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  • 1. El Albani, Abder
    et al.
    Mangano, M. Gabriela
    Buatois, Luis A.
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Riboulleau, Armelle
    Bekker, Andrey
    Konhauser, Kurt
    Lyons, Timothy
    Rollion-Bard, Claire
    Bankole, Olabode
    Lekele Baghekema, Stellina Gwenaelle
    Meunier, Alain
    Trentesaux, Alain
    Mazurier, Arnaud
    Aubineau, Jeremie
    Laforest, Claude
    Fontaine, Claude
    Recourt, Philippe
    Chi Fru, Ernest
    Machiarelli, Roberto
    Reynaud, Jean Yves
    Gauthier-Lafaye, François
    Canfield, Donald E.
    Organism motility in an oxygenated shallow-marine environment 2.1 billion years ago2019Ingår i: Proceedings of the National Academy of Sciences, ISSN 1091-6490, Vol. 116, nr 9, s. 3431-3436Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The 2.1 billion-year-old sedimentary strata contain exquisitely preserved fossils that provide an ecologic snapshot of the biota inhabiting an oxygenated shallow-marine environment. Most striking are the pyritized string-shaped structures, which suggest that the producer have been a multicellular or syncytial organism able to migrate laterally and vertically to reach for food resources. A modern analogue is the aggregation of amoeboid cells into a migratory slug phase in modern cellular slime molds during time of food starvation. While it remains uncertain whether the amoeboidlike organisms represent a failed experiment or a prelude to subsequent evolutionary innovations, they add to the growing record of comparatively complex life forms that existed more than a billion years before animals emerged in the late Neoproterozoic.Evidence for macroscopic life in the Paleoproterozoic Era comes from 1.8 billion-year-old (Ga) compression fossils [Han TM, Runnegar B (1992) Science 257:232–235; Knoll et al. (2006) Philos Trans R Soc Lond B 361:1023–1038], Stirling biota [Bengtson S et al. (2007) Paleobiology 33:351–381], and large colonial organisms exhibiting signs of coordinated growth from the 2.1-Ga Francevillian series, Gabon. Here we report on pyritized string-shaped structures from the Francevillian Basin. Combined microscopic, microtomographic, geochemical, and sedimentologic analyses provide evidence for biogenicity, and syngenicity and suggest that the structures underwent fossilization during early diagenesis close to the sediment–water interface. The string-shaped structures are up to 6 mm across and extend up to 170 mm through the strata. Morphological and 3D tomographic reconstructions suggest that the producer may have been a multicellular or syncytial organism able to migrate laterally and vertically to reach food resources. A possible modern analog is the aggregation of amoeboid cells into a migratory slug phase in cellular slime molds at times of starvation. This unique ecologic window established in an oxygenated, shallow-marine environment represents an exceptional record of the biosphere following the crucial changes that occurred in the atmosphere and ocean in the aftermath of the great oxidation event (GOE).

  • 2.
    Sallstedt, Therese
    et al.
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Broman, Curt
    Stockholm University.
    Crill, Patrick M.
    Stockholm University.
    Canfield, Donald E.
    University of Southern Denmark.
    Evidence of oxygenic phototrophy in ancient phosphatic stromatolites from the Paleoproterozoic Vindhyan and Aravalli Supergroups, India.2018Ingår i: Geobiology, ISSN 1472-4677, E-ISSN 1472-4669, Vol. 16, s. 139-159Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fossil microbiotas are rare in the early rock record, limiting the type of ecological information extractable from ancient microbialites. In the absence of body fossils, emphasis may instead be given to microbially derived features, such as microbialite growth patterns, microbial mat morphologies, and the presence of fossilized gas bubbles in lithified mats. The metabolic affinity of micro-organisms associated with phosphatization may reveal important clues to the nature and accretion of apatite-rich microbialites. Stromatolites from the 1.6 Ga Chitrakoot Formation (Semri Group, Vindhyan Supergroup) in central India contain abundant fossilized bubbles interspersed within fine-grained in situ-precipitated apatite mats with average δ13Corg indicative of carbon fixation by the Calvin cycle. In addition, the mats hold a synsedimentary fossil biota characteristic of cyanobacterial and rhodophyte morphotypes. Phosphatic oncoid cone-like stromatolites from the Paleoproterozoic Aravalli Supergroup (Jhamarkotra Formation) comprise abundant mineralized bubbles enmeshed within tufted filamentous mat fabrics. Construction of these tufts is considered to be the result of filamentous bacteria gliding within microbial mats, and as fossilized bubbles within pristine mat laminae can be used as a proxy for oxygenic phototrophy, this provides a strong indication for cyanobacterial activity in the Aravalli mounds. We suggest that the activity of oxygenic phototrophs may have been significant for the formation of apatite in both Vindhyan and Aravalli stromatolites, mainly by concentrating phosphate and creating steep diurnal redox gradients within mat pore spaces, promoting apatite precipitation. The presence in the Indian stromatolites of alternating apatite-carbonate lamina may result from local variations in pH and oxygen levels caused by photosynthesis–respiration in the mats. Altogether, this study presents new insights into the ecology of ancient phosphatic stromatolites and warrants further exploration into the role of oxygen-producing biotas in the formation of Paleoproterozoic shallow-basin phosphorites.

  • 3.
    Ivarsson, Magnus
    et al.
    Naturhistoriska riksmuseet, Enheten för paleobiologi. University of Southern Denmark, Department of Biology and Nordic Center for Earth Evolution, Campusvej 55, Odense M, DK-5230, Denmark.
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Drake, Henrik
    Linnaeus University, Kalmar.
    Francis, Warren
    University of Southern Denmark.
    Fungi in deep subsurface environments2018Ingår i: Advances in Applied Microbiology, ISSN 0065-2164, Vol. 102, s. 83-116Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The igneous crust of the oceans and the continents represents the major part of Earth's lithosphere and has recently been recognized as a substantial, yet underexplored, microbial habitat. While prokaryotes have been the focus of most investigations, microeukaryotes have been surprisingly neglected. However, recent work acknowledges eukaryotes, and in particular fungi, as common inhabitants of the deep biosphere, including the deep igneous provinces. The fossil record of the subseafloor igneous crust, and to some extent the continental bedrock, establishes fungi or fungus-like organisms as inhabitants of deep rock since at least the Paleoproterozoic, which challenges the present notion of early fungal evolution. Additionally, deep fungi have been shown to play an important ecological role engaging in symbiosis-like relationships with prokaryotes, decomposing organic matter, and being responsible for mineral weathering and formation, thus mediating mobilization of biogeochemically important elements. In this review, we aim at covering the abundance and diversity of fungi in the various igneous rock provinces on Earth as well as describing the ecological impact of deep fungi. We further discuss what consequences recent findings might have for the understanding of the fungal distribution in extensive anoxic environments and for early fungal evolution.

  • 4.
    Ivarsson, Magnus
    et al.
    Naturhistoriska riksmuseet, Enheten för paleobiologi. University of Southern Denmark, Department of Biology and Nordic Center for Earth Evolution, Campusvej 55, Odense M, DK-5230, Denmark.
    Skogby, Henrik
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Phichaikamjornwut, Bongkot
    Gems and Jewelry Program, Faculty of Science, Srinakharinwirot University, Bangkok, Thailand .
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Siljeström, Sandra
    RISE Research Institutes of Sweden, Bioscience and Materials/Chemistry and Materials, Stockholm, Sweden.
    Ounchanum, Prayote
    Department of Geological Sciences, Faculty of Science, Chiang Mai University, Chiang Mai, Thailand.
    Boonsong, Apichet
    Department of Geological Sciences, Faculty of Science, Chiang Mai University, Chiang Mai, Thailand.
    Kruachanta, M
    Department of Geological Sciences, Faculty of Science, Chiang Mai University, Chiang Mai, Thailand .
    Marone, Federica
    Swiss Light Source, Paul Scherrer Institute, Villigen, Switzerland.
    Belivanova, Veneta
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Sara, Holmström
    Stockholm University, Department of Geological Sciences, Stockholm, Sweden.
    Intricate tunnels in garnets from soils and rivere sediments in Thailand - possible endolithic microborings2018Ingår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 13, nr 8, artikel-id e0200351Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Garnets from disparate geographical environments and origins such as oxidized soils and river sediments in Thailand host intricate systems of microsized tunnels that significantly decrease the quality and value of the garnets as gems. The origin of such tunneling has previously been attributed to abiotic processes. Here we present physical and chemical remains of endolithic microorganisms within the tunnels and discuss a probable biological origin of the tunnels. Extensive investigations with synchrotron-radiation X-ray tomographic microscopy (SRXTM) reveal morphological indications of biogenicity that further support a euendolithic interpretation. We suggest that the production of the tunnels was initiated by a combination of abiotic and biological processes, and that at later stages biological processes came to dominate. In environments such as river sediments and oxidized soils garnets are among the few remaining sources of bio-available Fe2+, thus it is likely that microbially mediated boring of the garnets has trophic reasons. Whatever the reason for garnet boring, the tunnel system represents a new endolithic habitat in a hard silicate mineral otherwise known to be resistant to abrasion and chemical attack.

  • 5. DOGUZHAEVA, Larisa
    et al.
    BENGTSON, Stefan
    REGUERO, Marcelo
    Mörs, Thomas
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    An Eocene orthocone from Antarctica shows convergent evolution of internally shelled cephalopods2017Ingår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 12, nr 3, artikel-id e0172169Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background

    The Subclass Coleoidea (Class Cephalopoda) accommodates the diverse present-day internally shelled cephalopod mollusks (Spirula, Sepia and octopuses, squids, Vampyroteuthis) and also extinct internally shelled cephalopods. Recent Spirula represents a unique coleoid retaining shell structures, a narrow marginal siphuncle and globular protoconch that signify the ancestry of the subclass Coleoidea from the Paleozoic subclass Bactritoidea. This hypothesis has been recently supported by newly recorded diverse bactritoid-like coleoids from the Carboniferous of the USA, but prior to this study no fossil cephalopod indicative of an endochochleate branch with an origin independent from subclass Bactritoidea has been reported.

    Methodology/Principal findings

    Two orthoconic conchs were recovered from the Early Eocene of Seymour Island at the tip of the Antarctic Peninsula, Antarctica. They have loosely mineralized organic-rich chitin-compatible microlaminated shell walls and broadly expanded central siphuncles. The morphological, ultrustructural and chemical data were determined and characterized through comparisons with extant and extinct taxa using Scanning Electron Microscopy/Energy Dispersive Spectrometry (SEM/EDS).

    Conclusions/Significance

    Our study presents the first evidence for an evolutionary lineage of internally shelled cephalopods with independent origin from Bactritoidea/Coleoidea, indicating convergent evolution with the subclass Coleoidea. A new subclass Paracoleoidea Doguzhaeva n. subcl. is established for accommodation of orthoconic cephalopods with the internal shell associated with a broadly expanded central siphuncle. Antarcticerida Doguzhaeva n. ord., Antarcticeratidae Doguzhaeva n. fam., Antarcticeras nordenskjoeldi Doguzhaeva n. gen., n. sp. are described within the subclass Paracoleoidea. The analysis of organic-rich shell preservation of A. nordenskjoeldi by use of SEM/EDS techniques revealed fossilization of hyposeptal cameral soft tissues. This suggests that a depositional environment favoring soft-tissue preservation was the factor enabling conservation of the weakly mineralized shell of A. nordenskjoeldi.

  • 6. Drake, Henrik
    et al.
    Ivarsson, Magnus
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Heim, Christine
    Siljeström, Sandra
    Whitehouse, Martin
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Broman, Curt
    Belivanova, Veneta
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Åström, Mats E.
    Anaerobic consortia of fungi and sulfate reducing bacteria in deep granite fractures2017Ingår i: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 8, nr 55, s. 1-9Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The deep biosphere is one of the least understood ecosystems on Earth. Although most microbiological studies in this system have focused on prokaryotes and neglected microeukaryotes, recent discoveries have revealed existence of fossil and active fungi in marine sediments and sub-seafloor basalts, with proposed importance for the subsurface energy cycle. However, studies of fungi in deep continental crystalline rocks are surprisingly few. Consequently, the characteristics and processes of fungi and fungus-prokaryote interactions in this vast environment remain enigmatic. Here we report the first findings of partly organically preserved and partly mineralized fungi at great depth in fractured crystalline rock (-740 m). Based on environmental parameters and mineralogy the fungi are interpreted as anaerobic. Synchrotron-based techniques and stable isotope microanalysis confirm a coupling between the fungi and sulfate reducing bacteria. The cryptoendolithic fungi have significantly weathered neighboring zeolite crystals and thus have implications for storage of toxic wastes using zeolite barriers.

  • 7.
    Bengtson, Stefan
    et al.
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Rasmussen, Birger
    Curtin University.
    Ivarsson, Magnus
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Muhling, Janet
    Curtin University.
    Broman, Curt
    Stockholm University.
    Marone, Federica
    Stampanoni, Marco
    Bekker, Andrey
    University of California Riverside.
    Fungus-like mycelial fossils in 2.4-billion-year-old vesicular basalt.2017Ingår i: Nature Ecology & Evolution, ISSN 2397-334X, Vol. 1, nr 6, s. 1-6, artikel-id 0141Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fungi have recently been found to comprise a significant part of the deep biosphere in oceanic sediments and crustal rocks. Fossils occupying fractures and pores in Phanerozoic volcanics indicate that this habitat is at least 400 million years old, but its origin may be considerably older. A 2.4-billion-year-old basalt from the Palaeoproterozoic Ongeluk Formation in South Africa contains filamentous fossils in vesicles and fractures. The filaments form mycelium-like structures growing from a basal film attached to the internal rock surfaces. Filaments branch and anastomose, touch and entangle each other. They are indistinguishable from mycelial fossils found in similar deep-biosphere habitats in the Phanerozoic, where they are attributed to fungi on the basis of chemical and morphological similarities to living fungi. The Ongeluk fossils, however, are two to three times older than current age estimates of the fungal clade. Unless they represent an unknown branch of fungus-like organisms, the fossils imply that the fungal clade is considerably older than previously thought, and that fungal origin and early evolution may lie in the oceanic deep biosphere rather than on land. The Ongeluk discovery suggests that life has inhabited submarine volcanics for more than 2.4 billion years.

  • 8. Yin, Zongjun
    et al.
    Cunningham, John A.
    Vargas, Kelly
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Zhu, Maoyan
    Donoghue, Philip C.J.
    University of Bristol.
    Nuclei and nucleoli in embryo-like fossils from the Ediacaran Weng’an Biota.2017Ingår i: Precambrian Research, ISSN 0301-9268, E-ISSN 1872-7433, Vol. 301, s. 145-151Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The embryo-like microfossils from the Ediacaran Weng’an Biota (ca. 609 million years old) are among the oldest plausible claims of animals in the fossil record. Fossilization frequently extends beyond the cellular, to preserve subcellular structures including contentious Large Intracellular Structures (LISs) that have been alternately interpreted as eukaryote nuclei or organelles, degraded remains, or abiological structures. Here we present new data on the structure, morphology, and development of the LISs in these embryo-like fossils, based on Synchrotron Radiation X-ray Tomographic Microscopy (SRXTM) and quantitative computed tomographic analysis. All the lines of evidence, including consistency in the number, shape, position, and relative size (LIS-to-cytoplasm ratio) of the LISs, as well as their occurrence within preserved cytoplasm, support their interpretation as cell nuclei. Our results allow us to reject the view that nuclei cannot be preserved in early eukaryote fossils, offering new potential for interpreting the fossil record of early eukaryote evolution.

  • 9.
    Ivarsson, Magnus
    et al.
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Oceanbottnarnas hemliga liv.2017Ingår i: Havsutsikt, ISSN 1104-0513, Vol. 2017, nr 2, s. 16-18Artikel i tidskrift (Övrig (populärvetenskap, debatt, mm))
    Abstract [sv]

    Berggrunden under havens bottensediment är en vidsträckt men svårtillgänglig och outforskad del av vår planet, särskilt när det gäller liv. Paradoxalt nog är det, förutom haven, världens volymmässigt största livsmiljö för mikroorganismer. Med nya metoder har forskare från Naturhistoriska riksmuseet vänt upp och ner på den gängse vetenskapliga uppfattningen. I den spruckna berggrunden under havssedimenten bor inte bara de förväntade extremt tåliga bakterierna och arkéerna – de har även gott sällskap av svampar.

  • 10. Davies, Thomas G.
    et al.
    Rahman, Imran A.
    Lautenschlager, Stephan
    Cunningham, John A.
    Naturhistoriska riksmuseet, Enheten för paleobiologi. University of Bristol.
    Asher, Robert J.
    Barrett, Paul M.
    Bates, Karl T.
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Benson, Roger B. J.
    Boyer, Doug M.
    Braga, José
    Bright, Jen A.
    Claessens, Leon P. A. M.
    Cox, Philip G.
    Dong, Xi-Ping
    Evans, Alistair R.
    Falkingham, Peter L.
    Friedman, Matt
    Garwood, Russell J.
    Goswami, Anjali
    Hutchinson, John R.
    Jeffery, Nathan S.
    Johanson, Zerina
    Lebrun, Renaud
    Martínez-Pérez, Carlos
    Marugán-Lobón, Jesús
    O’Higgins, Paul M.
    Metscher, Brian
    Orliac, Maeva
    Rowe, Timothy B.
    Rücklin, Martin
    Sánchez-Villagra, Marcelo R.
    Shubin, Neil H.
    Smith, Selena Y.
    Starck, J. Matthias
    Stringer, Chris
    Summers, Adam P.
    Sutton, Mark D.
    Walsh, Stig A.
    Weisbecker, Vera
    Witmer, Lawrence M.
    Wroe, Stephen
    Yin, Zongjun
    Rayfield, Emily J.
    Donoghue, Philip C.J.
    University of Bristol.
    Open data and digital morphology.2017Ingår i: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 284, nr 1852, s. 1-10Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Over the past two decades, the development of methods for visualizing and analysing specimens digitally, in three and even four dimensions, has transformed the study of living and fossil organisms. However, the initial promise that the widespread application of such methods would facilitate access to the underlying digital data has not been fully achieved. The underlying datasets for many published studies are not readily or freely available, introducing a barrier to verification and reproducibility, and the reuse of data. There is no current agreement or policy on the amount and type of data that should be made available alongside studies that use, and in some cases are wholly reliant on, digital morphology. Here, we propose a set of recommendations for minimum standards and additional best practice for three-dimensional digital data publication, and review the issues around data storage, management and accessibility.

  • 11.
    Kouchinsky, Artem
    et al.
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Landing, Ed
    New York State Museum.
    Steiner, Michael
    Freie Universität Berlin.
    Vendrasco, Michael
    Pasadena City College.
    Ziegler, Karen
    University of New Mexico.
    Terreneuvian stratigraphy and faunas from the Anabar Uplift, Siberia.2017Ingår i: Acta Palaeontologica Polonica, ISSN 0567-7920, E-ISSN 1732-2421, Vol. 62, nr 2, s. 311-440Artikel i tidskrift (Refereegranskat)
  • 12.
    Cunningham, John A.
    et al.
    Naturhistoriska riksmuseet, Enheten för paleobiologi. University of Bristol.
    Vargas, Kelly
    School of Earth Sciences, University of Bristol, Bristol.
    Yin, Zongjun
    State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing.
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Donoghue, Philip C.J.
    University of Bristol.
    The Weng’an Biota (Doushantuo Formation): an Ediacaran window on soft bodied and multicellular microorganisms.2017Ingår i: journal of the geological society, ISSN 2041-479X, Vol. 174, nr 5, s. 793-802Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Weng’an Biota is a fossil Konservat-Lagerstätte in South China that is approximately 570-600 million years old and provides an unparalleled snapshot of marine life during the interval in which molecular clocks estimate that animal clades were diversifying. It yields specimens that are three-dimensionally preserved in calcium phosphate with cellular and sometimes subcellular fidelity. The biota includes candidates for the oldest animals in the fossil record, including embryonic, larval and adult forms. We argue that, while the Weng’an Biota includes forms that could be animals, none can currently be assigned to this group with confidence. Nonetheless, the biota offers a rare and valuable window on the evolution of multicellular and soft-bodied organisms in the prelude to the Cambrian radiation.

  • 13.
    Bengtson, Stefan
    et al.
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Sallstedt, Therese
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Belivanova, Veneta
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Whitehouse, Martin
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Three-dimensional preservation of cellular and subcellular structures suggests 1.6 billion-year-old crown-group red algae2017Ingår i: PLoS biology, ISSN 1544-9173, E-ISSN 1545-7885, Vol. 15, nr 3, s. 1-38, artikel-id e2000735Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The ~1.6 Ga Tirohan Dolomite of the Lower Vindhyan in central India contains phosphatized stromatolitic microbialites. We report from there uniquely well-preserved fossils interpreted as probable crown-group rhodophytes (red algae). The filamentous form Rafatazmia chitrakootensis n. gen, n. sp. has uniserial rows of large cells and grows through diffusely distributed septation. Each cell has a centrally suspended, conspicuous rhomboidal disk interpreted as a pyrenoid. The septa between the cells have central structures that may represent pit connections and pit plugs. Another filamentous form, Denaricion mendax n. gen., n. sp., has coin-like cells reminiscent of those in large sulfur-oxidizing bacteria but much more recalcitrant than the liquid-vacuole-filled cells of the latter. There are also resemblances with oscillatoriacean cyanobacteria, although cell volumes in the latter are much smaller. The wider affinities of Denaricion are uncertain. Ramathallus lobatus n. gen., n. sp. is a lobate sessile alga with pseudoparenchymatous thallus, “cell fountains,” and apical growth, suggesting florideophycean affinity. If these inferences are correct, Rafatazmia and Ramathallus represent crown-group multicellular rhodophytes, antedating the oldest previously accepted red alga in the fossil record by about 400 million years.

  • 14.
    Ivarsson, Magnus
    et al.
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Carlsson, Diana
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Är magmatiska bergarterfossilförande?2017Ingår i: Geologiskt Forum, ISSN ISSN 1104-4721, nr 94, s. 20-23Artikel, forskningsöversikt (Övrig (populärvetenskap, debatt, mm))
    Abstract [sv]

    Förekomsten av fossil är lika starkt sammankopplad till sedimentära bergarter som magmatiska bergarter är till frånvaron av fossil. Detta har varit ett obestridbart faktum sedan geovetenskapernas gryning. Men nu börjar detta synsätt att ändra sig. Forskare vid Naturhistoriska riksmuseet utforskar ett fossilt arkiv som påträffas i sprickor och håligheter i magmatiska och vulkaniska bergarter. Detta kan spela stor roll framöver för studiet av djupbiosfären och det tidiga livet på jorden samt även för sökandet efter liv på Mars.

  • 15.
    Ivarsson, Magnus
    et al.
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Schnürer, Anna
    Swedish University of Agricultural Sciences.
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Neubeck, Anna
    Naturhistoriska riksmuseet, Enheten för paleobiologi. Stockholm University.
    Anaerobic fungi: a potential source of biological H2 in the oceanic crust.2016Ingår i: Frontiers in Microbiology, ISSN 1664-302X, E-ISSN 1664-302X, Vol. 7, nr 674, s. 1-8Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The recent recognition of fungi in the oceanic igneous crust challenges the understanding of this environment as being exclusively prokaryotic and forces reconsiderations of the ecology of the deep biosphere. Anoxic provinces in the igneous crust are abundant and increase with age and depth of the crust. The presence of anaerobic fungi in deep-sea sediments and on the seafloor introduces a type of organism with attributes of geobiological significance not previously accounted for. Anaerobic fungi are best known from the rumen of herbivores where they produce molecular hydrogen, which in turn stimulates the growth of methanogens. The symbiotic cooperation between anaerobic fungi and methanogens in the rumen enhance the metabolic rate and growth of both. Methanogens and other hydrogen-consuming anaerobic archaea are known from subseafloor basalt; however, the abiotic production of hydrogen is questioned to be sufficient to support such communities. Alternatively, biologically produced hydrogen could serve as a continuous source. Here, we propose anaerobic fungi as a source of bioavailable hydrogen in the oceanic crust, and a close interplay between anaerobic fungi and hydrogen-driven prokaryotes.

  • 16.
    Dong, Xi-ping
    et al.
    Peking University.
    Vargas, Kelly
    University of Bristol.
    Cunningham, John
    Naturhistoriska riksmuseet, Enheten för paleobiologi. University of Bristol.
    Zhang, Huaqiao
    Nanjing Institute of Geology and Palaeontology.
    Liu, Teng
    Peking University.
    Chen, Fang
    Peking University.
    Liu, Jianbo
    Peking University.
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Donoghue, Philip C.J.
    Developmental biology of the early Cambrian cnidarian Olivooides.2016Ingår i: Palaeontology, ISSN 0031-0239, E-ISSN 1475-4983, Vol. 59, nr 3, s. 387-407Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fossilized embryos afford direct insight into the pattern of development in extinct organisms, providing unique tests of hypotheses of developmental evolution based in comparative embryology. However, these fossils can only be effective in this role if their embryology and phylogenetic affinities are well constrained. We elucidate and interpret the development of Olivooides from embryonic and adult stages and use these data to discriminate among competing interpretations of their anatomy and affinity. The embryology of Olivooides is principally characterized by the development of an ornamented periderm that initially forms externally and is subsequently formed internally, released at the aperture, facilitating the direct development of the embryo into an adult theca. Internal anatomy is known only from embryonic stages, revealing two internal tissue layers, the innermost of which is developed into three transversally arranged walls that partly divide the lumen into an abapertural region, interpreted as the gut of a polyp, and an adapertural region that includes structures that resemble the peridermal teeth of coronate scyphozoans. The anatomy and pattern of development exhibited by Olivooides appears common to the other known genus of olivooid, Quadrapyrgites, which differs in its tetraradial, as opposed to pentaradial symmetry. We reject previous interpretations of the olivooids as cycloneuralians, principally on the grounds that they lack a through gut and introvert, in embryo and adult. Instead we consider the affinities of the olivooids among medusozoan cnidarians; our phylogenetic analysis supports their classification as totalgroup Coronata, within crown-Scyphozoa. Olivooides and Quadrapyrgites evidence a broader range of life history strategies and bodyplan symmetry than is otherwise commonly represented in extant Scyphozoa specifically, and Cnidaria more generally.

  • 17.
    Ivarsson, Magnus
    et al.
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Neubeck, Anna
    Naturhistoriska riksmuseet, Enheten för paleobiologi. Stockholm University.
    The igneous oceanic crust – Earth’s largest fungal habitat?2016Ingår i: Fungal ecology, ISSN 1754-5048, E-ISSN 1878-0083, Vol. 20, s. 249-255Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In recent years the igneous oceanic crust has been recognized as a substantial microbial habitat and a scientific frontier within Geology, Biology, and Oceanography. A few successful metagenomic investigations have indicated the presence of Archaea and Bacteria, but also fungi in the subseafloor igneous crust. A comprehensive fossil record supports the presence of fungi in these deep environments and provides means of investigating the fungal presence that complements metagenomic methods. Considering the vast volume of the oceanic crust and that it is the largest aquifer on Earth, we put forward that it is the largest fungal habitat on the planet. This review aims to introduce a yet unexplored fungal habitat in an environment considered extreme from a biological perspective. We present the current knowledge of fungal abundance and diversity and discuss the ecological role of fungi in the igneous oceanic crust.

  • 18.
    Cunningham, John A.
    et al.
    Naturhistoriska riksmuseet, Enheten för paleobiologi. University of Bristol.
    Liu, Alexander G.
    University of Cambridge.
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Donoghue, Philip C.J.
    University of Bristol.
    The origin of animals: Can molecular clocks and the fossil record be reconciled?2016Ingår i: Bioessays, ISSN 0265-9247, E-ISSN 1521-1878, Vol. 38, s. 1-12Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The evolutionary emergence of animals is one of the most significant episodes in the history of life, but its timing remains poorly constrained. Molecular clocks estimate that animals originated and began diversifying over 100 million years before the first definitive metazoan fossil evidence in the Cambrian. However, closer inspection reveals that clock estimates and the fossil record are less divergent than is often claimed. Modern clock analyses do not predict the presence of the crown-representatives of most animal phyla in the Neoproterozoic. Furthermore, despite challenges provided by incomplete preservation, a paucity of phylogenetically informative characters, and uncertain expectations of the anatomy of early animals, a number of Neoproterozoic fossils can reasonably be interpreted as metazoans. A considerable discrepancy remains, but much of this can be explained by the limited preservation potential of early metazoans and the difficulties associated with their identificationin the fossil record. Critical assessment of both recordsmay permitbetter resolutionof the tempo and mode of early animal evolution.

  • 19.
    Ivarsson, Magnus
    et al.
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Bengtson, Stefan
    Skogby, Henrik
    Lazor, Peter
    Broman, Curt
    Belivanova, Veneta
    Marone, Federica
    A fungal-prokaryotic consortium at the basalt-zeolite interface in subseafloor igneous crust2015Ingår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203Artikel i tidskrift (Refereegranskat)
  • 20.
    Kouchinsky, Artem
    et al.
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Clausen, Sébastien
    Université de Lille.
    Vendrasco, Michael J.
    California State University, Fullerton, CA.
    An early Cambrian fauna of skeletal fossils from the Emyaksin Formation, northern Siberia.2015Ingår i: Acta Palaeontologica Polonica, ISSN 0567-7920, E-ISSN 1732-2421, Vol. 60, nr 2, s. 421-512Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An assemblage of mineralised skeletal fossils containing molluscs, hyoliths, halkieriids, chancelloriids, tommotiids, lobopodians, paleoscolecids, bradoriids, echinoderms, anabaritids, hyolithelminths, hexactinnelid, and heteractinid sponges is described from the early Cambrian Emyaksin Formation exposed along the Malaya Kuonamka and Bol’shaya Kuonamka rivers, eastern flanks of the Anabar Uplift, northern Siberian Platform. The sampled succession is attributed to the Tommotian–Botoman Stages of Siberia and correlated with Stage 2 of Series 1–Stage 4 of Series 2 of the IUGS chronostratigraphical scheme for the Cambrian. Carbon isotope chemostratigraphy is applied herein for regional correlation. The fauna contains the earliest Siberian and probably global first appearances of lobopodians, paleoscolecids, and echinoderms, and includes elements in common with coeval faunas from Gondwana, Laurentia, and Baltica. For the first time from Siberia, the latest occurrence of anabaritids is documented herein from the Atdabanian Stage. Problematic calcium phosphatic sclerites of Fengzuella zhejiangensis have not been previously known from outside China. The sellate sclerites, Camenella garbowskae and mitral sclerites, C. kozlowskii are unified within one species, C. garbowskae. In addition to more common slender sclerites, Rhombocorniculum insolutum include broad calcium phosphatic sclerites. A number of fossils described herein demonstrate excellent preservation of fine details of skeletal microstructures. Based on new microstructural data, sclerites of Rhombocorniculum are interpreted as chaetae of the type occurring in annelids. A new mollusc Enigmaconus? pyramidalis Kouchinsky and Vendrasco sp. nov. and a hyolith Triplicatella papilio Kouchinsky sp. nov. are described.

  • 21. Chi Fru, Ernest
    et al.
    Ivarsson, Magnus
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Kilias, Stephanos
    Christoffer, Hemmingson
    Broman, Curt
    Bengtson, Stefan
    C, Chatzitheodoridis
    Biogenicity of an early Quaternary iron formation, Milos Island, Greece2015Ingår i: Geobiology, ISSN 1472-4677, E-ISSN 1472-4669, Vol. 13, s. 225-244Artikel i tidskrift (Refereegranskat)
  • 22.
    Bengtson, Stefan
    et al.
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Collins, Desmond
    Chancelloriids of the Cambrian Burgess Shale2015Ingår i: Palaeontologia Electronica, ISSN 1935-3952, E-ISSN 1094-8074, Vol. 18, nr 1, s. 1-67Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The cactus-like chancelloriids from the Middle Cambrian Burgess Shale are revised on the basis of Walcott’s (1920) original collections and new material containing several hundred specimens collected by Royal Ontario Museum field expeditions from 1975 to 2000. Walcott’s interpretation of chancelloriids as sponges was based on a misinterpretation of the dermal coelosclerites as embedded sponge-type spicules, an interpretation that further led to the lumping of three distinct taxa into one species, Chancelloria eros Walcott, 1920. The other two taxa are herein separated from C. eros and described as Allonnia tintinopsis n.sp. and Archiasterella coriacea n.sp., all belonging to the Family Chancelloriidae Walcott, 1920. Chancelloriids were sedentary animals, anchored to shells or lumps of debris in the muddy bottom, or to sponges, or to other chancelloriids. They had a radially symmetrical body and an apical orifice surrounded by a palisade of modified sclerites. Well-preserved integuments in Al. tintinopsis and Ar. coriacea do not show any ostium-like openings. Neither is there any evidence for internal organs, such as a gut. Partly narrowed specimens suggest that the body periodically contracted from the attached end to expel waste material from the body cavity. Chancelloriids were close in organization to cnidarians but shared the character of coelosclerites with the bilaterian halkieriids and siphogonuchitids. The taxon Coeloscleritophora is most likely paraphyletic.

  • 23.
    Cunningham, John
    et al.
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Vargas, Kelly
    Liu, Pengju
    Belivanova, Veneta
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Marone, Federica
    Martínez-Pérez, Carlos
    Guizar-Sicairos, Manuel
    Holler, Mirko
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Donoghue, Philip C.J.
    Critical appraisal of tubular putative eumetazoans from the Ediacaran Weng’an Doushantuo biota2015Ingår i: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 282, s. 1-9, artikel-id 2151169Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Molecular clock analyses estimate that crown-group animals began diversifying hundreds of millions of years before the start of the Cambrian period. However, the fossil record has not yielded unequivocal evidence for animals during this interval. Some of the most promising candidates for Precambrian animals occur in theWeng’an biota of South China, including a suite of tubular fossils assigned to Sinocyclocyclicus, Ramitubus, Crassitubus and Quadratitubus, that have been interpreted as soft-bodied eumetazoans comparable to tabulate corals. Here, we present new insights into the anatomy, original composition and phylogenetic affinities of these taxa based on data from synchrotron radiation X-ray tomographic microscopy, ptychographic nanotomography, scanning electron microscopy and electron probe microanalysis. The patterns of deformation observed suggest that the cross walls of Sinocyclocyclicus and Quadratitubus were more rigid than those of Ramitubus and Crassitubus. Ramitubus and Crassitubus specimens preserve enigmatic cellular clusters at terminal positions in the tubes. Specimens of Sinocyclocyclicus and Ramitubus have biological features that might be cellular tissue or subcellular structures filling the spaces between the crosswalls. These observations are incompatible with a cnidarian interpretation, in which the spaces between cross walls are abandoned parts of the former living positions of the polyp. The affinity of the Weng’an tubular fossils may lie within the algae.

  • 24. Donoghue, Philip C.J.
    et al.
    Cunningham, John
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Dong, Xi-ping
    Peking University.
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Embryology in deep time.2015Ingår i: Evolutionary Developmental Biology of Invertebrates 1 / [ed] Wanninger, Andreas, Wien: Springer Science+Business Media B.V., 2015, s. 45-63Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    For anyone who has cared for animal embryos, it beggars belief that these squishy cellular aggregates could be fossilised. Hence, with hindsight, it is possible to empathise with palaeontologists who found such fossils and, in their naming of Olivooides, Pseudooides, etc., drew attention to their likeness to animal eggs and embryos but without going so far as to propose such an interpretation. However, in 1994, Zhang Xi-guang and Brian Pratt described microscopic balls of calcium phosphate from Cambrian rocks of China, one or two of which preserved polygonal borders that resembled blastomeres on the surface of an early cleaving animal embryo. In retrospect, these fossils are far from remarkable, some of them may not be fossils at all, and it is not as if anyone ever conceived Cambrian animals as having lacked an embryology. But Zhang Xi-guang and Brian Pratt dared the scientific world, not least their fellow palaeontologists, to believe that the fragile embryonic stages of invertebrate animals could be fossilised, that there was a fossil record of animal embryology, that this record hailed from the interval of time in which animal body plans were first established, and that it had been awaiting discovery in the rocks, for want of looking. The proof of this concept came a few years later, when phosphatised Cambrian fossils from China and Siberia were shown to display indisputable features of animal embryonic morphologies. In the case of Olivooides, a series of developmental stages from cleavage to morphogenesis through hatching and juvenile growth could be tentatively identified; in Markuelia, the coiled-up body of an annulated worm-like animal could be clearly seen within its fertilisation envelope.

  • 25. Neubeck, Anna
    et al.
    Tulej, Marek
    Ivarsson, Magnus
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Broman, Curt
    Riedo, Andreas
    Wurz, Peter
    Bengtson, Stefan
    McMahon, Sean
    Mineralogical determination in situ of a highly heterogenous material using miniaturized laser ablation mass spectrometer with high spatial resolution2015Ingår i: International Journal of Astrobiology, ISSN 1473-5504, E-ISSN 1475-3006Artikel i tidskrift (Refereegranskat)
  • 26.
    Bengtson, Stefan
    et al.
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Ivarsson, Magnus
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Astolfo, Alberto
    Paul Scherrer Institute.
    Belivanova, Veneta
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Broman, Curt
    Stockholm University.
    Marone, Federica
    Paul Scherrer Institute.
    Stampanoni, Marco
    ETH Zürich.
    Deep-biosphere consortium of fungi and prokaryotes in Eocene sub-seafloor basalts.2014Ingår i: Geobiology, ISSN 1472-4677, E-ISSN 1472-4669, Vol. 12, nr 6, s. 489-496Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The deep biosphere of the subseafloor crust is believed to contain a significant part of Earth’s biomass, but because of the difficulties of directly observing the living organisms, its composition and ecology are poorly known. We report here a consortium of fossilized prokaryotic and eukaryotic microorganisms, occupying cavities in deep-drilled vesicular basalt from the Emperor Seamounts, Pacific Ocean, 67.5 meters below seafloor (mbsf). Fungal hyphae provide the framework on which prokaryote-like organisms are suspended like cobwebs and iron-oxidizing bacteria form microstromatolites (Frutexites). The spatial interrelationships show that the organisms were living at the same time in an integrated fashion, suggesting symbiotic interdependence. The community is contemporaneous with secondary mineralizations of calcite partly filling the cavities. The fungal hyphae frequently extend into the calcite, indicating that they were able to bore into the substrate through mineral dissolution. A symbiotic relationship with chemoautotrophs, as inferred for the observed consortium, may be a prerequisite for the eukaryotic colonization of crustal rocks. Fossils thus open a window to the extant as well as the ancient deep biosphere.

  • 27.
    Cunningham, John
    et al.
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Donoghue, Philip C.J.
    University of Bristol.
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Distinguishing biology from geology in soft-tissue preservation.2014Ingår i: Reading and Writing of the Fossil Record: Preservational Pathways to Exceptional Fossilization / [ed] Marc Laflamme, James D. Schiffbauer, Simon A. F. Darroch, The Paleontological Society , 2014, s. 275-287Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    Knowledge of evolutionary history is based extensively on relatively rare fossils that preserve soft tissues. These fossils record a much greater proportion of anatomy than would be known solely from mineralized remains and provide key data for testing evolutionary hypotheses in deep time. Ironically, however, exceptionally preserved fossils are often among the most contentious because they are difficult to interpret. This is because their morphology has invariably been affected by the processes of decay and diagenesis, meaning that it is often difficult to distinguish preserved biology from artifacts introduced by these processes. Here we describe how a range of analytical techniques can be used to tease apart mineralization that preserves biological structures from unrelated geological mineralization phases. This approach involves using a series of X-ray, ion, electron and laser beam techniques to characterize the texture and chemistry of the different phases so that they can be differentiated in material that is difficult to interpret. This approach is demonstrated using a case study of its application to the study of fossils from the Ediacaran Doushantuo Biota.

  • 28.
    Murdock, Duncan J.E.
    et al.
    University of Bristol.
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Marone, Federica
    Paul Scherrer Institute.
    Greenwood, Jenny M.
    Westfälische Wilhelms University.
    Donoghue, Philip C.J.
    University of Bristol.
    Evaluating scenarios for the evolutionary assembly of the brachiopod body plan.2014Ingår i: Evolution & Development, ISSN 1520-541X, E-ISSN 1525-142X, Vol. 16, nr 1, s. 13-24Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The fossil faunas of the Cambrian provide the only direct insight into the assembly of animal body plans. However, for many animal groups, their early fossil record is linked to disarticulated remains, interpretation of which is problematic since they possess few characters from which their affinity to phyla can be established and, indeed, few characters at all. One such group is the tommotiids, which has been interpreted, on the basis of skeletal anatomy, as a paraphyletic assemblage uniting brachiopods and phoronids, through the acquisition and subsequent modification, or loss, of an imbricated set of dorsal phosphatic sclerites. Here we present a reexamination of the fossil evidence uniting the tommotiids and brachiopods, supplemented with new anatomical data from synchrotron radiation X-ray tomographic microscopy of key tommotiid taxa. The characters used to support the complex hypothesis of character evolution in the brachiopod stem lineage relies on scleritome reconstructions and inferred mode of life which themselves rely on brachiopods being chosen as the interpretative model. We advocate a more conservative interpretation of the affinity of these fossils, based a priori on their intrinsic properties, rather than the modern analogue in whose light they have been interpreted.

  • 29. Bengtson, Stefan
    et al.
    Ivarsson, Magnus
    Fungal-prokaryotic symbiosis in the deep biosphere2014Konferensbidrag (Övrigt vetenskapligt)
  • 30. El Albani, Abderrazak
    et al.
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Canfield, Donald E.
    Riboulleau, Armelle
    Rollion Bard, Claire
    Macchiarelli, Roberto
    Ngombi Pemba, Lauriss
    Hammarlund, Emma
    Meunier, Alain
    Moubiya Mouele, Idalina
    Benzerara, Karim
    Bernard, Sylvain
    Boulvais, Philippe
    Chaussidon, Marc
    Cesari, Christian
    Fontaine, Claude
    Chi-Fru, Ernest
    Garcia Ruiz, Juan Manuel
    Gauthier-Lafaye, François
    Mazurier, Arnaud
    Pierson-Wickmann, Anne Catherine
    Rouxel, Olivier
    Trentesaux, Alain
    Vecoli, Marco
    Versteegh, Gerard J. M.
    White, Lee
    Whitehouse, Martin
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Bekker, Andrey
    The 2.1 Ga old Francevillian biota: biogenicity, taphonomy and biodiversity.2014Ingår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, nr 6:e99438, s. 1-18Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Paleoproterozoic Era witnessed crucial steps in the evolution of Earth’s surface environments following the first appreciable rise of free atmospheric oxygen concentrations ~2.3 to 2.1 Ga ago, and concomitant shallow ocean oxygenation. While most sedimentary successions deposited during this time interval have experienced thermal overprinting from burial diagenesis and metamorphism, the ca. 2.1 Ga black shales of the Francevillian B Formation (FB2) cropping out in southeastern Gabon have not. The Francevillian Formation contains centimeter-sized structures interpreted as organized and spatially discrete populations of colonial organisms living in an oxygenated marine ecosystem. Here, new material from the FB2 black shales is presented and analyzed to further explore its biogenicity and taphonomy. Our extended record comprises variably sized, shaped, and structured pyritized macrofossils of lobate, elongated, and rodshaped morphologies as well as abundant non-pyritized disk-shaped macrofossils and organic-walled acritarchs. Combined microtomography, geochemistry, and sedimentary analysis suggest a biota fossilized during early diagenesis. The emergence of this biota follows a rise in atmospheric oxygen, which is consistent with the idea that surface oxygenation allowed the evolution and ecological expansion of complex megascopic life.

  • 31. Ivarsson, Magnus
    et al.
    Bengtson, Stefan
    The deep biosphere of subseafloor crust and itsgeobiological impact2014Konferensbidrag (Övrigt vetenskapligt)
  • 32.
    Skovsted, Christian B.
    et al.
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Kouchinsky, Artem
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Holmer, Lars E.
    The problematic early Cambrian fossil Tumulduria incomperta represents the detached ventral interarea of a paterinid brachiopod.2014Ingår i: Acta Palaeontologica Polonica, ISSN 0567-7920, E-ISSN 1732-2421, Vol. 59, nr 2, s. 359-365Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The organophosphatic early Cambrian (Terreneuvian, Cambrian Stage 2) fossil Tumulduria incomperta has been problematic ever since its original description in 1969. Comparison of abundant specimens from the Lower Cambrian of Siberia with co-occurring brachiopod valves show that T. incomperta represents the central portion of the ventral interarea of a paterinid brachiopod similar to Cryptotreta neguertchenensis, and that the domed central portion of typical Tumulduria specimens represents the ridge-like pseudodeltidium of the interarea.

  • 33. Dong, Xi-ping
    et al.
    Cunningham, John A.
    University of Bristol.
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Thomas, Ceri-Wyn
    Liu, Jianbo
    Stampanoni, Marco
    Donoghue, Philip C.J.
    University of Bristol.
    Embryos, polyps and medusae of the early Cambrian scyphozoan Olivooides.2013Ingår i: Proceedings of the Royal Society Biological Sciences Series B, ISSN 0962-8452, Vol. 280, nr 2130071, s. 1-8Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Early Cambrian organism Olivooides is known from both embryonic and post-embryonic stages and, consequently, it has the potential to yield vital insights into developmental evolution at the time that animal body plans were established. However, this potential can only be realized if the phylogenetic relationships of Olivooides can be constrained. The affinities of Olivooides have proved controversial because of the lack of knowledge of the internal anatomy and the limited range of developmental stages known. Here, we describe rare embryonic specimens in which internal anatomical features are preserved. We also present a fuller sequence of fossilized developmental stages of Olivooides, including associated specimens that we interpret as budding ephyrae ( juvenile medusae), all of which display a clear pentaradial symmetry. Within the framework of a cnidarian interpretation, the new data serve to pinpoint the phylogenetic position of Olivooides to the scyphozoan stem group. Hypotheses about scalidophoran or echinoderm affinities of Olivooides can be rejected.

  • 34. Chi Fru, Ernest
    et al.
    Ivarsson, Magnus
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Kilias, Stephanos P
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Belivanova, Veneta
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Marone, Federica
    Paul Scherrer Institute.
    Fortin, Danielle
    Broman, Curt
    Stampanoni, Marco
    ETH Zürich.
    Fossilized iron bacteria reveal pathway to biological origin of banded iron formation.2013Ingår i: Nature Communications, ISSN 2041-1723, Vol. 4, nr 2050, s. 1-7Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Debates on the formation of banded iron formations in ancient ferruginous oceans are dominated by a dichotomy between abiotic and biotic iron cycling. This is fuelled by difficulties in unravelling the exact processes involved in their formation. Here we provide fossil environmental evidence for anoxygenic photoferrotrophic deposition of analogue banded iron rocks in shallow marine waters associated with an Early Quaternary hydrothermal vent field on Milos Island, Greece. Trace metal, major and rare earth elemental compositions suggest that the deposited rocks closely resemble banded iron formations of Precambrian origin. Well-preserved microbial fossils in combination with chemical data imply that band formation was linked to periodic massive encrustation of anoxygenic phototrophic biofilms by iron oxyhydroxide alternating with abiotic silica precipitation. The data implicate cyclic anoxygenic photoferrotrophy and their fossilization mechanisms in the construction of microskeletal fabrics that result in the formation of characteristic banded iron formation bands of varying silica and iron oxide ratios.

  • 35.
    Ivarsson, Magnus
    et al.
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Skogby, Henrik
    Naturhistoriska riksmuseet, Enheten för geovetenskap.
    Belivanova, Veneta
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Marone, Federica
    Paul Scherrer Institute.
    Fungal colonies in open fractures of subseafloor basalt.2013Ingår i: Geo-Marine Letters, ISSN 0276-0460, E-ISSN 1432-1157, Vol. 33, nr 4, s. 233-234Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The deep subseafloor crust is one of the few great frontiers of unknown biology on Earth and, still today, the notion of the deep biosphere is commonly based on the fossil record. Interpretation of palaeobiological information is thus central in the exploration of this hidden biosphere and, for each new discovery, criteria used to establish biogenicity are challenged and need careful consideration. In this paper networks of fossilized filamentous structures are for the first time described in open fractures of subseafloor basalts collected at the Emperor Seamounts, Pacific Ocean. These structures have been investigated with optical microscopy, environmental scanning electron microscope, energy dispersive spectrometer, X-ray powder diffraction as well as synchrotron-radiation X-ray tomographic microscopy, and interpreted as fossilized fungal mycelia.Morphological features such as hyphae, yeastlike growth and sclerotia were observed. The fossilized fungi are mineralized by montmorillonite, a process that probably began while the fungi were alive. It seems plausible that the fungi produced mucilaginous polysaccharides and/or extracellular polymeric substances that attracted minerals or clay particles, resulting in complete fossilization by montmorillonite. The findings are in agreement with previous observations of fossilized fungi in subseafloor basalts and establish fungi as regular inhabitants of such settings. They further show that fossilized microorganisms are not restricted to pore spaces filled by secondary mineralizations but can be found in open pore spaces as well. This challenges standard protocols for establishing biogenicity and calls for extra care in data interpretation.

  • 36.
    Ivarsson, Magnus
    et al.
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Broman, Curt
    Sturkell, Erik
    Ormö, Jens
    Siljeström, Sandra
    van Zuilen, Mark
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Fungal colonization of an Ordovician impact-induced hydrothermal system.2013Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 3, nr 3487, s. 1-6Artikel i tidskrift (Refereegranskat)
  • 37.
    Canfield, Donald E.
    et al.
    University of Southern Denmark.
    Ngombi Pemba, Lauriss
    Hammarlund, Emma
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Chaussidon, Marc
    Gauthier Lafaye, François
    Meunier, Alain
    Riboulleau, Armelle
    Rollion Bard, Claire
    Rouxel, Olivier
    Asael, Dan
    Wickmann, Anne Catherine
    El Albani, Abderrazak
    Oxygen dynamics in the aftermath of the Great Oxidation of the Earth’s atmosphere.2013Ingår i: Proceedings of the National Academy of Sciences, ISSN 0027-8424, Vol. 110, nr 42, s. 16736-16741Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The oxygen content of Earth’s atmosphere has varied greatly through time, progressing from exceptionally low levels before about 2.3 billion years ago, to much higher levels afterward. In the absence of better information, we usually view the progress in Earth’s oxygenation as a series of steps followed by periods of relative stasis. In contrast to this view, and as reported here, a dynamic evolution of Earth’s oxygenation is recorded in ancient sediments from the Republic of Gabon from between about 2,150 and 2,080 million years ago. The oldest sediments in this sequence were deposited in well-oxygenated deep waters whereas the youngest were deposited in euxinic waters, which were globally extensive. These fluctuations in oxygenation were likely driven by the comings and goings of the Lomagundi carbon isotope excursion, the longest–lived positive ?13C excursion in Earth history, generating a huge oxygen source to the atmosphere. As the Lomagundi event waned, the oxygen source became a net oxygen sink as Lomagundi organic matter became oxidized, driving oxygen to low levels; this state may have persisted for 200 million years.

  • 38.
    Bengtson, Stefan
    et al.
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Cunningham, John A.
    Yin, Chongyu
    Donoghue, Philip C.J.
    University of Bristol.
    A merciful death for the “earliest bilaterian,” Vernanimalcula.2012Ingår i: Evolution and Development, ISSN 1520-541x, Vol. 14, nr 5, s. 421-427Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fossils described as Vernanimalcula guizhouena, from the nearly 600 million-year-old Doushantuo Formation in South China, have been interpreted as the remains of bilaterian animals. As such they would represent the oldest putative record of bilaterian animals in Earth history, and they have been invoked in debate over this formative episode of early animal evolution. However, this interpretation is fallacious. We review the evidential basis of the biological interpretation of Vernanimalcula, concluding that the structures key to animal identity are effects of mineralization that do not represent biological tissues, and, furthermore, that it is not possible to derive its anatomical reconstruction on the basis of the available evidence. There is no evidential basis for interpreting Vernanimalcula as an animal, let alone a bilaterian. The conclusions of evolutionary studies that have relied upon the bilaterian interpretation of Vernanimalcula must be called into question.

  • 39.
    Kouchinsky, Artem
    et al.
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Runnegar, Bruce
    Skovsted, Christian
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Steiner, Michael
    Vendrasco, Michael
    Chronology of early Cambrian biomineralization.2012Ingår i: Geological Magazine, ISSN 0016-7568, Vol. 149, nr 2, s. 221-251Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Data on the first appearances of major animal groups with mineralized skeletons on the Siberian Platform and worldwide are revised and summarized herein with references to an improved carbon isotope stratigraphy and radiometric dating in order to reconstruct the Cambrian radiation (popularly known as the ‘Cambrian explosion’) with a higher precision and provide a basis for the definition of Cambrian Stages 2 to 4. The Lophotrochozoa and, probably, Chaetognatha were first among protostomians to achieve biomineralization during the Terreneuvian Epoch, mainly the Fortunian Age. Fast evolutionary radiation within the Lophotrochozoa was followed by radiation of the sclerotized and biomineralized Ecdysozoa during Stage 3. The first mineralized skeletons of the Deuterostomia, represented by echinoderms, appeared in the middle of Cambrian Stage 3. The fossil record of sponges and cnidarians suggests that they acquired biomineralized skeletons in the late Neoproterozoic, but diversification of both definite sponges and cnidarians was in parallel to that of bilaterians. The distribution of calcium carbonate skeletal mineralogies from the upper Ediacaran to lower Cambrian reflects fluctuations in the global ocean chemistry and shows that the Cambrian radiation occurred mainly during a time of aragonite and high-magnesium calcite seas.

  • 40. Cunningham, J.A.
    et al.
    Thomas, C.-W.
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Kearns, S.L.
    Xiao, S.
    Marone, Federica
    Paul Scherrer Institute.
    Stampanoni, Marco
    ETH Zürich.
    Donoghue, Philip C.J.
    University of Bristol.
    Distinguishing geology from biology in the Ediacaran Doushantuo biota relaxes constraints on the timing of the origin of bilaterians.2012Ingår i: Proceedings of the Royal Society. B. Biological Sciences, ISSN 0962-8452, Vol. 279, nr 1737, s. 2369-2376Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Ediacaran Doushantuo biota has yielded fossils that include the oldest widely accepted record of the animal evolutionary lineage, as well as specimens with alleged bilaterian affinity. However, these systematic interpretations are contingent on the presence of key biological structures that have been reinterpreted by some workers as artefacts of diagenetic mineralization. On the basis of chemistry and crystallographic fabric, we characterize and discriminate phases of mineralization that reflect: (i) replication of original biological structure, and (ii) void-filling diagenetic mineralization. The results indicate that all fossils from the Doushantuo assemblage preserve a complex me´lange of mineral phases, even where subcellular anatomy appears to be preserved. The findings allow these phases to be distinguished in more controversial fossils, facilitating a critical re-evaluation of the Doushantuo fossil assemblage and its implications as an archive of Ediacaran animal diversity. We find that putative subcellular structures exhibit fabrics consistent with preservation of original morphology. Cells in later developmental stages are not in original configuration and are therefore uninformative concerning gastrulation. Key structures used to identify Doushantuo bilaterians can be dismissed as late diagenetic artefacts. Therefore, when diagenetic mineralization is considered, there is no convincing evidence for bilaterians in the Doushantuo assemblage.

  • 41. Cunningham, J. A.
    et al.
    Thomas, C.-W.
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Marone, Federica
    Paul Scherrer Institute.
    Stampanoni, Marco
    ETH Zürich.
    Turner, F. R.
    Bailey, J. V.
    Raff, R. A.
    Raff, E. C.
    Donoghue, Philip C.J.
    University of Bristol.
    Experimental taphonomy of giant sulphur bacteria: implications for the interpretation of the embryo-like Ediacaran Doushantuo fossils.2012Ingår i: Proceedings of the Royal Society of London. B. Biological Sciences, ISSN 0962-8452, Vol. 279, nr 1734, s. 1857-1864Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Ediacaran Doushantuo biota has yielded fossils interpreted as eukaryotic organisms, either animal embryos or eukaryotes basal or distantly related to Metazoa. However, the fossils have been interpreted alternatively as giant sulphur bacteria similar to the extant Thiomargarita. To test this hypothesis, living and decayed Thiomargarita were compared with Doushantuo fossils and experimental taphonomic pathways were compared with modern embryos. In the fossils, as in eukaryotic cells, subcellular structures are distributed throughout cell volume; in Thiomargarita, a central vacuole encompasses approximately 98 per cent cell volume. Key features of the fossils, including putative lipid vesicles and nuclei, complex envelope ornament, and ornate outer vesicles are incompatible with living and decay morphologies observed in Thiomargarita. Microbial taphonomy of Thiomargarita also differed from that of embryos. Embryo tissues can be consumed and replaced by bacteria, forming a replica composed of a threedimensional biofilm, a stable fabric for potential fossilization. Vacuolated Thiomargarita cells collapse easily and do not provide an internal substrate for bacteria. The findings do not support the hypothesis that giant sulphur bacteria are an appropriate interpretative model for the embryo-like Doushantuo fossils. However, sulphur bacteria may have mediated fossil mineralization and may provide a potential bacterial analogue for other macroscopic Precambrian remains.

  • 42.
    Ivarsson, Magnus
    et al.
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Belivanova, Veneta
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Stampanoni, Marco
    ETH Zürich.
    Marone, Federica
    Paul Scherrer Institute.
    Tehler, Anders
    Naturhistoriska riksmuseet, Enheten för botanik.
    Fossilized fungi in subseafloor Eocene basalts.2012Ingår i: Geology, ISSN 0091-7613, Vol. 40, nr 2, s. 163-166Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The deep biosphere of subseafl oor basalts is thought to consist of mainly prokaryotes (bacteria and archaea). Here we report fossilized fi lamentous microorganisms from subseafl oor basalts interpreted as fossilized fungal hyphae, probably Dikarya, rather than fossilized prokaryotes. The basalts were collected during the Ocean Drilling Program Leg 197 at the Emperor Seamounts, North Pacifi c Ocean, and the fossilized fungi are observed in carbonate-fi lled veins and vesicles in samples that represent a depth of ~150 m below the seafl oor. Three-dimensional visualizations using synchrotron-radiation X-ray tomographic microscopy show characteristic fungal morphology of the mycelium-like network, such as frequent branching, anastomosis, and septa. Possible presence of chitin in the hypha walls was detected by staining with Wheat Germ Agglutinin conjugated with Fluorescein Isothiocyanate and examination using fl uorescence microscopy. The presence of fungi in subseafl oor basalts challenges the present understanding of the deep subseafl oor biosphere as being exclusively prokaryotic.

  • 43.
    Murdock, Duncan J.E.
    et al.
    University of Bristol.
    Donoghue, Philip C.J.
    University of Bristol.
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Marone, Federica
    Paul Scherrer Institute.
    Ontogeny and microstructure of the enigmatic Cambrian tommotiid Sunnaginia Missarzhevsky 1969.2012Ingår i: Palaeontology, ISSN 0081-0239, Vol. 55, nr 3, s. 661-676Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The tommotiids are a significant component of the earliest skeletal animal remains in the fossil record, occurring in large numbers in the Lower Cambrian. Sclerites of the tommotiid genus Sunnaginia have been implicated as integral to hypotheses regarding the evolution of the brachiopod body plan, with a morphology intermediate between the unspecialized sclerites of the tubular Eccentrotheca and the specialized sclerites of the tannuolinids. Abundant Sunnaginia ?imbricata sclerites, of a broad ontogenetic spectrum, were recovered from the Comley Limestone, Lower Cambrian (Stages 3–4), Shropshire, UK and compared to Sunnaginia imbricata from the Aldan River, Siberia (uppermost Tommotian). New microstructural data, collected using synchrotron radiation X-ray tomographic microscopy, reveal a unique microstructure for Sunnaginia ?imbricata sclerites among the tommotiids; interlamellar cavities spanned by a series of continuous pillars, giving a colonnaded appearance contrasting to that of S. imbricata. These data refute the inclusion of Eccentrotheca within the Sunnaginiidae and highlight the need for a revision of suprageneric classification of the tommotiids. Rather, structural similarities between Sunnaginia sclerites and those of the tannuolinids suggest a close affinity to this group. Recent phylogenetic hypotheses place the tannuolinids as stem-linguliform brachiopods, with Paterimitra plus the paterinid (and possibly rhynchonelliform) brachiopods as their sister group. Our new data therefore resolve Sunnaginia as close to the node defining crown-Brachiopoda. However, the characters supporting this phylogenetic scheme cannot be consistently applied to all taxa, nor do they define a series of nested clades. We therefore suggest that a more thorough phylogenetic analysis is required in the light of the data presented here and other recent descriptions.

  • 44. Huldtgren, Therese
    et al.
    Cunningham, John
    Yin, Chongyu
    Stampanoni, Marco
    ETH Zürich.
    Marone, Federica
    Paul Scherrer Institute.
    Donoghue, Philip C. J.
    University of Bristol.
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Response to comment on “Fossilized nuclei and germination structures identify Ediacaran ‘animal embryos’ as encysting protists”.2012Ingår i: Science, ISSN 0036-8075, Vol. 335, nr 6073, s. 1169d-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The objections of Xiao et al. to our reinterpretation are based on incorrect assumptions. The lack of nanocrystals lining the nuclear membrane is consistent with membrane fossilization, and nucleus volume through development is correlated to cytoplasm volume and fully consistent with sizes of eukaryote nuclei. Identical envelope structure unites the developmental stages of the fossils, and 2n cleavage and Y-shaped junctions are holozoan symplesiomorphies.

  • 45.
    Kouchinsky, Artem
    et al.
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Clausen, Sébastien
    Gubanov, Alexander
    Malinky, John M.
    Peel, John S.
    A Middle Cambrian fauna of skeletal fossils from the Kuonamka Formation, northern Siberia.2011Ingår i: Alcheringa, ISSN 0311-5518, Vol. 35, nr 1, s. 123-189Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An assemblage of mineralized skeletal fossils containing molluscs, hyoliths, chancelloriids, protoconodonts, lobopods, paleoscolecids, bradoriids, echinoderms and hexactinellid sponges is described from the middle Cambrian part of the Kuonamka Formation, exposed along the Malaya Kuonamka and Bol’shaya Kuonamka rivers, northern Siberian Platform. The sampled succession is attributed to the Kuonamkites and lower Tomagnostus fissus–Paradoxides sacheri biozones of the Amgan Stage of Siberia, correlated with Series 3, Stage 5—lower Drumian Stage of the IUGS chronostratigraphical scheme for the Cambrian. This work complements descriptions of molluscs from the same samples published by Gubanov et al. (2004) with additional material. It contains forms in common with coeval faunas from Australia, China, Western Gondwana, Avalonia, Laurentia and Baltica, increasing potential for global biostratigraphic correlation and understanding of palaeogeographic connections.

  • 46. Tang, Feng
    et al.
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Wang, Yue
    Wang, Xun-lian
    Yin, Chong-yu
    Eoandromeda and the origin of Ctenophora.2011Ingår i: Evolution & Development, ISSN 1520-541X, E-ISSN 1525-142X, Vol. 13, nr 5, s. 408-414Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Ediacaran fossil Eoandromeda octobrachiata had a high conical body with eight arms in helicospiral arrangement along the flanks. The arms carried transverse bands proposed to be homologous to ctenophore ctenes (comb plates). Eoandromeda is interpreted as an early stem-group ctenophore, characterized by the synapomorphies ctenes, comb rows, and octoradial symmetry but lacking crown-group synapomorphies such as tentacles, statoliths, polar fields, and biradial symmetry. It probably had a pelagic mode of life. The early appearance in the fossil record of octoradial ctenophores is most consistent with the Planulozoa hypothesis (Ctenophora is the sister group of Cnidaria + Bilateria) of metazoan phylogeny.

  • 47. Huldtgren, Therese
    et al.
    Cunningham, John
    Yin, Chongyu
    Stampanoni, Marco
    ETH Zürich.
    Marone, Federica
    Paul Scherrer Institute.
    Donoghue, Philip C. J.
    University of Bristol.
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Fossilized nuclei and germination structures identify Ediacaran ‘animal embryos’ as encysting protists.2011Ingår i: Science, ISSN 0036-8075, Vol. 334, nr 6063, s. 1696-1699Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Globular fossils showing palintomic cell cleavage in the Ediacaran Doushantuo Formation, China, are widely regarded as embryos of early metazoans, although metazoan synapomorphies, tissue differentiation, and associated juveniles or adults are lacking. We demonstrate using synchrotron-based x-ray tomographic microscopy that the fossils have features incompatible with multicellular metazoan embryos. The developmental pattern is comparable with nonmetazoan holozoans, including germination stages that preclude postcleavage embryology characteristic of metazoans. We conclude that these fossils are neither animals nor embryos. They belong outside crown-group Metazoa, within total-group Holozoa (the sister clade to Fungi that includes Metazoa, Choanoflagellata, and Mesomycetozoea) or perhaps on even more distant branches in the eukaryote tree. They represent an evolutionary grade in which palintomic cleavage served the function of producing propagules for dispersion.

  • 48.
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Presentation of the 2010 Charles Schuchert Award of the Paleontological Society to Philip C. J. Donoghue.2011Ingår i: Journal of Paleontology, ISSN 0022-3360, E-ISSN 1937-2337, Journal of Paleontology, Vol. 85, nr 5, s. 1015-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    LADIES AND gentlemen, friends and colleagues, the winner of the 2010 Charles Schuchert Award is Professor Philip Donoghue of the University of Bristol. In the natural progression of our personal lives, the transition from young snot to old fart is so gradual that one tends not to recognize it, least of all in oneself. Most of us— those further along in their careers— have passed through the stage of young, promising paleontologist to become middleaged promising paleontologists. Not so Phil Donoghue. I first met him when he was a graduate student at the University of Leicester. We got into a discussion about the nature of conodonts and certain pet ideas of mine that I had published. Phil did not agree with me so he went down in my book as a young snot. Soon thereafter, he published a ground-breaking, paradigm-changing paper, together with Peter Forey and Dick Aldridge, on the phylogenetic position of conodonts. Now, I realized that it was I who was the old fart. Phil had demonstrated that he had skipped the young-and-promising stage. He was, and is, young and delivering. Most people who start working on conodonts tend to remain with them. There is something about that mouth apparatus and the way in which it grabs hold of you. But Phil quickly tore himself loose from its grip. He quickly demonstrated an unquenchable zeal in attacking central issues in evolutionary paleontology, such as the origin of microstructures in teeth, the origin of teeth in jaws, the origin of jaws in vertebrates, the origin of vertebrates among animals, the origin of animals in the biosphere, and so on. I fear he will not stop until he has solved the question of the origin of life, the universe, and everything else. The breadth of questions he has already addressed is one aspect of Phil’s work. The diversity of tools he brings to bear on them is another. There is a lot of grinding powder under his fingernails, and lots of devo in his evo. After a sabbatical at the University of Bath, where he seems to have broken every rule of the Sabbath, he came out as a full-fledged molecular biologist, with RNA libraries at his fingertips. He is at the forefront in marrying data from living organisms with that from fossil taxa in phylogenetic analyses. Recently, he came out in defense of the paraphyletic stem group with arguments such that I have high hopes for his post-Schuchert development. Yes, paraphyletic groups are much more interesting than the monophyletic dead-ends called clades, although Phil of course refuses to call them groups. When Phil and some colleagues published a paper in Nature on the Cambrian fossil embryo Markuelia (again showing me wrong on a central issue), it caught the eye of Marco Stampanoni, a physicist who works at the Swiss Light Source (SLS) synchrotron near Zu¨ rich, in Switzerland. Marco had been developing methods of X-ray microtomography, using SLS beamlines. He contacted Phil with a proposal to collaborate, and Phil contacted me. Now, our collaboration based on this revolutionary technique, with Phil at the forefront, has opened our eyes to a huge amount of information to which we did not have access only a few years ago. Taphonomy is like the weather, people speak about it, but few do anything about it. But if you neglect it, you are in deep peril. Phil is much more concerned about taphonomy than most colleagues I know, and he does something about it. He started a project with embryologist Rudy Raff to determine how bacteria go about decomposing embryos in ways such that they are upgraded to exquisite fossils. He is engaging many colleagues, post-docs and students in the investigation of these processes and their end results. As a result, we are gaining insight into how bacteria can invade, devour and faithfully replicate intracellular features, and how different populations of bacteria play different roles in the process. An intriguing observation has emerged from Phil’s taphonomic work with Mark Purnell. Taphonomic degradation tends to bring about a stemward slippage of taxa in their apparent phylogenetic relationships, on account of sequential disappearance of preserved apomorphies. The general significance of this observation has still to be tested, but its potential importance for the phylogenetic analysis of fossils is obvious. Phil is leading an amazingly diverse and successful program in paleontology at the University of Bristol, permeated by his holistic approach and addressing everything from organismbased paleontology to molecular biology. Molecular, organismic, orgiastic paleontology—that’s the realm of Phil Donoghue. Mr. President, please hand the Schuchert Award for 2010 over to Phil. He thoroughly deserves it.

  • 49.
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Presentation of the 2010 Paleontological Society Medal to Bruce Runnegar.2011Ingår i: Journal of Paleontology, ISSN 0022-3360, E-ISSN 1937-2337, Journal of Paleontology, Vol. 85, nr 5, s. 1012-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ladies and gentlemen, friends and colleagues, the 2010 Paleontological Society Medal is awarded to Professor Bruce Runnegar of the University of California at Los Angeles. Preparing for this presentation, I got hold of a list of Bruce’s invited lectures, given during the past ten years. There are 86 titles on almost as many subjects. I will mention what these presentations were about, so you can get an impression of this Renaissance mind: Carbon isotopes and ocean evolution; Precambrian–Cambrian stratigraphy; Molecular evolution and the fossil record; Ediacaran organisms; Life on Mars; Oxygen and metazoan evolution; Orbital dynamics of the Earth–Moon system; Snowball Earth; Multiplated mollusks; Mass-independent fractionation of sulfur; Biomineralization; The Cambrian Explosion; Geobiology in the Archean; Cross-calibration of geological and astronomical time scales; Origins of biological complexity; Astrobiology of the Earth; Astrobiology of everything else; The Acraman impact of the Ediacaran; Biosignatures in ancient rocks; Microbial metabolism in the Early Archean. Now, most people can waffle about almost anything. A good teacher can read up on such topics and deliver useful lectures on them to students. But, as you will know if you are the least bit familiar with Bruce’s work, these are nearly all topics in fields where he has made startlingly innovative and pioneering contributions. Some would say that his most important contributions are missing from this list, such as molecular paleobiology, for example, or—if you prefer more tangible fossils—the systematics and evolution of Cambrian and Permian mollusks. But what is represented on the list is sufficient to document several brilliant careers in science: Bruce broke new ground in understanding the biomineralization processes of early mollusks by working with natural phosphatic replicas of the now vanished crystals of various species of calcium carbonate. He published a seminal set of papers on the evolution of the earliest mollusks, together with his longtime friend John Pojeta. And, as a leader of the astrobiology movement, Bruce has not only inspired everyone to start looking at life in a universal context, he has also brought his visions to life as Director of NASA’s Astrobiology Institute. It was in this context that Bruce was formally transformed from a U.S.-based Aussie to a full-fledged Australian– American (which is, I think, the politically correct term). In reference to molecular paleontology, I have some personal recollections. Bruce and I both have backgrounds as editors of paleontological journals. Bruce founded and for several years edited the successful Australasian journal Alcheringa, which is still going strong. Some of my first interactions with Bruce occurred in the 1970s, when he submitted manuscripts to Lethaia, of which I was an editor. One of my early forays was to question the number of authors of one of these manuscripts. I knew that no less than five authors of a single paper was excessive and confronted Bruce with this. It may have been the first time I really annoyed him, as he politely told me not to forget to turn my brain on, next time I wrote to him. Well, recently I saw an article in Nature with 230 authors, at which point it finally became clear to me that Bruce was ahead of his time. But back in those times I was a wee bit miffed, so when Bruce sent me a manuscript in which he estimated geological ages of major animal lineages using molecular clock techniques, I knew I could get my revenge. I sent the paper out for review by the sharpest molecular biologists of the day, smugly expecting to receive patronizing comments about paleontologists who should stick to their snail shells rather than pretending to be real scientists. No such luck. The reviews that came in were extravagant in their praise of the paper. Published in 1982, it predated by almost 15 years the avalanche of contributions that later came out on this topic. As usual, Bruce was ahead of the pack, but when others reached the spot where he had stood 15 years earlier, he wasn’t there anymore. Discrepancies between molecular and fossil data for a while seemed insurmountable, not to mention the discrepancies between different sets of molecular data and different sorts of analyses. But Bruce had inspired a bright set of younger biologists and paleontologists to refine their calculations. When the dust settled, one of those with whom Bruce had shared his spark, Kevin Peterson, was able to show that there is no significant conflict between the dates provided by fossils and by molecules. But I mentioned molecular paleontology. In 1986, Bruce published a seminal paper with just that title. In it he expressed his credo, thus: ‘‘palaeontologists should use all available sources of information to understand the evolution of life and its effect on the planet.’’ These are not empty words; they present a formidable challenge. Like all splendid visions, they stake out a direction rather than a goal. That it is possible to pursue this vision we see from the example set by this year’s Schuchert Award winner, Phil Donoghue, who together with Kevin Peterson and Roger Summons wrote a stimulating twenty-first century follow-up to Bruce’s earlier paper. But the foremost example is Bruce Runnegar himself. Here is a taste of the way in which his productive mind works. In 1982, Bruce used the anatomy and hypothesized physiology of the Ediacaran fossil Dickinsonia to estimate constraints for ambient oxygen levels in the Ediacaran atmosphere. This paper is much cited, and geochemists are only now catching up with him, developing geochemical proxies to test the hypothesis that a rising oxygen level was a trigger for the Cambrian Explosion, or, as Bruce so aptly put it, that one ‘‘ingredient, as in most explosives, may well have been a strong oxidising agent.’’ Finally, consider another example. In 1998, Bruce published a cladistic analysis of glaciogenic sediments, testing and corroborating the hypothesis that there were only two major Neoproterozoic glaciations, a result that still seems to stand. Who but Bruce would have thought of such a preposterous idea, using cladistics to resolve a stratigraphical conundrum? Bruce Runnegar has, over the years, formed collegial bonds with many scientists. The many younger people inspired by him include Phil Donoghue, now standing on Bruce’s shoulders. Bruce himself has stood on the shoulders of other giants, as he is quick to acknowledge. But, like Sir Isaac Newton, he has no reason to be bashful about his success, and I don’t think he is. The Paleontological Society Medal was really made for Bruce Runnegar, so please, Mr. President, give it to him!

  • 50. Doguzhaeva, Larisa
    et al.
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    The capsule – a newly discovered organic shell structure in the Late Cretaceous belemnite Gonioteuthis from north-west Germany.2011Ingår i: Palaeontology, ISSN 0031-0239, E-ISSN 1475-4983, Palaeontology, Vol. 54, nr 2, s. 397-415Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An unusual, bilaterally symmetrical black structure that embraces the protoconch and the phragmocone and is overlain by a rostrum has been studied in the Santonian– early Campanian (Late Cretaceous) belemnite genus Gonioteuthis from Braunschweig, north-west Germany. The structure is here named the capsule. Energy dispersed spectrometry analyses of the capsule show a co-occurrence of sulphur with zinc, barium, iron, lead and titanium, suggesting their chemical association. The capsule was originally made of organic material that was diagenetically transformed into sulphur-containing matter. The material of the capsule differs from the chitin of the connecting rings in the same specimens. The capsule has a complex morphology: (1) ventral and dorsal wing-like projections that are repeated in a breviconic shape of the alveolus, (2) an aperture with lateral lobes and ventral and dorsal sinuses copied by growth lines and (3) a ventral ridge that fits with the position of the fissure in the rostrum. The alveolus in the most anterior part of the rostrum is crater-like. It is lined with thin, pyritized, laminated material, which appears to be the outermost portion of the capsule attached to the inner surface of the rostrum. A flare along the periphery of the alveolus marks a region where the rostrum was not yet formed, suggesting that the capsule extended beyond the rostrum. Modification of the skeleton in Gonioteuthis comprises a set of supposedly interrelated changes, such as innovation of the organic capsule, partial elimination of the calcareous rostrum and a diminishing of the pro-ostracum, resulting in the appearance of a new type of pro-ostracum that became narrower and shorter and lost the spatula-like shape and gently curved growth lines of a median field that are typical for the majority of Jurassic and Cretaceous belemnites. The partial replacement of a calcareous rostrum with an organic capsule in belemnitellids may have been an adaptive reaction to an unfavourable environmental condition, perhaps related to difficulties in calcium carbonate secretion during the Late Cretaceous that forced animals to reduce carbonate production and to secret an organic capsule around the protoconch and the phragmocone.

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