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Wyszukujesz frazę "Early Silurian" wg kryterium: Temat


Wyświetlanie 1-3 z 3
Tytuł:
Mat-forming coccoid cyanobacteria from Early Silurian marine deposits of Sudetes, Poland
Autorzy:
Kremer, B
Powiązania:
https://bibliotekanauki.pl/articles/22597.pdf
Data publikacji:
2006
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
organic matter
marine environment
Cyanoprokaryota
Early Silurian
nitrogen fixation
marine deposit
Polska
Silurian
remains
coccoid cyanobacteria
Sudetes Mountains
paleontology
Opis:
Mass occurrence of mats comprised of benthic coccoid cyanobacteria is reported from early Silurian black radiolarian cherts exposed at Żdanow village (Bardzkie Mountains, Sudetes, southwestern Poland). The cherts contain laminated organic matter representing degraded benthic coccoid cyanobacterial mats. The remains of cyanobacteria occur as laminated agglomerations of variously preserved subglobular colonies composed of spherical cells of variable size and numbers. The morphology of remnants of cells and their mucilaginous envelopes, structure of colonies, and particularly the presence of small granular structures resembling reproductive cells known in extant coccoid cyanobacteria as baeocytes, permit to compare the Silurian microbiota with modern cyanobacteria assigned to the genera Stanieria or Chroococcidiopsis.
Źródło:
Acta Palaeontologica Polonica; 2006, 51, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A new genus of Late Ordovician-Early Silurian pentameride brachiopods and its phylogenetic relationships
Autorzy:
Jin, J
Popov, L.E.
Powiązania:
https://bibliotekanauki.pl/articles/22557.pdf
Data publikacji:
2008
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
pentameride brachiopod
brachiopod
paleontology
new genus
Siberia
Late Ordovician
Canada
Brachiopoda
Early Silurian
Protanastrophia repanda
Parastrophinidae
Opis:
Protanastrophia repanda gen. et sp. nov. is a reef−dwelling parastrophinid brachiopod in the Lower Silurian (uppermost Telychian) Attawapiskat Formation of the Hudson Bay region of Canada. It is characterized by a small, quasi−smooth shell with gentle anterior costae, a tendency towards an asymmetrical, sigmoidal anterior commissure, and widely separate, subparallel inner hinge plates. Protanastrophia first appeared in the marginal seas of Siberia (Altai, Mongolia) during the Late Ordovician, retaining the primitive character of discrete inner hinge plates in the superfamily Camerelloidea, and preferred a carbonate mound depositional environment. It survived the Late Ordovician mass extinction and subsequently spread to Baltica and Laurentia during Early Silurian (Llandovery) time. Superficially similar asymmetrical shells of Parastrophina portentosa occur in the Upper Ordovician carbonate mound facies of Kazakhstan but differ internally from the new genus in having a septum−supported septalium. Phylogenetic analysis indicates that, within the Camerelloidea, asymmetrical shells with a sigmoidal anterior commissure evolved in Protanastrophia repanda and Parastrophina portentosa independently during the Late Ordovician as a case of homoplasy. The two species belong to separate parastrophinid lineages that evolved in widely separate palaeogeographic regions.
Źródło:
Acta Palaeontologica Polonica; 2008, 53, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A review of Silurian fishes from north-western Hunan, China and related biostratigraphy
Autorzy:
Zhao, W. -J.
Zhu, M.
Gai, Z. -K.
Pan, Z. -H.
Cui, X. -D.
Cai, J. -C.
Powiązania:
https://bibliotekanauki.pl/articles/139181.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
early vertebrates
biostratigraphy
Silurian
north-western Hunan
China
kręgowce
biostratygrafia
sylur
Hunan
Chiny
Opis:
The Silurian fishes from north-western Hunan, China are characterised by the earliest known galeaspids Dayongaspis Pan and Zeng, 1985 and Konoceraspis Pan, 1992, and the earliest known antiarch Shimenolepis Wang J.-Q., 1991, as well as rich sinacanth fin spines. Shimenolepis from Lixian County in north-western Hunan, which was dated as the Telychian (late Llandovery), has long been regarded as the oldest representative of the placoderms in the world. As such, in addition to eastern Yunnan and the Lower Yangtze Region, north-western Hunan represents another important area in South China that yields important fossil material for the research of early vertebrates and related stratigraphy. Here we summarise the Silurian fishes known in north-western Hunan so far, and classify them into three vertebrate assemblages (i.e., the Wentang, Maoshan, and Yangtze assemblages). Based on the updated Silurian vertebrate and stratigraphic databases, the Silurian fish-bearing strata in north-western Hunan can be subdivided into the Rongxi, Huixingshao, and Xiaoxi formations in ascending chronological order, which can be correlated with the Lower Red Beds, the Upper Red Beds, and the Ludlow Red Beds in South China, respectively. A new look at the Silurian strata in Lixian suggests that the age of Shimenolepis is late Ludlow rather than late Llandovery as previously suggested. The research on Silurian fishes and biostratigraphy in north-western Hunan not only provides morphological data of early vertebrates, but also offers new palaeoichthyological evidence for the subdivision, correlation, and age assignment of the Silurian marine red beds in South China. The establishment of a related high-precision Silurian stratigraphic framework in north-western Hunan will help to elucidate the temporal and spatial distribution of Silurian fossil fishes, deepen the understanding of the evolution of early vertebrates, and unravel the coevolution between Silurian vertebrates and the palaeoenvironment.
Źródło:
Acta Geologica Polonica; 2018, 68, 3; 475-486
0001-5709
Pojawia się w:
Acta Geologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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