Search results for "IOS"
showing 10 items of 8115 documents
Les Ammonoïdes (Mollusca, Cephalopoda) : avancées et contributions récentes à la paléobiologie évolutive.
2009
12 pages; Les ammonoïdes qui perdurent 335 Ma constituent un modèle de choix dans l'analyse du fait évolutif. Cet article de synthèse se propose d'aborder (1) : leur place phylogénétique au sein des céphalopodes et le choix d'un modèle actuel de référence ; (2) : la construction d'espaces phénotypiques qui offrent un angle d'étude pertinent de l'évolution biologique ; (3) : les concordances et discordances entre reconstruction phylogénétique et registre fossile et (4) : les reconquêtes postcrises, modèles d'étude de l'évolution à grande échelle. Il ressort que les ammonoïdes peuvent servir d'appui à de nombreuses thématiques paléontologiques (dynamique de la biodiversité, analyse phylogénét…
Conodont biostratigraphy of the Yujiang Formation (Emsian, Lower Devonian) at Shizhou, Guangxi, South China
2018
Abstract We study conodonts from the upper part of the Shizhou Member of the Yujiang Formation in Liujing area for the first time. Relatively abundant conodonts were collected from six sampling levels located between the uppermost part of the Shizhou Member to the lowermost part of the Daliancun Member at the Shizhou section, Liujing, Guangxi. The material includes Polygnathus excavatus excavatus Carls and Gandl, P. excavatus ssp. 114 Carls and Valenzuela-Rios, P. nothoperbonus Mawson, P. perbonus (Philip) as well as “ Ozarkodina ” midundenta (Wang and Ziegler) and “ O. ” prolata Mawson. The lowest record of P. nothoperbonus is documented 0.35 m below the boundary between the Shizhou and Da…
Les Gregoryceras (Ammonitina) de l'Oxfordien moyen terminal et supérieur téthysien : révision systématique, biostratigraphie et évolution.
2009
43 pages; Les Gregoryceras Spath, 1924 (Ammonitina, Peltoceratina) de la fin de l'Oxfordien moyen (sous-zone à Rotoides) et de la base de l'Oxfordien supérieur (zone à Bifurcatus) sont révisés. Les coupes ayant fourni la plupart des spécimens de ce travail (Espagne et Maghreb) sont décrites et datées sur la base de comparaisons fauniques entre les domaines téthysien et subtéthysien. Le meilleur outil pour ces corrélations est la présence du genre Gregoryceras. La succession des espèces de Gregoryceras est identique pour les deux domaines suscités, ce qui permet de compléter l'échelle biostratigraphique proposée antérieurement et parallèle à la zonation standard. Les espèces reconnues et red…
Biostratigraphy and isotope stratigraphy of upper Maastrichtian–Danian marine deposits of the Kopet-Dagh Basin, northeast Iran
2018
Abstract Biostratigraphy, using foraminifera and echinoids, plus high-resolution carbon isotope stratigraphy of the upper Maastrichtian–Danian interval in the western part of the Kopet-Dagh Basin in northeast Iran are outlined. Our study of shallow-marine carbonate platform deposits of the Kalat Formation, rich in larger benthic foraminifera (predominantly Clypeorbis mammillatus Schlumberger, Lepidorbitoides sp. and Siderolites calcitrapoides Lamarck), has allowed the definition of a C. mammillatus-S. calcitrapoides Assemblage Zone, of late Maastrichtian age. Clypeorbis mammillatus is here recorded for the first time from the Maastrichtian Kalat Formation and represents the most easterly fi…
The lower Ovetian Stage (lower Cambrian Stage 3) trilobite zonation in Spain and correlation with West Gondwana
2020
New trilobites from the upper part of the Pusa Formation (base of Cambrian Stage 3) in Central Spain are studied for their systematic and biostratigraphic significance. The trilobites Proabadiella ...
Upper Ovetian trilobites from Spain and their implications for the palaeobiogeography and correlation of the Cambrian Stage 3 in Gondwana
2016
Abstract The upper part of the La Herreria Formation in Los Barrios de Luna (Leon Province, N Spain) has been revised from a palaeontological and biostratigraphical point of view. Two stratigraphic sections have been studied including their trilobite and ichnofossils contents. The ichnofossil assemblages have a high diversity of species characterising the Cruziana ichnofacies, suggesting a shallow sublittoral environment for the upper part of the La Herreria Formation. The trilobites species recognised are Lunagraulos antiquus , Dolerolenus formosus , Dolerolenus longioculatus , Lunolenus lunae , Metadoxides richterorum , Metadoxides armatus and Sardaspis ? sp. from the upper Ovetian (lower…
Turonian marine amniotes from the Opole area in southwest Poland
2018
A few isolated plesiosaurian and mosasauroid squamate teeth were collected from the Opole area in southwest Poland during the late nineteenth century. Calcareous nannofossil analysis of their associated rock matrix indicates an early Turonian age (nannofossil zone UC7; Mytiloides ex gr. labiatus and Inoceramus apicalis inoceramid zones), which is significant because this constitutes a globally enigmatic interval of marine amniote evolution. The Opole plesiosaurian teeth are attributable to polycotylids, but an indeterminate mesopodial was also recovered. They are similar to specimens from the Cenomanian-Turonian in the Saxonian Cretaceous Basin of Germany and the Chalk succession of England…
Planktonic foraminifera biozones and isotope stratigraphy of the Cenomanian-Turonian boundary in the western part of the Kopet-Dagh Basin, NE Iran
2018
Abstract A biostratigraphic study based on the planktonic foraminifera and isotope stratigraphy of the Cenomanian-Turonian interval has been undertaken in the western part of the Kopet-Dagh Basin (NE Iran). In this research, two stratigraphic sections including: Maraveh Tappeh and Qareh Galdy have been sampled and studied. Based on planktonic foraminifera, three biozones were assigned to this interval. These are the Rotalipora cushmani Zone, Whiteinella archaeocretacea Zone and Helvetoglobotruncana helvetica Zone, These biostratigraphic data confirm a gradual faunal turnover of planktonic foraminifera, at the Cenomanian-Turonian boundary in Whiteinella archaeocretacea Zone characterized by:…
Biostratigraphy, Chronostratigraphy and Paleonvironmental Reconstruction of the Palermo Historical Centre Quaternary succession
2016
Marine deposits from the Palermo Plain were historically relevant for the Quaternary Period definition. Here we show lithostratigraphic, biostratigraphic and chronostratigraphic data collected on three boreholes in the Palermo historical centre that recovered 36.8, 42.0 and 52.0 metres of sediments overlaying the Numidian Flysch. Marine sedimentary sequences span from the Calabrian Stage (calcareous nannofossil Zone MNN 19d) to the Middle Pleistocene (dominance of medium-sized gephyrocapsids within the MNN 19f Zone) and also include a short Holocene depositional event. Calcareous nannofossil, benthic and planktonic foraminifera assemblages point to a shallow coastal environment, possibly < …
A Cretaceous carbonate escarpment from Western Sicily (Italy): biostratigraphy and tectono-sedimentary evolution
2020
Abstract The presence of a huge carbonate slope of Cretaceous age is recorded in some imbricated thrust sheets from the Maghrebian fold-and-thrust belt cropping out in northwesternmost Sicily (southern Italy). The sedimentological features of this escarpment, named as the Western Sicily Cretaceous Escarpment (WSCE), have been recently described. The present paper aims to provide a detailed bio-chronostratigraphic characterization of the different facies types that occur in the four lithostratigraphic units spanning the whole slope depositional system. The detailed biostratigraphic analysis and correlation of a number of well-exposed sections allowed to differentiate eight informal biozones …