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Wyszukujesz frazę "Early Cambrian" wg kryterium: Temat


Wyświetlanie 1-11 z 11
Tytuł:
The Jarlsbergian unconformity (Proterozoic/Cambrian boundary )and the problem of Varangian tillites in South Spitsbergen
Autorzy:
Birkenmajer, Krzysztof
Powiązania:
https://bibliotekanauki.pl/articles/2052817.pdf
Data publikacji:
1991
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Arctic
Spitsbergen
Late Proterozoic
Early Cambrian
unconformity
Źródło:
Polish Polar Research; 1991, 12, 3; 269-278
0138-0338
2081-8262
Pojawia się w:
Polish Polar Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An enigmatic, possibly chemosymbiotic, hexactinellid sponge from the early Cambrian of South China
Autorzy:
Botting, J.P.
Muir, L.A.
Li, X.-F.
Lin, J.-P.
Powiązania:
https://bibliotekanauki.pl/articles/19994.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Porifera
Hexactinellida
symbiosis
chemosynthesis
Early Cambrian
South China
Cambrian
China
Opis:
Six specimens of a strongly curved, cylindrical hexactinellid sponge have been recovered from the Tommotian– Atdabanian Hetang Biota of South China, and are described as Decumbispongia yuani gen. et sp. nov. The robust, thick−walled sponge shows no evidence of an osculum or basal structures, and the body form is inconsistent with an upright, filter−feeding life position. Interpretations as a detritivore feeding by amoeboid extensions, or as a facultative chemosynthetic symbiosis of sponge and bacteria are considered. The latter interpretation is preferred due to the highly constrained body shape, and the body form is interpreted from this perspective. The species indicates that Cambrian sponges occupied at least some autecological niches that appear to have been vacant since that time.
Źródło:
Acta Palaeontologica Polonica; 2013, 58, 3
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sedimentary characteristics of the Hüdaý Formation (Early Cambrian) within the Aydincik (ÝÇEL) area, S Turkey
Autorzy:
Eren, M.
Öner, F.
Powiązania:
https://bibliotekanauki.pl/articles/191184.pdf
Data publikacji:
2000
Wydawca:
Polskie Towarzystwo Geologiczne
Tematy:
sedimentology
Early Cambrian
clastics
Hüdai Formation
facies
Turkey
Opis:
The study area is located in Aydýncýk (ÝÇEL) area where Early Cambrian rocks are represented by the Hüdai Formation. The formation represents three different parts in the vertical sequence which has a thickness of approximately 830 metres. The basal part of the formation consists of a rhytmic alternation of horizontal laminated sandstone, ripple trough cross-laminated sandstone, mixed sandstone-shale, and rarely metashales. The middle part comprises dominantly metashales. The upper part is made up by an alternation of horizontal laminated sandstone, mixed sandstone-shale and rarely metashales. Vertical variations in the formation is caused by marine transgressious and regressious, and by fluctuations in sediment supply. Lower to middle parts of the formation characterize a fining-upward sequence, and middle to upper parts display a coarsening-upward sequence. In the Hüdai Formation, four lithofacies are recognized based on lithology and sedimentary structures. These are (1) horizontal laminated sandstone (predominantly quartzarenite) indicating deposition from tidal currents during the high velocity phases of tidal cycles; (2) ripple cross-laminated sandstone (predominantly quartzwacke) deposited in lower part of intertidal (sand-flat) environment; (3) mixed sandstone-shale revealing deposition in mid-intertidal flat environment; and (4) shale (or metashale) deposited mainly in upper intertidal (mudflat) environment.
Źródło:
Annales Societatis Geologorum Poloniae; 2000, 70, No. 3-4; 251-259
0208-9068
Pojawia się w:
Annales Societatis Geologorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Early Cambrian origin of thylacocephalan arthropods
Autorzy:
Vannier, J
Chen, J.Y.
Huang, D.Y.
Charbonnier, S.
Wang, X.Q.
Powiązania:
https://bibliotekanauki.pl/articles/23320.pdf
Data publikacji:
2006
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
fauna
thylacocephalan arthropod
Lagerstatte
Zhenghecaris shankouensis
China
arthropod
Arthropoda
Early Cambrian
Cambrian
paleontology
Opis:
Zhenghecaris shankouensis gen. et sp. nov. is one of the largest “bivalved” arthropods of the Lower Cambrian Maotianshan Shale fauna. Its non−mineralized carapace was dome−like, laterally compressed, armed with rostral features, and probably enclosed the entire body of the animal. Zhenghecaris was provided with elliptical stalked lateral eyes. The carapace design, external ornament and visual organs of Zhenghecaris suggest affinities with the Thylacocephala, an extinct (Lower Silurian to Upper Cretaceous) group of enigmatic arthropods whose origins remain poorly understood. The bivalved arthropodsIsoxys and Tuzoia (Lower and Middle Cambrian) are two other potential thylacocephalan candidates making this group of arthropods a possible new component of Cambrian marine communities. Zhenghecaris, Isoxys, and Tuzoia are interpreted as nektonic animals that probably inhabited the lower level of the water column in shallow shelf settings at depths of perhaps 100–150 m or less. Their feeding mode either in the water column (e.g., mesozooplankton) or on the substrate (e.g., small epibenthos, detritus) is uncertain, although some of these arthropods were possibly mid−water predators (e.g., Isoxys with raptorial appendages).
Źródło:
Acta Palaeontologica Polonica; 2006, 51, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Shell microstructures in Early Cambrian molluscs
Autorzy:
Kouchinsky, A
Powiązania:
https://bibliotekanauki.pl/articles/23294.pdf
Data publikacji:
2000
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
skeletal fossil
microstructure
shell
biomineralization
mollusc
Early Cambrian
mollusc-like organism
taxonomy
Cambrian
paleontology
Opis:
The affinities of a considerable part of the earliest skeletal fossils are problematical, but investigation of their microstructures may be useful for understanding biomineralization mechanisms in early metazoans and helpful for their taxonomy. The skeletons of Early Cambrian mollusc-like organisms increased by marginal secretion of new growth lamellae or sclerites, the recognized basal elements of which were fibers of apparently aragonite. The juvenile part of some composite shells consisted of needle-like sclerites; the adult part was built of hollow leaf-like sclerites. A layer of mineralized prism-like units (low aragonitic prisms or flattened spherulites) surrounded by an organic matrix possibly existed in most of the shells with continuous walls. The distribution of initial points of the prism-like units on a periostracurn-like sheet and their growth rate were mostly regular. The units may be replicated on the surface of internal molds as shallow concave polygons, which may contain a more or less well-expressed tubercle in their center. Tubercles are often not enclosed in concave polygons and may co-occur with other types of textures. Convex polygons seem to have resulted from decalcification of prism-like units. They do not co-occur with tubercles. The latter are interpreted as casts of pore channels in the wall possibly playing a role in biomineralization or pits serving as attachment sites of groups of mantle cells. Casts of fibers and/or lamellar units may overlap a polygonal texture or occur without it. They may reflect an inner layer consisting of aragonitic fibers fused into more or less well-developed lamellar units. It seems that nacreous and crossed-lamellar aragonitic microstructures evolved in the Cambrian from such lamellar aragonitic microstructures independently in different groups of molluscs.
Źródło:
Acta Palaeontologica Polonica; 2000, 45, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Cambrian microfossils from glacial erratics of King George Island, Antarctica
Autorzy:
Wrona, R
Powiązania:
https://bibliotekanauki.pl/articles/22565.pdf
Data publikacji:
2004
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
skeletal fossil
Antarctic
Australia
Middle Cambrian
Early Cambrian
microfossil
Cape Melville Formation
Cambrian
paleontology
Early Miocene
King George Island
Opis:
Limestone erratics in the Early Miocene glacio−marine Cape Melville Formation of King George Island, West Antarctica, have yielded Early and Middle Cambrian small skeletal fossils (SSF) accompanied by calcified cyanobacteria, archaeocyath and spiculate sponges, trilobites and echinoderms. The SSF assemblage comprises disarticulated sclerites of chancelloriids, halkieriids, tommotiids, lapworthellids, palaeoscolecids, hyolithelminths, lingulate brachiopods, helcionelloid molluscs, hyoliths, and bradoriids. All 24 described species are common to Antarctica and Australia. Most are recorded here from Antarctica for the first time, including Shetlandia multiplicata gen. et sp. nov. and two new species Byronia? bifida and Hadimopanella staurata. The lithological and fossil contents of the boulders are almost identical with autochthonous assemblages from the Shackleton Limestone in the Argentina Range and Transantarctic Mountains. Cambrian outcrops around the Weddell Sea are a plausible source of the erratics. The fauna is closely similar to that from the uppermost Botomian Wilkawillina Limestone in the Flinders Ranges and Parara Limestone on Yorke Peninsula, and Toyonian Wirrealpa and Aroona Creek Limestones in the Flinders Ranges, as well as the Ramsay Limestone on Yorke Peninsula, all in the Arrowie and Stansbury Basins of South Australia. These very similar faunal and facies successions for Antarctica and Australia strongly support their common biotic and sedimentary evolution on the same margin of a greater Gondwana supercontinent throughout the Early Cambrian.
Źródło:
Acta Palaeontologica Polonica; 2004, 49, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Trunk ornament on the palaeoscolecid worms Cricocosmia and Tabelliscolex from the Early Cambrian Chengjiang deposits of China
Autorzy:
Han, J
Liu, J.
Zhang, Z.
Zhang, X.
Shu, D.
Powiązania:
https://bibliotekanauki.pl/articles/23260.pdf
Data publikacji:
2007
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Tabelliscolex hexagonus
Palaeoscolecida
Priapulida
Chengjiang deposit
Cricocosmia jinningensis
trunk ornament
fossil worm
China
Early Cambrian
Cambrian
Lower Cambrian
paleontology
Opis:
Cricocosmia jinningensis, one of the most abundant palaeoscolecid worms from the Lower Cambrian Chengjiang deposits of south China, was originally described as bearing double longitudinal rows of lateral conical sclerites on the trunk. New observation reveals that the ventral trunk bears an additional set of ventral sclerites while the lateral sclerites display a tubercle−bearing (inner surface) and net−like (outer surface) microstructure similar to that of Tabelliscolex hexagonus. These findings mean that: (1) Cricocosmia shows a dorso−ventral and antero−posterior differentiation in trunk ornament; (2) as seen from the microstructure, Cricocosmia is close to Tabelliscolex hexagonus, supporting the idea that lobopodians and arthropods, both of which show an upper capping layer in the outer sclerites, are more closely related than the palaeoscolecidans; and (3) the similarities among the scalids, pharyngeal teeth and the trunk spines of palaeoscolecidans are superficial. Tabelliscolex maanshanensis sp. nov., characterized by an inner concentric circlet of laminae in each tubercle of the lateral trunk plate, is proposed herein. Element mapping reveal that four known pathways of preservation can be found co−occurring in a single specimen of Cricocosmia or Tabelliscolex, which sheds new light on the preservation of the Chengjiang fossils.
Źródło:
Acta Palaeontologica Polonica; 2007, 52, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Early Cambrian trace fossils at the northern margin of the Arabian Plate; Telbesmi Formation, Turkey
Autorzy:
Demírcan, H.
Gürsu, S.
Göncüoğlu, M. C.
Powiązania:
https://bibliotekanauki.pl/articles/138729.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
ichnofossils
Telbesmi Formation
Early Cambrian
Derik (SE Turkey)
skamieniałość śladowa
formacja
wczesny kambr
Turcja
Opis:
The Telbesmi Formation, at the northern margin of the Arabian Plate, Turkey, is composed of alternating darkbrown, pinky-brown fluvial arkosic sandstone/mudstones with thin-bedded cherty limestones and channel conglomerates. The formation contains rare and poorly diversified trace fossils. The siltstone/sandstone beds of levels 1 and 2 of the formation yielded, however, a moderately diverse assemblage composed of: Cochlichnus isp., Palaeophycus isp., Planolites beverleyensis, Teichichnus isp. and ?Treptichnus rectangularis. This assemblage, made up of traces left by deposit feeding organisms, represents the Scoyenia ichnofacies. Treptichnus rectangularis and Palaeophycus isp., of the assemblage, can be considered markers for the base of the Cambrian in southeast Turkey.
Źródło:
Acta Geologica Polonica; 2018, 68, 2; 135-145
0001-5709
Pojawia się w:
Acta Geologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The tommotiid Camenella reticulosa from the Early Cambrian of South Australia: morphology, scleritome reconstruction, and phylogeny
Autorzy:
Skovsted, C B
Balthasar, U.
Brock, G.A.
Paterson, J.R.
Powiązania:
https://bibliotekanauki.pl/articles/21581.pdf
Data publikacji:
2009
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
tommotiid
paleontology
Camenella reticulosa
Early Cambrian
Cambrian
South Australia
Australia
morphology
scleritome reconstruction
phylogenesis
Tommotiida
scleritome
Atdabanian
Botomian
sclerite
Opis:
The tommotiid Camenella reticulosa is redescribed based on new collections of well preserved sclerites from the Arrowie Basin (Flinders Ranges), South Australia, revealing new information concerning morphology and microstructure. The acutely pyramidal mitral sclerite is described for the first time and the sellate sclerite is shown to be coiled through up to 1.5 whorls. Based on Camenella, a model is proposed by which tommotiid sclerites are composed of alternating dense phosphatic, and presumably originally organic−rich, laminae. Camenella is morphologically most similar to Lapworthella, Kennardia, and Dailyatia, and these taxa are interpreted to represent a monophyletic clade, here termed the “camenellans”, within the Tommotiida. Potential reconstructions of the scleritome of Camenella are discussed and although a tubular scleritome construction was recently demonstrated for the tommotiids Eccentrotheca and Paterimitra, a bilaterally symmetrical scleritome model with the sclerites arranged symmetrically on the dorsal surface of a vagrant animal can not be ruled out.
Źródło:
Acta Palaeontologica Polonica; 2009, 54, 3; 525-540
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Early Cambrian 'soft-shelled' brachiopods as possible stem-group phoronids
Autorzy:
Balthasar, U
Butterfield, N.J.
Powiązania:
https://bibliotekanauki.pl/articles/21500.pdf
Data publikacji:
2009
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
paleontology
Early Cambrian
brachiopod
soft-shelled brachiopod
phoronid
Brachiopoda
Phoronida
Lophophorata
Lophotrochozoa
Lingulosacculus nuda
Mural Formation
preservation
Opis:
Brachiopods and phoronids are widely recognised as closely related lophophorate phyla, but the lack of morphological intermediates linking the bivalved bodyplan of brachiopods with tubular phoronids has frustrated precise phylogenetic placement. Here we describe Lingulosacculus nuda gen. et sp. nov., a new “soft−shelled” brachiopod from the Early Cambrian Mural Formation of western Alberta which provides a plausible candidate for a phoronid stem−group within (paraphyletic) Brachiopoda. In addition to its non−biomineralised shell, L. nuda had a ventral valve with an exceptionally long, pocket−like extension (pseudointerarea) that would have allowed the transformation of criss−crossing brachiopod−type musculature to the longitudinal arrangement typical of phoronids. “Soft−shelled” linguliform brachiopods have previously been reported from both the Chengjiang and Burgess Shale Lagerstätten which, together with L. nuda, probably represent two independent losses of shell mineralisation in brachiopods.
Źródło:
Acta Palaeontologica Polonica; 2009, 54, 2; 307-314
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The evolution of late Ediacaran riverine-estuarine system in the Lublin-Podlasie slope of the East European Craton, southeastern Poland
Autorzy:
Pacześna, J.
Powiązania:
https://bibliotekanauki.pl/articles/1182491.pdf
Data publikacji:
2010
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
sedymentologia
stratygrafia sekwencji
równia aluwialna
estuarium
późny ediakar
wczesny dolny kambr
kraton wschodnioeuropejski
południowo-wschodnia Polska
sedimentology
sequence stratigraphy
alluvial plain
estuary
Late Ediacaran
early Lower Cambrian
East European Craton
south-eastern Poland
Opis:
Na podstawie zdefiniowania asocjacji facjalnych i systemów depozycyjnych oraz przedstawienia ram wydzieleń wysokorozdzielczej stratygrafii sekwencji sformułowano model rozwoju i destrukcji późnoediakarskiego systemu fluwialno-estuariowego, rozprzestrzenionego w obniżeniu podlaskim i lubelskim skłonie kratonu wschodnioeuropejskiego. Wyróżniono dwie grupy systemów depozycyjnych - aluwialne i estuariowe oraz system otwartego wybrzeża. System aluwialny był początkowo reprezentowany w północno-wschodnich i zachodnich depocentrach synryftowych przez stożki aluwialne. Dystalne części stożków były obszarami depozycji fluwialnej. Duże, piaskodenne rzeki roztokowe spływały poprzecznie do osi basenu sedymentacyjnego. W końcowych stadiach ewolucji basenu aluwialnego wyrównanie topografii ryftowej i wzrost tempa subsydencji w jego południowo-wschodniej części spowodowały rozwój rzek systemu anastomozującego. Spływały one wzdłuż osi basenu z północy na południe. Zmiana rodzaju przepływu rzek roztokowych z okresowego we wczesnych etapach rozwoju basenu aluwialnego na ciągły w późniejszych stadiach, rozwój równi zalewowych rzek systemu anastomozującego i zmiana koloru osadów akumulowanych przez rzeki świadczą o zmianie klimatu suchego, pustynnego na bardziej wilgotny, umiarkowany. Późnoediakarska sukcesja silikoklastyczna basenu lubelskiego jest zapisem transgresywnego etapu ewolucji estuarium. Jej przebieg odzwierciedla pięć kolejnych parasekwencji budujących transgresywny ciąg systemowy. W najwcześniejszych etapach rozwoju estuarium lubelskie miało charakter mieszany, falowo-pływowy. W fazie maksymalnego rozwoju, w miarę znaczącego wzrostu oddziaływania pływów, było to makropływowe, hypersynchroniczne estuarium o kominowej geometrii. Na przełomie ediakaru i kambru wraz z rozwojem ciągu systemowego wysokiego stanu względnego poziomu morza rozpoczął się regres i stopniowa likwidacja estuarium lubelskiego, które przekształciło się w estuarium o mieszanej energii falowo-pływowej i następnie w otwarte wybrzeże z udziałem falowania.
Źródło:
Polish Geological Institute Special Papers; 2010, 27; 1-96
1507-9791
Pojawia się w:
Polish Geological Institute Special Papers
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-11 z 11

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