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  • 1.
    Aase-Remedios, Madeleine E.
    et al.
    Univ Durham, Dept Biosci, Durham DH1 3LE, England..
    Janssen, Ralf
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Leite, Daniel J.
    Univ Durham, Dept Biosci, Durham DH1 3LE, England..
    Sumner-Rooney, Lauren
    Leibniz Inst Evolut & Biodiversitatsforsch, Museum Nat Kunde, D-10115 Berlin, Germany..
    McGregor, Alistair P.
    Univ Durham, Dept Biosci, Durham DH1 3LE, England..
    Wittkopp, Patricia
    Evolution of the Spider Homeobox Gene Repertoire by Tandem and Whole Genome Duplication2023In: Molecular biology and evolution, ISSN 0737-4038, E-ISSN 1537-1719, Vol. 40, no 12, article id msad239Article in journal (Refereed)
    Abstract [en]

    Gene duplication generates new genetic material that can contribute to the evolution of gene regulatory networks and phenotypes. Duplicated genes can undergo subfunctionalization to partition ancestral functions and/or neofunctionalization to assume a new function. We previously found there had been a whole genome duplication (WGD) in an ancestor of arachnopulmonates, the lineage including spiders and scorpions but excluding other arachnids like mites, ticks, and harvestmen. This WGD was evidenced by many duplicated homeobox genes, including two Hox clusters, in spiders. However, it was unclear which homeobox paralogues originated by WGD versus smaller-scale events such as tandem duplications. Understanding this is a key to determining the contribution of the WGD to arachnopulmonate genome evolution. Here we characterized the distribution of duplicated homeobox genes across eight chromosome-level spider genomes. We found that most duplicated homeobox genes in spiders are consistent with an origin by WGD. We also found two copies of conserved homeobox gene clusters, including the Hox, NK, HRO, Irx, and SINE clusters, in all eight species. Consistently, we observed one copy of each cluster was degenerated in terms of gene content and organization while the other remained more intact. Focussing on the NK cluster, we found evidence for regulatory subfunctionalization between the duplicated NK genes in the spider Parasteatoda tepidariorum compared to their single-copy orthologues in the harvestman Phalangium opilio. Our study provides new insights into the relative contributions of multiple modes of duplication to the homeobox gene repertoire during the evolution of spiders and the function of NK genes.

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  • 2.
    Agbaje, Oluwatoosin B. A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology. Department of Earth and Environmental Sciences, Macquarie University, Sydney, Australia; Department of Biological Sciences, Macquarie University, Sydney, Australia.
    Brock, Glenn A.
    Department of Biological Sciences, Macquarie University, Sydney, Australia; State Key Laboratory of Continental Dynamics, Shaanxi Key Laboratory of Early Life and Environments, Department of Geology, Northwest University, Xi’an, 710069, China.
    Zhang, Zhifei
    State Key Laboratory of Continental Dynamics, Shaanxi Key Laboratory of Early Life and Environments, Department of Geology, Northwest University, Xi’an, 710069, China.
    Duru, Kingsley C.
    Department of Technology for Organic Synthesis, Ural Federal University, Yekaterinburg, Russia; Department of Biomedical Sciences, Macquarie University, Sydney, Australia.
    Liang, Yue
    State Key Laboratory of Continental Dynamics, Shaanxi Key Laboratory of Early Life and Environments, Department of Geology, Northwest University, Xi’an, 710069, China.
    George, Simon C.
    Department of Earth and Environmental Sciences, Macquarie University, Sydney, Australia.
    Holmer, Lars E.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology. State Key Laboratory of Continental Dynamics, Shaanxi Key Laboratory of Early Life and Environments, Department of Geology, Northwest University, Xi’an, 710069, China.
    Biomacromolecules in recent phosphate-shelled brachiopods: identification and characterization of chitin matrix2021In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 56, no 36, p. 19884-19898Article in journal (Refereed)
    Abstract [en]

    Phosphate-shelled brachiopods differ in filter-feeding lifestyle, with Lingula anatina an active infaunal burrower, and Discinisca tenuis a shallow marine epibenthic animal. The shells of these animals are built of organophosphatic constituents, the organic fibres/sheets reinforced with calcium phosphate to provide a sophisticated ultrastructural robustness. This investigation examined the nature of the organic fibres in order to improve understanding of how living organisms produce hierarchically structured biomaterials. Unlike powdered samples commonly used in previous studies, organic fibres were isolated for the first time and the shell fractions were purified, in order to study the content and nature of the biopolymer fibres. Biochemical methods including Calcofluor staining revealed a chitin matrix. Ultrastructural analysis, thermal gravimetric analysis, and spectroscopic analyses show that the core polysaccharide framework is composed of layers of β-chitin sheets and/or fibrils that are coated with a fibrous organic matrix. There is more chitin matrix in the L. anatina shells (26.6 wt.%) compared to the D. tenuis shells (12.9 wt.%). Taken together, the data show that the chitin matrix contributes to increased skeletal strength, making L. anatina highly adapted for life as an active burrower. In comparison, D. tenuis contains less chitin and lives as attached epibenthos in a shallow marine environment.

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  • 3.
    Agbaje, Oluwatoosin B. A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology. Macquarie Univ, Dept Earth & Environm Sci, Sydney, NSW, Australia.;Macquarie Univ, Dept Biol Sci, Sydney, NSW, Australia..
    Dominguez, J. Gabriel
    Macquarie Univ, Dept Biol Sci, Sydney, NSW, Australia..
    Jacob, Dorrit E.
    Macquarie Univ, Dept Earth & Environm Sci, Sydney, NSW, Australia.;Australian Natl Univ, Res Sch Earth Sci, Canberra, ACT, Australia..
    Organic biopolymers of venus clams: Collagen-related matrix in the bivalve shells with crossed-lamellar ultrastructure2021In: Biochemistry and biophysics reports, ISSN 2405-5808, Vol. 26, article id 100939Article in journal (Refereed)
    Abstract [en]

    Background: Biochemical studies and spectroscopic techniques have shown that chitin-silk fibroins are common in nacroprismatic bivalve shells. However, the nature of organic biopolymers in the less well studied shell architectures, such as crossed lamellar shells, remain unknown. Here, two venus shells, Callista disrupta and Callista kingii, with crossed lamellar ultrastructure have been studied.

    Methods: We employed thermal gravimetric analysis, optical-, confocal- and scanning electron-microscopes, gel-sodium dodecyl sulfate (gel-SDS), FTIR, ultra-performance liquid chromatography and high-performance anion-exchange chromatography system with pulsed amperometric detection to analyse organic macromolecules in the shells.

    Results: Thermal analysis showed a low concentration of organic macromolecules in C. disrupta (1.38 wt%) and in C. kingii (1.71 wt%). A combination of biochemical protocols, including Calcofluor White staining and FTIR spectroscopic assessment, indicate that amino-polysaccharide chitin together with proteins, are present in the organic scaffolding of the shells. Scanning electron microscope of insoluble acid biopolymer extracts as well as FTIR technique show that the hierarchical structural organizations of organic biopolymers consist collagen-related matrix. Our histochemical fixing and staining techniques reveal many discrete proteins and glycoproteins from soluble organic macromolecules on the gel-SDS. We show here 'singlet' and 'doublet' glycosaminoglycan bands that are far above 260 kDa.

    General significance/conclusions: The presence of collagen matrix in Callista shells shows promise for the new source of biomaterials. Most importantly, the structural organization of the proteinaceous motif is predominantly helical structures and not silk-fibroin unlike in nacreous bivalve shells.

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  • 4.
    Agbaje, Oluwatoosin B. A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology. Department of Earth and Environmental Sciences and MQ Marine Research Centre, Macquarie University, Sydney, Australia; Department of Biological Sciences, Macquarie University, Sydney, Australia.
    George, Simon C.
    Department of Earth and Environmental Sciences and MQ Marine Research Centre, Macquarie University, Sydney, Australia.
    Zhang, Zhifei
    State Key Laboratory of Continental Dynamics, Shaanxi Key Laboratory of Early Life & Environments, Department of Geology, Northwest University, Xi'an, China.
    Brock, Glenn A.
    Department of Biological Sciences, Macquarie University, Sydney, Australia; State Key Laboratory of Continental Dynamics, Shaanxi Key Laboratory of Early Life & Environments, Department of Geology, Northwest University, Xi'an, China.
    Holmer, Lars E.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology. State Key Laboratory of Continental Dynamics, Shaanxi Key Laboratory of Early Life & Environments, Department of Geology, Northwest University, Xi'an, China.
    Characterization of organophosphatic brachiopod shells: spectroscopic assessment of collagen matrix and biomineral components2020In: RSC Advances, E-ISSN 2046-2069, Vol. 10, p. 38456-38467Article in journal (Refereed)
    Abstract [en]

    The shells of linguloid brachiopods such as Lingula and Discinisca are inorganic–organic nanocomposites with a mineral phase of calcium phosphate (Ca-phosphate). Collagen, the main extracellular matrix in Ca-phosphatic vertebrate skeletons, has not previously been clearly resolved at the molecular level in organophosphatic brachiopods. Here, modern and recently-alive linguliform brachiopod shells of Lingula and Discinisca have been studied by microRaman spectroscopy, Fourier transform infrared spectroscopy, field emission gun scanning electron microscopy, and thermal gravimetric analysis. For the first time, biomineralized collagen matrix and Ca-phosphate components were simultaneously identified, showing that the collagen matrix is an important moiety in organophosphatic brachiopod shells, in addition to prevalent chitin. Stabilized nanosized apatitic biominerals (up to ∼50 nm) permeate the framework of organic fibrils. There is a ∼2.5-fold higher wt% of carbonate (CO32−) in Lingula versus Discinisca shells. Both microRaman spectroscopy and infrared spectra show transient amorphous Ca-phosphate and octacalcium phosphate components. For the first time, trivalent moieties at ∼1660 cm−1 and divalent moieties at ∼1690 cm−1 in the amide I spectral region were identified. These are related to collagen cross-links that are abundant in mineralized tissues, and could be important features in the biostructural and mechanical properties of Ca-phosphate shell biominerals. This work provides a critical new understanding of organophosphatic brachiopod shells, which are some of the earliest examples of biomineralization in still-living animals that appeared in the Cambrian radiation.

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  • 5.
    Agic, Heda
    et al.
    Department of Earth Science, University of California at Santa Barbara, Santa Barbara, USA.
    Moczydłowska, Małgorzata
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Högström, Anette
    Tromsø Universitetsmuseum.
    Ebbestad, Jan Ove R.
    Uppsala University, Music and Museums, Museum of Evolution.
    Jensen, Sören
    Área de Paleontología, Universidad de Extremadura, Avenida de Elvas s/n, Badajoz, Spain.
    Meinhold, Guido
    Geowissenschaftliches Zentrum der Universität Göttingen, Germany.
    Palacios, Teodor
    Área de Paleontología, Universidad de Extremadura, Avenida de Elvas s/n, Badajoz, Spain.
    Taylor, Wendy L.
    Department of Geological Sciences, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa.
    Novis, Linn K.
    Tromsø Universitetsmuseum.
    Unusual organic-walled microfossil from the late Neoproterozoic Nyborg Formation, Digermulen Peninsula, Arctic Norway2017In: ISECT 2017, 2017Conference paper (Other academic)
    Abstract [en]

    The late Neoproterozoic Nyborg Formation is exposed in the Tanafjord area, Finnmark, Arctic Norway, on Digermulen and Varanger Peninsulas. The succession is composed of ~400 m of interbedded shales, siltstone and purple to grey sandstone, deposited between Neoproterozoic low latitude glacial deposits. The Nyborg Fm. lies on top of the Smalfjord diamictite, and is overlain by the Mortensnes diamictite (the latter was attributed to both Marinoan (650-635 Ma) and Gaskiers (579 Ma) glaciations) and the Ediacaran-Cambrian Stáhpogieddi Formation. Thus, the Nyborg Fm. represents late Neoproterozoic, probably the last Cryogenian interglacial interval. Presented material was collected in 2014 by members of Digermulen Early Life Research Group, from organic-rich, grey-green shales and siltstones of the Nyborg Mbr. D, uppermost Nyborg Fm. between Árasulluokta and Guvssájohka valleys. Organic-walled microfossils were extracted from shale via standard palynological acetolysis in hydrofluoric acid, and studied via light and scanning electron microscopy. Microfossils from the Nyborg Fm. include Synsphaeridium-type aggregated cells, unbranched bacterial filaments (Polythrichoides and Siphonophycus), sphaeromorph and envelope-bearing acritarchs (leiosphaerids, Stictosphaeridium, Simia), and previously unrecognized aggregated tubular microfossils. These taxa are long-ranging, but common in glacial-interglacial units worldwide, and thus broadly corroborate the Cryogenian age of the Nyborg sediments. The novel fossil, up to 300 μm in size, is a parenchymatous meshwork of interconnected organic-walled tubes that terminate in cup-shaped apices 4-11 µm in diameter. Irregular tube clusters are truncated both in macerates and in thin sections, suggesting post mortem transport. Elemental EDXS analysis indicates that extracted meshwork microfossils are predominantly composed of carbonaceous material and also associated with small amounts of titanium and vanadium. Considering the branching and adjoined body plan of carbonaceous fossil, it was likely multicellular and of eukaryotic affinity. As such, it may represent an important step in the evolution of complex multicellularity and morphological complexity several million years before the appearance of Ediacaran organisms.

  • 6.
    Agić, Heda
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    A new species of small acritarch with porous wall structure from the early Cambrian of Estonia, and implications for the fossil record of eukaryotic picoplankton2016In: Palynology, ISSN 0191-6122, E-ISSN 1558-9188, Vol. 40, no 3, p. 343-356Article in journal (Refereed)
    Abstract [en]

    The Proterozoic-Phanerozoic transition records a general trend of decrease in phytoplankton cell size, in contrast tothe earlier and much larger Ediacaran acritarchs. Particularly minute, unornamented but sculptured organic-walledmicrofossils have been recovered from the lower Cambrian Lükati Formation in northern Estonia. The lack of anysignificant thermal alteration in the formation allowed for excellent preservation of fine microstructures on thesemicrofossils. Among the rich palynomorph assemblage in Lükati, a new species of tiny, spheroidal eukaryoticmicrofossil is recorded: Reticella corrugata gen. et sp. nov. It is characterised by a corrugated and flexible vesicle wallthat is densely perforated by nano-scale pores. Despite its unique morphology, the new species shares diagnosticcharacters with fossil and extant prasinophyte algae. R. corrugata is among the smallest microfossils with typicaleukaryotic morphology (conspicuous wall sculpture) and contributes to the diversity of the size class of smallacritarchs. Size, abundance, inferred prasinophyte affinity and eukaryotic wall sculpture make this new taxon alikely member of the early eukaryotic picoplankton.

  • 7.
    Agić, Heda
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Fossil Focus: Acritarchs2016In: Palaeontology Online, Vol. 6, no 11, p. 1-13Article in journal (Other (popular science, discussion, etc.))
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  • 8.
    Agić, Heda
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Microfossils of eukaryotic cysts through time: A study of Precambrian-Ordovician organic-walled microbiota2014Licentiate thesis, comprehensive summary (Other academic)
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    microfossils of eukaryotic cysts -licH.A.
  • 9.
    Agić, Heda
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Palaeobiology and diversification of Proterozoic-Cambrian photosynthetic eukaryotes2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    One of the most important events in the history of life is the evolution of the complex, eukaryotic cell. The eukaryotes are complex organisms with membrane-bound intracellular structures, and they include a variety of both single-celled and multicellular organisms: plants, animals, fungi and various protists. The evolutionary origin of this group may be studied by direct evidence of past life: fossils. The oldest traces of eukaryotes have appeared by 2.4 billion years ago (Ga), and have additionally diversified in the period around 1.8 Ga. The Mesoproterozoic Era (1.6-1 Ga) is characterised by the first evidence of the appearance complex unicellular microfossils, as well as innovative morphologies, and the evolution of sexual reproduction and multicellularity. For a better understanding of the early eukaryotic evolution and diversification patterns, a part of this thesis has focused on the microfossil records from various time periods and geographic locations. Examination of microfossil morphology, cell wall microstructure and biochemical properties, reflect their intracellular complexity and function, and allow reconstructions of their life cycle, as well as observing the evolutionary pattern of change from Mesoproterozoic, to Cambrian-Ordovician transition. Several case studies included assemblages deriving from Mesoproterozoic, Neoproterozoic and early Paleozoic time intervals that show disparate morphotypes and innovative features indicative of algal clades. The Mesoproterozoic Ruyang Group in northern China has yielded a diverse microfossil assemblage that provides important clues about the diversification of different eukaryotic groups. Furthermore these microfossils contributed an additional evidence for the emergence of the crown group Eukarya by 1.7-1.4 Ga. In another part of this thesis, examination of wall microstructure and chemical properties via Raman spectroscopy has been used to assess the biological affinities of various Neoproterozoic problematic carbonaceous compression fossils. Studies on the early Phanerozoic (c. 545-485 Ma) assemblages from Estonia reconstructed patterns of the early radiations of phytoplankton and its evolutionary innovations. A continuing theme in this thesis has been using a combination of evidence of microfossils’ fine-scale morphology, ecology and chemical properties to determine their function in life, in addition to their systematic position.

    List of papers
    1. Affnity, life cycle, and intracellular complexity of organic-walled microfossils from the Mesoproterozoic of Shanxi, China
    Open this publication in new window or tab >>Affnity, life cycle, and intracellular complexity of organic-walled microfossils from the Mesoproterozoic of Shanxi, China
    2015 (English)In: Journal of Paleontology, ISSN 0022-3360, E-ISSN 1937-2337, Vol. 89, no 1, p. 28-50Article in journal (Refereed) Published
    Abstract [en]

    Light microscope and scanning electron microscope observations on new material of unicellularmicrofossils Dictyosphaera macroreticulata and Shuiyousphaeridium macroreticulatum, from the MesoproterozoicRuyang Group in China, provide insights into the microorganisms’ biological affinity, life cycle and cellularcomplexity. Gigantosphaeridium fibratum n. gen. et sp., is described and is one of the largest Mesoproterozoicmicrofossils recorded. Phenotypic characters of vesicle ornamentation and excystment structures, properties ofresistance and cell wall structure in Dictyosphaera and Shuiyousphaeridium are all diagnostic of microalgalcysts. The wide size ranges of the various morphotypes indicate growth phases compatible with the development ofreproductive cysts. Conspecific biologically, each morphotype represents an asexual (resting cyst) or sexual (zygotic cyst)stage in the life cycle, respectively. We reconstruct this hypothetical life cycle and infer that the organism demonstrates areproductive strategy of alternation of heteromorphic generations. Similarly in Gigantosphaeridium, a metabolicallyexpensive vesicle with processes suggests its protective role as a zygotic cyst. In combination with all these charactersand from the resemblance to extant green algae, we propose the placement of these ancient microorganisms in the stemgroup of Chloroplastida (Viridiplantae). A cell wall composed of primary and secondary layers in Dictyosphaera andShuiyouisphaeridium required a high cellular complexity for their synthesis and the presence of an endomembranesystem and the Golgi apparatus. The plastid was also present, accepting the organism was photosynthetic. The biotareveals a high degree of morphological and cell structural complexity, and provides an insight into ongoing eukaryoticevolution and the development of complex life cycles with sexual reproduction by 1200Ma.

    Place, publisher, year, edition, pages
    Cambridge Journals, 2015
    Keywords
    organic-walled microfossils; early eukaryotes; Mesoproterozoic; Dictyosphaera; Shuiyousphaeridium; algae; evolution; intracellular complexity
    National Category
    Geology
    Research subject
    Earth Science with specialization in Historical Geology and Palaeontology; Biology with specialization in Systematics
    Identifiers
    urn:nbn:se:uu:diva-247264 (URN)10.1017/jpa.2014.4 (DOI)000351478500003 ()
    Funder
    Swedish Research Council, 621-2009-4445
    Available from: 2015-03-16 Created: 2015-03-16 Last updated: 2017-12-04Bibliographically approved
    2. Diversity of organic-walled microfossils from the early Mesoproterozoic Ruyang Group, North China Craton - a window into the early eukaryote evolution
    Open this publication in new window or tab >>Diversity of organic-walled microfossils from the early Mesoproterozoic Ruyang Group, North China Craton - a window into the early eukaryote evolution
    2017 (English)In: Precambrian Research, ISSN 0301-9268, E-ISSN 1872-7433, p. 101-130Article in journal (Refereed) Published
    Abstract [en]

    Mesoproterozoic Era was an important time for the initial diversification of eukaryotic groups and the appearance of the first complex morphologies. While eukaryotes evolved around 2.4 Ga, the first microfossils with ornamentation and sculpture occur in the 1.8-1.6 Ga successions worldwide. Shales and siltstones of the Ruyang Group, Shanxi Province, North China Craton, record a high diversity of such organic-walled microfossils. Recently, the depositional ages of this succession has been constrained to 1.75-1.40 Ga via   zircon U-Pb dating. This dating extends back the time of the first appearance of complex eukaryotic characters (e.g. processes, complex wall structure) in the fossil record. We have conducted a biostratigraphic investigation on of the samples throughout the fossiliferous Ruyang Group to provide an estimate of the early eukaryotic diversity in the Mesoproterozoic. Light- and scanning electron microscope studies have documented 26 species, including several that are reported for the first time, and some that were previously known only from younger, Neoproterozoic strata. Fossil diversity is high in the upper Baicaoping Formation, declines in the middle and reaches its peak in the upper Beidajian Formation. Novel morphologies among the unicellular Ruyang biota include a variety of processes, from tube-like extensions to hirsute spines, vesicles with velutinous outer membranes, as well as numerous specimens with internal bodies of varying sizes. We have also recorded the globally distributed Mesoproterozoic taxa Dictyosphaera, Shuiyousphaeridium, and Tappania. Key characters displayed by the Ruyang biota are consistent with reproductive structures (especially cysts among modern protists. These microfossils provide an additional evidence for the emergence of the crown group Eukarya by 1.7-1.4 Ga.

    Keywords
    Mesoproterozoic, Ruyang Group, organic-walled microfossils, eukaryotic evolution, North China, Dictyosphaera.
    National Category
    Natural Sciences Geology
    Research subject
    Earth Science with specialization in Historical Geology and Palaeontology
    Identifiers
    urn:nbn:se:uu:diva-265216 (URN)10.1016/j.precamres.2017.04.042 (DOI)000404697200006 ()
    Projects
    Palaeobiology and diversification of Proterozoic-Cambrian photosynthetic eukaryotes
    Funder
    Swedish Research Council, 621-2009-4445
    Available from: 2015-10-25 Created: 2015-10-25 Last updated: 2018-02-22Bibliographically approved
    3. Raman spectroscopy and microstructural comparison of carbonaceous compression and body fossils from the Neoproterozoic of Siberian and Eastern European platforms
    Open this publication in new window or tab >>Raman spectroscopy and microstructural comparison of carbonaceous compression and body fossils from the Neoproterozoic of Siberian and Eastern European platforms
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    Macroscopic, organic-walled fossils preserved as carbonaceous compressions and body fossils are commonly occurring in the Neoproterozoic-Cambrian successions worldwide. Most of these fossils, including studied here Chuaria, Tawuia, and Beltemelliformis, have been accepted as algae, and Sabellidites as an early metazoan. They possess limited characters for biological identification and differ in gross morphology of spherodial vs. tubular millimetre-sized specimens. Consequently, other methods than morphologic observations are needed to elucidate their affinities and, ultimately, phylogeny. Here we present a comparison of the Raman spectrographic signatures and new scanning electron microscope (SEM) observations on different carbonaceous compression and body fossils from the Khajpakh Formation (Siberian Platform), and Nekrasovo Formation (East European Platform), referred to the Tonian-Cryogenian transitional interval (c. 840-700 Ma) and the lowermost Cambrian stage, respectively. Data from the Raman spectroscopy of the walls of non-mineralised organisms reveal their chemical properties, and, in additions to microstructural characters, may be used to resolve the fossils’ phylogenetic affinities. To test the basic recognition of organic matter in studied photosynthetic organisms vs. animals, we have examined algal compression fossils and organically-preserved body-fossil. Differences in the Raman spectroscopic signature between various taxa have been observed. Vibrational absorption bands similar to those characteristic of α-chitin signature have been detected in the organic wall of Sabellidites, consistent with its metazoan identity. Distinct organic matter spectra of the macroalgae Chuaria, Tawuia and Beltanelliformis, and the possible early annelid Sabellidites indicate that Raman spectroscopy could be a useful method in identifying different branches of the early eukaryotes. Additionally, the recognition of the earliest metazoans among un-diagnostic tubular fossils by biochemical signatures and wall ultrastructure, could provide the minimum age of their origins.

    Keywords
    Neoproterozoic, Cambrian, tubular fossils, organic body fossils, Raman spectroscopy, SEM, East European Platform, Siberian Platform
    National Category
    Natural Sciences Geology
    Research subject
    Earth Science with specialization in Historical Geology and Palaeontology
    Identifiers
    urn:nbn:se:uu:diva-265206 (URN)
    Projects
    Palaeobiology and diversification of Proterozoic-Cambrian photosynthetic eukaryotes
    Funder
    Swedish Research Council, 621-2012-1669
    Available from: 2015-10-25 Created: 2015-10-25 Last updated: 2015-12-04
    4. Ecdysozoan-like sclerites among Ediacaran microfossils
    Open this publication in new window or tab >>Ecdysozoan-like sclerites among Ediacaran microfossils
    2015 (English)In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 152, no 6, p. 1145-1148Article in journal (Refereed) Published
    Abstract [en]

    We report the occurrence of organically preserved microfossils from the subsurface Ediacaran strata overlying the East European Platform in Poland, in the form of sclerites and cuticle fragments of larger organisms. They are morphologically similar to those known from Cambrian strata and associated with various metazoan fossils of recognized phyla. The Ediacaran age of the microfossils is evident from the stratigraphic position below the base of the Cambrian System and above the isotopically dated tuff layers at c. 551±4Ma. Within this strata interval, other characteristic Ediacaran microorganisms co-occur such as cyanobacteria, vendotaenids, microalgae, Ceratophyton,Valkyria and macroscopic annelidan Sabellidites. The recent contributions of organic sclerites in revealing the scope of the Cambrian explosion are therefore also potentially extendable back to the Ediacaran Period when animals first appear in the fossil record.

    Place, publisher, year, edition, pages
    Cambridge: Cambridge University Press, 2015
    Keywords
    Ediacaran metazoans; small carbonaceous fossils; Poland; organic preservation; refractory biopolymers
    National Category
    Geology
    Research subject
    Earth Science with specialization in Historical Geology and Palaeontology
    Identifiers
    urn:nbn:se:uu:diva-264156 (URN)10.1017/S001675681500045X (DOI)000367730400013 ()
    Funder
    Swedish Research Council, 621-2012-1669, 621-2011-4703
    Available from: 2015-10-06 Created: 2015-10-06 Last updated: 2017-12-01Bibliographically approved
    5. A new species of small acritarch with porous wall structure from the early Cambrian of Estonia, and implications for the fossil record of eukaryotic picoplankton
    Open this publication in new window or tab >>A new species of small acritarch with porous wall structure from the early Cambrian of Estonia, and implications for the fossil record of eukaryotic picoplankton
    2016 (English)In: Palynology, ISSN 0191-6122, E-ISSN 1558-9188, Vol. 40, no 3, p. 343-356Article in journal (Refereed) Published
    Abstract [en]

    The Proterozoic-Phanerozoic transition records a general trend of decrease in phytoplankton cell size, in contrast tothe earlier and much larger Ediacaran acritarchs. Particularly minute, unornamented but sculptured organic-walledmicrofossils have been recovered from the lower Cambrian Lükati Formation in northern Estonia. The lack of anysignificant thermal alteration in the formation allowed for excellent preservation of fine microstructures on thesemicrofossils. Among the rich palynomorph assemblage in Lükati, a new species of tiny, spheroidal eukaryoticmicrofossil is recorded: Reticella corrugata gen. et sp. nov. It is characterised by a corrugated and flexible vesicle wallthat is densely perforated by nano-scale pores. Despite its unique morphology, the new species shares diagnosticcharacters with fossil and extant prasinophyte algae. R. corrugata is among the smallest microfossils with typicaleukaryotic morphology (conspicuous wall sculpture) and contributes to the diversity of the size class of smallacritarchs. Size, abundance, inferred prasinophyte affinity and eukaryotic wall sculpture make this new taxon alikely member of the early eukaryotic picoplankton.

    Keywords
    Cambrian, Estonia, organic-walled microfossils, picoplankton, prasinophytes, small acritarchs
    National Category
    Geology Ecology
    Research subject
    Earth Science with specialization in Historical Geology and Palaeontology
    Identifiers
    urn:nbn:se:uu:diva-265208 (URN)10.1080/01916122.2015.1068879 (DOI)000386047200007 ()
    Projects
    Palaeobiology and diversification of Proterozoic-Cambrian photosynthetic eukaryotes
    Funder
    Swedish Research Council, 621-2012-1669
    Available from: 2015-10-25 Created: 2015-10-25 Last updated: 2020-01-17Bibliographically approved
    6. Reproductive cyst and operculum formation in the Cambrian-Ordovician galeate-plexus microfossils
    Open this publication in new window or tab >>Reproductive cyst and operculum formation in the Cambrian-Ordovician galeate-plexus microfossils
    2016 (English)In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 138, no 2, p. 278-294Article in journal (Refereed) Published
    Abstract [en]

    Unicellular organic-walled microfossils from the Cambrian-Ordovician transition in Estonia (ca. 490-480 million years ago) exhibit rare characters reflecting their function as reproductive algal cysts. The studied assemblages record the evolutionary history of phytoplankton in the early Paleozoic Era: novel morphologies appearing through the Cambrian and subsequently diversifying in the Ordovician. Well preserved specimens were extracted following a standard palynological method and studied by light transmitted microscopy. The galeate plexus acritarchs Caldariola, Priscogalea and Stelliferidium have revealed exceptionally preserved morphological elements and a rare structure among both fossil and extant protists – an opening with operculum (lid) in reproductive cysts, in addition to lavish vesicle ornamentation and sculpture. Analogous morphology is observed in the living dasycladalean alga Acetabularia (Chlorophyta), which possesses an intrinsic lid-forming apparatus used during organism’s reproductive stage. Based on the observations on the fossil material and studies on the Acetabularia lid-formation, we propose a model of operculum formation in the galeate plexus microorganisms. Due to strong morphological and ecological similarities between galeate fossils and dasycladalean cysts, and the antiquity of this algal order, galeates may be positioned within green algae, more specifically Dasycladales. Unique morphology of the operculum-bearing microbiota would have required a high degree of intracellular complexity for its development, suggesting that advanced intracellular machinery was present already in the early Paleozoic phytoplankton. Additionally, minute prasinophyte microfossils Reticella corrugata  are reported for the first time in the Upper Cambrian strata. 

    Keywords
    acritarchs, Baltica, cyst-formation, Dasycladales, Estonia, galeate plexus, microfossils, operculum, Ordovician, palaeobiology
    National Category
    Geology Botany
    Research subject
    Earth Science with specialization in Historical Geology and Palaeontology
    Identifiers
    urn:nbn:se:uu:diva-265207 (URN)10.1080/11035897.2015.1116603 (DOI)000379763500001 ()
    Projects
    Palaeobiology and diversification of Proterozoic-Cambrian photosynthetic eukaryotes
    Funder
    Swedish Research Council, 621-2012-1669Danish National Research Foundation, DNRF53
    Available from: 2015-10-25 Created: 2015-10-25 Last updated: 2017-12-01Bibliographically approved
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  • 10.
    Agić, Heda
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology. Univ Calif Santa Barbara, Dept Earth Sci, Santa Barbara, CA 93106 USA.
    Högström, Anette E. S.
    UiT Arctic Univ Norway, Arctic Univ Museum Norway, N-9037 Tromso, Norway.
    Moczydlowska, Malgorzata
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Jensen, Sören
    Univ Extremadura, Area Paleontol, E-06006 Badajoz, Spain.
    Palacios, Teodoro
    Univ Extremadura, Area Paleontol, E-06006 Badajoz, Spain.
    Meinhold, Guido
    Keele Univ, Sch Geog Geol & Environm, Keele ST5 5BG, Staffs, England;Univ Gottingen, Dept Sedimentol & Environm Geol, Goldschmidtstr 3, D-37077 Gottingen, Germany.
    Ebbestad, Jan Ove R.
    Uppsala University, Music and Museums, Museum of Evolution.
    Taylor, Wendy L.
    Univ Cape Town, Dept Geol Sci, ZA-7701 Rondebosch, South Africa.
    Höyberget, Magne
    Rennesveien 14, N-4513 Mandal, Norway.
    Organically-preserved multicellular eukaryote from the early Ediacaran Nyborg Formation, Arctic Norway2019In: Scientific Reports, E-ISSN 2045-2322, Vol. 9, article id 14659Article in journal (Refereed)
    Abstract [en]

    Eukaryotic multicellularity originated in the Mesoproterozoic Era and evolved multiple times since, yet early multicellular fossils are scarce until the terminal Neoproterozoic and often restricted to cases of exceptional preservation. Here we describe unusual organically-preserved fossils from mudrocks, that provide support for the presence of organisms with differentiated cells (potentially an epithelial layer) in the late Neoproterozoic. Cyathinema digermulense gen. et sp. nov. from the Nyborg Formation, Vestertana Group, Digermulen Peninsula in Arctic Norway, is a new carbonaceous organ-taxon which consists of stacked tubes with cup-shaped ends. It represents parts of a larger organism (multicellular eukaryote or a colony), likely with greater preservation potential than its other elements. Arrangement of open-ended tubes invites comparison with cells of an epithelial layer present in a variety of eukaryotic clades. This tissue may have benefitted the organism in: avoiding overgrowth, limiting fouling, reproduction, or water filtration. C. digermulense shares characteristics with extant and fossil groups including red algae and their fossils, demosponge larvae and putative sponge fossils, colonial protists, and nematophytes. Regardless of its precise affinity, C. digermulense was a complex and likely benthic marine eukaryote exhibiting cellular differentiation, and a rare occurrence of early multicellularity outside of Konservat-Lagerstatten.

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  • 11.
    Agić, Heda
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Moczydłowska, Małgorzata
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Is cyst formation in early eukaryotes a requirement for their preservation in the fossil record?2015In: Abstracts of the Astrobiology Science Conference 2015: Habitability, Habitable Worlds and Life: EARTH’S EARLY BIOSPHERE: LIFE ON AN “ALIEN” PLANET, 2015Conference paper (Refereed)
    Abstract [en]

    Most of the Archaean-Proterozoic fossil record consists of non-biomineralizing microorganisms or their signatures. Body fossils of bacteria and early eukaryotes are preserved in siliciclastics, shales and carbonates, and are usually studied by preparation of thin sections or extraction from the rock matrix via acid maceration.The first eukaryotic organic-walled microfossils (OWM) appear at least by 1.8 Ga and undergo morphological diversification and evolutionary radiation in the Mesoproterozoic. There are no preserved eukaryotic-grade microfossils except OWM until the onset of biomineralization much later in the Neoproterozoic, evident in the record of testate amoebae (VSM) and microfossils with scaly elements.OWM are a less conspicuous component of the fos-sil record than taxa with skeletal or shelly elements. Organic matter decays quickly upon death of the organism, due to autolytic enzymes or degradation via het-erotrophy. However, species producing vegetative cells, resting cysts, zygotes, or spores, show considerable resistance to autolysis. Case studies on extractable carbonaceous OWM indicate they are preserved due to complex refractory molecules in the structure of their sturdy vesicle walls. Living analogues across protistan clades utilise such sporopollenin-like compounds for the cyst wall construction during reproductive phase. Algaenan-containing trilaminar sheath structure (TLS) is secreted during aplanospore formation in extant chlorophyte alga Haematococcus. TLS has also been documented in Leiosphaeridia acritarchs from the Cambrian Lükati Formation in Estonia. Leiosphaeridia is a long ranging morphotype, dating as far back as 1.8 Ga. Presence of TLS in these fossils suggests their function as reproductive cyst. Dictyosphaera-Shuiyousphaeridium plexus from the Mesoproterozoic Ruyang Group, China, also exhibits cyst-like morphology and unique elements of wall reinforcement: internally secreted organic platelets.In addition to these early OWM, many Meso-Neoproterozoic taxa such as Tappania, Trachyhystrychosphaera and Kildinella contain cyst-like characters: 1) reproductive openings, 2) ornamentation, 3) occa-sionally preserved internal bodies and 4) acetolysis-resistant vesicle walls – properties observed among extant encysting protists.Ornamented (process-bearing) microfossils in par-ticular bear strong similarities with zygotes of living unicellular algae. Property of acetolysis-resistant vesicle is a result of sporopollenin-like macromolecules in the wall, synthesized most commonly by the autotrophic eukaryotes. Presence of such recalcitrant organic walls requires significant metabolic investment by the microorganism, which suggests a protective and/or reproductive function. This also allows for easier, and more detailed preservation in the rock record.One of the concerns arising from the studies on the early eukaryotic fossils is the bias towards encysting organisms. The eventual search for the fossil record on other planetary bodies could face the same challenges as the Precambrian palaeobiology: fossilisation and eventual detection might be problematic for any unicellular eukaryotic-grade organisms if they have not evolved reproduction via encystment, or cyst formation as means of coping with adverse environmental conditions.

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  • 12.
    Agić, Heda
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Moczydłowska, Małgorzata
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Raman spectra analysis and comparison of Neoproterozoic organic-walled mesofossils2012In: The 2012 Fermor Meeting of the Geological Society: The Neoproterozoic Era: Evolution, Glaciation, Oxygenation / [ed] Fairchild I., Condon D., Lenton T., Shields-Zhou G., Brasier M.D., London, 2012, Vol. 1, p. 86-Conference paper (Refereed)
    Abstract [en]

    Skeletal material first appears in the rock record in the terminal Ediacaran, leaving most of the Earth’s history only to minute organic fossils. Aside from abundant acritarchs (unicellular organic-walled phytoplankton) present from at least ~2.5 Ga, other Proterozoic organic fossils of complex (eukaryotic) organisms include fungi and macroscopic algae of still debated taxonomy. Often preserved as flattened carbonaceous filaments in several morphologies: (1) rounded, (2) stick-like elongate and (3) branching, these Neoproterozoic fossils, including Chuaria, Morania, Beltanelloides, Vendotaenia, possess limited characters and differ little in gross morphology. As a result, other methods are needed to elucidate their biological affinities and, ultimately, phylogeny.

    Here we present the comparison of the Raman spectra analysis of different macroalgal genera from Yakutia, Siberia, as well as that of a putative polychaete Sabellidites from the East European Platform, dated to the early Cryogenian (840-700 Ma) and lowermost Cambrian respectively.

    Data from the vibrational modes of organic molecules from the wall of unmineralised organisms reveal their chemistry and partially wall ultrastructure, presumably an indication of their relationships. Polyaromatic chain hydrocarbons and n-aliphatic pyrolysates suggest algal affinity for some of the Neoproterozoic organic problematica, yet most of the Raman spectra results are still difficult to fully identify, partially owing to the thermal maturity of the host rocks. However, there are clear differences between various groups, differentiating between parts of a single plexus (cf previous studies of Chuaria-Tawuia suggesting them to be components of a multicellular plant) and elements from other taxa. Additionally, the distinct organic matter spectra of Chuaria and Sabellidites indicate that Raman spectroscopy could be a useful method in identifying different branches of the early eukaryotes.

    As they are usually shallow-water and dependant on sunlight, the record of sturdy photosynthetic macroorganisms in the  Neoproterozoic strengthens the evidence that limits the extent of the harsh environmental conditions during the Cryogenian period, at least during the Kaigas and Sturtian glaciations.

  • 13.
    Agić, Heda
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Moczydłowska, Małgorzata
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Raman spectroscopy and microstructural comparison of carbonaceous compression and body fossils from the Neoproterozoic of Siberian and Eastern European platformsManuscript (preprint) (Other academic)
    Abstract [en]

    Macroscopic, organic-walled fossils preserved as carbonaceous compressions and body fossils are commonly occurring in the Neoproterozoic-Cambrian successions worldwide. Most of these fossils, including studied here Chuaria, Tawuia, and Beltemelliformis, have been accepted as algae, and Sabellidites as an early metazoan. They possess limited characters for biological identification and differ in gross morphology of spherodial vs. tubular millimetre-sized specimens. Consequently, other methods than morphologic observations are needed to elucidate their affinities and, ultimately, phylogeny. Here we present a comparison of the Raman spectrographic signatures and new scanning electron microscope (SEM) observations on different carbonaceous compression and body fossils from the Khajpakh Formation (Siberian Platform), and Nekrasovo Formation (East European Platform), referred to the Tonian-Cryogenian transitional interval (c. 840-700 Ma) and the lowermost Cambrian stage, respectively. Data from the Raman spectroscopy of the walls of non-mineralised organisms reveal their chemical properties, and, in additions to microstructural characters, may be used to resolve the fossils’ phylogenetic affinities. To test the basic recognition of organic matter in studied photosynthetic organisms vs. animals, we have examined algal compression fossils and organically-preserved body-fossil. Differences in the Raman spectroscopic signature between various taxa have been observed. Vibrational absorption bands similar to those characteristic of α-chitin signature have been detected in the organic wall of Sabellidites, consistent with its metazoan identity. Distinct organic matter spectra of the macroalgae Chuaria, Tawuia and Beltanelliformis, and the possible early annelid Sabellidites indicate that Raman spectroscopy could be a useful method in identifying different branches of the early eukaryotes. Additionally, the recognition of the earliest metazoans among un-diagnostic tubular fossils by biochemical signatures and wall ultrastructure, could provide the minimum age of their origins.

  • 14.
    Agić, Heda
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Moczydłowska, Małgorzata
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Canfield, Donald
    University of Southern Denmark.
    Cyst and operculum formation in Cambrian-Ordovician galeate acritarchs from Estonia: implications for the algal phylogeny and blooms in the early Paleozoic2014In: 4th International Palaeontological Congress Abstract Volume: The history of life: a view from the Southern Hemisphere, 2014, p. 913-Conference paper (Other academic)
    Abstract [en]

    Unicellular organic-walled microfossils have been recovered from the Cambrian Lükati Formation and the Tremadocian Varangu Formation exposed in northern Estonia. Due to a combination of main morphological and biochemical characters, mainly a) excystment opening, b) processes, c) acetolysis-  resistant vesicle wall, microfossils have been interpreted as reproductive cysts of green algae. Both microfossil assemblages reflect the evolutionary patterns though the early Palaeozoic: from the Cambrian radiation of morphologically innovative taxa to increase in diversity and more disparate Ordovician forms. Combined light transmitted and scanning electron microscopy on the Middle Cambrian to Tremadocian galeate plexus acritarchs CaldariolaPriscogalea and Stelliferidium, revealed exceptionally preserved morphological elements and rare structure among fossil and extant microbiota – an opening with operculum (lid) in reproductive cyst, in addition to lavish vesicle ornamentation and sculpture. Operculum formation model is reconstructed from fossils at different stages of operculum position and attachment. Comparative morphology shows strong similarity of galeates to the reproductive cysts of the extant algae of Dasycladales (Chlorophyta), where the lid covering the cyst opening is determined by an intrinsic lid-forming apparatus during the organism’s reproductive stage. Opercula in Cambro-Ordovician galeate acritarchs and Dasycladales may be considered a homologous character. Unique morphology of the operculum-bearing microbiota would have required a degree of intracellular sophistication for its development, suggesting advanced intracellular machinery present already in the early Palaeozoic phytoplankton. Additionally, a new species of minute, sphaeromorphic and aggregated eukaryotic microfossils is recorded. It possesses a vesicle wall with corrugated sculpture and perforated by nano-scale pores. These minute early Cambrian microfossils have diagnostic characters of prasinophyte algae.

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  • 15.
    Agić, Heda
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Moczydłowska, Małgorzata
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Canfield, Donald
    University of Southern Denmark .
    Reproductive cyst and operculum formation in the Cambrian-Ordovician galeate-plexus microfossils2016In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 138, no 2, p. 278-294Article in journal (Refereed)
    Abstract [en]

    Unicellular organic-walled microfossils from the Cambrian-Ordovician transition in Estonia (ca. 490-480 million years ago) exhibit rare characters reflecting their function as reproductive algal cysts. The studied assemblages record the evolutionary history of phytoplankton in the early Paleozoic Era: novel morphologies appearing through the Cambrian and subsequently diversifying in the Ordovician. Well preserved specimens were extracted following a standard palynological method and studied by light transmitted microscopy. The galeate plexus acritarchs Caldariola, Priscogalea and Stelliferidium have revealed exceptionally preserved morphological elements and a rare structure among both fossil and extant protists – an opening with operculum (lid) in reproductive cysts, in addition to lavish vesicle ornamentation and sculpture. Analogous morphology is observed in the living dasycladalean alga Acetabularia (Chlorophyta), which possesses an intrinsic lid-forming apparatus used during organism’s reproductive stage. Based on the observations on the fossil material and studies on the Acetabularia lid-formation, we propose a model of operculum formation in the galeate plexus microorganisms. Due to strong morphological and ecological similarities between galeate fossils and dasycladalean cysts, and the antiquity of this algal order, galeates may be positioned within green algae, more specifically Dasycladales. Unique morphology of the operculum-bearing microbiota would have required a high degree of intracellular complexity for its development, suggesting that advanced intracellular machinery was present already in the early Paleozoic phytoplankton. Additionally, minute prasinophyte microfossils Reticella corrugata  are reported for the first time in the Upper Cambrian strata. 

  • 16.
    Agić, Heda
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Moczydłowska, Małgorzata
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Yin, Leiming
    Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences.
    Affnity, life cycle, and intracellular complexity of organic-walled microfossils from the Mesoproterozoic of Shanxi, China2015In: Journal of Paleontology, ISSN 0022-3360, E-ISSN 1937-2337, Vol. 89, no 1, p. 28-50Article in journal (Refereed)
    Abstract [en]

    Light microscope and scanning electron microscope observations on new material of unicellularmicrofossils Dictyosphaera macroreticulata and Shuiyousphaeridium macroreticulatum, from the MesoproterozoicRuyang Group in China, provide insights into the microorganisms’ biological affinity, life cycle and cellularcomplexity. Gigantosphaeridium fibratum n. gen. et sp., is described and is one of the largest Mesoproterozoicmicrofossils recorded. Phenotypic characters of vesicle ornamentation and excystment structures, properties ofresistance and cell wall structure in Dictyosphaera and Shuiyousphaeridium are all diagnostic of microalgalcysts. The wide size ranges of the various morphotypes indicate growth phases compatible with the development ofreproductive cysts. Conspecific biologically, each morphotype represents an asexual (resting cyst) or sexual (zygotic cyst)stage in the life cycle, respectively. We reconstruct this hypothetical life cycle and infer that the organism demonstrates areproductive strategy of alternation of heteromorphic generations. Similarly in Gigantosphaeridium, a metabolicallyexpensive vesicle with processes suggests its protective role as a zygotic cyst. In combination with all these charactersand from the resemblance to extant green algae, we propose the placement of these ancient microorganisms in the stemgroup of Chloroplastida (Viridiplantae). A cell wall composed of primary and secondary layers in Dictyosphaera andShuiyouisphaeridium required a high cellular complexity for their synthesis and the presence of an endomembranesystem and the Golgi apparatus. The plastid was also present, accepting the organism was photosynthetic. The biotareveals a high degree of morphological and cell structural complexity, and provides an insight into ongoing eukaryoticevolution and the development of complex life cycles with sexual reproduction by 1200Ma.

  • 17.
    Agić, Heda
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Moczydłowska, Małgorzata
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Yin, Leiming
    Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences.
    Diversity of organic-walled microfossils from the early Mesoproterozoic Ruyang Group, North China Craton - a window into the early eukaryote evolution2017In: Precambrian Research, ISSN 0301-9268, E-ISSN 1872-7433, p. 101-130Article in journal (Refereed)
    Abstract [en]

    Mesoproterozoic Era was an important time for the initial diversification of eukaryotic groups and the appearance of the first complex morphologies. While eukaryotes evolved around 2.4 Ga, the first microfossils with ornamentation and sculpture occur in the 1.8-1.6 Ga successions worldwide. Shales and siltstones of the Ruyang Group, Shanxi Province, North China Craton, record a high diversity of such organic-walled microfossils. Recently, the depositional ages of this succession has been constrained to 1.75-1.40 Ga via   zircon U-Pb dating. This dating extends back the time of the first appearance of complex eukaryotic characters (e.g. processes, complex wall structure) in the fossil record. We have conducted a biostratigraphic investigation on of the samples throughout the fossiliferous Ruyang Group to provide an estimate of the early eukaryotic diversity in the Mesoproterozoic. Light- and scanning electron microscope studies have documented 26 species, including several that are reported for the first time, and some that were previously known only from younger, Neoproterozoic strata. Fossil diversity is high in the upper Baicaoping Formation, declines in the middle and reaches its peak in the upper Beidajian Formation. Novel morphologies among the unicellular Ruyang biota include a variety of processes, from tube-like extensions to hirsute spines, vesicles with velutinous outer membranes, as well as numerous specimens with internal bodies of varying sizes. We have also recorded the globally distributed Mesoproterozoic taxa Dictyosphaera, Shuiyousphaeridium, and Tappania. Key characters displayed by the Ruyang biota are consistent with reproductive structures (especially cysts among modern protists. These microfossils provide an additional evidence for the emergence of the crown group Eukarya by 1.7-1.4 Ga.

  • 18.
    Agić, Heda
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Moczydłowska, Małgorzata
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Yin, Leiming
    Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences.
    Morphology of the Proterozoic eukaryotic microfossils as a reflection of their intracellular complexity2014In: 4th International Palaeontological Congress Abstract Volume: The history of life: a view fom the southern hemisphere / [ed] Esperanza CERDEÑO, 2014, p. 256-Conference paper (Refereed)
    Abstract [en]

    Mesoproterozoic is a time of increasing diversity of microscopic life and appearance of intricate new cell morphologies. First eukaryotes may have evolved around 2.4 Ga, but the first microbiota with intricate sculpture and ornamentation are found in the younger, 1.8.-1.6 Ga successions worldwide. Such microfossils were uncovered from the Ruyang Formation in Shanxi, China and Roper Group, Northern Territories, Australia, dating back to 1.6-1.0 Ga ago. Some of these unicellular organic-walled fossils share characters with Ediacaran and Phanerozoic fossils, as well as extant green microalgae. Key characters among some Precambrian acritarchs are acetolysis-resistant vesicle with multi-layered walls; vesicle ornamentation by diverse processes that are produced during cyst formation; and excystment openings for the release of gametes or daughter-cells. Combination of these morphological elements, also present in extant phytoplankton, reflects the fossils’ protective function as reproductive cysts, indicating that complex life cycles and reproduction were well under way in Mesoproterozoic. Several case studies of microfossil morphology likely induced by intrinsic eukaryotic mechanisms are presented.

    Distinctive vesicle wall composed of the primary layer reinforced by polygonal platelets in Mesoproterozoic taxa Dictyosphaera and Shuiyouisphaeridium, as well as the sophisticated vesicle-wall patterning on the fossil sphaeromorphs Valeria and younger Cerebrosphaera would have required a certain degree of complexity for their formation, as observed in the present day analogues among eukaryotic protists. This suggests the activity of the key eukaryotic organelles and cellular mechanisms and signalling for the cyst formation. Considering that Golgi apparatus and the endoplasmatic reticulum are the organelles regulating eukaryotic secretory pathway and synthesis of biopolymers used in cell-wall construction, they would have been required for the complex morphology observed in these Precambrian taxa. Therefore, the presence of GA and ER in the eukaryotic cell is inferred at the minimum age of 1.6-1.4 Ga. Similarly, morphology of acritarchs of the Cambrian galeate plexus, namely openings with opercula, is likely induced by the activity of the LFA organelle (lid-forming apparatus) as in the extant dasycladalean alga Acetabularia.

    Additionally, several new morphotypes from the Ruyang Formation are presented. These unicellular fossils bear a velutinous outer membrane surrounding an internal sphere, which suggests a protective function of a reproductive or a resting cyst.

    Cyst-like morphology varies in disparity, but its key features are consistent through Mesoproterozoic, Neoproterozoic and early Palaeozoic.

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  • 19.
    Agić, Heda
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Ward, L.
    Juarez Rivera, M.
    Kerrigan, Z.
    Petryshyn, V.A.
    Corsetti, F.A.
    Tripati, A.
    Lateral growth of Late Pleistocene stromatolites from Walker Lake (Nevada) and proxy constraints on environmental change2014In: 2014 GSA Annual Meeting in Vancouver, 2014Conference paper (Refereed)
    Abstract [en]

    Walker Lake, a terminal sodium bicarbonate lake in Western Nevada (Great Basin, USA) contains numerous carbonate structures, including stromatolites. The lake is a remnant of the larger Pleistocene Lake Lahontan system that has been isolated for the last ~12 ka. Stromatolites of unique macroscale morphology were collected at the ancient Lahontan shoreline during the 2014 International Geobiology Course.

    Initial observations of a stromatolite bed revealed a bowl-shaped carbonate framework composed of stacked, weakly laminated, vertical and horizontal petal-like structures with copious pore space. One laterally-oriented petal was taken off of the main structure and studied. Petrographical observations exhibit two types of alternating microfabrics and three transitions in microfabric. Both sparry crystal fans of calcite, and convex layers of fine micrite with occasional trapped crystals and fossils, were observed.

    Calibrated 14C ages (IntCal13) for the proximal and the distal end of the stromatolite are 35,540 YBP and 33,580 YBP, respectively. Clumped isotope (D47)-based estimates of temperature steadily increase throughout most of this interval, from the beginning of accretion, to the middle of the structure. By the distal end, values are at their peak, and at the tip temperatures decrease again. D47-temperatures correspond to microfabric, with textural changes associated with evidence for climatic fluctuations.

    We suggest the stromatolite formation may have been initiated during warmer intervals, induced by the chemical precipitation of calcite fans which served as a substrate for a biofilm growth. Microbial activity trapped the fine sediment and formed micrite. Colder conditions propagated fan precipitation. Microfabric alternation throughout the stromatolite records environmental change in the span of ca. 2000 years of Lake Lahontan history, likely in response to lake level fluctuations.

  • 20.
    Agić, Heda
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Ward, Lewis
    California Institute of Technology.
    Juarez Rivera, Marisol
    University of California-Davis.
    Kerrigan, Zak
    University of Rhode Island.
    Petryshyn, Victoria A.
    University of California, Los Angeles.
    Corsetti, Frank A.
    University of Southern California.
    Tripati, Aradhna
    University of California, Los Angeles.
    Lateral growth of Late Pleistocene stromatolites from Walker Lake (Nevada) and proxy constrains on environmental change2014In: Geological Society of America Abstracts with Programs, Geological Society of America , 2014, p. 300-4-Conference paper (Other academic)
    Abstract [en]

    Walker Lake, a terminal sodium bicarbonate lake in Western Nevada (Great Basin, USA) contains numerous carbonate structures, including stromatolites. The lake is a remnant of the larger Pleistocene Lake Lahontan system that has been isolated for the last ~12 ka. Stromatolites of unique macroscale morphology were collected at the ancient Lahontan shoreline during the 2014 International Geobiology Course.

    Initial observations of a stromatolite bed revealed a bowl-shaped carbonate framework composed of stacked, weakly laminated, vertical and horizontal petal-like structures with copious pore space. One laterally-oriented petal was taken off of the main structure and studied. Petrographical observations exhibit two types of alternating microfabrics and three transitions in microfabric. Both sparry crystal fans of calcite, and convex layers of fine micrite with occasional trapped crystals and fossils, were observed.

    Calibrated 14C ages (IntCal13) for the proximal and the distal end of the stromatolite are 35,540 YBP and 33,580 YBP, respectively. Clumped isotope (D47)-based estimates of temperature steadily increase throughout most of this interval, from the beginning of accretion, to the middle of the structure. By the distal end, values are at their peak, and at the tip temperatures decrease again. D47-temperatures correspond to microfabric, with textural changes associated with evidence for climatic fluctuations.

    We suggest the stromatolite formation may have been initiated during warmer intervals, induced by the chemical precipitation of calcite fans which served as a substrate for a biofilm growth. Microbial activity trapped the fine sediment and formed micrite. Colder conditions propagated fan precipitation. Microfabric alternation throughout the stromatolite records environmental change in the span of ca. 2000 years of Lake Lahontan history, likely in response to lake level fluctuations.

  • 21.
    Ahlberg, Per. E.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Physiology and Developmental Biology, Evolutionary Organism Biology.
    Blom, H.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology, Palaeontology group.
    Clack, J. A.
    The axial skeleton of the Devonian Tetrapod Ichthyostega2003In: The Gross Symposium 2. Advances in Palaeoichthyology. Riga, Latvia., 2003, p. 7-8Conference paper (Refereed)
  • 22.
    Ahlberg, Per E.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Physiology and Developmental Biology, Evolutionary Organism Biology.
    Clack, J. A.
    Blom, H.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology, Palaeontology group.
    The axial skeleton of the Devonian Tetrapod Ichthyostega.2003In: 51st symposium of vertebrate palaeontology and comparative anatomy, Oxford University Museum of Natural History, Oxford, 2003, p. 3-Conference paper (Refereed)
  • 23.
    Aldahan, Ala Adin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Morad, Sadoon
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Ion Physics.
    Sturesson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    ElSaiy, A.
    10Be in rhodochrosite nodules from Neogene sediments along the Galapagos Ridge, equatorial Pacific2010In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 268, no 7-8, p. 1253-1256Article in journal (Refereed)
    Abstract [en]

    Microcrystalline, calcian rhodochrosite occurs as nodules around burrows in late Neogene pelagic sediments from the Galapagos Ridge in the Guatemala Basin, eastern equatorial Pacific (DSDP Leg 68; Site 503). Be-10 isotope revealed that the rhodochrosite nodules have formed under growth conditions much faster than those reported for Fe-Mn nodules. The overall REE patterns of the nodules and host pelagic sediments indicate element derivation mainly from marine pore water. However, variations in the shale normalised Eu values suggest influx of hydrothermal fluids into mounds area at Galapagos, which is also evidenced by the similar minor and major element contents in the nodules and host sediments.

  • 24.
    Altenburger, Andreas
    et al.
    Section for Evolutionary Genomics, Natural History Museum of Denmark, University of Copenhagen, Copenhagen, Denmark.
    Martinez, Pedro
    Department of Genetics, University of Barcelona, Barcelona, Spain; Institut Català de Recerca i EstudisAvancats, Barcelona, Spain.
    Budd, Graham E.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Holmer, Lars E.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Gene Expression Patterns in Brachiopod Larvae Refute the "€œBrachiopod-Fold"€ Hypothesis2017In: Frontiers in Cell and Developmental Biology, E-ISSN 2296-634X, Vol. 5, p. 1-3, article id 74Article in journal (Refereed)
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  • 25. Altenburger, Andreas
    et al.
    Wanninger, Andreas
    Holmer, Lars E.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Metamorphosis in Craniiformea revisited: Novocrania anomala shows delayed development of the ventral valve2013In: Zoomorphology, ISSN 0720-213X, E-ISSN 1432-234X, Vol. 132, no 4, p. 379-387Article in journal (Refereed)
    Abstract [en]

    We revisited the brachiopod fold hypothesis and investigated metamorphosis in the craniiform brachiopod Novocrania anomala. Larval development is lecithotrophic and the dorsal (brachial) valve is secreted by dorsal epithelia. We found that the juvenile ventral valve, which consists only of a thin layer that was previously described as periostracal, is not a valve and is not secreted by the same epithelia as the dorsal valve. It is secreted by the attachment area of the larva at the posterior-most tip of the posterior larval lobe. The same attachment area is used by larvae of rhynchonelliform brachiopods during metamorphosis to cement their pedicle to the substrate. N. anomala is therefore not initially attached by a valve but by material corresponding to pedicle cuticle. This is different to previous descriptions, which had led to speculations about a folding event in the evolution of Brachiopoda. We show that the “brachiopod fold hypothesis,” which argues that brachiopods are transversely “folded” across the ontogenetic anterior–posterior axis, should be rejected at least with respect to the craniiforms. The data now suggest that the Craniiformea may be a derived group within the Rhynchonelliformea. This interpretation suggests that the last common ancestor of the Craniiformea has lost the pedicle and the ventral valve in early juvenile development. Characters that have previously been considered to be shared between the Craniiformea and the Linguliformea (clade Inarticulata), such as a through-gut and missing hinge articulation, may thus be secondarily derived characters of the Craniiformea within the Rhynchonelliformea.

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  • 26.
    Amores, Marcos
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Global Warming Induced by Oceanic Anoxic Event 1a Had a Pronounced Impact on the Early Cretaceous Terrestrial Vegetation of Southern Sweden2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The Mesozoic is punctuated by several rapid global warming events that are marked by the worldwide deposition of organic-rich marine sediments. These events, known as oceanic anoxic events (OAEs), are characterised by intervals where the worldwide carbon cycle suffers a disruption due to major palaeoceanographic and climatic shifts, leading to anoxic marine environments and the creation of black shales. For this study, the Oceanic Anoxic Event 1a (OAE 1a), which occurred during the Early Cretaceous Aptian age (~120 Ma) was analysed. It was likely triggered by the Greater Ontong Java underwater volcanic event and is associated with major changes in marine environments and ecosystems, including nekton and plankton turnover, and sea water composition changes. The impact of this event on terrestrial land-based ecosystems is, however, less well understood. Here I document well preserved and diverse spore-pollen assemblages spanning OAE 1a from southern Sweden by examining the Höllviken I core.

    Before the OAE, palynofloras are dominated by conifers, suggestive of a relatively mild and dry coastal environment. At the onset of the OAE a fern spike occurs, where there is a shift to early successional stage vegetation. Gymnosperm diversity and abundance sharply decrease, and the palynofloral assemblages become dominated by ferns, indicating a shift to warm and wet conditions. Gymnosperms gradually recover thereafter, but the formerly abundant conifer pollen Classopollis does not recover and remains rare. Dinoflagellate cysts and microforaminiferal test linings increase in abundance after OAE 1a, suggesting a higher degree of marine influence.

    These findings show that OAE 1a had a substantial impact on the composition and diversity of high latitude terrestrial vegetation and marine plankton communities. 

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  • 27.
    Andersson, Ki
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences, Palaeontology group.
    Aspects of locomotor evolution in the Carnivora (Mammalia)2003Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In this thesis, the shape of the distal humerus trochlea is analysed using landmark-based morphometrics and multivariate methods, with the aim of exploring locomotor evolution in carnivorans. Elbow joint morphology is used together with body size and craniodental morphology to characterize past and present carnivorans. Evolutionary implications are studied at the ordinal, familial, and species levels, testing specific hypotheses about scaling, morphological constraints, evolutionary trajectories, and potential for social pack-hunting behaviour. The circumference of the distal humerus trochlea is found to be highly correlated with body mass, and appears to scale similarly throughout the order Carnivora. A general predictive model for carnivoran bodymass is presented (a=0.601; b= 2.552; r2=0.952, SEE=0.136, p<0001, n=92), which removes the need for the investigator to actively choose between the diverging estimates that different predictors and their equations often produce. At the elbow joint, manual manipulation and locomotion appear to be conflicting functions, thus suggesting mutually exclusive lifestyles involving either forelimb grappling or pursuit. At large body sizes, carnivorans are distributed over a strongly dichotomised pattern (grappling or locomotion), a pattern coinciding with the postulated threshold in predator-prey size ratio at 21.5-25 kg. This pattern is compared to that of two carnivoran faunas from the Tertiary. In the Oligocene (33.7-23.8 Myr BP), the overall pattern is remarkably similar to that observed for extant Carnivora. In the Miocene (23.8-11.2 Myr BP) carnivores show a similarly dichotomised pattern as the Oligocene and Recent, although the whole pattern is shifted towards larger body sizes. This difference is suggested to be a reflection of the extraordinary species richness of browsing ungulates in the early Miocene of North America. Such an increase in prey spectrum would create a unique situation, in which large carnivores need not commit to a cursorial habitus in order to fill their nutritional requirements. Finally, the elbow joints and craniodental morphology (14 measurements) of fossil canids were examined with the aim of assessing the potential for pack-hunting in fossil canids. It is clear that small and large members of the Recent Caninae share similar craniodental morphologies. However, this pattern is not present in Borophaginae and Hesperocyoninae. In the latter, large representatives are characterized by being short-faced, with reduced anterior premolars and enlarged posterior premolars, thus approaching a “pantherine-like” craniodental configuration. These traits are interpreted as an adaptation for killing prey with canine bites. It is similarly determined that, unlike recent Caninae, all analyzed species of borophagines and hesperocyonines have retained the ability to supinate their forearms. It is therefore likely that manual manipulation was part of their hunting behaviour, thus removing an essential part of the argument for social pack-hunting in these forms, as the benefits of such a strategy become less obvious.

    List of papers
    1. Predicting carnivoran body mass from a weight bearing joint
    Open this publication in new window or tab >>Predicting carnivoran body mass from a weight bearing joint
    2004 (English)In: Journal of Zoology, ISSN 0952-8369, E-ISSN 1469-7998, Vol. 262, no 2, p. 161-172Article in journal (Refereed) Published
    Abstract [en]

    Predictors used to calculate the body mass of extinct carnivorans often scale differently between different taxa, thus yielding body mass estimates that diverge considerably depending on which predictive equation is used. This requires the investigator to choose the ones most suitable, a procedure that is best avoided if possible. The carnivoran elbow joint is here explored with the aim of producing a single general body mass predictor that can be used over a broad range of terrestrial and arboreal carnivorans. The circumference of the distal humerus trochlea is found to be highly correlated with body mass, and trochlea circumference seems to scale similarly throughout the order Carnivora. This scaling is not as theoretically predicted by elastic similarity and is slightly higher than that predicted by geometric similarity, indicating a slight positive allometry for the latter. Some degree of differential scaling between carnivoran families and between animals of large and small size cannot be ruled out, but this result is inconclusive. A predictive model that allows mass estimations for a broad range of carnivorans is presented (a=0.601; b=2.552; r2=0.952, SEE=0.136, P<0001, n=92). Body mass for eight extinct carnivoran species are calculated and these generally conform to earlier mass predictions.

    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:uu:diva-90745 (URN)10.1017/S0952836903004564 (DOI)
    Available from: 2003-09-01 Created: 2003-09-01 Last updated: 2017-12-14Bibliographically approved
    2. Elbow-joint morphology as a guide to forearm function and foraging behaviour in mammalian carnivores
    Open this publication in new window or tab >>Elbow-joint morphology as a guide to forearm function and foraging behaviour in mammalian carnivores
    2004 (English)In: Zoological Journal of the Linnean Society, ISSN 0024-4082, E-ISSN 1096-3642, Vol. 142, no 1, p. 91-104Article in journal (Refereed) Published
    Abstract [en]

    Among the hunting strategies employed by members of the order Carnivora (Mammalia), two, stalk and ambush and sustained pursuit, are particularly prevalent among larger species of the order. It has been difficult to identify morphological traits that support this distinction and ecological observations have shown that most carnivorans adopt a continuum of strategies, depending on available habitat and prey. In this paper, the shape of the distal humerus articulation is analysed, with the aim of exploring the use of the forelimb in prey procurement, and as a guide to such behaviour among fossil carnivorans. The results suggest that manual manipulation and locomotion are conflicting functions. Elbow-joint morphology supports a division between grapplers (i.e. ambushers) and nongrapplers (i.e. pursuers). Joints of the former are characterized by being relatively wide and the latter, by being relatively narrow and box-like with pronounced stabilizing features. At intermediate and large body sizes, carnivorans show a pattern suggesting mutually exclusive feeding strategies that involve either grappling with prey or sustained pursuit. The former allows for large body sizes, such as pantherine felids and ursids; the latter includes species of only moderate size, such as hyenids and canids. Elbow-joint morphology is closely linked to phylogeny, but the morphology of the cheetah converges with that of nongrapplers, showing that strong selective forces may override the phylogenetic component. Two taxa of giant mustelids from the Miocene were analysed to test whether this sort of analysis is applicable to carnivorans of the past. The African Late Miocene species Ekorus ekakeran has a joint morphology comparable to that of modern-day nongrapplers. Two joint morphologies were found in the North American Late Oligocene-Early Miocene Megalictis ferox. The first morphology is comparable to that of modern pantherine cats and the second forms  an  intermediate  between  grapplers  and  nongrapplers  that  is  not  present  in  the  modern  carnivoran  fauna.

    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:uu:diva-90746 (URN)10.1111/j.1096-3642.2004.00129.x (DOI)
    Available from: 2003-09-01 Created: 2003-09-01 Last updated: 2017-12-14Bibliographically approved
    3. The evolution of cursorial carnivores in the Tertiary: implications of elbow-joint morphology
    Open this publication in new window or tab >>The evolution of cursorial carnivores in the Tertiary: implications of elbow-joint morphology
    2003 In: Biology letters, Vol. Published online 6 AugustArticle in journal (Refereed) Published
    Identifiers
    urn:nbn:se:uu:diva-90747 (URN)
    Available from: 2003-09-01 Created: 2003-09-01Bibliographically approved
    4. Potential for pack-hunting in Tertiary canids (Canidae, Carnivora)
    Open this publication in new window or tab >>Potential for pack-hunting in Tertiary canids (Canidae, Carnivora)
    Manuscript (Other academic)
    Identifiers
    urn:nbn:se:uu:diva-90748 (URN)
    Available from: 2003-09-01 Created: 2003-09-01 Last updated: 2010-01-13Bibliographically approved
    Download full text (pdf)
    FULLTEXT01
  • 28.
    Andersson, Ki
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology, Palaeontology group.
    Elbow-joint morphology as a guide to forearm function and foraging behaviour in mammalian carnivores2004In: Zoological Journal of the Linnean Society, ISSN 0024-4082, E-ISSN 1096-3642, Vol. 142, no 1, p. 91-104Article in journal (Refereed)
    Abstract [en]

    Among the hunting strategies employed by members of the order Carnivora (Mammalia), two, stalk and ambush and sustained pursuit, are particularly prevalent among larger species of the order. It has been difficult to identify morphological traits that support this distinction and ecological observations have shown that most carnivorans adopt a continuum of strategies, depending on available habitat and prey. In this paper, the shape of the distal humerus articulation is analysed, with the aim of exploring the use of the forelimb in prey procurement, and as a guide to such behaviour among fossil carnivorans. The results suggest that manual manipulation and locomotion are conflicting functions. Elbow-joint morphology supports a division between grapplers (i.e. ambushers) and nongrapplers (i.e. pursuers). Joints of the former are characterized by being relatively wide and the latter, by being relatively narrow and box-like with pronounced stabilizing features. At intermediate and large body sizes, carnivorans show a pattern suggesting mutually exclusive feeding strategies that involve either grappling with prey or sustained pursuit. The former allows for large body sizes, such as pantherine felids and ursids; the latter includes species of only moderate size, such as hyenids and canids. Elbow-joint morphology is closely linked to phylogeny, but the morphology of the cheetah converges with that of nongrapplers, showing that strong selective forces may override the phylogenetic component. Two taxa of giant mustelids from the Miocene were analysed to test whether this sort of analysis is applicable to carnivorans of the past. The African Late Miocene species Ekorus ekakeran has a joint morphology comparable to that of modern-day nongrapplers. Two joint morphologies were found in the North American Late Oligocene-Early Miocene Megalictis ferox. The first morphology is comparable to that of modern pantherine cats and the second forms  an  intermediate  between  grapplers  and  nongrapplers  that  is  not  present  in  the  modern  carnivoran  fauna.

  • 29.
    Andersson, Ki
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences, Palaeontology group.
    Potential for pack-hunting in Tertiary canids (Canidae, Carnivora)Manuscript (Other academic)
  • 30.
    Andersson, Ki
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology, Palaeontology group.
    Predicting carnivoran body mass from a weight bearing joint2004In: Journal of Zoology, ISSN 0952-8369, E-ISSN 1469-7998, Vol. 262, no 2, p. 161-172Article in journal (Refereed)
    Abstract [en]

    Predictors used to calculate the body mass of extinct carnivorans often scale differently between different taxa, thus yielding body mass estimates that diverge considerably depending on which predictive equation is used. This requires the investigator to choose the ones most suitable, a procedure that is best avoided if possible. The carnivoran elbow joint is here explored with the aim of producing a single general body mass predictor that can be used over a broad range of terrestrial and arboreal carnivorans. The circumference of the distal humerus trochlea is found to be highly correlated with body mass, and trochlea circumference seems to scale similarly throughout the order Carnivora. This scaling is not as theoretically predicted by elastic similarity and is slightly higher than that predicted by geometric similarity, indicating a slight positive allometry for the latter. Some degree of differential scaling between carnivoran families and between animals of large and small size cannot be ruled out, but this result is inconclusive. A predictive model that allows mass estimations for a broad range of carnivorans is presented (a=0.601; b=2.552; r2=0.952, SEE=0.136, P<0001, n=92). Body mass for eight extinct carnivoran species are calculated and these generally conform to earlier mass predictions.

  • 31.
    Andersson, Ki
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Were there pack-hunting canids in the Tertiart, and how can we know2005In: Paleobiology, Vol. 31, no 1, p. 56-72Article in journal (Refereed)
  • 32.
    Andersson, Ki
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Kaakinen, Anu
    Floodplain processes in the shaping of fossil bone assemblages: an example from the Late Miocene, Bahe Formation, Lantian, China2004In: GFF, Vol. 126, p. 279-287Article in journal (Refereed)
  • 33.
    Andersson, Ki
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences, Palaeontology group.
    Werdelin, Lars
    The evolution of cursorial carnivores in the Tertiary: implications of elbow-joint morphology2003In: Biology letters, Vol. Published online 6 AugustArticle in journal (Refereed)
  • 34.
    Andren, Elinor
    et al.
    Sodertom Univ, Sch Nat Sci Technol & Environm Studies, Huddinge, Sweden..
    Klimaschewski, Andrea
    Queens Univ Belfast, Sch Geog Archaeol & Palaeoecol, Belfast BT7 1NN, Antrim, North Ireland..
    Self, Angela E.
    Nat Hist Museum, Dept Life Sci, London SW7 5BD, England..
    Amour, Natalie St.
    Univ Western Ontario, Dept Earth Sci, London, ON, Canada..
    Andreev, Andrei A.
    Univ Cologne, Inst Geol & Mineral, D-50931 Cologne, Germany.;Kazan Fed Univ, Inst Geol & Petr Technol, Kazan, Russia..
    Bennett, Keith D.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology. Queens Univ Belfast, Sch Geog Archaeol & Palaeoecol, Belfast BT7 1NN, Antrim, North Ireland..
    Conley, Daniel J.
    Lund Univ, Dept Geol, Quaternary Sci, Lund, Sweden..
    Edwards, Thomas W. D.
    Univ Waterloo, Dept Earth & Environm Sci, Waterloo, ON N2L 3G1, Canada..
    Solovieva, Nadia
    Kazan Fed Univ, Inst Geol & Petr Technol, Kazan, Russia.;UCL, Dept Geog, London WC1E 6BT, England..
    Harnmarlund, Dan
    Lund Univ, Dept Geol, Quaternary Sci, Lund, Sweden..
    Holocene climate and environmental change in north-eastern Kamchatka (Russian Far East), inferred from a multi-proxy study of lake sediments2015In: Global and Planetary Change, ISSN 0921-8181, E-ISSN 1872-6364, Vol. 134, p. 41-54Article in journal (Refereed)
    Abstract [en]

    A sediment record from a small lake in the north-eastern part of the Kamchatka Peninsula has been investigated in a multi-proxy study to gain knowledge of Holocene climatic and environmental change. Pollen, diatoms, chironomids and selected geochemical parameters were analysed and the sediment record was dated with radiocarbon. The study shows Holocene changes in the terrestrial vegetation as well as responses of the lake ecosystern to catchment maturity and multiple stressors, such as climate change and volcanic eruptions. Climate change is the major driving force resulting in the recorded environmental changes in the lake, although recurrent tephra deposition events also contributed. The sediment record has an age at the base of about 10,000 cal yrs BP, and during the first 400 years the climate was cold and the lake exhibited extensive ice-cover during winter and relatively low primary production. Soils in the catchment were poor with shrub alder and birches dominating the vegetation surrounding the lake. At about 9600-8900 cal yrs BP the climate was cold and moist, and strong seasonal wind stress resulted in reduced ice-cover and increased primary production. After ca. 8900 cal yrs BP the forest density increased around the lake, runoff decreased in a generally drier climate resulting in decreased primary production in the lake until ca. 7000 cal yrs BP. This generally dry climate was interrupted by a brief climatic perturbation, possibly attributed to the 8.2 ka event, indicating increasingly windy conditions with thick snow cover, reduced ice-cover and slightly elevated primary production in the lake. The diatom record shows maximum thermal stratification at ca. 6300-5800 cal yrs BP and indicates together with the geochemical proxies a dry and slightly warmer climate resulting in a high productive lake. The most remarkably change in the catchment vegetation occurred at ca. 4200 cal yrs BP in the form of a conspicuous increase in Siberian dwarf pine (Pinus pumila), indicating a shift to a cooler climate with a thicker and more long-lasting snow cover. This vegetational change was accompanied by marked shifts in the diatom and chironomid stratigraphies, which are also indicative of colder climate and more extensive ice-cover.

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    fulltext
  • 35.
    Antonsson, Karin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Seppä, H.
    Holocene temperatures in Bohuslan, southwest Sweden: A quantitative reconstruction from fossil pollen data2007In: Boreas, ISSN 0300-9483, E-ISSN 1502-3885, Vol. 36, no 4, p. 400-410Article in journal (Refereed)
    Abstract [en]

    Inferred mean annual temperatures (Tann) from a radiocarbon-dated fossil pollen stratigraphy obtained from Lake Trehörningen, southwest Sweden, provide evidence of climate variability during the Holocene in the boreal-nemoral zone of Sweden. The record indicates low early Holocene temperatures, followed by a rising trend and maximum temperature values from about 7000 to 4000 cal. yr BP. During the later part of the Holocene until present day, a cooling trend is reflected in the temperature record. At about 8200 cal. yr BP, temperatures temporarily drop, and at 8000 cal. yr BP the rising temperature trend is recovered. Inferred mid-Holocene temperatures are about 2.5-3°C higher than at present, and also higher than other pollen-inferred mid-Holocene temperatures of 1.5-2.5°C further to the north and east in Scandinavia. The reconstructed long-term climate pattern in Trehörningen has an overall consistency with temperature reconstructions from Scandinavia, suggesting a regional climate link for the Holocene variability in Sweden. Holocene climate trends in Trehörningen also show a remarkably similar pattern with the classic work on postglacial climate change by Sernander (1893, Sernander 1909), Andersson (1909) and von Post (1924).

  • 36. Armbrecht, Linda
    et al.
    Thompson, Peter A.
    Wright, Simon W.
    Schaeffer, Amandine
    Roughan, Moninya
    Henderiks, Jorijntje
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Armand, Leanne K.
    Comparison of the cross-shelf phytoplankton distribution of two oceanographically distinct regions off Australia2015In: Journal of Marine Systems, ISSN 0924-7963, E-ISSN 1879-1573, Vol. 148, p. 26-38Article in journal (Refereed)
    Abstract [en]

    The coastline of Australia spans tropical to temperate latitudes and encompasses a highly diverse phytoplankton community. Yet little is known about environmental driving forces of compositional and distributional patterns in natural phytoplankton communities of Australia. We investigate the relationships of phytoplankton (pico-, nano-, microphytoplankton, determined by microscopy and CHEMTAX) with a variety of environmental variables along cross-shelf gradients. Case studies were conducted in two highly distinct oceanographic regions of Australia (2010/2012): the tropical-temperate Coffs Harbour region (similar to 30 degrees S, 153 degrees E), where the shelf is narrow (similar to 30 km), and the tropical Kimberley region (similar to 16 degrees S, 122 degrees E), where the shelf is-wide (similar to 200 km). We distinguished three water masses in both study regions: relatively cold, nutrient-rich inshore waters; oligotrophic, stratified offshore waters; and cold, nutrient-rich deep waters. Most phytoplankton taxa (cyanobacteria, cryptophytes, dinoflagellates, haptophytes and prasinophytes) showed group-specific relationships with similar environmental variables in both regions. Diatoms occurred in nutrient-rich inshore waters in the Kimberley, whereas they were widely spread across the narrow continental shelf at Coffs Harbour. Off Coffs Harbour, a senescent bloom of the diatom Leptocylindrus danicus probably caused shelf-scale surface nutrient depletion. While microphytoplankton clearly increased, pico- and nanophytoplankton decreased with distance from the coast over the wide shelf in the Kimberley region. In contrast, the abundance of individual phytoplankton size-classes remained relatively constant across the narrow Coffs Harbour shelf. We conclude that general similarities exist between the relationship of phytoplankton and cross-shelf environmental variables in the two sites and assign differences primarily to the varying spatial resolution of our case studies.

  • 37.
    Arnold, Hannah
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Vascular Biology.
    Panara, Virginia
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Vascular Biology.
    Gorniok, Beata Filipek
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Skoczylas, Renae
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Vascular Biology.
    Ranefall, Petter
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Visual Information and Interaction. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction.
    Gloger, Marleen
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Vascular Biology.
    Hogan, Benjamin M.
    Koltowska, Katarzyna
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Vascular Biology.
    Mafba and  Mafbb Differentially Regulate Lymphatic Endothelial Cell Migration in Topographically Distinct Manners2021In: SSRN Electronic Journal, E-ISSN 1556-5068Article in journal (Refereed)
    Abstract [en]

    Lymphangiogenesis is the formation of lymphatic vessels from pre-existing vessels, a dynamic process that requires cell migration. Regardless of location, lymphatic endothelial cell (LEC) progenitors probe their surroundings while migrating to form the lymphatic network. Lymphatic development regulation depends on the transcription factor MAFB in different species. Zebrafish Mafba, expressed in LEC progenitors, is essential for their migration in the trunk. However, the transcriptional mechanism that orchestrate LEC migration in different lymphatic endothelial beds remains elusive. Here, we uncover topographically different requirements of the two paralogues, Mafba and Mafbb, for lymphatic cell migration. Both mafba and mafbb are necessary for facial lymphatic development, but mafbb is dispensable for trunk lymphatic development. On the molecular level, we demonstrate a regulatory network where Vegfc-Vegfd-SoxF-Mafba-Mafbb are essential in the facial lymphangiogenesis. We identify that mafba and mafbb fine-tune the directionality of LEC migration and vessel morphogenesis that is ultimately necessary for lymphatic function. 

  • 38.
    Arnold, Hannah
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Vascular Biology.
    Panara, Virginia
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Vascular Biology.
    Hussmann, Melina
    WWU Munster, Med Fac, Inst Cardiovasc Organogenesis & Regenerat, Munster, Germany..
    Gorniok, Beata Filipek
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Skoczylas, Renae
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Vascular Biology.
    Ranefall, Petter
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Visual Information and Interaction.
    Gloger, Marleen
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Vascular Biology.
    Allalou, Amin
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Visual Information and Interaction.
    Hogan, Benjamin M.
    Univ Melbourne, Dept Anat & Physiol, Melbourne, Vic 3000, Australia.;Univ Melbourne, Sir Peter MacCallum Dept Oncol, Melbourne, Vic 3000, Australia.;Peter MacCallum Canc Ctr, Organogenesis & Canc Program, Melbourne, Vic 3000, Australia..
    Schulte-Merker, Stefan
    WWU Munster, Med Fac, Inst Cardiovasc Organogenesis & Regenerat, Munster, Germany..
    Koltowska, Katarzyna
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology.
    mafba and mafbb differentially regulate lymphatic endothelial cell migration in topographically distinct manners2022In: Cell Reports, E-ISSN 2211-1247, Vol. 39, no 12, article id 110982Article in journal (Refereed)
    Abstract [en]

    Lymphangiogenesis, formation of lymphatic vessels from pre-existing vessels, is a dynamic process that requires cell migration. Regardless of location, migrating lymphatic endothelial cell (LEC) progenitors probe their surroundings to form the lymphatic network. Lymphatic-development regulation requires the transcription factor MAFB in different species. Zebrafish Mafba, expressed in LEC progenitors, is essential for their migration in the trunk. However, the transcriptional mechanism that orchestrates LEC migration in different lymphatic endothelial beds remains elusive. Here, we uncover topographically different requirements of the two paralogs, Mafba and Mafbb, for LEC migration. Both mafba and mafbb are necessary for facial lymphatic development, but mafbb is dispensable for trunk lymphatic development. On the molecular level, we demonstrate a regulatory network where Vegfc-Vegfd-SoxF-Mafba-Mafbb is essential in facial lymphangiogenesis. We identify that mafba and mafbb tune the directionality of LEC migration and vessel morphogenesis that is ultimately necessary for lymphatic function.

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  • 39.
    Arvestål, Emma
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Changes in Arsenic Levels in the Precambrian Oceans in Relation to the Upcome of Free Oxygen2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Life on Earth could have existed already 3.8 Ga ago, and yet, more complex, multicellular life did not evolve until over three billion years later, about 700 Ma ago. Many have searched for the reason behind this apparent delay in evolution, and the dominating theories put the blame on the hostile Precambrian environment with low oxygen levels and sulphide-rich oceans. There are, however, doubts whether this would be the full explanation, and this thesis therefore focuses on a new hypothesis; the levels of the redox sensitive element arsenic increased in the oceans as a consequence of the change in weathering patterns that followed the upcome of free oxygen in the atmosphere at about 2.4 billion years ago. Given its toxicity, this could have had negative effects upon the life of the time. To test the hypothesis, 66 samples from drill cores coming from South Africa and Gabon with ages between 2.7 and 2.05 Ga were analysed for their elemental composition, and their arsenic content were compared with carbon isotope data from the same samples. These confirmed that a rise in arsenic concentration following the upcome of free oxygen in the atmosphere and the onset of oxidative weathering of continental sulphides. Arsenic, which is commonly found in sulphide minerals, was weathered together with the sulphide and delivered into the oceans, where it in the Palaeoproterozoic increased to over 600% compared to the older Archaean levels, at least locally. Iron had the strongest control over the arsenic levels in the anoxic (ferruginous and sulphidic) oceans, probably due to its ability to remove arsenic through adsorption. During oxygenated conditions, sulphur instead had the strongest influence upon arsenic, likely because of the lack of dissolved iron. The highest arsenic levels were found in samples recognised as coming from oxygenated conditions, although this might be due to the oxygenation state of arsenic affecting its solubility. Arsenic is toxic already at low doses, especially if the necessary arsenic detoxification systems had not yet evolved. However, the lack of correlation between arsenic and changes in δ13C indicated that the increase of arsenic did not affect the primary production between 2.7 and 2.05 Ga. Thus, whether arsenic could have affected the evolution of life during the Mesoproterozoic remains to be shown.

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  • 40.
    Arvestål, Emma
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Organic microfossils from the Ediacaran of Estonia—behind the scenes2017In: Abstract Volume, International Symposium on the Ediacaran-Cambrian transition, St. John’s / [ed] D. McIlroy, 2017, p. 9-9Conference paper (Refereed)
    Abstract [en]

    When seeing a play, one easily gets caught by everything therein; the music, the dancing, and of course, the story. Still, most of the work took place before it even had its premiere. When the evolutionary curtain was lifted for most of the animals back in the beginning of the Cambrian, it had been preceded by many hundreds of millions of years of preparation. Still, as for any play, it was in the very last few moments that everything was coming together, that the scene became set. Hence, if we truly want to understand the events that was about to happen, we should peek behind the curtain before act one, into the Ediacaran Period and on its very busy little stage workers: the acritarchs. In order to better understand the dynamics of acritarch evolution at the Ediacaran-Cambrian transition two drill cores of allegedly Ediacaran age were studied. The drill cores had been taken in northern Estonia, and a total of 48 samples were prepared with the purpose of identifying the acritarchs and other organic microfossils using light microscopy. However, despite a relatively high taxonomic diversity, the recovered associations were strikingly different from other well-described Ediacaran acritarch faunas, most prominently by the absence of the large acanthomorphic acritarchs known from Australia, China and Siberia. Equally absent were the much smaller acanthomorphic acritarchs, characteristic of Cambrian sediments. Instead, a number of smooth-walled leiospheres was found to dominate the associations together with a variety of different types of filaments as well as unusually shaped fragments from yet unidentified organisms. It seems that the acritarchs were more than just stage workers: they had their own play going on, and this play appears to have been full of surprises.

  • 41.
    Arvestål, Emma
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Streng, Michael
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    A new species of Cyrtograptus (Graptoloidea) from the Llandovery of Västergötland (Sweden)2011In: The 2nd Wiman Meeting: Carl Wiman's Legacy: 100 years of Swedish Palaeontology, Uppsala, 2011, p. 2-2Conference paper (Refereed)
    Abstract [en]

    A new species of the genus Cyrtograptus from the late Llandovery of southern Sweden (Västergötland) is presented. The new species has been found near the top of Kinnekulle (Högkullen) in the Retiolites Shales, which are part of the lapworthi zone (late Telychian). Although it resembles the coeval C. lapworthi in appearance, a detailed comparison of the type material of C. lapworthi revealed distinct differences: the new species is more openly coiled in the proximal part, has a larger Two Thecae Repeat Distance (2TRD), and, most significantly, bears a second order cladium. Second order cladia are unknown from C. lapworthi. The new species is also compared with other species of Cyrtograptus that are characterized by second order cladia, such as the cotemporaneous C. laqueus and the slightly younger C. insectus (insectus zone; latest Telychian). However, C. laqueus differs from the new species in having a lower number of thecae separating the cladia, and also by the appearance of its proximal part, which forms a loop by crossing its own main stipe. C. insectus differs by having wider spaced cladia and a stronger coiled proximal part. Furthermore, the need of a redefinition of C. lapworthi is highlighted, due to the large morphological variations within this species.

  • 42.
    Arvestål, Emma
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Streng, Michael
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Cyrtograptids from the Telychian (upper Llandovery) of Kinnekulle Mountain, southern Sweden2013In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 135, no 1, p. 45-56Article in journal (Refereed)
    Abstract [en]

    The late Llandovery graptolite fauna of the Retiolites Shales on Kinnekulle Mountain in the province of Västergötland has long been known but never illustrated or studied in detail. New collections of graptolites from an interval at the very top of the exposed succession confirm previous reports of cyrtograptids, which make the shales on Kinnekulle the youngest preserved Palaeozoic rocks in the area. The co-occurrence of Oktavites spiralis and Cyrtograptus lapworthi constrains the strata to the lower lapworthi Biozone of the upper Telychian. The associated graptolite fauna comprises numerous monograptids and Retiolites angustidens as well as Cyrtograptus kinnekullensis n. sp., characterised by its open coiling and the presence of a second-order cladium on the second thecal cladium. This early occurrence of a cyrtograptid species with a second-order cladium on Baltica matches evolutionary patterns observed in Laurentia, suggesting that the ability to grow cladia of both first and higher order evolved approximately, synchronously and at the very beginning of cyrtograptid evolution.

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  • 43.
    Arvestål, Emma
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Streng, Michael
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Cyrtograptids from the Telychian (upper Llandovery) of Kinnekulle Mountain, southern Sweden2012Conference paper (Other academic)
  • 44.
    Arvestål, Emma
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Willman, Sebastian
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Organic-walled microfossils in the Ediacaran of Estonia: Biodiversity on the East European Platform2020In: Precambrian Research, ISSN 0301-9268, E-ISSN 1872-7433, Vol. 341, article id 105626Article in journal (Refereed)
    Abstract [en]

    Precambrian organic-walled microfossils are not only a source for studying evolution but also increasingly associated with stratigraphic correlation, based on key fossils and assemblage composition. For this reason, two drill cores from north-eastern Estonia have been studied for their content and stratigraphic distribution of organic-walled microfossils (OWM), analysing samples from the Precambrian Gdov, Kotlin, and Voronka formations. The recovered assemblages are generally well-preserved and diverse consisting of abundant sphaeromorphs, such as Leiosphaeridiaspp. and Pterospermopsimorpha spp., filamentous cyanobacteria, e.g. Cephalonyx geminatus and Palaeolyngbya catenata, and different types of cellular/colonial aggregates. In contrast, acanthomorphic acritarchs are rare with only a few unidentified examples present. The presence of taxa such as Pomoria rhomboidalisand Primoflagella speciosa in combination with the absence of large acanthomorphs suggests a late Ediacaran age of the studied samples. All in all, 38 species within 22 different genera are described herein, as are 9 taxa of unknown taxonomic affiliation. Another 11 taxa are briefly mentioned and depicted in order to provide for a better overview of the diversity of the assemblage. The stratigraphic distribution of the recognized taxa and assemblages can provide a powerful tool for correlation on the East European Platform as well as between Baltica and other palaeogeographic regions during the Ediacaran.

  • 45.
    Atkins, Christian J.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Peel, John S.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology. Uppsala University, Museums etc., Museum of Evolution.
    Yochelcionella (Mollusca, Helcionelloida) from the lower Cambrian of North America2008In: Bulletin of Geosciences, ISSN 1214-1119, E-ISSN 1802-8225, Vol. 83, no 1, p. 23-38Article in journal (Refereed)
    Abstract [en]

    Five named species of the helcionelloid mollusc genus Yochelcionella Runnegar & Pojeta, 1974 are recognized from the lower Cambrian (Cambrian Series 2) of North America: Yochelcionella erecta (Walcott, 1891), Y. americana Runnegar & Pojeta, 1980, Y. chinensis Pei, 1985, Y. greenlandica Atkins & Peel, 2004 and Y. gracilis Atkins & Peel, 2004, linking lower Cambrian outcrops along the present north-eastern seaboard. Yochelcionella erecta, an Avalonian species, is described for the first time, other species are derived from Laurentia. A revised concept of the Chinese species, Y. chinensis, is based mainly on a large sample from the Forteau Formation of western Newfoundland and the species may have stratigraphic utility between Cambrian palaeocontinents.

  • 46.
    Atkins, Christian J.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences. Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Peel, John Stuart
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences. Uppsala University, Museums etc., Museum of Evolution. Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    New species of Yochelcionella (Mollusca; Helcionelloida) from the Lower Cambrian of Greenland2004In: Bulletin, Geological Society of Denmark, ISSN 0011-6297, Vol. 51, p. 1-9Article in journal (Refereed)
  • 47.
    Auer, Gerald
    et al.
    Japan Agcy Marine Earth Sci & Technol, Dept Biogeochem, Yokosuka, Kanagawa, Japan.
    De Vleeschouwer, David
    Univ Bremen, MARUM Ctr Marine & Environm Sci, Bremen, Germany.
    Smith, Rebecca A.
    Univ Massachusetts, Dept Geosci, Amherst, MA 01003 USA.
    Bogus, Kara
    Texas A&M Univ, Int Ocean Discovery Program, College Stn, TX USA;Univ Exeter, Camborne Sch Mines, Penryn, England.
    Groeneveld, Jeroen
    Univ Bremen, MARUM Ctr Marine & Environm Sci, Bremen, Germany.
    Grunert, Patrick
    Univ Cologne, Inst Geol & Mineral, Cologne, Germany.
    Castaneda, Isla S.
    Univ Massachusetts, Dept Geosci, Amherst, MA 01003 USA.
    Petrick, Benjamin
    Max Planck Inst Chem, Mainz, Germany.
    Christensen, Beth
    Adelphi Univ, Environm Studies Program, Garden City, NY USA.
    Fulthorpe, Craig
    Univ Texas Austin, Inst Geophys, Austin, TX USA.
    Gallagher, Stephen J.
    Univ Melbourne, Sch Earth Sci, Melbourne, Vic, Australia.
    Henderiks, Jorijntje
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Timing and Pacing of Indonesian Throughflow Restriction and Its Connection to Late Pliocene Climate Shifts2019In: Paleoceanography and Paleoclimatology, ISSN 2572-4517, E-ISSN 2572-4525, Vol. 34, no 4, p. 635-657Article in journal (Refereed)
    Abstract [en]

    The Pliocene was characterized by a gradual shift of global climate toward cooler and drier conditions. This shift fundamentally reorganized Earth's climate from the Miocene state toward conditions similar to the present. During the Pliocene, the progressive restriction of the Indonesian Throughflow (ITF) is suggested to have enhanced this shift toward stronger meridional thermal gradients. Reduced ITF, caused by the northward movement of Australia and uplift of Indonesia, impeded global thermohaline circulation, also contributing to late Pliocene Northern Hemisphere cooling via atmospheric and oceanographic teleconnections. Here we present an orbitally tuned high-resolution sediment geochemistry, calcareous nannofossil, and X-ray fluorescence record between 3.65 and 2.97 Ma from the northwest shelf of Australia within the Leeuwin Current. International Ocean Discovery Program Site U1463 provides a record of local surface water conditions and Australian climate in relation to changing ITF connectivity. Modern analogue-based interpretations of nannofossil assemblages indicate that ITF configuration culminated similar to 3.54 Ma. A decrease in warm, oligotrophic taxa such as Umbilicosphaera sibogae, with a shift from Gephyrocapsa sp. to Reticulofenestra sp., and an increase of mesotrophic taxa (e.g., Umbilicosphaera jafari and Helicosphaera spp.) suggest that tropical Pacific ITF sources were replaced by cooler, fresher, northern Pacific waters. This initial tectonic reorganization enhanced the Indian Oceans sensitivity to orbitally forced cooling in the southern high latitudes culminating in the M2 glacial event (similar to 3.3 Ma). After 3.3 Ma the restructured ITF established the boundary conditions for the inception of the Sahul-Indian Ocean Bjerknes mechanism and increased the response to glacio-eustatic variability.

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  • 48. Babcock, LE
    et al.
    Hollingsworth, JS
    Rode, AL
    Ford, LA
    Borkow, PS
    Polak, K
    Holmer, Lars E
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Leslie, SA
    Rees, M
    Peel, JS
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Macrofauna from the Poleta Formation (Cambrian) of Nevada: Influences of Sedimentary Conditions, Biodegraders, and Microbial Biofilms on Exceptional Preservation2004In: International Subcomission on Cambrian Stratigraphy: Plenary Meeting Korea, 2004Conference paper (Refereed)
  • 49. Babcock, L.E.
    et al.
    Peel, John Stuart
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences. Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Anatomy, paleoecology, and taphonomy of the trilobite Buenellus from the Sirius Passet biota (Cambrian), North Greenland2002Conference paper (Other academic)
    Abstract [en]

    Specimens of the nevadiid trilobite Buenellus higginsi from the Sirius Passet Biota (Buen Formation: Cambrian) of North Greenland show a combination of features reflecting both biomineralized and non-biomineralized anatomy, and providing direct or indirect evidence of paleoecologic associations and taphonomic history. Buenellus illustrates some key aspects of the role that trilobites played in the Early Paleozoic Marine Revolution (apparently serving as both predator and prey); its role in sediment-excavation, however, is unknown.

    The Sirius Passet Biota has a low diversity and low abundance of mineralizing organisms. Buenellus specimens, which account for most of the biomineralized skeletal parts, are normally preserved as decalcified, articulated exoskeletons, parallel to bedding. Their composition is dominated by clay minerals, although quartz, chlorite, muscovite, and chloritoid, are present, indicating metamorphism of shale to greenschist grade. Specimens of B. higginsi were preferentially oriented ventral-up as collected; this suggests both that minor current reorientation of remains occurred on the sea floor, and that strata at the Sirius Passet locality are overturned.

    Carnivory on B. higginsi is implied by the remains of anomalocaridids and other potential predators, and by sublethal predation scars. Slight disarticulation in the thoracic region of some fossils may have resulted from either decay or scavenging. Slender traces associated with various arthropod body fossils, including those of B. higginsi, suggests scavenging. Coprolites containing trilobite sclerites are unknown, and isolated, fragmentary sclerites are rare.

    Preserved non-biomineralized parts of B. higginsi are: 1, slender antennae projecting from under the exoskeleton; and 2, axial structures (inflated cavities lined with silica and limonite). Three types of axial structures are present: 1, a large cavity in the rear-subcentral part of the cephalon (interpreted as the stomach cavity); 2, a narrow, smooth-sided, medial tube that tapers slightly posteriorly (interpreted as the intestinal tract); and 3, metamerically divided pairs of sagitally located structures (interpreted as midgut glands). A carnivorous feeding habit is suggested by the lack of sediment-filled guts in B. higginsi.

  • 50.
    Balinski, A.
    et al.
    Instytut Paleobiologii PAN, ul. Twarda 51/55, PL-00-818 Warszawa, Poland..
    Holmer, L. E.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    The Late Devonian trematid lingulate brachiopod Schizobolus from Poland1999In: Acta Paleontologica Polonica, ISSN 0567-7920, Vol. 44, no 3, p. 335-346Article in journal (Refereed)
    Abstract [en]

    A new species of the poorly known lingulate brachiopod Schizobolus is described from the Famennian (Upper Devonian) of Poland. S. polonicus sp. n. has a triangular pedicle notch and a small listrium, indicating that it belongs to the Trematidae within the superfamily Discinoidea. S. polonicus retains some linguloid features, such as a linguloid-like 'pedicle groove' and a V-shaped imprint of the pedicle nerve. The disturbance band, which occurs in the apical part of the larval shell, probably delimits two stages of growth, namely pre-larval (embryonic?) and larval, or, early-larval and late-larval. S. polonicus is the youngest member of the genus, and of the family Trematidae. Five incompletely preserved discinids from the Famennian of Łagów are described as Trematidae gen. et sp. indet

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