Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 8

Liczba wyników na stronie
first rewind previous Strona / 1 next fast forward last
Wyniki wyszukiwania
help Sortuj według:

help Ogranicz wyniki do:
first rewind previous Strona / 1 next fast forward last
EN
During fieldwork in the early 1990s at the then still active quarry near Nasiłów, on the left bank of the River Vistula (Wisła), accompanied by Professor Andrzej Radwański, some lobster remains were collected. A fragmentary anterior portion of a decapod crustacean carapace, recovered from a level about 2 m below the Cretaceous–Paleogene (K/Pg) boundary, in a siliceous chalk unit locally referred to as ‘opoka’, constitutes the oldest record of the thaumastocheliform genus Dinochelus Ahyong, Chan and Bouchet, 2010, D. radwanskii sp. nov. The other, more complete, individual is from c. 3 m above the K/Pg boundary, coming from marly gaizes or ‘siwak’; this is ascribed to a new species of Hoploparia M’Coy, 1849, H. nasilowensis sp. nov., the first to be recorded from Danian (lower Paleocene) strata. Although both ‘opoka’ and ‘siwak’ facies in the Nasiłów area are very rich in diverse biota, including some brachyurans, no macruran remains had so far been recorded from the region.
EN
We describe a new echinoid assemblage, composed of specimens of Bolbaster sp., Cyclaster danicus (Schlüter, 1897), Diplodetus vistulensis (Kongiel, 1950) and Linthia? sp. in a distinctive phosphatic preservation, from the so-called Greensand, a marly glauconitic sandstone horizon at the base of the Danian succession in the Kazimierz Dolny area (central Poland). This assemblage presumably is of early Danian age, with Cyclaster danicus occurring in the lower Danian of Denmark and southern Sweden. The specimens are preserved as internal moulds, composed of phosphatised glauconitic sandstone, occasionally with some test material adhering. The genesis of these moulds involved the following steps: (1) infilling of tests of dead echinoids with glauconitic sand; (2) penetration of the infills by coelobiotic deposit-feeding organisms that produced burrows along the inner test surface; (3) early-diagenetic cementation of infills by calcium phosphate; and (4) exhumation and intraformational reworking of specimens, leading to abrasion, fragmentation and loss of test material in some individuals. Co-occurring are unphosphatised moulds of Echinocorys ex gr. depressa (von Eichwald, 1866) and Pseudogibbaster cf. depressus (Kongiel in Kongiel and Matwiejewówna, 1937), which may represent a younger (middle to late Danian) assemblage. Additionally, the presence of derived late Maastrichtian echinoids, e.g., Temnocidaris (Stereocidaris) ex gr. herthae (Schlüter, 1892), Pleurosalenia bonissenti (Cotteau, 1866) and Hemicara pomeranum Schlüter, 1902, is confirmed for the Greensand, based on new material and re- examination of previously recorded specimens. In summary, members of three echinoid assemblages of different age and preservation occur together in the Greensand. Our results are compatible with former interpretations of this unit as a condensed, transgressive lag with mixed faunas of different age and provenance. However, they are incompatible with the hypothesis that phosphatised Danian fossils preserved in the Greensand are derived from a facies equivalent, now gone, of the lower Danian Cerithium Limestone in eastern Denmark, because all moulds are composed of phosphatised glauconitic sandstone that is utterly different from the calcareous dinocyst-dominated, fine crystalline matrix of the Cerithium Limestone.
EN
A re-examination of heteromorph ammonites of late Campanian age from the Zeltberg section at Lüneburg has demonstrated that the type series of Hamites wernickei in fact comprises two different species that are here assigned to the nostoceratid Nostoceras Hyatt, 1894 and the polyptychoceratid Oxybeloceras Hyatt, 1900. Nostoceras (Didymoceras) wernickei (Wollemann, 1902) comb. nov., to which three of the four specimens that were described and illustrated by Wollemann (1902) belong, has irregularities of ribbing and tuberculation and changes its direction of growth at the transition from the helicoidal whorls to the hook, which is a typical feature of members of the subfamily Nostoceratinae. Torsion of body chambers is not developed in hairpin-shaped ammonite species, which means that the species name wernickei is no longer available for such polyptychoceratine diplomoceratids. Consequently, the fourth specimen figured and assigned to Hamites wernickei by Wollemann (1902) is here transferred to Oxybeloceras and considered conspecific to material from the Hannover area (Lehrte West Syncline) as O. aff. crassum (Whitfield, 1877). In addition to the "Heteroceras-Schicht des Mucronaten-Senons" of Lüneburg (bipunctatum /roemeri Zone, upper upper Campanian), the geographic range of N. (D.) wernickei probably includes Upper Austria, Tunisia and the Donbass region, while O. aff. crassum is known from the Hannover area (northern Germany), southern France, northern Spain and Upper Austria.
EN
A fragmentary specimen of the diplomoceratid heteromorph Diplomoceras cylindraceum, one of three ammonite markers used for the definition of the base of the Maastrichtian Stage, is recorded from the middle Campanian of the Roztocze Hills, southeast Poland. The new find, well constrained by associated ammonites and inoceramid bivalves, represents the earliest well-dated occurrence of this species worldwide to date. Therefore, the first occurrence (FO) of D. cylindraceum is conspicuously below the traditional base of the Maastrichtian as defined by the FO of the belemnite Belemnella lanceolata. Indeed, this is also far below the boundary designated in the Global Stratotype Section at Tercis les Bains (Landes, France). A comparison of the FOs of D. cylindraceum in sections acrossEurope clearly shows a significant diachroneity, which diminishes its value for definition of the Campanian/Maastrichtian boundary.
5
Content available In defence of an iconic ichnogenus : Oichnus Bromley
EN
By establishing the bioerosion ichnogenus Oichnus, Richard Bromley (1981) addressed ‘small round holes in shells’ and catalysed a series of still ongoing discussions on ichnotaxonomical principles. In a recent revision by Zonneveld and Gingras (2014), Oichnus was rejected, together with Tremichnus Brett, 1985 and Fossichnus Nielsen, Nielsen and Bromley, 2003, by means of subjective synonymisation with the presumed senior synonym Sedilichnus Müller, 1977. However, Sedilichnus is nomenclaturally unavailable, because it is an atelonym (conditionally proposed). In addition, reinvestigation of the type material of ‘Sedilichnus’ shows that it probably describes variably shaped oscula and thus is a genuine morphological character of the host sponge Prokaliapsisjanus, rather than a bioerosion trace fossil. The ichnogenera Oichnus and Tremichnus are re vised, leading to the synonymisation of Balticapunctum Rozhnov, 1989 with Tremichnus, and of Fossichnus with Oichnus. The refined ichnogeneric diagnoses return Oichnus to complete or incomplete bioerosive penetrations in calcareous skeletal substrates, commonly interpreted as praedichnia with or without signs of attachment, while Tremichnus (now including O. excavatus) exclusively refers to shallow pits passing into echinoderm skeletons that are interpreted as domichnia or fixichnia.
EN
To date, the strongest arguments for ammonite survival into the Danian (earliest Paleogene) are based on material from the lower Danian Cerithium Limestone at Stevns Klint (Denmark), where ammonites occur above a clay layer with impact products at its base, the latter defining the Cretaceous-Paleogene (K-Pg) boundary. The best-preserved specimen is filled with Danian sediment rather than with Maastrichtian chalk, which would be expected had this been reworked material. Arguments for ammonite survival into the Danian have also been provided by specimens from the sporomorph and calcareous nannoplankton-dated lowermost Danian strata of Meerssen Member unit IVf-7, the Netherlands. Their good preservation indicates that they were not subject to any significant transport or redeposition. However, there are no unequivocal impact-related signatures in unit IVf-7, except for rare shocked quartz grains, recorded from burrows at its base. Sections in the Manasquan Basin, New Jersey, USA, provide equivocal data as far as the problem of ammonite survival into the Danian is concerned. At the top of the Tinton Formation there is a Pinna layer replete with fossils, inclusive of ammonites. Their exquisite preservation and occurrence in monospecific clusters rule out redeposition. The Pinna layer contains exclusively late Maastrichtian microfossils. However, a clear iridium anomaly has been noted at its base. Either the New Jersey ammonites survived the K-Pg event for a short time or the iridium is not in situ due to post-depositional repositioning by percolating water. Planned work is to focus on: 1) a detailed centimetre by centimetre sampling of some Cerithium Limestone basins in Denmark in search of additional ammonite material, 2) palaeontological and taphonomic analysis of ammonites and search for impact signatures in unit IVf-7 in the Netherlands, and 3) geochemical study of the iridium anomaly in New Jersey in order to determine whether its position in respect to the ammonite-bed is original or secondary.
EN
The Campanian strata in the Wolbrom-Miechów area at Wierzchowisko, Jeżówka and Rzeżuśnia (i.e., the southwestern part of the Miechów Trough, southern Poland) have been studied in some detail. Collections of macrofossils available to date include generally well-preserved and diverse cephalopods (ammonoids, coleoids), inoceramid bivalves and irregular echinoids of considerable stratigraphic and correlative value. For the present paper, taxa which allow a preliminary correlation with northern Germany (Lagerdorf, Lehrte West Syncline and Munsterland Basin) are singled out for brief discussion. Stratigraphically useful taxa include the ammonites Pachydiscus (P.) haldemsis (SCHLUTER), Lewyites elegans (MOBERG), Scaphites (S.) hippocrepis III sensu COBBAN, S. (S.) gibbus SCHLUTER and Trachyscaphites spiniger spiniger (SCHLUTER), the coleoids Belemnitella ex gr. mucronata (VON SCHLOTHEIM) and Gonioteuthis quadrata (DE BLAINVILLE),the inoceramids Cataceramus dariensis (DOBROV & PAVLOVA), "Inoceramus" azerbaydjanensis ALIEV and "I." agdjakendsis ALIEV, and the echinoids Offaster pilula (LAMARCK), Galeola papillosa (LESKE), Echinocorys ex gr. subglobosa/turrita, E. ex gr. conica, Micraster (Gibbaster) ex gr. fastigatus/stolleyi and M. (M.) ex gr. schroederi/glyphus. The ammonite fauna, which is dominated by pachydiscids and diplomoceratids, is closely comparable to that from the Busko Zdrój area (i.e., the southeastern part of the Miechów Trough), but hoplitoplacenticeratids are still unknown from the Wolbrom-Miechów area which, taken together with inoceramid data, may point to a gap in the upper Lower Campanian (equivalent of conica/mucronata Zone).
EN
Late Cretaceous and Early Palaeogene echinoid faunules collected in recent years from the surface of an active mudflow at the Gschliefgraben near Gmunden (east of the Traunsee, Upper Austria) are both fairly diverse and of considerable palaeobiogeographic interest. So far, only (Late) Campanian taxa have been described and illustrated. In the present paper, notes are presented on additional Campanian, Maastrichtian and Palaeogene taxa, namely Lampadocorys? estermanni sp.nov., Lampadocorys? sp.nov. 1, Lampadocorys? sp.nov. 2, Rispolia cf. subtrigonata (CATULLO), Seunaster cf. heberti (SEUNES), Echinocorys ancileformis MOSKVIN & SHIMANSKAYA, Echinocorys ex gr. fonticola ARNAUD, Ganbirretia? sp., Micraster aturicus HEBERT in SEUNES, Micraster corcolumbarium DESOR, Micraster stolleyi (LAMBERT in DE GROSSOUVRE), Pseudogibbaster? sp., and Coraster beneharnicus SEUNES.These species indicate a close relationship with the Tethyan areas of northern Spain and SW France, the Crimea, Georgia and the northern Caucasus, although a number of holasteroid and micrasterid taxa would appear to be more common and widely distributed in boreal settings (e.g., NW Europe).
first rewind previous Strona / 1 next fast forward last
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.