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  • MARRAMÀ, GIUSEPPE
    et al.
    Department of Paleontology, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria..
    ENGELBRECHT, ANDREA
    Department of Paleontology, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria..
    Mörs, Thomas
    Swedish Museum of Natural History, Department of Paleobiology.
    REGUERO, MARCELO A.
    Division Paleontologia de Vertebrados, Museo de La Plata, Paseo del Bosque s/n, 81900 FWA La Plata, Argentina.
    KRIWET, JÜRGEN
    Department of Paleontology, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria..
    THE SOUTHERNMOST OCCURRENCE OF BRACHYCARCHARIAS (LAMNIFORMES, ODONTASPIDIDAE) FROM THE EOCENE OF ANTARCTICA PROVIDES NEW INFORMATION ABOUT THE PALEOBIOGEOGRAPHY AND PALEOBIOLOGY OF PALEOGENE SAND TIGER SHARKS2018In: Rivista italiana di paleontologia e stratigrafia, ISSN 0035-6883, E-ISSN 2039-4942Article in journal (Refereed)
    Abstract [en]

     The first record of one of the most common and widespread Paleogene selachians, the sand tiger shark Brachycarcharias, in the Ypresian strata of the La Meseta Formation, Seymour Island, Antarctica, is provided herein. Selachians from the early Eocene horizons of this deposit represent the southernmost Paleogene occurrences in the fossil record, and are represented by isolated teeth belonging to orectolobiforms, lamniforms, carcharhiniforms, squatiniforms and pristiophoriforms. The combination of dental characters of the 49 isolated teeth collected from the horizons TELMs 2, 4 and 5 supports their assignment to the odontaspidid Brachycarcharias lerichei (Casier, 1946), a lamniform species widely spread across the Northern Hemisphere during the early Paleogene. The unambiguous first report of this lamniform shark in the Southern Hemisphere in the Eocene of the La Meseta Formation improves our knowledge concerning the diversity and paleobiology of the cartilaginous fishes of this deposit, and provides new insights about the biotic turnovers that involved the high trophic levels of the marine settings after the end-Cretaceous extinction and before the establishment of the modern marine ecosystems.

  • Mutvei, Harry
    Swedish Museum of Natural History, Department of Paleobiology.
    Cameral deposits in Paleozoic cephalopods2018In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 40, p. 254-263Article in journal (Refereed)
    Abstract [en]

    Calcareous cameral deposits have been described in several orthocerid and actinocerid nautiloids. According to the prevailing hypothesis, they were secreted during the lifetime of the animal, either by living tissues in the shell chambers, or by precipitation from the cameral liquid. In the present paper, cameral deposits are described in three species of Carboniferous orthocerid-like coleoid (Order Colorthocerida) from USA. The shell walls and septa in these coleoids are very thin and poorly calcified. In one half of the population of the three species, the septa are completely fragmented and there are no cameral deposits. In the other half of the population, the septa are partially fractioned and their surfaces are covered by welldeveloped cameral deposits. In contrast to the septa, the cameral deposits do not show any fractioning. To explain the origin of the cameral deposits, the following hypothetical scenario is the most realistic. After the death of the animals, the shells were accumulated on the sea floor and in one half of the population the septa became fully fractioned by the hydrostatic pressure. In shells of another half of the population, the septa were only partially fractioned. The calcifying bacteria entered the chambers of the dead shells through the porous connecting rings and gave rise to the cameral deposits.

  • Mutvei, Harry
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Mapes, Royal H.
    bAmerican Museum of Natural History, New York, NY, USA.
    Carboniferous coleoids with mixed coleoid-orthocerid characteristics: a new light oncephalopod evolution2018In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 140, p. 11-24Article in journal (Refereed)
    Abstract [en]

    Orthocerid-like coleoids with mixed orthocerid-coleoid characteristics are described for the first time from the Carboniferous of USA. The appearance of these coleoids represents transitional morphology between the orthoconic nautiloid and coleoid lineages. This transitional state is based on the new genus Colorthoceras n. gen. with three assigned new species (C. inflata n. sp., C. tubulata n. sp. and C. concavus n. sp.) in the new family Colorthoceridae of the new order Colorthocerida. Orthocerid nautiloid characteristics include a longiconic phragmocone with a well-developed body chamber, and a central, sub-central or sub-ventral siphuncle with endosiphuncular deposits. The shell wall in the new order Colorthocerida is characterized by the coleoid characteristics of a lack of the nacreous layer, with a high content of chitin that created a somewhat semi-elastic shell. The connecting rings are uni-layered, directly continuous from the septal neck, and have a mixed chitinous-calcareous composition similar to that in order Mixosiphonata. The shell wall structure in these unique orthocerid-like coleoids is similar to that in the previously described Carboniferous bactritoid-like coleoids. The evolution of these coleoid characteristics appears to represent an unsuccessful evolutionary experiment, as the diversity of this nautiloid lineage was in gradual decline in the Upper Paleozoic.

  • Biagioni, Cristian
    et al.
    Università di Pisa, Italy..
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Pasero, Marco
    Università di Pisa, Italy..
    Nuovi minerali Italiana - La approvazioni 20172018In: Revista Mineralogica Italiana, ISSN 0391-9641, Vol. 42, no 3, p. 190-197Article in journal (Other (popular science, discussion, etc.))
  • Hålenius, Ulf
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Hatert, Frédéric
    Université de Liège, Belgium..
    Pasero, Marco
    Università di Pisa, Italy..
    Mills, Stuart J.
    Museum Victoria, Melbourne, Australia..
    IMA Commission on New Minerals, Nomenclature and Classification (CNMNC) Newsletter 442018In: Mineralogical magazine, ISSN 0026-461X, E-ISSN 1471-8022, Vol. 82, no 4, p. 1015-1021Article in journal (Other academic)
  • McLoughlin, Stephen
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Haig, David W.
    Centre for Energy Geoscience, School of Earth Sciences, The University of Western Australia, Perth 6009, Australia.
    Siversson, Mikael
    Department of Earth and Planetary Sciences, Western Australian Museum, Welshpool, WA 6106, Australia.
    Einarsson, Elisabeth
    Department of Geology, Lund University, S-223 62 Lund, Sweden.
    Did mangrove communities exist in the Late Cretaceous of the Kristianstad Basin, Sweden?2018In: Palaeogeography, Palaeoclimatology, Palaeoecology, ISSN 0031-0182, E-ISSN 1872-616X, Vol. 498, p. 99-114Article in journal (Refereed)
    Abstract [en]

    Previous inferences of oyster-dominated communities occupying mangrove-like depositional settings in the Kristianstad Basin, Sweden, during the late early Campanian are reassessed. A significant percentage of oysters (Acutostrea incurva) from the Belemnellocamax mammillatus zone in Bed 3 at Åsen bear indentations on their left valves indicating attachment to plant axes. Many of these axes bear morphological features characteristic of the distal subaerial portions of woody plant branches and appear to have been rafted into the marine environment rather than representing in situ mangrove stems and roots. Foraminiferal assemblages recovered from sediment within the oyster body cavities differ from modern mangrove-community associations by the absence of siliceous agglutinated Foraminifera, the presence of diverse and relatively abundant Lagenida, relatively common triserial Buliminida, and a notable percentage of planktonic taxa. Chondrichthyan teeth assemblages from the same beds are similarly incompatible with the interpretation of a mangrove depositional environment based on comparisons with the distribution of related extant taxa. Apart from oyster shells and belemnite rostra, these beds are notably depauperate in diversity and abundance of macroinvertebrate remains compared with coeval carbonate shoal and rocky shoreline assemblages from the same basin. The collective palaeontological and sedimentological evidence favours an inner neritic sandy-substrate setting, but not nearshore or mangrove-like depositional environment for the oyster-rich Bed 3 at Åsen. The absence of mangrove-like assemblages at Åsen is consistent with the development of modern mangrove ecosystems much later (during the Maastrichtian and Cenozoic) based on the global palynological record.

  • McLoughlin, Stephen
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Pott, Christian
    Swedish Museum of Natural History, Department of Paleobiology. Museum für Naturkunde Paläontologische Bodendenkmalpflege Sentruper Straße 285 48161 Münster.
    Sobbe, Ian H.
    Ancient Environments, Queensland Museum, PO Box 3300, South Brisbane, 4101 Qld, Australia, and School of Earth and Environmental Sciences, University of Queensland, St Lucia 4072, Australia.
    The diversity of Australian Mesozoic bennettitopsid reproductive organs2018In: Palaeobiodiversity and Palaeoenvironments, ISSN 1867-1594, E-ISSN 1867-1608, Vol. 98, p. 71-95Article in journal (Refereed)
    Abstract [en]

    Several dispersed reproductive organs of bennettitopsid gymnosperms are described and illustrated from Triassic to Cretaceous strata of Australia: Williamsonia eskensis sp. nov. (Middle Triassic), Williamsonia ipsvicensis sp. nov. (Upper Triassic), Williamsonia durikaiensis sp. nov. (Lower Jurassic), Williamsonia sp. (Lower Jurassic), Williamsonia rugosa sp. nov. (Middle Jurassic), Williamsonia gracilis sp. nov. (Lower Cretaceous), Cycadolepis ferrugineus sp. nov. (Lower Jurassic), Cycadolepis sp. (Lower Cretaceous), and Fredlindia moretonensis Shirley 1898 comb. nov. (Upper Triassic). Among these, W. eskensis appears to represent the oldest bennettitalean reproductive structure yet identified. Although global floras expressed less provincialism during the Mesozoic and many genera are cosmopolitan, Australian bennettopsid species appear to have been endemic based on the morphological characters of the reproductive structures. Bennettopsids have a stratigraphic range of around 210 million years in Australia and are widely and abundantly represented by leaf fossils, but only around 20 specimens of reproductive structures, of which half are attributed to Fredlindia, have been recovered from that continent’s geological archive. The extremely low representation of reproductive organs vis-à-vis foliage is interpreted to reflect a combination of physical disintegration of the seed-bearing units while attached to the host axis and, potentially, extensive vegetative reproduction in bennettopsids growing at high southern latitudes during the Mesozoic.

  • Sallstedt, Therese
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Bengtson, Stefan
    Swedish Museum of Natural History, Department of Paleobiology.
    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.2018In: Geobiology, ISSN 1472-4677, E-ISSN 1472-4669, Vol. 16, p. 139-159Article in journal (Refereed)
    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.