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Tytuł:
A Cooksonia-type flora from the Upper Silurian of the Holy Cross Mountains, Poland
Autorzy:
Bodzioch, A
Kozlowski, W.
Poplawska, A.
Powiązania:
https://bibliotekanauki.pl/articles/20471.pdf
Data publikacji:
2003
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
land plant
stratigraphy
Upper Silurian
Cooksonia
Polska
flora
vascular plant
Holy Cross Mountains
paleogeography
paleoenvironment
Opis:
Silurian land plants from the Holy Cross Mts. are described for the first time. The fossil assemblage occurs in a nearshore, marine, terrigenous deposit of Ludlowian/Pridolian age. It contains Cooksonia sp., Cooksonia−related species, and some problematical forms. The flora, which needs further study, is of importance to our understanding of early vascular plants and Late Silurian palaeogeography.
Źródło:
Acta Palaeontologica Polonica; 2003, 48, 4
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A giant boring in a Silurian stromatoporoid analysed by computer tomography
Autorzy:
Beuck, L
Wisshak, M.
Munnecke, A.
Freiwald, A.
Powiązania:
https://bibliotekanauki.pl/articles/20045.pdf
Data publikacji:
2008
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Upper Visby Formation
computer tomography
Sweden
Densastroma pexisum
paleontology
Gotland Island
Silurian
stromatoporoid
trace fossil
Osprioneides kampto
analysis
Opis:
This study describes the largest known Palaeozoic boring trace, Osprioneides kampto igen. et isp. nov., found within a stromatoporoid Densastroma pexisum from the Upper Visby Formation (lower Wenlock, Silurian) on the island of Gotland, Sweden. Differences between the physical properties of the stromatoporoid and the dense micritic infilling of the borings allowed the application of the CT−scan technology for the 2D and 3D−visualisation of this rare trace. The additional application of a stereoscopic technique on these CT images and movies enhances its value for unravelling spatial orientations. This non−destructive method has a great potential for future macroas well as microboring analyses. The trace maker, most likely a worm, infested the hosting colony post−mortem with up to 120 mm long borings measuring 5–17 mm in diameter. Smaller forms of Trypanites and Palaeosabella within the same stromatoporoid preferentially occur in the outer coenosteum and occasionally in abandoned borings of O. kampto. The stratigraphic position of O. kampto follows the “Great Ordovician Biodiversification Event” in time, and reflects the increase in diversity of boring species. Borings with penetration depths of 120 mm are, however, unique findings for the Palaeozoic and were not exceeded until some 260 million years later (Bajocian, Middle Jurassic) when the “Mesozoic Marine Revolution” led to convergent reinventions as a result of enhanced predation, grazing pressure, and ecospace competition.
Źródło:
Acta Palaeontologica Polonica; 2008, 53, 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 new type of colony in Silurian (upper Wenlock) retiolitid graptolite Spinograptus from Poland
Autorzy:
Kozlowska, A.
Dobrowolska, K.
Bates, D.E.B.
Powiązania:
https://bibliotekanauki.pl/articles/22266.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
new type
colony
Silurian
retiolitid graptolite
Spinograptus
Graptoloidea
Retiolitidae
Polska
paleontology
Opis:
The new retiolitid species, Spinograptus tubothecalis, is described from the Colonograptus praedeubeli and C. deubeli biozones from two localities in Poland: a borehole on the East European Platform and the Holy Cross Mountains. This was a recovery phase after the severe Silurian Cyrtograptus lundgreni Event. The new species has a unique, previously undescribed form of finite rhabdosome. Unlike the species Spinograptus reticulolawsoni and S. lawsoni, in which the fi− nite rhabdosomes taper distally, its rhabdosome is parallel−sided with the two distal thecae developed as isolated tubes without genicular processes, with a small appendix between them. The new species also has preserved membranes of the sicula, thecae and ancora sleeve, similar to a few species of Spinograptus from the lower Homerian. Spinograptus tubothecalis, like Spinograptus clathrospinosus and S. spinosus, has paired reticulofusellar genicular processes on the pre−thecal ventral orifices, similar to but shorter than thecal processes. Transverse rods, a rare character in post−Cyrto− graptus lundgreni Event retiolitids occur in the new species in rudimentary form.
Źródło:
Acta Palaeontologica Polonica; 2013, 58, 1
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
Tytuł:
Acritarch assemblages from the Silurian Pomeranian Caledonides and their foreland
Autorzy:
Jachowicz, M.
Powiązania:
https://bibliotekanauki.pl/articles/2059448.pdf
Data publikacji:
2000
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Pomeranian Caledonides
Silurian
acritarch assemblages
Opis:
Comprehensive palynological studies of the Silurian rocks of the Pomeranian Caledonides are described, the first since Eisenack's (1972) work. 250 clastic rock samples were analysed, all from deep boreholes. Three of these boreholes (Lębork IG 1, Gdańsk IG 1 and Kościerzyna IG 1) are located NE of the Teisseyre-Tornquist Zone (TTZ) and contain horizontal successions of the western, marginal part of the East European Craton. Other boreholes studied (Bydgoszcz IG 1, Klosnowo IG 1 and Stobno 1) penetrated folded Lower Palaeozoic sediments, and lie SE of the TTZ. The investigations included a complete Silurian profile from the Llandovery to the Poidoli, which is documented in detail by graptolites. Associations of microflora (Acritarcha, Prasinophyceae, Sporites) and microfauna (Chitinozoa, Scolecodonta) varied in quality and quantity. There was considerable variability in the preservation and thermal maturity of the organic-walled microfossils. Detailed investigations of the acritarchs are described. 7 characteristic acritarch assemblages have been distinguished, and these are correlated with the graptolite biozones. Llandovery rocks contain assemblages with Domasia, Ammonidium and Tylotopalla genera. Wenlock deposits include Tylotopalla, Leptobrachion and Cymbosphaeridium. The Upper Ludlow deposits contain well preserved assemblages with Visbysphaera, Veryhachium, Onondagella and Leoniella, accompanied by Neoveryhachium carminae, Geron gracilis, and some Deflandrastrum and Visbysphaera species generally considered characteristic of Gondwana. Throughout the Silurian profile, individual specimens of typical Ordovician genera such as Acanthodiacrodium, Frankea, Striatotheca and Coryphidium occur. The acritarch assemblages overall show mixed characters, typical of both Baltica and Gondwana.
Źródło:
Geological Quarterly; 2000, 44, 3; 317-331
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Agastograptus, a synonym of Plectograptus [Retiolitidae, Graptolithina]
Autorzy:
Kozlowska-Dawidziuk, A
Powiązania:
https://bibliotekanauki.pl/articles/22767.pdf
Data publikacji:
2002
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Agastograptus robustus
synonym
Retiolitidae
Graptolithina
Silurian
Agastograptus
taxonomy
Plectograptus
paleontology
Opis:
Agastograptus robustus Obut and Zaslavskaya, 1983, the type species of the genus Agastograptusis herein recognized as a species of Plectograptus. Large proximal lateral orifices are one of the significant characters of Plectograptus. P. robustus differs from the type species, Plectograptus macilentus Törnquist, 1887, in possessing paired apertural processes. Other species of Agastograptus have been assigned to three different genera: Spinograptus, S. clathrospinosus (Eisenack, 1951), S. munchi (Eisenack, 1951), Neogothograptus, N. balticus (Eisenack, 1951), and Cometograptus, C. nevadensis (Berry and Murphy, 1975). The main diagnostic feature used for Agastograptus, the spinoreticular paired apertural processes, is recognized as a species feature, characteristic mostly for Spinograptus, whereas the generic features are the arrangement of the proximal end, ventral walls, and ancora sleeve of the rhabdosome. Therefore the genus Agastograptus is a synonym of Plectograptus.
Źródło:
Acta Palaeontologica Polonica; 2002, 47, 3
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An atypical Silurian myodocope ostracod from the Armorican Massif, France
Autorzy:
Perrier, V.
Powiązania:
https://bibliotekanauki.pl/articles/22621.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Silurian
paleontology
myodocope ostracod
ostracod
Armorican Massif
France
Arthropoda
Crustacea
Ostracoda
Myodocopa
Entomozoidae
taxonomy
Opis:
A new myodocope ostracod Sineruga insolita gen. et sp. nov. is herein described from the Armorican Massif (France). Sineruga resembles Silurian myodocopes (i.e., bolbozoids and cypridinids) in having anterior features (thinner carapace) possibly related to vision. On the other hand, it resembles entomozoid ostracods in having a bean−shaped outline along with a deep adductorial sulcus and a simple muscle spot, but lacks their characteristic ribbed ornament. The data available suggest that Sineruga insolita was probably an atypical, non−ribbed member of the entomozoids thus indicating that early entomozoids may have had smooth representatives. Comparisons with other Recent and fossils ostracods show that the presence of a rostrum and/or symmetrical vision related carapace features (i.e., indicating lateral eyes) can be used as diagnostic characters for myodocope ostracods. The position and shape of the dorsal connection and to a lesser extent that of the sulcus and the adductorial muscle scar can be used to discriminate the higher groups of Silurian myodocopes (bolbozoids, cypridinids, and entomozoids).
Źródło:
Acta Palaeontologica Polonica; 2012, 57, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analiza petrofizyczna łupków sylurskich z synklinorium lubelskiego
Petrophysical analysis of Silurian shales from the Lublin synclinorium
Autorzy:
Krakowska, P.
Puskarczyk, E.
Jędrychowski, M.
Habrat, M.
Madejski, P.
Jarzyna, J.
Powiązania:
https://bibliotekanauki.pl/articles/972364.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Instytut Gospodarki Surowcami Mineralnymi i Energią PAN
Tematy:
petrofizyka
łupki sylurskie
synklinorium lubelskie
spektrometria magnetycznego rezonansu jądrowego
rentgenowska tomografia komputerowa
petrophysics
Silurian shales
Lublin synclinorium
nuclear magnetic resonance
X-ray computed tomography
Opis:
Wyniki badań laboratoryjnych formacji sylurskich pozwalają na uzyskanie szczegółowych informacji na temat złożoności przestrzeni porowej, występowania mikroszczelin, a także obecności pirytu w skale. Trzy próbki mułowców sylurskich pochodzące z różnych głębokości, z jednego otworu zlokalizowanego w synklinorium lubelskim, zostały przebadane pod kątem wyznaczenia właściwości sprężystych, czyli prędkości fal podłużnych P i poprzecznych S, dynamicznych modułów: sprężystości podłużnej (Younga), odkształcenia postaci, odkształcenia objętości, współczynnika Poissona oraz zbiornikowych, z wykorzystaniem spektrometrii magnetycznego rezonansu jądrowego (porowatość całkowita i efektywna, zawartość wody wolnej, kapilarnej i nieredukowalnej). W ramach dodatkowych analiz przeprowadzono badania laboratoryjne przepuszczalności absolutnej w skali nano-Darcy, a także granulometrii. Rentgenowska tomografia komputerowa dała możliwość interpretacji jakościowej wykształcenia przestrzeni porowej oraz mikroszczelin, a także formy występowania pirytu w skale. Interpretacja ilościowa obrazów tomograficznych dostarczyła parametrów geometrycznych porów, pirytów i mikroszczelin, tj. wielkości porów i kryształów pirytów, mikroszczelin itp. Komplementarna analiza petrofizyczna skał łupkowych, wykonana przy wykorzystaniu różnorodnych metod badawczych, stała się kluczem do zrozumienia budowy wewnętrznej tego typu skał, które wykazują silną heterogeniczność parametrów fizycznych i chemicznych szkieletu ziarnowego i przestrzeni porowej.
The results of laboratory measurements of the Silurian formations allow detailed information on the complexity of pore space, the occurrence of microcracks, as well as the presence of pyrite in the rock to be obtained. Three samples of Silurian mudstones from different depths, from one well located in the Lublin synclinorium, were tested for elastic properties, i.e. the longitudinal waves P and transverse S, the dynamic moduli: Young, shear, bulk, Poisson ratio and reservoir using nuclear magnetic resonance spectrometry (total and effective porosity, free water, capillary and irreducible water). Additional laboratory analyses of the absolute permeability on a nano-Darcy scale as well as granulometry were performed. X-ray computed tomography provided an opportunity to interpret the qualitative development of porous space as well as the microscopic and forms of pyrite in the rock. The quantitative interpretation of tomographic images provided the geometric parameters of pores, pyrites and microcracks, i.e. the size of pores, pyrite crystals and microcracks. The complementary petrophysical analysis of shale gas deposits, made using a variety of research methods, became the key to understanding the internal structure of this type of rock, which exhibits strong heterogeneity in physical and chemical parameters of the particle's skeleton and pore space.
Źródło:
Zeszyty Naukowe Instytutu Gospodarki Surowcami Mineralnymi i Energią PAN; 2017, 101; 293-301
2080-0819
Pojawia się w:
Zeszyty Naukowe Instytutu Gospodarki Surowcami Mineralnymi i Energią PAN
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Assessment of hydrocarbon potential of the Lower Palaeozoic strata in the Tarnogród–Stryi area (SE Poland and western Ukraine)
Autorzy:
Więcław, D.
Kosakowski, P.
Kotarba, M.J.
Koltun, Y. V.
Kowalski, A.
Powiązania:
https://bibliotekanauki.pl/articles/191878.pdf
Data publikacji:
2012
Wydawca:
Polskie Towarzystwo Geologiczne
Tematy:
source rock
hydrocarbon potential
Cambrian
Ordovician
Silurian
Carpathian Foredeep basement
SE Poland
Western Ukraine
Opis:
Quantity, genetic type and maturity of organic matter dispersed in the Lower Palaeozoic sequence from the Lower Cambrian to Silurian strata of the Polish and Ukrainian parts of the Carpathian Foredeep basement in the Tarnogród–Stryi area were evaluated based on the results of geochemical analyses of 475 rock samples collected from 45 wells. The best source rocks were found in the Silurian strata where the present total organic carbon (TOC) content is up to 2.6 wt%. They occur in the vicinity of Wola Obszańska, where the median of the present and the initial total organic carbon (TOC) contents in the individual wells amount to 0.98 and 1.6 wt%, respectively. The Cambrian and Ordovician strata have a poorer hydrocarbon potential and their present TOC content never exceeds 1 wt%. In all of the investigated Lower Palaeozoic strata, organic matter is represented by the oil-prone Type-II kerogen deposited in anoxic or sub-oxic conditions. The maturity of source rocks ranges from early mature (the initial phase of the low-temperature thermogenic processes) in selected zones of the Silurian strata in the vicinity of Wola Obszańska, through the middle and the final phase of “oil window” in the Ordovician and Cambrian strata in the Polish part of the study area, to the overmature stage in the Ordovician strata in the south-eastern part of the study area (Ukraine).
Źródło:
Annales Societatis Geologorum Poloniae; 2012, 82, 1; 65--80
0208-9068
Pojawia się w:
Annales Societatis Geologorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Charakterystyka petrograficzna paleozoicznych skał łupkowych basenu bałtyckiego : konsekwencje dla rozpoznawania i wydobycia gazu łupkowego
Petrography of palaeozoic shale from Baltic basin : implications for recognition and exploitation of shale gas
Autorzy:
Gąsiński, A.
Poszytek, A.
Powiązania:
https://bibliotekanauki.pl/articles/394923.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Instytut Gospodarki Surowcami Mineralnymi i Energią PAN
Tematy:
łupki sylursko-ordowickie
gaz łupkowy
porowatość
mineralogia
Silurian-Ordovician shale
shale gas
porosity
mineralogy
Opis:
W pracy zaprezentowano wyniki szczegółowych badań mineralogicznych, które wraz z obserwacjami w wysokorozdzielczym mikroskopie skaningowym dostarczyły informacji na temat składu mineralnego, tekstur i charakteru wykształcenia porowatości w ordowicko-sylurskich skałach łupkowych basenu bałtyckiego. Głównymi składnikami tych skał są minerały ilaste oraz kwarc, kalcyt, dolomit, piryt i skalenie. Znaczna część kwarcu ma charakter diagenetyczny, co korzystnie wpływa na możliwości szczelinowania skał. Na podstawie uzyskanych wyników opisano także procesy, które w zasadniczy sposób wpłynęły na formowanie obecnie występującej porowatości. Stwierdzono, że najważniejszym procesem mającym wpływ na powstanie wtórnej porowatości było przeobrażanie minerałów ilastych (smektyt-illit), a współwystępująca wraz z tym procesem cementacja krzemionką spowodowała prawie całkowite wypełnienie powstałej przestrzeni porowej. Prawdopodobnie pory były wypełniane również przez autogeniczne ziarna chlorytów. Pory zachowane w badanych skałach łupkowych podzielono na cztery typy, biorąc pod uwagę morfologię i charakter ich występowania. Stwierdzono potencjalną możliwość występowania drobnych połączeń pomiędzy porami, co może pozwalać na powolną migrację mediów w skale.
The paper presents the results of detailed mineralogical studies of shales in Ordovician-Silurian Baltic basin. Main constituents of these rocks are clay minerals (illite and smectite), quartz, calcite, dolomite, pyrite and feldspars. Significant part of quarz grains is of authigenic origin, which positively influences the process of hydraulic fracturing. Observations in the high-resolution scanning electron microscope gave information about the nature of porosity in the shale and the processes which significantly contributed to the formation of porosity. It was found that the most important process affecting the secondary porosity of shale was the transformation of clay minerals (smectite-illite). Created pore space was almost completely filled by silica cement. Preserved pores were divided into four types according to their morphology and nature of occurrence. There was also found the potential for occurrence of interconnections between fine pores that allow fluid migration.
Źródło:
Zeszyty Naukowe Instytutu Gospodarki Surowcami Mineralnymi i Energią PAN; 2013, 85; 79-88
2080-0819
Pojawia się w:
Zeszyty Naukowe Instytutu Gospodarki Surowcami Mineralnymi i Energią PAN
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Coexistence of algae and a graptolite-like problematicum: a case study from the late Silurian of Podolia (Ukraine)
Autorzy:
Skompski, Stanisław
Kozłowski, Wojciech
Łuczyński, Piotr
Kozłowska, Anna
Powiązania:
https://bibliotekanauki.pl/articles/27323966.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
Dasycladales
Graptolite-like epibionts
Silurian
Ludlow
Ukraine
periti dal environment
glony
graptolity
epibionty
sylur
ludlow
Ukraina
Opis:
This contribution presents the record of an abundant assemblage of well-preserved, thallophytic noncalcified algae and of an epibiotic form that has been recognised as a putative graptolite from the upper Silurian (Ludlow, Gorstian–Ludfordian) of Podolia (western part of Ukraine). The sediments represent a shallow peritidal zone of the shelf. A new genus and species, Voronocladus dryganti, belonging to the Dasycladales Pascher, 1931, is established. Most of the specimens representing the algal thallus are overgrown by problematical epibiotic graptolites, described as Podoliagraptus algaeoides gen. et sp. nov. This phenomenon is explained as an epiphytic mode of life of the putative graptolite on algae, and is herein compared to recently known coexistences of algae with other organisms. The excellent state of preservation, and the abundance of studied Dasycladales algae and epibiotic problematics indicate that the investigated mudstone layer can be treated as a ‘Konservat Lagerstätte’ sensu Seilacher (1970).
Źródło:
Acta Geologica Polonica; 2023, 73, 2; 115--133
0001-5709
Pojawia się w:
Acta Geologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Concentrations of Silurian nautiloid cephalopods from Russia and Kazakhstan
Autorzy:
Bogolepova, O K
Holland, C H
Powiązania:
https://bibliotekanauki.pl/articles/22316.pdf
Data publikacji:
1995
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Cephalopoda
cephalopod
Silurian
concentration
Russia
living population
Kazakhstan
paleontology
nautiloid cephalopod
Opis:
Silurian cephalopod limestones known from northern Asia are usually singular beds or horizons of nodules. They range in their taphonomic character from the Mojero river type, with postmortem concentration from rich living populations by relatively gentle bottom currents into a submarine low, to that of the Karabutak Formation of the South Urals, where there has been concentration by strong wave or current action.
Źródło:
Acta Palaeontologica Polonica; 1995, 40, 4
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Convergent evolution of two Silurian graptolites
Autorzy:
Lenz, A C
Melchin, M.J.
Powiązania:
https://bibliotekanauki.pl/articles/21551.pdf
Data publikacji:
2008
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
taxonomy
biostratigraphy
paleontology
Graptoloidea
nomenclature
graptolite species
convergent evolution
Cochlograptus veles
Testograptus testis
Silurian graptolite
Monograptidae
Opis:
The two graptolite speciesCochlograptus veles(Telychian, Upper Llandovery) and Testograptus testis(lower Homerian, upper Wenlock) are remarkably and uniquely similar in being strongly ventrally and planispirally coiled and in demonstrating an abrupt deflection in the immediate post−sicular regions of their rhabdosomes. The two species, however, are separated by a relatively large biostratigraphic gap and a global mass extinction, and they differ morphologically in the proportion of thecal overlap, different angles of inclination of the interthecal septa, relative proportions of the widths occupied by the free metathecae, the position of the sharp dorsal flexure relative to the tip of the sicula, and the presence of a distinctive, keel−like structure on T. testis. It is suggested therefore, that in spite of the strong proximal morphological parallelism between the two species, their origin is best explained as a remarkable example of convergent evolution. It is suggested that C. veles perhaps evolved from some modified monograptid such as Stimulograptus, whereas the small Testograptus group may have derived from some monograptid such as Monograptus flemingii. Cladistic analysis fully supports the independent derivation the two species. If correct, this hypothesis supports the validity of separate generic names for the two species, despite the close and unique rhabdosomal similarities, including proximal metathecal form.
Źródło:
Acta Palaeontologica Polonica; 2008, 53, 3
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Crinoids from the Silurian of Western Estonia
Autorzy:
Ausich, W.I.
Wilson, M.A.
Vinn, O.
Powiązania:
https://bibliotekanauki.pl/articles/21031.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
crinoid
Silurian
Western Estonia
Estonia
Echinodermata
Crinoidea
Pridoli
paleontology
new species
Calceocrinus balticensis
Desmidocrinus laevigatus Eucalyptocrinites tumidus
Saaremaacrinus estoniensis
Opis:
The Silurian crinoids of Estonia are re−evaluated based on new collections and museum holdings. Nineteen species−level crinoid taxa are now recognized. All crinoid names applied to Estonian Silurian crinoids during the middle 19th century are disregarded. Especially significant is the fauna reported herein from the Pridoli because coeval crinoids are very poorly known from the Baltic region and elsewhere. One new genus and four new species are described from Estonia, namely Calceocrinus balticensis sp. nov., Desmidocrinus laevigatus sp. nov., Eucalyptocrinites tumidus sp. nov., and Saaremaacrinus estoniensis gen. et sp. nov.
Źródło:
Acta Palaeontologica Polonica; 2012, 57, 3
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 85

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