Temat: Ludlow - Prolib Integro

Skocz do pozycji: 1.

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
Tematy:: Dasycladales
Graptolite-like epibionts
Silurian
Ludlow
Ukraine
periti dal environment
glony
graptolity
epibionty
sylur
ludlow
Ukraina; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czasopisma i Monografie PAN
Powiązania:: https://bibliotekanauki.pl/articles/27323966.pdf Link otwiera się w nowym oknie
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).
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Evolution of retiolitid graptolites - a synopsis
Autorzy:: Kozlowska-Dawidziuk, A
Tematy:: Holoretiolites
Ludlow
Retiolitidae
retiolitid graptolite
paleobiology
Silurian
evolution
Graptoloidea
paleontology
rhabdosome reduction; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:: https://bibliotekanauki.pl/articles/23196.pdf Link otwiera się w nowym oknie
Opis:: Twenty million years of retiolitid evolution reflect environmental changes, the most severe being the Silurian Cyrtograptus lundgreni Event. Five biostratigraphically and morphologically constrained retiolitid faunas are distinguished and characterized according to their rhabdosomal modifications: (1) the oldest and long−ranging Llandovery group of mostly large and morphologically complex rhabdosomes, (2) the less diverse Telychian−Sheinwoodian group, (3) the Cyrtograptus lundgreni Biozone varied group of intermediate size, and two short−ranged (4) late Homerian, and (5) early Ludlow groups with small rhabdosomes. Although the evolutionary history of retiolitids was complex and not linear, a common tendency toward reduction of rhabdosome size in most lineages is observed. The greatest reduction in both number and volume of thecae, and in skeletal elements is demonstrated in the Gothograptus and Plectograptusfaunas. Contrary to the thecal decrease, a distinctive increase of sicula size is observed in retiolitids. Two types of colonies are distinguished: L−colonies with a small sicula and numerous large thecae of similar size, and S−colonies with a long sicula and a few, small thecae. These changes imply modification of the soft body: an increase in siculozooid length and a decrease in the size of the zooids. Thus, the siculozooid probably produced great amounts of morphogen inhibiting zooid growth. In consequence the phenomenon of colony reduction occurred. The most extreme stages of rhabdosome reduction in Ludlow retiolitids can be seen in Plectodinemagraptus gracilis of the Plectograptuslineage and in the new species Holoretiolites helenaewitoldi, possibly representing the last stage of skeletal reduction in the Gothograptus lineage; the next hypothetical stage would be its total loss. The sicula length of Holoretiolites, about 2 mm, is reported herein for the first time.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Adaptive radiation of monograptids after the Late Wenlock crisis
Autorzy:: Koren, T N
Urbanek, A
Tematy:: sylur
fauna graptoloidowa
Pristiograptus dubius
ewolucja
wymieranie gatunkow
skamienialosci
monograptidy
ludlow
paleontologia
wenlok; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:: https://bibliotekanauki.pl/articles/22957.pdf Link otwiera się w nowym oknie
Opis:: Succession of late Wenlock graptolites in the Kursala Formation, Tien Shan (Kirghizia), documents of the early recovery phase after the global C. lundgreni Event. Pristiograptus dubius was the only survivor among monograptids. After displaying a mass occurrence and an increased variation, the P. dubius stem lineage splits into two main trends: line A, represented by Pristiograptus idoneus and line B, represented by Colonograptus? praedeubeli. The former leads to Lobograptus? sherrardae, a generalized forerunner of such diverse trends as linograptids, cucullograptids and possibly also neocucullograptids (via Bohemograptus). The latter initiates the Colonograptus-Saetograptus line. The P. idoneus - L.? sherrardae lineage shows distinct gracilization, an apomorphic feature, while the other one preserves ancestral robustness, a plesiomorphic character. Hence, the bulk of the later monograptids of Gorstian and Ludfordian age may be derived from the P. dubius stem lineage. In respect of this conservative lineage a non-cladistic approach is prefered, because its morphological spectrum and evolutionary potential, and as we believe its specific identity, were preserved, in spite of numerous speciation events, until the early Pridoli.
Współczesne badania nad kryzysem biotycznym jaki dotknął monograptidy w późnym wenloku (tzw. zdarzenie C. lundgreni), pozwalają ocenić zarówno skalę masowego wymierania (przeżywa tylko jeden gatunek, Pristiograptus dubius), jak i przebieg procesów składających się na wczesny etap odradzania fauny graptoloidowej. Duże znaczenie dla poznania tych ostatnich miało zbadanie obfitej fauny z formacji Kursala, w górach Tien Szań (Kyrgystan). Różnicowanie się szczepu Pristiograptus dubius było poprzedzone jego masowym występowaniem i zwiększoną zmiennoscią. Następnie doszło do oddzielenia się dwu głównych linii ewolucyjnych: linii A, reprezentowanej przez P. idoneus oraz linii B, którą wyznacza pojawienie się Colonograptus? praedeubeli. Pierwszy gatunek dał początek Lobograptus? sherrardae, stanowiącemu wspólnego przodka tak rozbieżnych trendów ewolucyjnych jak linograptidy (Neodiversograptus nilssoni), kukullograptidy (Lobograptus progenitor), a prawdopodobnie także neokukullograptidy (za pośrednictwem Bohemograptus). Natomiast C.? praedeubeli, przedstawiciel lini B, zapoczątkowuje rozwój charakterystycznych dla wczesnego ludlowu monograptidów "kolczastych" (Colonograptus, Saetograptus). Rozejście się wspomnianych linii ewolucyjnych określone jak "wczesna schizma", wyznacza zarazem główne kierunki ewolucji monograptidów ludlowu.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Late Variscan deformation events in the Bardo Syncline revealed by biotite K-Ar dating of Ludlow-age tuffite (Holy Cross Mountains, Poland)
Autorzy:: Wójcik, Emil
Pacek, Adrian
Pelc, Andrzej
Tematy:: Niewachlów tuffites
biotite deformation dating
illite-smectite
Ludlow
Daleszyce Fault Zone
Holy Cross Fold Belt.; Pokaż więcej
Wydawca:: Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Powiązania:: https://bibliotekanauki.pl/articles/2058714.pdf Link otwiera się w nowym oknie
Opis:: n the Bardo Syncline (Holy Cross Mountains, Poland), two beds of tuffite (named the Niewachlów tuffites) have been discovered within greywackes of Ludlow (Silurian) age. K-Ar dating of the lower bed yielded an age of 292.8 ±4.0 Ma, while the upper bed provided an age of 341.9 ±4.3 Ma. The dates pertain to metamorphic alteration of the tuffite, related to reactivation of the Daleszyce Fault Zone. In this zone, biotite crystals present in the foliation zones were recrystallized and their K-Ar isotopic system was rejuvenated in a temperature range of ~270–300°C. The dates that were obtained define the ages of two tectono-metamorphic episodes and reflect the timing of displacements along the fault which, in turn, reflect two deformation phases during the Variscan Orogeny (Mississippian and Early Permian). Moreover the dates may be correlated with Late Variscan magmatic activity in the Holy Cross Mountains and adjacent areas. The deformation of the Daleszyce Fault Zone may be regarded as resulting from displacements of lithospheric blocks within the Trans European Suture Zone during the Late Variscan reconstruction of the Baltica palaeocontinent margin.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Late Caradoc and early Ludlow Radiolaria from Baltic erratic boulders
Autorzy:: Gorka, H
Tematy:: karadok
sylur
Baltyk
ordowik
skamienialosci
ludlow
glazy narzutowe
wapien baltycki
szkielet
paleontologia
Radiolaria
mikroorganizmy kopalne; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:: https://bibliotekanauki.pl/articles/20279.pdf Link otwiera się w nowym oknie
Opis:: Glacial erratic boulders of the Ostseekalk type, late Caradoc in age, contain spumellarian radiolarians with their skeleton substituted by iron minerals secondarily oxidized to goethite. Species of both the Inaniguttidae, characterized by the presence of a small spherical central shell, and Entactiniidae, with a transverse central bar, have been identified. A similar radiolarian assemblage, but with original siliceous skeletons preserved, has been identified in a graptolitic lirnestone boulder, early Ludlow in age.
Opracowano Radiolaria (Polycystina) z ordowickich i sylurskich głazów narzutowych regionu bałtyckiego. Ordowickie głazy narzutowe, to tak zwany "wapień bałtycki", którego wiek określa się na późny karadok. Zawarte w nich szkielety Radiolaria są zlimonityzowane lub spirytyzowane, co jest częstym zjawiskiem w przypadku tej grupy mikroorganizmów kopalnych. Przedstawiono historię badań nad skamieniałościami zawartymi w wapieniu bałtyckim ze szczególnym uwzględnieniem prac polskich autorów oraz nad Radiolariami z ordowickich i sylurskich osadów.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: The Silurian retiolitid graptolite Plectograptus: New observations and new species
Autorzy:: Bates, D.E.B.
Kozlowska, A.
Maletz, J.
Kirk, N.H.
Lenz, A.
Tematy:: Graptoloidea
Plectograptus
Retiolitidae
rhabdosome
Silurian
graptolite
new species
paleontology
retiolitid graptolite
Ludlow
morphology
terminology
systematics; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:: https://bibliotekanauki.pl/articles/20525.pdf Link otwiera się w nowym oknie
Opis:: The Ludlow genus Plectograptus, with the type species Retiolites macilentus Törnquist, 1887, collected from Thuringia (Germany), has been a widely−identified, monospecific, but poorly understood taxon for almost one hundred years. This was due to poor and incomplete preservation of the type material, and misidentification by subsequent authors up to 1995. The original, and only, type specimen of P. macilentus collected by Törnquist being lost, a neotype is herein selected from a small collection of Thuringian material. The genus has now been redefined and based on this, and SEM studies of isolated material, the defining characteristics of the genus are (i) the possession of a simple ancora umbrella with five radial lists with an incompletely developed rim; (ii) an ancora umbrella separated from lateral ancora sleeve walls by exceptionally large lateral orifices; (iii) the possession of mid−ventral lists; (iv) simple, orderly zigzag lateral wall ancora sleeve lists. Recently, two additional species, P. robustus and P. wimani, previously placed in different genera, were assigned to Plectograptus. This study recognizes three new species: P. mobergi, P. toernquisti, and P. trijunctus, bringing the total number of species to six. Species are distinguished by the presence or absence of genicular processes, inclination of the thecal ventral walls and mid−ventral lists, presence or absence of reticular lists, and three−way or four−way sleeve/lateral rod/apertural lip junctions.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Evolution of the retiolitid Neogothograptus [Graptolithina] and its new species from the upper Wenlock of Poland, Baltica
Autorzy:: Kozlowska, A
Lenz, A.
Melchin, M.
Tematy:: evolution
retiolitid
Neogothograptus
Graptolithina
new species
Upper Wenlock
Polska
Wenlock
Ludlow
Silurian
Retiolitidae
Gothograptus
biostratigraphy
ocean current
Colonograptus praedeubeli
Lobograptus progenitor
Neogothograptus reticulatus; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:: https://bibliotekanauki.pl/articles/20789.pdf Link otwiera się w nowym oknie
Opis:: Neogothograptus reticulatus sp. nov. from the upper Homerian Colonograptus praedeubeli Biozone, and N. thorsteinssoni and N. alatiformis from the Lobograptus progenitor Biozone, are described for the first time from three localities: borehole, Baltic erratic boulder of East European Platform and Holy Cross Mountains of Poland. N. reticulatus, presently the oldest known species of Neogothograptus, is also tentatively identified from upper Homerian strata of southeastern Australia. The two other species are previously known only from Arctic Canada, and possibly China. The morphology of the Neogothograptus reticulatus rhabdosome, its appendix, thecal profile, densely reticulated rhabdosome and genicular hoods suggest a close relationship to N. eximinassa from Colonograptus ludensis Biozone. N. reticulatus and N. eximinassa are most similar to Gothograptus nassa, the earliest−known retiolitid to appear immediately following the Cyrtograptus lundgreni extinction event. The biostratigraphic position of N. reticulatus suggests it might be considered as a potential ancestor to all younger (Ludlow) species of Neogothograptus. Cladistic analysis, however, provides no direct support for such an interpretation and, instead, suggests that Baculograptus batesi may be the ancestor. The occurrences of Neogothograptus, as well as G. nassa, from a number of Silurian terranes mostly from low paleolatitude regions, but also from high paleolatitudes, demonstrate their tolerance to a broad range of paleoenvironments.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Silurian aphrosalpingid sphinctozoans from Alaska and Russia
Autorzy:: Rigby, J K
Nitecki, M.H.
Soja, C.M.
Blodgett, R.B.
Tematy:: fauna kopalna
Aphrosalpingidae
sylur
gabki kopalne
skamienialosci
Aphrosalpinx nana
Cystothalamiella alaskensis
Nematosalpinx hormathodes
Cystothalamiella irregularis
ludlow
cechy morfologiczne
dendroklony
sfinktozoa
Alaska
szkielet
paleontologia
gabki
formacja Haceta
trikranoklony; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:: https://bibliotekanauki.pl/articles/23278.pdf Link otwiera się w nowym oknie
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Marine snow and epipelagic suspensoids in the Reda carbonates and a pronounced mid-Ludfordian (Silurian) CIE in the axis of the Baltic Basin (Poland)
Autorzy:: Kozłowski, Wojciech
Tematy:: pelagic carbonates
Sparoids
marine snow
algal blooms
eolian dust
carbonate supersaturation
euxinia
Baltic basin
Reda Member
ludlow
Silurian
węglany pelagiczne
sparoidy
śnieg morski
zakwit glonów
osady eoliczne
basen bałtycki
sylur; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/1835581.pdf Link otwiera się w nowym oknie
Opis:: The mid-Ludfordian pronounced, positive carbon isotope excursion (CIE), coincident with the Lau/kozlowskii extinction event, has been widely studied so far in shallow-water, carbonate successions, whereas its deep-water record remains insufficiently known. The aim of this research is to reconstruct the sedimentary environments and the palaeoredox conditions in the axial part of the Baltic-Podolian Basin during the event. For these purposes, the Pasłęk IG-1 core section has been examined using microfacies analysis, framboid pyrite diameter and carbon isotope measurements. The prelude to the event records an increased influx of detrital dolomite interpreted as eolian dust, coupled with a pronounced decrease in the diameter of the pyrite framboids, indicating persistent euxinic conditions across the event. The event climax is recorded as the Reda Member and consists of calcisiltites, composed of calcite microcrystals (‘sparoids’), which are interpreted as suspensoids induced by phytoplankton blooms in the hipersaturation conditions present in the epipelagic layer of the basin. Both the prelude and climax facies show lamination, interpreted as having resulted from periodical settling of marine snow, combined with hydraulic sorting within a ‘benthic flocculent layer’, which additionally may be responsible for a low organic matter preservation rate due to methanogenic decomposition. Contrary to the observed basinward CIE decline in the benthic carbonates in the basin, the Reda Member records an extremely positive CIE (up to 8.25‰). Given the pelagic origin of the sparoids, the CIE seems to record surface-water carbon isotope ratios. This points to a large carbon isotope gradient and kinetic fractionation between surface and bottom waters during the mid-Ludfordian event in a strongly stratified basin. The Reda facies-isotope anomaly is regarded as undoubtedly globally triggered, but amplified by the stratified and euxinic conditions in the partly isolated, Baltic-Podolian basin. Hence, the common interpretation of the basin record as representative for the global ocean needs to be treated with great caution.
Dostawca treści:: Biblioteka Nauki

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