Earth and Space Sciences, University of Science and Technology of China, Heifei 230026, China.
    Yao, Xiaogang
    State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Paleontology, Nanjing 210008, China.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    Triassic–Jurassic climate in continental high-latitude Asia was dominated by obliquity-paced variations (Junggar Basin, Ürümqi, China)2015In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 112, no 12, p. 3624-3629Article in journal (Refereed)
    Abstract [en]

    Empirical constraints on orbital gravitational solutions for the Solar System can be derived from the Earth’s geological record of past climates. Lithologically based paleoclimate data from the thick, coal-bearing, fluvial-lacustrine sequences of the Junggar Basin of Northwestern China (paleolatitude ∼60°) show that climate variability of the warm and glacier-free high latitudes of the latest Triassic–Early Jurassic (∼198–202 Ma) Pangea was strongly paced by obliquity-dominated (∼40 ky) orbital cyclicity, based on an age model using the 405-ky cycle of eccentricity. In contrast, coeval low-latitude continental climate was much more strongly paced by climatic precession, with virtually no hint of obliquity. Although this previously unknown obliquity dominance at high latitude is not necessarily unexpected in a high CO2 world, these data deviate substantially from published orbital solutions in period and amplitude for eccentricity cycles greater than 405 ky, consistent with chaotic diffusion of the Solar System. In contrast, there are indications that the Earth–Mars orbital resonance was in today’s 2-to-1 ratio of eccentricity to inclination. These empirical data underscore the need for temporally comprehensive, highly reliable data, as well as new gravitational solutions fitting those data.

  • 31.
    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.

  • 32.
    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.

  • 33.
    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.

  • 34.
    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.

  • 35.
    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.

  • 36.
    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.

  • 37.
    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.

  • 38. 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.

  • 39.
    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. 

  • 40.
    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. 

  • 41.
    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.

  • 42.
    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.

  • 43.
    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.

  • 44.
    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.

  • 45.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology.
    Stevns Klint2014In: Geologiskt forum, Vol. 21, no 83, p. 14-19Article in journal (Other (popular science, discussion, etc.))
  • 46.
    Vajda, Vivi
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Bercovici, Antoine
    Cui, Ying
    Yu, Jianxin
    Forel, Marie-Béatrice
    Terrestrial paleoenvironment characterization across the Permian–Triassic boundary in South China2015In: Journal of Asian Earth Sciences, ISSN 1367-9120, E-ISSN 1878-5786, Vol. 98, p. 225-246Article in journal (Refereed)
    Abstract [en]

    Well-preserved marine fossils in carbonate rocks permit detailed studies of the end-Permian extinction event in the marine realm. However, the rarity of fossils in terrestrial depositional environments makes it more challenging to attain a satisfactory degree of resolution to describe the biotic turnover on land. Here we present new sedimentological, paleontological and geochemical (X-ray fluorescence) analysis from the study of four terrestrial sections (Chahe, Zhejue, Mide and Jiucaichong) in Western Guizhou and Eastern Yunnan (Yangtze Platform, South China) to evaluate paleoenvironmental changes through the Permian–Triassic transition.

    Our results show major differences in the depositional environments between the Permian Xuanwei and the Triassic Kayitou formations with a change from fluvial–lacustrine to coastal marine settings. This change is associated with a drastic modification of the preservation mode of the fossil plants, from large compressions to small comminuted debris. Plant fossils spanning the Permian–Triassic boundary show the existence of two distinct assemblages: In the Xuanwei Formation, a Late Permian (Changhsingian) assemblage with characteristic Cathaysian wetland plants (mainly Gigantopteris dictyophylloides, Gigantonoclea guizhouensis, G. nicotianaefolia, G. plumosa, G. hallei, Lobatannularia heinanensis, L. cathaysiana, L. multifolia, Annularia pingloensis, A. shirakii, Paracalamites stenocostatus, Cordaites sp.) is identified. In the lowermost Kayitou Formation, an Early Triassic (Induan) Annalepis–Peltaspermum assemblage is shown, associated with very rare, relictual gigantopterids. Palynological samples are poor, and low yield samples show assemblages almost exclusively represented by spores. A ∼1 m thick zone enriched in putative fungal spores was identified near the top of the Xuanwei Formation, including diverse multicellular forms, such as Reduviasporonites sp. This interval likely corresponds to the PTB “fungal spike” conventionally associated with land denudation and ecosystem collapse. While the floral turnover is evident, further studies based on plant diversity would be required in order to assess contribution linked to the end-Permian mass extinction versus local paleoenvironmental changes associated with the transition between the Xuanwei and Kayitou formations.

  • 47.
    Vajda, Vivi
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Calner, Mikael
    Ahlberg, Anders
    Palynostratigraphy of dinosaur footprint-bearing deposits from theTriassic–Jurassic boundary interval of Sweden2013In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 135, p. 120-130Article in journal (Refereed)
    Abstract [en]

    The Triassic–Jurassic boundary (c. 200 Ma) marks one of the five largest Phanerozoic mass extinction events and is characterized by a major turnover in biotas. A palynological study of sedimentary rock slabs bearing dinosaur footprints from Rhaeto–Hettangian strata of Skåne, Sweden was carried out. The theropod dinosaur footprints (Kayentapus soltykovensis) derive from the southern part of the abandoned Vallåkra quarry (Höganäs Formation) and were originally dated as earliest Jurassic (Hettangian) based on lithostratigraphy. Our results reveal that two of the footprints are correlative with the latest Triassic (latest Rhaetian) disaster zone typified by a high abundance of the enigmatic gymnosperm pollen Ricciisporites tuberculatus and Perinopollenites elatoides together with the key taxon Limbosporites lundbladii and fern spores. Two footprints are dated to correlate with the Transitional Spore-spike Interval. One footprint is interpreted as Hettangian in age based on the relatively high abundance of Pinuspollenites spp. together with the presence of the key taxa Retitriletes semimuris and Zebrasporites intercriptus. Our new palynological study suggests that the Kayentapus ichnogenus already appeared in the end of Triassic, and our study highlights the use of palynology as a powerful tool to date historical collections of fossils in museums, universities and elsewhere. The Hettangian footprint reflects a marine influence while all other studied ichnofossil specimens occur in non-marine (floodplain and delta interdistributary) sediments. The sediments associated with the Hettangian footprint include a significant proportion of charcoal transported from land after wildfires. The Rhaeto–Hettangian vegetation was otherwise characterized by multi-storey gymnosperm–pteridophyte communities.

  • 48.
    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.

  • 49.
    Vajda, Vivi
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Lyson, Tyler R.
    Bercovici, Antoine
    Doman, Jessamy H.
    Pearson, Dean
    A snapshot into the terrestrial ecosystem of an exceptionally well preserved dinosaur (Hadrosauridae) from the Upper Cretaceous of North Dakota, USA2013In: Cretaceous research (Print), ISSN 0195-6671, E-ISSN 1095-998X, Vol. 46, p. 114-122Article in journal (Refereed)
    Abstract [en]

    A palynological investigation of sedimentary rocks enclosing an exceptionally well-preserved fossil dinosaur (Hadrosauridae) discovered in the upper part of the Hell Creek Formation in south western North Dakota was conducted in order to document the immediate paleoenvironment of this dinosaur. The specimen, an Edmontosaurus annectens is remarkable in having exceptional three-dimensional preservation of soft tissue around the skeleton, indicating rapid burial. A well-preserved palynological assemblage dominated by fern and bryophyte spores, with lesser gymnosperm and angiosperm pollen was recovered. Sparse fresh-water algae and marine dinoflagellate cysts were also recorded. The palynofacies is dominated by wood fragments, including charcoal, with little amorphous organic matter. The presence of some typical pollen taxa of the Wodehouseia spinata Assemblage Zone including Striatellipollis striatellus, Tricolpites microreticulatus, Leptopecopites pocockii as well as a diverse suite of Aquilapollenites, is fully consistent with a Late Cretaceous (late Maastrichtian) age. The palynoflora indicates a local vegetation composed of a canopy of conifers dominated by Pinaceae and a minor sub-canopy of Taxodium and cycads, as well as an understory of hydrophilous ferns, mosses and herbaceous angiosperms, indicative of a warm and humid climate e an environment where this specific hadrosaur roamed over 66 million years ago.

  • 50.
    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.

12 1 - 50 of 55
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf