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The conodont apparatus of Zieglerodina eladioi (Valenzuela Rios, 1994)
Full text linkZieglerodina eladioi (Valenzuela-Ríos) è una specie di conodonti ozarkodinidi documentata dalla parte più alta del Přídolí (Siluriano superiore) al Lochkoviano medio (Devoniano Inferiore). La specie è stata istituita nei Pirenei spagnoli e fino a ora è documentata in diverse aree del nord Gondwana (Marocco, Alpi Carniche, Sardegna, Repubblica Ceca e Turchia). L’apparato di Zieglerodina eladioi viene ricostruito basandosi su ritrovamenti in Marocco, Sardegna e nelle Alpi Carniche; esso comprende sei elementi (P1, P2, M, S0, S1 e S2) in cui gli elementi ramiformi sono caratterizzati da una denticolazione alternata con denticoli aghiformi. La morfologia dell’apparato conferma l’attribuzione della specie al genere Zieglerodina.Zieglerodina eladioi (Valenzuela-Ríos) is a small ozarkodinid from the latest Přídolí (Silurian) and the Lochkovian (Lower Devonian), up to now documented only in areas of North Gondwana. Material from Morocco, the Carnic Alps, and Sardinia provide the basis for the seximembrate reconstruction of this conodont species’ apparatus (consisting of P1, P2, M, S0, S1, and S2 elements). The ramiform elements of Zieglerodina eladioi are characterised by an alternate denticulation with spike-like denticles, further confirming the attribution of the species to the genus Zieglerodina
Silurian-Lower Devonian conodonts from the Rifugio Lambertenghi Fontana III (RLF III) Section (Carnic Alps, Italy)
No full textThe Lochkovian of the Carnic Alps (Italy and Austria): conodont fauna and biostratigraphic correlations
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The Silurian/Devonian sequence at Perda s'Altari (SW Sardinia, Italy).
No full textIn the Perda S’altari area, north of Fluminimaggiore, black shales of the Silurian Genna Muxerru Formation and limestones of the Devonian Mason Porcus Formation are exposed. The area is strongly tectonized, and poorly preserved fossils occur only in a few outcrops. Graptolites of Telychian and Rhuddanian age have been collected from the shales, whereas conodonts indicate the Lochkovian Icr. postwoschmidti and Ad. transitans zones. The problematic Eurytholia bohemica species is here documented from Devonian rocks for the first time outside the Czech Republic. A gradual transition between the Genna Muxerru Fm. and the Mason Porcus Fm. suggests an update to the lithostratigraphical scheme of the Silurian and Lower Devonian of SW Sardinia
The new genus Walliserognathus and the origin of Polygnathoides siluricus (Conodonta, Silurian)
Full text linkThe new Genus Walliserognathus is described to host the species posthamata (Walliser). The genus is monospecific. The shape of P1 and P2 elements of Walliserognathus posthamatus, characterized by a small platform along the whole elements, and its stratigraphic distribution limited to the A. ploeckensis Zone suggest that the species may have been the bridge in the phylogenesis from Wurmiella to Polygnathoides
Running across the Silurian/Devonian Boundary along Northern Gondwana: A Conodont Perspective
Full text linkThe Global Stratotype Section and Point (GSSP) of the Silurian/Devonian boundary, Lower Devonian Series and Lochkovian Stage was formally placed in 1977 at Klonk, in the Czech Republic, at the first appearance of the graptolite Uncinatograptus uniformis uniformis (Přibyl). However, since then, correlation of this limit has been often hampered in carbonate facies where graptolites are uncommon or totally absent. A large calcareous deposition occurred at the Silurian/Devonian boundary along the northern and peri-Gondwana margin, thus representing an ideal location to select and test a possible additional biostratigraphic marker of the limit among conodonts. The first appearance of Caudicriodus hesperius almost simultaneously at the base of the Devonian in Bohemia, the Carnic Alps, Sardinia, Morocco and elsewhere indicates that this taxon is the conodont that best approximates the beginning of the Period. The first or last appearance of other species (e.g., Ozarkodina confluens, Zieglerodina klonkensis, Z. remscheidensis and Caudicriodus woschmidti) may help to recognise the boundary as well
Conodonts across the Silurian/Devonian boundary in the Carnic Alps (Austria and Italy)
Full text linkIn the Carnic Alps, located across the border between Italy and Austria, several sections span the Silurian/Devonian boundary in different sedimentary settings, from very shallow water to moderately deep shelf. All studied sections yielded conodonts and based on the first and last occurrences of the conodont taxa in the upper part of the Upper Oul. el. detortus Zone and in the lower part of the I. hesperius Zone a detailed conodont biostratigraphic framework was able to be constructed for this interval. Comparison of data from different depositional settings demonstrates that, although the majority of species are documented everywhere in the Carnic basin, a few taxa, mainly represented by coniforms, are limited to shallow water, whereas others, mainly ozarkodinids, occur only in open sea deposit
The Devonian/Carboniferous boundary in Sardinia (Italy)
No full textIn Sardinia (Italy) two sections, located in the southeastern part of the island, expose the Devonian/Carboniferous Boundary: the Monte Taccu Section and the Bruncu Bullai section. Both expose limestones from the middle Famennian to the lower Tournaisian Siphonodella jii Zone. The limestone sequence is interrupted by a thin level of shales representing the Hangenberg Event. Data on conodont biostratigraphy and magnetic susceptibility across the Devonian/Carboniferous Boundary are here summarised and reviewed
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