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  • 1.
    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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  • 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 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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  • 3.
    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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  • 4. 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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  • 5. 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)
  • 6.
    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

  • 7.
    Balthasar, Uwe
    et al.
    University of Glasgow.
    Brazeau, Martin
    Brock, Glenn
    Macquarie University, Australia.
    Harper, David
    Durham University.
    Holmer, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    McGowan, Alistair
    Skovsted, Christian B.
    Naturhistoriska Riksmuseet.
    Streng, Michael
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Zhang, Zhifei
    Northwest University, Xi'an.
    Early evolution of biomineralization in brachiopods2012Conference paper (Other academic)
  • 8.
    Balthasar, Uwe
    et al.
    University of Glasgow.
    Brazeau, Martin
    Brock, Glenn
    Macquarie University, Australia.
    McGowan, Alistair
    Harper, David
    Holmer, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Skovsted, Christian B.
    Naturhistoriska Riksmuseet.
    Streng, Michael
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Zhang, Zhifei
    Brachiopod phylogeny revisited: Using stem groups to flesh out molecular tree topology2011Conference paper (Other academic)
  • 9.
    Balthasar, Uwe
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Skovsted, Christian B.
    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.
    Brock, A
    Department of Biological Sciences, Macquarie University, Australia .
    Homologous skeletal secretion in tommotiids and brachiopods2009In: Geology, ISSN 0091-7613, E-ISSN 1943-2682, Vol. 37, no 12, p. 1143-1146Article in journal (Refereed)
    Abstract [en]

    Tommotiids are distinctive components of the early Cambrian small shelly fauna, almost invariably represented by isolated phosphatic sclerites derived from a multielement protective cover (scleritome). The unusual range of tommotiid sclerite morphologies and unknown construction of the scleritome have severely hampered our understanding of their phylogenetic affinities. However, recent description of rare, articulated scleritome material belonging to the tommotiid genera Eccentrotheca and Paterimitra support the hypothesis that some tommotiids fall within the stem group of the lophophorate phyla Phoronida and Brachiopoda and that at least some tommotiid sclerites are homologous precursors of the shells of organophosphatic brachiopods. Here we show that the shell microstructure of Eccentrotheca and Paterimitra share substantial similarities with paterinid brachiopods. While paterinids possess an overall brachiopod morphology, their microstructure appears more similar to Eccentrotheca and Paterimitra than to nonpaterinate lingulids. These findings strongly support the existence of a brachiopod total group that is solidly rooted within tommotiids, and identify the organophosphatic skeletal composition as plesiomorphic with calcareous shells as derived. The microstructural changes of the proposed tommotiid-brachiopod transition probably reflect an adaptation to fluctuating food and phosphorous intake that came with the switch to a sessile life style at the base of the tommotiid clade.

  • 10.
    Bassett, M Ichael G.
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Holmer, Lars
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences, Palaeobiology. Palaeobiology.
    Popov, Leonid E.
    Cambrian brachiopoda of the Rift Valley, Jordan and Israel2004Conference paper (Other scientific)
  • 11.
    Bassett, MG
    et al.
    National Museums & Galleries of Wales, Department of Geology, Cardiff , Wales.
    Popov, LE
    National Museums & Galleries of Wales, Department of Geology, Cardiff , Wales.
    Holmer, LE
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Organophosphatic brachiopods: Patterns of biodiversification and extinction in the early Palaeozoic1999In: Geobios, ISSN 0016-6995, E-ISSN 1777-5728, Vol. 32, no 2, p. 145-163Article in journal (Refereed)
    Abstract [en]

    From a database of 226 Cambrian - Ordovician genera of organophosphatic-shelled brachiopods comprisingthe Subphylum Linguliformea, 11 sets of morphological characters typify all orders and superfamilies. Seven sets of these large-scale evolutionary novelties were established already by the end of the mid Cambrian, 2 more by the end of the late Cambrian, and the remaining 2 before the end of the Arenig. The earliest linguliformeans are of Tommotian age and represent some of the oldest known benthic organisms with a mineralised skeleton. Major diversification at the generic level took place during the mid and late Cambrian, by which time members of the Order Lingulida spread from near-shore to deep-water environments and became dominant in low diversity benthic assemblages that inhabited mobile sandy bottoms. There was a significant decline in diversity of linguliformeans during the latest Cambrian. Following recovery in the late Tremadoc-early Arenig, they then became one of the most distinctive components of benthic assemblages inhabiting marginal environments, e.g. eutrophic basins, shallow mobile sands, and abyssal depths. During the Llanvirn, there was a significant, worldwide turnover in linguliformean brachiopod faunas, when the majority of epibenthic lingulides of the families Obolidae, Zhanatellidae and Elkaniidae became extinct and were replaced, in shallow marine biofacies, by assemblages dominated by bivalved molluscs and burrowing lingulides. There is no trace until the mid Ashgill of a significant decline of micromorphic taxa in linguliformean assemblages characteristic of outer shelf environments. However, all siphonotretides, paterinides and most acrotretide genera disappeared towards the end of the late Ordovician pre-Hirnantian Dicellograptus anceps Biozone.

  • 12. Bassett, M.G.
    et al.
    Popov, L.E.
    Holmer, L.E.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    The oldest-known metazoan parasite?2004In: Journal of Paleontology, ISSN 0022-3360, E-ISSN 1937-2337, Vol. 78, no 6, p. 1214-1216Article in journal (Refereed)
  • 13. Bassett, Michael G.
    et al.
    Popov, L. E.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Holmer, L. E.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Brachipods: Cambrian-Tremadoc precursors to Ordovician radiation events2002In: Palaeobiogeography and Biodiversity Change: the Ordovician and Mesozoic-Cenozoic Radiations / [ed] James Alastair Crame, Alan Wilfrid Owen, Geological Society of London, 2002, Vol. 194, p. 13-23Chapter in book (Refereed)
  • 14. Bassett, Michael G.
    et al.
    Popov, L. E.
    Holmer, L. E.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Functional morphology of articulatatory structures and implications for patterns of musculature in Cambrian rhynchonelliform brachiopods.2001In: Brachiopods Past and Present / [ed] H. Brunton, L.R.M. Cocks and S.L. Long, London: Department of Palaeontology. The Natural History Museum , 2001, Vol. 63, p. 163-176Chapter in book (Refereed)
  • 15. Bauert, Heikki
    et al.
    Isozaki, Yukio
    Holmer, Lars Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Aoki, Kazumasa
    Sakata, Shuhei
    Hirata, Takafumi
    New U-Pb zircon ages of the Sandbian (Upper Ordovician) "Big K-bentonite" in Baltoscandia (Estonia and Sweden) by LA-ICPMS2014In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 136, no 1, p. 30-33Article in journal (Refereed)
    Abstract [en]

    Oscillatory-zoned euhedral single zircons from the upper Sandbian (Upper Ordovician) Kinnekulle K-bentonite exposed in a hillock at Paaskula in Estonia and at the type locality on Mt Kinnekulle in Sweden were dated in a grain-by-grain manner by laser ablation-inductively coupled plasma mass spectrometer. The U-Pb (weighed mean) ages of the 25 grains from Mt Kinnekulle and 24 grains from Paaskula are 453.4 +/- 6.6 and 454.9 +/- 4.9Ma, respectively. This study provides the first ca. 454Ma (late Sandbian) age for the Ordovician K-bentonite in northern Estonia and confirmed its correlation with the type Kinnekulle bed across the Baltic Sea.

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  • 16. Brock, Glenn A.
    et al.
    Holmer, Lars E
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Early Ordovician brachiopods from the Emanuel Formation, Canning Basin, Western Australia2004In: Memoirs of the Association of Australasian Palaeontologists, ISSN 0810-8889, no 30, p. 113-132Article in journal (Refereed)
    Abstract [en]

    The lingulate brachiopods from the type section of the Emanuel Fonnation, Canning Basin, Western Australia are described. The fauna consists on new obolid taxa, Libecoviella divaricata n. sp., Wahwahlingula? emanuelensis n. sp., and Zhanatellidae n. gen? A, and two acrotretoids, Semitreta lauriei n. sp., and Ottenbyella shidertensis (Popov & Holmer, 1994). Contemporaneous trilobite and conodont faunas indicate a late Lancefieldian (La3) to mid Bendigonian (Be2) (=earliest Arenigian) age for the Emanuel Fonnation. The lingulate fauna is largely endemic at the species level, with minor faunal links to Kazakhstan and Bohemia.

  • 17.
    Butler, Aodhan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Holmer, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Bauert, Heikki
    NGO Geoguide Baltoscandia, Estonia.
    Streng, Michael
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Agić, Heda
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Recent palaeobiological and stratigraphical advances from the Cambrian of Estonia2011In: The 2nd Wiman Meeting: Carl Wiman's Legacy: 100 years of Swedish Palaeontology, Uppsala, 2011, p. 5-5Conference paper (Refereed)
    Abstract [en]

    The unique Cambrian sediments of Estonia represent an important and understudied component of the Baltic system. Here we present an overview of recent field studies conducted by Uppsala University in association with colleagues from the Baltic Geotourism project, that have revealed a number of exciting discoveries in terms of Cambrian palaeontology and stratigraphy of Estonia. These include new purported stem lophotrochozoans with bizarre shell structure. Current efforts to describe and systematically appraise this material are outlined. The presence of unusual shell structure and whether this is the result of taphonomic alteration or indeed represents a novel shell structure type is examined. We propose herein affinities to the inarticulate stem-brachiopod Mickwitzia based upon the presence of an umbo and the overall gross morphology.  Possible new records of Estoniadiscus discinoides (Schmidt 1888), an extremely rare enigmatic organism with postulated affinities to eldonioids or other stem-group lophophorates are also described from the type section at Kakumägi, within the Kakumägi member Member of the lower Cambrian Tiskre formationFormation. The discovery of Dictyonema Rhabdinopora sp. graptolites, which have until now demarcated the Cambrian-Ordovician boundary, in-situ approximately 3 m below the previous reported occurrence from the Pakri cape section of the Kallavere formation Formation is also significant. Our findings highlight the need for both a stratigraphical and palaeobiological reapprasal of these important sequences, and their correlative implications for the Swedish and broader Baltoscandian regions.

  • 18.
    Butler, Aodhan
    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.
    Garwood, Russel
    Manchester X-Ray Imaging Facility.
    Lowe, Tristan
    Manchester X-Ray Imaging Facility.
    Holmer, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Constructing Cambrian body-plans: critical evaluation of tommotiid and stem-brachiopod character homologies2012Conference paper (Other academic)
  • 19.
    Butler, Aodhan
    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.
    Holmer, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Babcock, Loren
    Lund University.
    Exceptional preservation of lower Cambrian mickwitziidsfrom the Indian Springs Lagerstätte, Nevada, and implications for early brachiopod phylogeny2011In: The Palaeontological Association, 55th Annual Meeting: Programme and Abstracts, 2011, p. 44-45Conference paper (Refereed)
  • 20.
    Butler, Aodhan
    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.
    Skovsted, Christian B.
    Naturhistoriska Riksmuseet.
    Holmer, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Resolving the position of problematic lower to middle Cambrian lophotrochozoans: a critical appraisal of tommotiid and stem-brachiopod character homologies2012Conference paper (Other academic)
  • 21.
    Butler, Aodhán D.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Garwood, Russell
    The University of Manchester, School of Earth Atmospheric and Environmental Sciences.
    Streng, Michael
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Lowe, Tristan
    The Manchester X-Ray Imaging Facility, School of Materials, The University of Manchester.
    Holmer, Lars E.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    X-ray microtomography of the tommotiid Micrina reveals cellular and ultrastructural preservation, confirming a tommotiid stem-linguliform affinityManuscript (preprint) (Other academic)
  • 22.
    Butler, Aodhán D.
    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.
    Holmer, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Babcock, Loren
    Lund.
    Exceptionally-preserved Mickwitzia from the Indian Springs Lagerstätte.In: Journal of Paleontology, ISSN 0022-3360, E-ISSN 1937-2337Article in journal (Other academic)
    Abstract [en]

    A new assemblage of the early Cambrian stem group brachiopod Mickwitzia is described from the Indian Springs Lagerstätte possessing exceptionally preserved mantle setae. Critical analysis of shell structure and mantle setae from these specimens with those from additional sites with variable diagenetic history reveals the extent of taphonomic alteration and further sheds light on the phylogenetic position of the mickwitziids. A morphometric approach to shell outline and growth landmarks within these specimens reveals a clear species level discriminant signal of Nevada Mickwitzia in comparison to M. monlifera from Sweden. Detailed electron micrographs allow revision of the genus diagnosis for Mickwitzia based on presence of inward pointing phosphatic cones and tangential setae bearing tubes. We also conclude the inward pointing cone structures are not consistent with setal bearing structures as previously thought, but rather represent an endopunctae-like structure. A tommotiid-like shell architecture and presence of acrotretid columns in the dorsal juvenile shell of M. cf. occidens further strengthens the proposed close relationship between stem-group brachiopods and tommotiids.

  • 23.
    Butler, Aodhán D.
    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.
    Holmer, Lars E.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Babcock, Loren E.
    Exceptionally preserved Mickwitzia from the Indian Springs Lagerstätte (Cambrian Stage 3), Nevada2015In: Journal of Paleontology, ISSN 0022-3360, E-ISSN 1937-2337, Vol. 89, no 6, p. 933-955Article in journal (Refereed)
    Abstract [en]

    ABSTRACT Exceptionally preserved specimens of the Cambrian stem-group brachiopod Mickwitzia occidens Walcott, 1908 are described in detail from the Indian Springs LagerstÀtte in Nevada, USA. Shell structure and preserved mantle setae from these specimens reveal a variable diagenetic (taphonomic) history and provide insight into the phylogenetic position of mickwitziids. Morphologic and morphometric comparison to M. monilifera (Linnarsson, 1869) from Sweden and M. muralensis Walcott, 1913 from British Columbia, Canada reveals clear species-level distinctions. Scanning electron microscopic analysis allows revision of the generic diagnosis. The Mickwitzia shell is characterized by the presence of inwardly pointing phosphatic cones and tangential setae-bearing tubes. The inwardly pointing cone structures are not consistent with setal bearing structures as previously thought, but rather represent endopunctae-like structures. Acrotretid-like shell structures and shell-penetrating setae in M. occidens strengthen the previously proposed close relationship between stem-group brachiopods and tommotiids, a group of small shelly fossils.

  • 24.
    Claybourn, Thomas M.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology. Department of Biological Sciences, Macquarie University, Sydney, NSW 2109.
    Jacquet, Sarah M.
    Department of Geological Sciences, University of Missouri, Columbia, USA.
    Skovsted, Christian B.
    Swedish Museum of Natural History, Stockholm, Sweden.
    Topper, Timothy P.
    Shaanxi Key laboratory of Early Life and Environments, State Key Laboratory of Continental Dynamics and Department of Geology, Northwest University, Xi'an 710069, China.
    Holmer, Lars E.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology. Shaanxi Key laboratory of Early Life and Environments, State Key Laboratory of Continental Dynamics and Department of Geology, Northwest University, Xi'an 710069, China.
    Brock, Glenn A.
    Department of Biological Sciences, Macquarie University, Sydney, Australia.
    Mollusks from the upper Shackleton Limestone (Cambrian Series 2), Central Transantarctic Mountains, East Antarctica2019In: Journal of Paleontology, ISSN 0022-3360, E-ISSN 1937-2337, Vol. 93, no 3, p. 437-459Article in journal (Refereed)
    Abstract [en]

    An assemblage of Cambrian Series 2, Stages 3–4, conchiferan mollusks from the Shackleton Limestone, Transantarctic Mountains, East Antarctica, is formally described and illustrated. The fauna includes one bivalve, one macromollusk, and 10 micromollusks, including the first description of the species Xinjispira simplex Zhou and Xiao, 1984 outside North China. The new fauna shows some similarity to previously described micromollusks from lower Cambrian glacial erratics from the Antarctic Peninsula. The fauna, mainly composed of steinkerns, is relatively low diversity, but the presence of diagnostic taxa, including helcionelloid Davidonia rostrata (Zhou and Xiao, 1984), bivalve Pojetaia runnegari Jell, 1980, cambroclavid Cambroclavus absonus Conway Morris in Bengtson et al., 1990, and bradoriid Spinospitella coronata Skovsted et al., 2006, as well as the botsfordiid brachiopod Schizopholis yorkensis (Ushatinskaya and Holmer in Gravestock et al., 2001), in the overlying Holyoake Formation correlates the succession to the Dailyatia odyssei Zone (Cambrian Stages 3–4) in South Australia.

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  • 25.
    Claybourn, Thomas M.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology. Macquarie University.
    Skovsted, Christian B.
    Holmer, Lars E.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology. Northwest University, Xián, China.
    Pan, Bing
    Myrow, Paul M.
    Topper, Timothy P.
    Brock, Glenn A.
    Brachiopods from the Byrd Group (Cambrian Series 2, Stage 4) Central Transantarctic Mountains, East Antarctica: Biostratigraphy, Phylogeny and Systematics2020In: Papers in Palaeontology, ISSN 2056-2799, E-ISSN 2056-2802, Vol. 6, no 3, p. 349-383Article in journal (Refereed)
    Abstract [en]

    Brachiopods from Cambrian Series 2, Stage 4 carbonate strata of the Byrd Group in the Central Transantarctic Mountains, East Antarctica, are described for the first time. These include six lingulate, one paterinate and one rhynchonelliform taxon, including the new lingulate brachiopod Plicarmus wildi gen. et sp. nov. The biostratigraphy correlates closely to the brachiopods recently reported from the Xinji Formation (Shuiyu section) in North China, as well as brachiopods recovered from the Dailyatia odyssei Zone across the Arrowie Basin of South Australia. These findings also support the previously identified close palaeobiogeographyof these regions. The first unambiguous example of the acrotretid brachiopod Eohadrotreta zhenbaensis Li & Holmer outside South China is also identified in the context of its ontogenetic stages. Well-preserved specimens of the acrotheloid Schizopholis yorkensis (Holmer & Ushatinskaya) facilitate a new reconstruction of its musculature and visceral region. These data are synthesized into a new cladistic analysis that resolves Acrotheloidea as a well-supported monophyletic clade and supports previous hypotheses of a morphocline in acrotheloid evolution.

  • 26.
    Claybourn, Thomas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Skovsted, Christian B.
    Betts, Marissa J.
    Holmer, Lars E.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology. Northwest University, Xián, China.
    Bassett-Butt, Lucy
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Brock, Glenn A.
    Camenellan tommotiids from the Cambrian Series 2 of East Antarctica: Biostratigraphy, palaeobiogeography, and systematics2021In: Acta Palaeontologica Polonica, ISSN 0567-7920, E-ISSN 1732-2421, Vol. 66, no 1, p. 207-229Article in journal (Refereed)
    Abstract [en]

    Cambrian Series 2 shelly fossils from thick carbonate successions in East Antarctica have received limited systematic treatment through the 20th century. Described here are the East Antarctic camenellan tommotiids from the Shackleton Limestone in the Central Transantarctic Mountains and the Schneider Hills limestone in the Argentina Range. This material comes from both newly sampled collections and incompletely described material from older collections. The assemblage supports correlation to the Dailyatia odyssei Zone and Pararaia janeae Trilobite Zone of South Australia, with the newly examined specimens of Dailyatia decobruta from the Shackleton Limestone providing direct correlation to the Mernmerna Formation of the Ikara-Flinders Ranges and White Point Conglomerate of Kangaroo Island. These East Antarctic assemblages include five species referred to Dailyatia, in addition to an undetermined kennardiid species and fragments of the problematic Shetlandia multiplicata. The results further corroborate the notion that fossiliferous carbonate clasts found on King George Island were sourced from the same carbonate shelf as the Shackleton Limestone, with the taxon S. multiplicata found in both units. The Schneider Hills limestone in the Argentina Range has yielded sclerites of Dailyatia icari sp. nov., currently only known from this location.

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  • 27. Cohen, B. L.
    et al.
    Holmer, L. E.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology. Palaeobiology.
    Lüter, C.
    The brachiopod fold: a neglected body plan hypothesis2003In: Palaeontology, ISSN 0031-0239, E-ISSN 1475-4983, Vol. 46, no 1, p. 59-65Article in journal (Refereed)
    Abstract [en]

    Attention is drawn to Nielsen's radical body plan concept, here named the 'brachiopod fold hypothesis', under which brachiopods and phoronids are recognized to be transversely folded across the ontogenetic anterior–posterior axis so that, to make useful comparisons with other phyla, these organisms must be conceptually unfolded. Under the hypothesis brachiopod brachial and pedicle shell valves are respectively 'anterior' and 'posterior' rather than 'dorsal' and 'ventral' as traditionally described. The hypothesis makes sense of the symmetry axes of the brachiopod shell, is consistent with various indications from fossil and Recent brachiopods, and gives rise to predicted patterns of axis–determining gene expression that differ from those obtaining under the traditional view of the body plan, whilst the variety of folding movements in different lineages implies that superficially dissimilar morphogenetic folds may be fundamentally homologous. Convergent folding patterns are noted in some other organisms. A previous conjecture that inarticulate linguloid brachiopods were derived from halkieriid–like ancestors is elaborated with proposals that recognize possible functional continuities of coelomic and marginal sclerite functions, and it is noted that an ancestrally facultative fold could have become incorporated by genetic assimilation into the brachiopod developmental program. An experimental approach is outlined to test the possibility that some members of the 'small shelly fauna' may have been members of the halkieriid–like brachiopod stem lineage and it is also suggested that buoyancy modification may have been an important function of mineralization amongst Lower Cambrian floaters and swimmers, since negative buoyancy would facilitate access to the benthic niche.

  • 28. Cusack, M.
    et al.
    Balthasar, U.
    School of Geographical and Earth Sciences, University of Glasgow, UK .
    Faryma, L.
    School of Geographical and Earth Sciences, University of Glasgow, UK .
    Chung, P.
    School of Geographical and Earth Sciences, University of Glasgow, UK .
    Holmer, L. E.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Jin, J.
    Department of Earth Sciences, University of Western Ontario, London, Ontario Canada .
    Percival, I. G.
    Popov, L. E.
    Department of Geology, National Museum of Wales, UK .
    Relic aragonite from Ordovician-Silurian brachiopods: Implications for the evolution of calcification2011In: Geotechnique, ISSN 0016-8505, E-ISSN 1751-7656, Vol. 39, no 10, p. 967-970Article in journal (Refereed)
    Abstract [en]

    Understanding the influence of aragonite/calcite sea conditions on the evolution of biocalcification relies strongly on the correct interpretation of the original composition of calcareous taxa. Aragonite dissolves or inverts into calcite over geological time, and its preservation is currently unknown to predate the Pennsylvanian. Here we present direct evidence for the common occurrence of relic aragonite in Ordovician and Silurian trimerellid brachiopods, thereby extending the known range of aragonite preservation by more than 130 million years. Together with associated hypercalcifying taxa of putatively original aragonite or high-magnesium calcite composition and considerations of the temperature dependence of aragonite and calcite precipitation, our results suggest that the evolution of aragonite biomineralization might have presented an adaptive advantage in shallow marine tropical waters of calcite seas. A targeted search for Paleozoic aragonite should both resolve the original composition of consistently recrystallized taxa and enable the reassessment of the aragonite/calcite sea paradigm in a paleoenvironmental context.

  • 29. Devaere, Lea
    et al.
    Holmer, Lars Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Clausen, Sebastien
    Vachard, Daniel
    Oldest mickwitziid brachiopod from the Terreneuvian of southern France2015In: Acta Palaeontologica Polonica, ISSN 0567-7920, E-ISSN 1732-2421, Vol. 60, no 3, p. 755-768Article in journal (Refereed)
    Abstract [en]

    Kerberellus marcouensis Devaere, Holmer, and Clausen gen. et sp. nov., originally described as Dictyonina? sp., from the Terreneuvian of northern Montagne Noire (France) is reinterpreted as the oldest relative to or member of mickwitziid-like stem-group brachiopods. Were extracted 170 partial to complete phosphatic internal moulds of two types of adult and one type of juvenile disarticulated valves, rarely externally coated with phosphates, from the calcareous Heraultia Member of the Marcou Formation. They correspond to microbially infested, ventribiconvex, inequivalved, bivalved shells. The ventral interarea is bisected by a triangular sinus. The shell, most probably dominantly organic in origin, is orthogonally pierced throughout its entire thickness by radially-aligned, smooth-walled, cylindrical to hourglass shaped canals except for the sub-apical planar field (interarea). The through-going canals of K. marcouensis are compared with brachiopods endopunctae and with canals of mickwitziid brachiopods. The absence of striations on K. marcouensis canal walls, typical of mickwitziids, implies that (i) the tubes could have been depleted of setae or; (ii) traces of the microvilli were not preserved on the tube wall (taphonomic bias) or, (iii) the tubes could have been associated with an outer epithelial follicle.

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  • 30.
    Dronov, A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Holmer, L. E.
    Depositional sequences in the Ordovician of Baltoscandia1999In: Acta Universitatis Carolinea - Geologica, 1999, Vol. 43, p. 133-136Conference paper (Refereed)
  • 31.
    Dronov, A. Ju.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Koren, T. N.
    Popov, L.
    Tolmacheva, T. Ju.
    Holmer, L. E.
    Uppermost Cambrian and Lower Ordovician in northwestern Russia: sequence stratigraphy, sea level changes and bioevents1995In: Ordovician Odyssey: short papers for the Seventh International Symposium on the Ordovician System, 1995, p. 319-322Conference paper (Refereed)
  • 32. Dronov, A. V.
    et al.
    Holmer, Lars
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences, Palaeobiology. Palaeobiology.
    Ordovician Eustacy2004Conference paper (Other scientific)
  • 33.
    Duan, Xiaolin
    et al.
    State Key Laboratory of Continental Dynamics, Shaanxi Key Laboratory of Early Life and Environments, Department of Geology, Northwest University, Xi'an, 710069, China.
    Betts, Marissa J.
    State Key Laboratory of Continental Dynamics, Shaanxi Key Laboratory of Early Life and Environments, Department of Geology, Northwest University, Xi'an, 710069, China; Division of Earth Sciences, School of Environmental and Rural Science, University of New England, Armidale, NSW 2351, 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.
    Chen, Yanlong
    State Key Laboratory of Continental Dynamics, Shaanxi Key Laboratory of Early Life and Environments, Department of Geology, Northwest University, Xi'an, 710069, China.
    Liu, Fan
    State Key Laboratory of Continental Dynamics, Shaanxi Key Laboratory of Early Life and Environments, Department of Geology, Northwest University, Xi'an, 710069, China.
    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.
    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.
    Early Cambrian (Stage 4) brachiopods from the Shipai Formation in the Three Gorges area of South China2021In: Journal of Paleontology, ISSN 0022-3360, E-ISSN 1937-2337, Vol. 95, no 3, p. 497-526Article in journal (Refereed)
    Abstract [en]

    Diverse and abundant fossil taxa have been described in the lower Cambrian Shipai Formation in the Three Gorges area of Hubei Province, South China, but the taxonomy and diversity of the co-occurring brachiopod fauna are still far from clear. Here we describe the brachiopod fauna recovered from the Shipai Formation in the Three Gorges area of South China, including representatives of the subphylum Linguliformea: linguloids (Lingulellotreta ergalievi, Eoobolus malongensis, and Neobolidae gen. indet. sp. indet.), and an acrotretoid (Linnarssonia sapushanensis); and representatives from the subphylum Rhynchonelliformea: the calcareous-shelled Kutorginates (Kutorgina sinensis, Kutorgina sp., and Nisusia liantuoensis). This brachiopod assemblage and the first occurrence of Linnarssonia sapushanensis shell beds permit correlation of the Shipai Formation in the Three Gorges area of Hubei Province with the Stage 4 Wulongqing Formation in the Wuding area of eastern Yunnan. This correlation is further strengthened by the first appearance datum (FAD) of the rhynchonelliform brachiopod Nisusia in the upper silty mudstone of both the Shipai and Wulongqing formations. The new well-preserved material, derived from siliciclastic rocks, also gives critical new insights into the fine shell structure of L. sapushanensis. Microstructural studies on micromorphic acrotretoids (like Linnarssonia) have previously been restricted to fossils that were acid-etched from limestones. This is the first study to carry out detailed comparative ultrastructural studies on acrotretoid shells preserved in siliciclastic rocks. This work reveals a hollow tube and solid column microstructure in the acrotretoid shells from the Shipai Formation, which is likely to be equivalent of traditional column and central canal observed in shells dissolved from limestones.

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  • 34. Duan, Xiaolin
    et al.
    Liang, Yue
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology. Northwest University, Xi’an.
    Holmer, Lars E.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology. Northwest University, Xi’an.
    Zhang, Zhifei
    First report of acrotretoid brachiopod shell beds in the lower Cambrian (Stage 4) Guanshan Biota of eastern Yunnan, South China2021In: Journal of Paleontology, ISSN 0022-3360, E-ISSN 1937-2337, Vol. 95, no 1, p. 40-55Article in journal (Refereed)
    Abstract [en]

    Brachiopod shell accumulations are abundant and diverse in the lower Cambrian strata of Yunnan Province, South China, but most commonly they are composed of linguloid and acrotheloid brachiopods. Here, we describe the first record of shell beds with high-density accumulations of microscopic acrotretoid brachiopods (usually <2 mm in width) in the muddy deposits of the Wulongqing Formation (Guanshan Biota, Cambrian Stage 4) in the Wuding area of Yunnan Province. The acrotretoid shell beds from the Wulongqing Formation vary from thin mm-thick pavements to more well-developed beds, several centimeters thick. The occurrence of remarkably rich acrotretoid shell beds indicates that microscopic lingulates began to exert an important role in hardening and paving the soft-substrate seafloor during the early Cambrian evolution of Phanerozoic “mixgrounds.” The new Guanshan material is referred to a new species, Linnarssonia sapushanensis n. sp., which differs from other species of Linnarssonia mainly in having a well-developed internal pedicle tube, as well as a relatively longer dorsal median septum. The occurrence of Linnarssonia sapushanensis n. sp. in the Wulongqing Formation in eastern Yunnan extend the oldest record of the genus on the Yangtze Platform of South China back to at least Cambrian Stage 4.

  • 35.
    Ebbestad, Jan Ove R.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Holmer, Lars E.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Ceratopygekalken - den “ordoviciska explosionens” förstenade rester2000Other (Other (popular science, discussion, etc.))
  • 36.
    Egerquist, Eva
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology, Palaeontology group.
    Holmer, Lars E.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Early-Middle Ordovician (Billingen-Volkhov stages) Orthide and Protorthide brachiopods from the East Baltic2006In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 128, no 4, p. 339-348Article in journal (Refereed)
    Abstract [en]

    Three new orthide species: Orthidium lavensis, Orthidium gambolovensis and Ranorthis rotunda, and one new protorthide species: Skenidioides minutus, are described from the Early-Middle Ordovician (Billingen-Volkhov stages) of Estonia and north-western Russia. This is the first record of Orthidium from Baltica, whereas Skenidioides was known previously only from the Keila and Oandu stages in Estonia.

  • 37. Fang, Ruisen
    et al.
    Liang, Yue
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Chen, Yanlong
    Liu, Fan
    Hua, Hong
    Holmer, Lars E.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Zhang, Zhifei
    Late Ediacaran cavity-dwelling filamentous microorganisms accommodated in a valve-like organism from the uppermost Dengying Formation in eastern Yunnan of South China2022In: Precambrian Research, ISSN 0301-9268, E-ISSN 1872-7433, Vol. 379Article in journal (Refereed)
    Abstract [en]

    The Ediacaran–Cambrian transition, one of the major turning points in Earth’s history, is characterized by an epoch-making change in biosphere. In South China, the late Ediacaran Dengying Formation (ca. 551–538 Ma) is an important stratigraphic unit yielding trace fossils, tubular skeletal fossils and some complex forms that represent possible bilateral animals. The fossil-bearing Ediacaran strata of eastern Yunnan is hitherto known from the Jiucheng Member containing the Jiangchuan Biota, together with the enigmatic cosmopolitan taxon Shaanxilithes. Here, we present for the first time cavity-dwelling filamentous microorganisms accommodated within a valve-like fossil from the upper Baiyanshao Member of the Dengying Formation at the Sujiawa Section in Huize County, eastern Yunnan of China. SEM scanning and Micro-CT reconstruction indicate that the well-preserved filaments were characterized by mycelial network structures with abundant branching pattern. Preservation of filamentous microorganisms might result from the decay process of soft parts that were originally accommodated and enclosed within the valve-like organism, and subsequently preserved by early diagenetic phosphatization, which obscures their original organic identity and chemical composition. This paper potentially presents the first fossil evidence of a saprophytic relationship between microorganisms as decomposers and a valve-like organism prior to the eve of the Cambrian Explosion of metazoan animals.

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  • 38.
    Felitsyn, S
    et al.
    Institute of Precambrian Geology and Geochronology, Russian Academy of Science, St. Petersburg, Russia .
    Sturesson, U
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Popov, L
    All-Russian Scientific Research Geological Institute, St. Petersburg, Russia .
    Holmer, L
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Nd isotope composition and rare earth element distribution in early Paleozoic biogenic apatite from Baltoscandia: A signature of Iapetus ocean water1998In: Geology, ISSN 0091-7613, E-ISSN 1943-2682, Vol. 26, no 12, p. 1083-1086Article in journal (Refereed)
    Abstract [en]

    Analyses of the Nd isotopic composition and REE distribution in biogenic apatite (organophosphatic brachiopods and conodont elements) from the Cambrian and Ordovician sequences of the Baltic plate give new insights into the development of the southeastern segment of the continental margin bounding the Iapetus ocean. The Nd isotope analyses show ϵNd(t) of ∼−8.0 for the Cambrian, indicating that the main source of the sedimentary deposition came from weathered sedimentary rocks of Vendian and Cambrian age. The increase of ϵNd(t) to ∼−5.0 for the Early Ordovician indicates the appearance of a new source of radiogenic Nd in the surrounding area—most likely a volcanic arc along the western borderland of Baltic plate from Arenigian time. Samples of Cambrian biogenic apatite show significantly lower total amounts of REE than do the Ordovician samples, and this is probably due to a shorter exposure to seawater before burial during Ordovician sedimentary accumulation in Baltoscandia. These preliminary results suggest that biogenic apatite from the Baltoscandian basin preserves geochemical signatures of the water masses that will be important for understanding the evolution of the Iapetus ocean during the early Paleozoic.

  • 39.
    Freeman, Rebecca
    et al.
    Missouri State University.
    Miller, James
    Missouri State University.
    Holmer, Lars
    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.
    Linguate brachiopod extinction and global migration coinciding with three laurentian trilobite extinction events during the late cambrian-earliest ordovician2011In: GSA Annual Meeting in Minneapolis, Minnesota USA, 2011, p. 543-543Conference paper (Refereed)
    Abstract [en]

    Laurentian lingulate brachiopods on the outer shelf were affected by a series of three extinction events coinciding with trilobite extinctions (biomere boundaries). There was rapid turnover of the brachiopod faunas during each event. These extinctions are seen at the Steptoean/Sunwaptan, Sunwaptan/Skullrockian, and Skullrockian/Stairsian North American Upper Cambrian–lowest Ordovician stage boundaries. Lingulate brachiopods were examined from the Orr, Notch Peak, House, and Fillmore formations of western Utah and from the Catlin Formation and Hales Limestone of Nevada. Associated with each extinction event, brachiopod genera/species appeared that are also found in coeval strata in Kazakhstan and/or western Gondwana (e.g., Quadrisonia minorZhanatella rotunda, and species of Eurytreta). Some of these taxa may have appeared in the deeper water/higher latitude environments of Kazakhstan or Gondwana before appearing on the Laurentian shelf. Eurytreta may have appeared in deep-water slope environment at Tybo Canyon, Nevada before appearing in shelf environments in Utah.

    The Steptoean/Sunwaptan and Sunwaptan/Skullrockian boundaries were also examined in the Wilberns and Tanyard formations of central Texas. Latest Steptoean strata yield taxa widely distributed in Laurentia, although endemic to it, such as Linnarssonella girtyi. There is abrupt faunal change at the base of the Sunwaptan, followed by a fauna that is also endemic to Laurentia and is virtually identical to a fauna described from the Snowy Range Formation of Wyoming and Montana. This fauna is not present in coeval strata in Utah and Nevada. Mid-Sunwaptan strata in Texas yield a fauna with strong affinities to coeval strata in Utah; all species are endemic to Laurentia. The Sunwaptan/Skullrockian boundary is also characterized by complete turnover, this time with a replacement fauna having affinities both to the Laurentian outer shelf and to Gondwana and Kazakhstan.

    This pattern of events suggests that Late Cambrian–earliest Ordovician extinctions in Laurentia were caused by environmental changes that altered conditions on the Laurentian shelf to conditions more similar to those in deeper water (Kazakhstan) or higher latitudes (Gondwana), and these changes facilitated migration of globally distributed lingulate brachiopods.

  • 40.
    Frisk, Åsa
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences, Palaeobiology. Paleobiologi.
    Holmer, Lars
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences, Palaeobiology. Paleobiologi.
    Linguliform and Craniiform Brachiopods from the Ordovician Tvären Crater, Sweden2005In: The 5th International Brachiopod Conference, Copenhagen, Denmark, 2005Conference paper (Other scientific)
    Abstract [en]

    Linguliform and Craniiform Brachiopods from the Ordovician Tvären Crater, Sweden

    Åsa M. Frisk1 and Lars E. Holmer1

    1Department of Earth Sciences, Palaeobiology, Uppsala University, Norbyvägen 22, SE-752 36 Uppsala, Sweden

    During the Ordovician several bolides hit the Baltoscandian Epicontinental Sea. One of the impacts occurred at a water depth of 300 m and resulted in the 2 km wide Tvären crater, now situated in the Stockholm Archipelago, Sweden. The pre-impact sedimentary sequence at Tvären consisted of Ordovician carbonates resting on non-lithified sands of Early to earliest Middle Cambrian age. Following the impact event, deposition of carbonates continued (Dalby Limestone). The crater acted like a sheltering rim for the deposition of sediments, also displaying pure new settings for the fauna still living in the surrounding sea.

    The studied material from Tvären consists of glacial erratics from the area immediately southeast of the bay of Tvären on the coast of Södermanland. The limestone boulders are all fairly fossiliferous and have yielded numerous ostracods and brachiopods, the brachiopods being the next most common group; however the brachiopod fauna has never been previously studied in detail. The linguliform brachiopod fauna recorded from the erratic boulders include a large new lingulid genus and species, as well as new species of Schizotreta and Paterula. Eoconulus robustus Holmer is the only linguliform species previously recorded from the Dalby Limestone in Sweden.

  • 41.
    Frisk, Åsa
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences, Palaeobiology. Paleobiologi.
    Lindström, Maurits
    Holmer, Lars
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    A marine impact crater as an Ordovician ecosystem; the Tvären crater2005In: SEPM Research Conference; The sedimentary Record of Meteorite Impacts, 2005Conference paper (Other scientific)
    Abstract [en]

    A marine impact crater as an Ordovician ecosystem; the Tvären crater

    Frisk, Å.1, Lindström, M.2 & Holmer, L.E1

    1Department of Earth Sciences, Palaeobiology, Uppsala University, Norbyvägen 22, SE-752 36 Uppsala, Sweden, asa.frisk@geo.uu.se, lars.holmer@pal.uu.se

    2Department of Geology and Geochemistry, Stockholm University, Sweden, maurits.lindström@geo.su.se

    The Tvären crater was formed as a result of an impact in the Ordovician Baltoscandian epicontinental sea, now situated in the Stockholm Archipelago, Sweden. The bolide impact resulted in an approximately 2 km wide crater and the pre-impact sedimentary sequence consists of Ordovician carbonates resting on non-lithified sands of Early to earliest Middle Cambrian age. After the impact event and the settling of the impact ejecta and resurge material, deposition of carbonates continued (Dalby Limestone). The lithology and thickness of the post-impact Dalby Limestone vary depending on the depositional environment relative to the cratered seascape. The crater itself acted like a sheltering rim for the deposition of sediments, also causing a fairly rapid sedimentation rate compared to the normal sedimentation of the Dalby limestone. The area consequently displayed pure new settings for the marine fauna still living in the surrounding sea, though not affected by the impact, and thus creating a new ecosystem. This particular condition makes it possible to get a good precision of the sedimentation and faunal succession occurring in the crater. Drillings in the Tvären crater were conducted in 1991 resulting in an almost complete drill core through the sedimentary succession in the crater. The base of the core consists of crystalline breccia followed by resurge deposits and then the sedimentation of the Dalby Limestone. The post-impact fossil fauna mostly consists of chitinozoans, graptolites, trilobites, bryozoans, ostracodes, echinoderms, cephalopods and brachiopods. Certain groups are restricted to deeper or lower water levels, varying during the sedimentation, while some occur throughout the succession. A detailed biostratigraphy through the post-impact succession of the drill core is being conducted to understand how the abundance of species changed in relation to the varied environments and how the pre-impact faunal groups recovered gradually as life returned onto a sterile seafloor.

  • 42.
    Frisk, Åsa
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences, Palaeobiology. Paleobiologi.
    Lindström, Maurits
    Holmer, Lars
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences, Palaeobiology. Paleobiologi.
    Faunal recovery in the Ordovician Lockne and Tvären craters2005In: Lundadagarna i Historisk Geologi och Paleontologi IX, 2005Conference paper (Other scientific)
    Abstract [en]

    FAUNAL RECOVERY IN THE ORDOVICIAN LOCKNE AND TVÄREN CRATER

    Åsa Frisk1, Maurits Lindström2 & Lars Holmer1

    1Uppsala University, Department of Earth Sciences, Palaeobiology, Norbyvägen 22, SE-752 36 Uppsala, Sweden.

    2Stockholm University, Department of Geology and Geochemistry, SE-106 91 Stockholm, Sweden

    Limited amount of work has been carried out looking at the aftermath of marine impacts; in particular the patterns of faunal recovery in and around marine craters have never been studied in detail. In Baltoscandia several marine impacts occurred during the Ordovician, and this project focuses on the Lockne and Tvären craters. The Lockne crater in Jämtland, Sweden, is well exposed on land while the Tvären crater, located under water in the Stockholm archipelago, Sweden, is available as drill cores and erratic boulders. The impacted sedimentary sequence at Tvären consisted of Ordovician carbonates resting on non-lithified sands of Early to earliest Middle Cambrian age whereas at Lockne the same kind of limestone rests on Middle to Upper Cambrian bituminous mud. After the impact events and the settling of the impact ejectas and resurge materials, deposition of carbonates continued (Dalby Limestone).

    After impact the substrate became devoid of life. Large areas were affected by the local extinction of the fauna and thus provided virgin ground for the settling of marine fauna still living in the surrounding sea, though not affected by the impact. A dramatic alteration of the seafloor topography, caused by the impact, offered new habitats characterized by the crater morphology and sheltering rims. The immigrating biota, mostly consisting of chitinozoans, graptolites, trilobites, bryozoans, ostracodes, echinoderms, cephalopods and brachiopods, developed new ecosystems. Certain groups are restricted to deeper or lower water levels, varying during the sedimentation in the crater, while some occur throughout the succession. A detailed biostratigraphic study of the post-impact succession in the craters is being carried out in order to understand how the abundance of species changed in relation to the varied environments and how the pre-impact faunal groups recovered gradually as life returned onto a sterile seafloor.

  • 43.
    Frisk, Åsa
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences, Palaeobiology. Paleobiologi.
    Lindström, Maurits
    Paleobiologi.
    Holmer, Lars
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences, Palaeobiology. Paleobiologi.
    Palaeoecology of a marine impact crater in the Ordovician sea2005In: Palaeontological Association 49th Annual Meeting: University of Oxford, 2005Conference paper (Other scientific)
    Abstract [en]

    Palaeoecology of a marine impact crater in the Ordovician sea

    Åsa Frisk1, Maurits Lindström2 and Lars Holmer1

    1Department of Earth Sciences, Palaeobiology, Uppsala University, Sweden

    2Department of Geology and Geochemistry, Stockholm University, Sweden

    The aftermath of marine impacts, in particular the patterns of faunal recovery in and around marine craters, are poorly understood. In the Ordovician Baltoscandian epicontinental sea a bolide impact resulted in the Tvären crater. At present it is located in the Stockholm archipelago, Sweden, where drillings in 1991 resulted in two drill cores.

  • 44.
    Frisk, Åsa M
    et al.
    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.
    Diversity and distribution of post-impact Linguliform and Craniiform brachiopod colonizers in Upper Ordovician marine impact cratersManuscript (preprint) (Other (popular science, discussion, etc.))
  • 45. Funder, S
    et al.
    Holmer, Lars E
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Jacobs, P
    Evaluation of Estonian geological research2001Report (Other (popular science, discussion, etc.))
  • 46. Ghobadi Pour, M.
    et al.
    Popov, L
    Holmer, Lars E.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Hosseini-Nezhad, M.
    Rasuli, R.
    Fallah, K.
    Amini, A.
    Jahangir, H.
    Early Ordovician (Tremadocian) faunas and biostratigraphy of the Gerd-Kuh section, eastern Alborz, Iran2015In: Stratigraphy, ISSN 1547-139X, E-ISSN 2331-656X, Vol. 12, no 2, p. 55-61Article in journal (Refereed)
    Abstract [en]

    The Tremadocian of the East Alborz Region is dominated by condensed fine clasticsediments. These beds have yielded low to medium diversity trilobite associations, which belong to theolenid, nileid and raphiophorid biofacies, characteristic of an outer shelf environment. Five successivetrilobite biozones can be recognised in the Tremadocian succession of Alborz. The lower TremadocianAsaphellus inflatus–Dactylocephalus and Psilocephalina lubrica zones are characterised by mediumdiversity trilobite associations with strong links to contemporaneous faunas of South China. Three upperzones are documented in the section at Gerd-Kuh, the successive Vachikaspis insueta and Kayseraspiszones represent a low diversity interval during a time of rapid changes in the sea level changes; themedium diversity fauna of the Asaphellus fecundus–Taihungshania miqueli zone shows strong links tothe faunas of Mediterranean segment of Gondwana. Brachiopods in Gerd-Kuh are represented by themonotaxic Tarfaya Association and the low diversity Paralenorthis–Xinanorthis Association. Therecurrent oligotaxic Protambonites Association invaded the area in the late Tremadocian during shortterm regressive episodes.

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  • 47. Hairapetian, Vachik
    et al.
    Pour, Mansoureh Ghobadi
    Popov, Leonid E
    Hejazi, S Hassan
    Holmer, Lars E
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Evans, David
    Sharafi, Ali
    Ordovician of the Anarak Region: implications in understanding Early Palaeozoic history of Central Iran2015In: Stratigraphy, ISSN 1547-139X, E-ISSN 2331-656X, Vol. 12, no 2, p. 22-30Article in journal (Refereed)
    Abstract [en]

    The Pol-e Khavand area south-east of the town of Anarak preserves important clues for understanding geological evolution of Central Iran during the Palaeozoic. New observations confirm the non-conformable relationship between Doshakh metamorphites and overlying unmetamorphosed Lower Palaeozoic sediments, suggesting accretion of the volcanic arc in front of the Yazd block sometime in the late Cambrian to early Ordovician. The newly introduced volcano-sedimentary Polekhavand Formation preserves evidence of a ?Late Cambrian to Early Ordovician post-collisional bimodal volcanism and related extensional regime in the Pol-e Khavand area during that time. The Middle to Upper Ordovician interval of the studied succession is assigned to the newly introduced Chahgonbad Formation. The Darriwilian age of the base of this lithostratigraphical unit is demonstrated by the brachiopods Tritoechia and Yangtzeella which co-occur with a diverse a cephalopod assemblage. The low diversity fauna including brachiopods Hibernodonta sp., Hindella sp., Rostricellula cf. ambigena and trilobites Vietnamia cf. teichmulleri suggest a Katian age for the upper part of the unit. There is insufficient evidence for the existence of the hypothetical Palaeo Tethys suture zone south of the Pol-e Khavand area.

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    fulltext
  • 48.
    Hansen, Jesper
    et al.
    Department of Natural Sciences, Tromsø University Museum, NO-9037 Tromsø, Norway.
    Holmer, Lars E.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Taxonomy and biostratigraphy of Ordovician brachiopods from northeastern Ny Friesland, Spitsbergen2011In: Zootaxa, ISSN 1175-5326, E-ISSN 1175-5334, no 3076, p. 1-122Article in journal (Refereed)
    Abstract [en]

    We describe Early and Middle Ordovician brachiopod faunas from northeastern Spitsbergen and discuss their biostratigraphical and palaeoecological implications. We recognise 60 species and 41 genera representing both linguliform and rhynchonelliform brachiopods. These include one new genus, the obolid Lenticulella with the type species Lenticulella amphora (Krause & Rowell, 1975), and 23 new species: Ectenoglossa? oviforma, Elliptoglossa vulgaris, Rosobolus? elongatus, Broeggeria obscura, Mirilingula? svalbardensis, Schizotreta marginalis, Conotreta convexa, Cyrtonotreta profilbekkiensis, Cyrtonotreta spinosa, Eurytreta subtriangularis, Hisingerella maniformis, Semitreta basisslettaensis, Semitreta pustulosa, Semitreta spitsbergensis, Numericoma? proclina, Eoconulus subquadratus, Dictyonites mugilis, Pelonomia sulcata, Leptella (Leptella) inequicostellata, Protosken-idioides promontorium, Anomalorthis rossi, Nothorthis subpyramidalis and Phragmorthis noda. The Ordovician succession contains both intertidal and deep-sea deposits with brachiopod faunas from nearly the whole range of environments. The Tremadocian is represented by a succession of low-diversity, rhynchonelliform-dominated assemblages occupying shallow-marine environments. With the abrupt and large-scale drowning during the Floian, these faunas were replaced by a sparse slope fauna of micromorphic linguliforms. The outer shelf environments established in the latest Floian were occupied by a highly diverse brachiopod fauna dominated by micromorphic linguliform taxa. As the environment shifted toward the mid-shelf during the Darriwilian, however, the composition of the fauna changed to an Orthidiella-dominated assemblage of mostly rhynchonelliform taxa. The very late occurrence of the Orthidiella assemblage suggests that the Dapingian Orthidiella Zone found in America is probably diachronic. Although it includes many endemic species, the Middle Ordovician fauna shows a strong resemblance to the brachiopod fauna of Nevada. This study is based on approximately 16 500 brachiopod specimens obtained from both crack-out samples and acetic-acid-treated bulk samples.

  • 49. Hansen, Jesper
    et al.
    Holmer, Lars Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Diversity fluctuations and biogeography of Ordovician brachiopod faunas in northeastern Spitsbergen2010In: Bulletin of Geosciences, ISSN 1214-1119, E-ISSN 1802-8225, Vol. 85, no 3, p. 497-504Article in journal (Refereed)
    Abstract [en]

    Investigations of Lower and Middle Ordovician brachiopods in northeastern Spitsbergen have revealed strong ties to faunas in North America and Greenland at the generic level, although the fauna appears mostly endemic at the species level. During the early Palaeozoic, the archipelago of Svalbard, including Spitsbergen, was located at equatorial latitudes along the northeastern margin of Laurentia. The northeastern part of Spitsbergen experienced significant sea level changes, changing from very shallow water in the Tremadocian to deep water in the Floian and slowly back to shallow- water carbonate environments in the Middle Ordovician. The Tremadocian and early Floian brachiopod fauna was of low diversity with a high proportion of cosmopolitan warm-water related rhynchonelliform genera. In the late Floian there was an abrupt diversification event, taking place against the background of the increasing isolation of Laurentia, leading to a diverse, mostly endemic fauna. This diverse fauna remained into the Middle Ordovician. A similar diversification event has been recorded in North America, but here it occurs later, in the Dapingian. The diachroneity of brachiopod diversification within different parts of a continent has previously been shown for South China, suggesting that it may be a common phenomenon. In contrast to the mostly endemic Middle Ordovician rhynchonelliform genera, the linguliform brachiopods included many genera with a wide distribution. This difference is attributed to their different dispersal strategies.

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  • 50.
    Harper, David A. T.
    et al.
    Durham University, Department of Earth Sciences, Palaeoecosystems Group; Lund University, Department of Geology.
    Popov, Leonid E.
    Department of Geology, National Museum of Wales.
    Holmer, Lars E.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Brachiopods: origin and early history2017In: Palaeontology, ISSN 0031-0239, E-ISSN 1475-4983, Vol. 60, no 5, p. 609-631Article in journal (Refereed)
    Abstract [en]

    Despite many major advances in recent years, three key challenges remain in bringing clarity to the early history of the phylum: (1) identifying the origin, morphology and life modes of the first brachiopods; (2) understanding the relationships of the major groups to each other and higher sister taxa; and (3) unravelling the roles of the Cambrian and Ordovician radiations that set the agenda for much of subsequent brachiopod evolution. Since some 95% of all brachiopod taxa are extinct, the fossil record is the primary source of data to frame and test models for the evolution of the phylum. The acquisition of new, and the redescription of existing faunas, in precise spatial and temporal frameworks, using new and well-established analytical and investigative techniques, are as important as ever.

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