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Wyszukujesz frazę "Lower Cambrian" wg kryterium: Wszystkie pola

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    Wyświetlanie 1-5 z 5
    Tytuł:
    The oldest brachiopods from the lower Cambrian of South Australia
    Autorzy:
    Topper, T.P.
    Holmer, L.E.
    Skovsted, C.B.
    Brock, G.A.
    Balthasar, U.
    Larsson, C.M.
    Stolk, S.P.
    Harper, D.A.T.
    Powiązania:
    https://bibliotekanauki.pl/articles/22055.pdf
    Data publikacji:
    2013
    Wydawca:
    Polska Akademia Nauk. Instytut Paleobiologii PAN
    Tematy:
    brachiopod
    Cambrian
    South Australia
    Brachiopoda
    Tommotiida
    Paterinida
    Askepasma
    microstructure
    morphology
    shell
    Arrowie Basin
    Lower Cambrian
    Australia
    paleontology
    Opis:
    The morphology and organophosphatic shell structure of the paterinate brachiopod Askepasma is documented using new and previously collected specimens from the lower Cambrian of South Australia. Lack of adequately preserved material has seen the majority of paterinate specimens previously reported from South Australia referred to the genus Askepasma and treated under open nomenclature. Large collections of paterinates from the lower Cambrian Wilkawillina, Ajax, and Wirrapowie limestones in the Arrowie Basin, South Australia have prompted redescription of the type species Askepasma toddense and the erection of a new species, Askepasma saproconcha sp. nov. Askepasma saproconcha sp. nov. currently represents the oldest known brachiopod from the lower Cambrian successions in South Australia with a FAD in pre−trilo− bitic (Terreneuvian, Cambrian Stage 2, lower Atdabanian) strata in the basal part of the Wilkawillina and Wirrapowie limestones. Askepasma toddense predominantly occurs in Abadiella huoi Zone equivalent strata (Unnamed Cambrian Se− ries 2, Stage 3, middle–upper Atdabanian) in the upper part of the lower Wilkawillina, Wirrapowie, and Ajax limestones. The shell microstructure of Askepasma suggests a proximal stem group position within the Brachiopoda and similarities with tommotiid taxa provides further evidence that the ancestry of crown group brachiopods is firmly entrenched within the Tommotiida.
    Źródło:
    Acta Palaeontologica Polonica; 2013, 58, 1
    0567-7920
    Pojawia się w:
    Acta Palaeontologica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The new stem-group brachiopod Oymurania from the lower Cambrian of Siberia
    Autorzy:
    Kouchinsky, A.
    Holmer, L.E.
    Steiner, M.
    Ushatinskaya, G.T.
    Powiązania:
    https://bibliotekanauki.pl/articles/21826.pdf
    Data publikacji:
    2015
    Wydawca:
    Polska Akademia Nauk. Instytut Paleobiologii PAN
    Tematy:
    Brachiopoda
    brachiopod
    Oymurania
    Mickwitzia
    Micrina
    Setatella
    Lower Cambrian
    Cambrian
    Siberia
    Opis:
    A stem-group brachiopod, Oymurania gravestocki Ushatinskaya gen. et sp. nov. is described herein from the middle Atdabanian-lower Botoman Stages (-Cambrian Stage 3) of the Siberian Platform. The fossils were extracted from limestone beds of the Emyaksin, Perekhod, and Pestrotsvet formations as assemblages of disarticulated orthoconic to cyrtoconic porous shells in apatite preservation. The originally organophosphatic shells of Oymurania are externally similar to mitral sclerites (ventral valves) of the stem-group brachiopod Micrina, although no sellate-like sclerites, nor differentiated subapical area with apophyses were recognised in our material. The range of Oymurania shells with sub-central to posteromarginal apex is similar to that of ventral valves ofMickwitzia. Oymurania is also characterised by the system of radial and orthogonal canals open in pairs or triplets in small depressions or indentations of growth lamellae in the outer shell surface. The orthogonal (Micrina-Setatella type) and radial (horizontal setigerous tubes) canals are widespread among the early Cambrian stem-group brachiopods, such as Micrina, Mickwitzia, and Setatella. In addition to these canals, Oymurania exhibits a well-developed acrotretoid columnar microstructure, also known from Setatella. A broad subapical platform in cyrtoconic shells (presumably ventral valves) of Oymurania is interpreted homologous to the deltoid area in mitrals of Micrina and pseudointerarea/interarea in ventral valves of Setatella/paterinid brachiopods. Except with probable cell imprints and openings of orthogonal canals, no morphological differentiation was, however, reflected by the shell interior of Oymurania gravestocki. Being closely related to tannuolinids and mickwitziids, Oymurania complements the picture of diversification of the early Cambrian stem-group brachiopods that occurred in parallel with radiation of paterinids and other crow-group brachiopods on the Siberian Platform and worldwide.
    Źródło:
    Acta Palaeontologica Polonica; 2015, 60, 4
    0567-7920
    Pojawia się w:
    Acta Palaeontologica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Soft-tissue preservation in the Lower Cambrian linguloid brachiopod from South China
    Autorzy:
    Zhang, Z
    Han, J.
    Zhang, X.
    Liu, J.
    Shu, D.
    Powiązania:
    https://bibliotekanauki.pl/articles/20001.pdf
    Data publikacji:
    2004
    Wydawca:
    Polska Akademia Nauk. Instytut Paleobiologii PAN
    Tematy:
    Lingulellotreta malongensis
    Chengjiang Lagerstatte
    soft tissue preservation
    lophophore
    brachiopod
    linguloid brachiopod
    China
    Linguloidea
    gastrointestinal tract
    Cambrian
    Lower Cambrian
    paleontology
    Opis:
    The organization of the lophophore and the digestive system are recognized as two of the diagnostic characters in the definition of higher brachiopod taxa, and hence play a major role in their phylogenetic analysis, their structure, however, is very rarely fossilized. Here we describe and interpret specimens of the brachiopod Lingulellotreta malongensis, from the Lower Cambrian Chengjiang Lagerstätte (South China), one of the earliest known taxa of the Lingulellotretidae, in which lophophores and intact, U−shaped digestive tracts are extraordinarily well−preserved. The lophophore, with clearly preserved tentacles, corresponds to an early spirolophe developmental stage. The digestive tract consists of a mouth, esophagus, distended stomach, intestine and an anterior anus, and differs from that of the Chengjiang obolid Lingulella chengjiangensis by the presence of the dilated stomach and by the absence of a looped intestine as in Lingula. In addition, the relative sizes of the mantle and visceral cavities of Lingulellotreta malongensis also are described. These fossils demonstrate that by the Atdabanian brachiopods had already possessed advanced features, and suggest that a lophophore and a U−shaped intestine with an anterior anus are brachiopod plesiomorphies.
    Źródło:
    Acta Palaeontologica Polonica; 2004, 49, 2
    0567-7920
    Pojawia się w:
    Acta Palaeontologica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Small shelly fossils from the argillaceous facies of the Lower Cambrian Forteau Formation of Western Newfoundland
    Autorzy:
    Skovsted, C.B.
    Peel, J.S.
    Powiązania:
    https://bibliotekanauki.pl/articles/20504.pdf
    Data publikacji:
    2007
    Wydawca:
    Polska Akademia Nauk. Instytut Paleobiologii PAN
    Tematy:
    Brachiopoda
    Cambrian
    Forteau Formation
    geological setting
    Helcionellidae
    Hyolitha
    Lower Cambrian
    Newfoundland
    argillaceous facies
    brachiopod
    facies
    fossil
    helcionelloid mollusc
    hyolith
    mollusc
    paleontology
    small shelly fossil
    systematics
    Opis:
    A diverse fauna of helcionelloid molluscs, hyoliths, and other small shelly fossils is described from limestone layers within the Forteau Formation of the Bonne Bay region in western Newfoundland. The fauna is dominated by internal moulds of various molluscs and tubular problematica, but also includes hyolith opercula, echinoderm ossicles, and other calcareous small shelly fossils preserved by phosphatisation. Originally organophosphatic shells are comparatively rare, but are represented by brachiopods, hyolithelminths, and tommotiids. The fauna is similar to other late Early Cambrian faunas from slope and outer shelf settings along the eastern margin of Laurentia and may be of middle Dyeran age. The similarity of these faunas indicates that at least by the late Early Cambrian, a distinctive and laterally continuous outer shelf fauna had evolved. The Forteau Formation also shares elements with faunas from other Early Cambrian provinces, strengthening ties between Laurentia and Australia, China, and Europe during the late Early Cambrian. Two new taxa of problematic fossil organisms are described, the conical Clavitella curvata gen. et sp. nov. and the wedge−shaped Sphenopteron boomerang gen. et sp. nov.
    Źródło:
    Acta Palaeontologica Polonica; 2007, 52, 4
    0567-7920
    Pojawia się w:
    Acta Palaeontologica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Soft-part preservation in a linguliform brachiopod from the lower Cambrian Wulongqing Formation [Guanshan fauna] of Yunnan, South China
    Autorzy:
    Hu, S
    Zhang, Z.
    Holmer, L.E.
    Skovsted, C.B.
    Powiązania:
    https://bibliotekanauki.pl/articles/20740.pdf
    Data publikacji:
    2010
    Wydawca:
    Polska Akademia Nauk. Instytut Paleobiologii PAN
    Tematy:
    paleontology
    preservation
    linguliform brachiopo
    Lower Cambrian
    Cambrian
    Wulongqing Formation
    Yunnan Province
    South China
    brachiopod
    Linguliformea
    benthic community
    China
    Opis:
    Linguliform brachiopods were important components of early Cambrian benthic communities. However, exceptionally preserved soft parts in Cambrian linguliform brachiopods are extremely sparse, and the most important findings are from the early Cambrian Chengjiang Konservat Lagerstätte of Kunming, southern China. Here we describe the first record of preserved soft−part anatomy in a linguliform brachiopod from the early Cambrian Guanshan fauna (Wulongqing Formation, Palaeolenus Zone); a unit which is considerably younger than the Chengjiang fauna. The well preserved soft anatomy include linguliform pedicles, marginal setae and, in a few cases, an intact lophophore imprint. The pedicle has pronounced surface annulations, with its proximal−most part enclosing the apex of the ventral pseudointerarea; the pedicle is up to 51 mm long, corresponding to more than 4 times the sagittal length of the shell, and 12% of the maximum valve width. In details of their preservation, these new fossils exhibit striking similarities with the linguliforms from the older Chengjiang fauna, and all specimens are preserved in a compressed state as flattened impressions. The new linguliform has an elongate oval to subtriangular shell and an elongate triangular ventral pseudointerarea; the pedicle emerged from an apical foramen through a poorly preserved internal pedicle tube. The new linguliform is most similar to the mostly organic−shelled siphonotretoid−like brachiopod Acanthotretella spinosa, recently described from the classic middle Cambrian Burgess Shale Konservat Lagerstätte, British Columbia, Canada. The new species Acanthotretella decaius sp. nov. is described; it differs from A. spinosa in having a slightly thicker pedicle, and a larger and more rigid, probably partly mineralised shell, indicating that the mostly organic shell of A. spinosa may represent a secondary reduction of shell mineralisation. However, the spine−like setae of the new species are unfortunately poorly preserved only at the margin of the shell, but the new species is referred tentatively to the Superfamily Siphonotretoidea. The occurrence of A. decaius in the Guanshan fauna is the first lower Cambrian (Series 2, early Stage 4) record of both Acanthotretella and siphonotretoids, and it represents the first description of a lophophore and digestive tract from the siphonotretoid lineage.
    Źródło:
    Acta Palaeontologica Polonica; 2010, 55, 3; 495-505
    0567-7920
    Pojawia się w:
    Acta Palaeontologica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-5 z 5

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