El Devónico Inferior del Dominio Obejo-Valsequillo-Puebla de la Reina (Zona de Ossa-Morena): conodontos, braquiópodos, corales, ostrácodos y peces

La escasez de estudios paleontológicos adecuados, la complejidad tectónica y la discontinuidad de los afloramientos dificulta el conocimiento de la secuencia lito y bioestratigráfica del Dominio Obejo-Valsequillo-Puebla de la Reina. Este hecho, nos ha animado a comenzar un estudio multidisciplinar (fundamentalmente conodontos, braquiópodos, corales, estromatoporoideos, ostrácodos, restos de peces y biofacies) del Devónico Inferior de la parte oriental de este Dominio. En este trabajo se presentan datos paleontológicos de cuatro secciones que permiten el establecimiento de un marco temporal preliminar que servirá para futuros estudios de detalle. Estas secciones son, de oeste a este, Guadámez 2 (GUA 2), Zújar (ZUJ), Peñón Cortado (PCR) y Pozo del Rincón (PZR)

Early Devonian ostracodes of Thuringian Ecotype from NW Anatolia (Turkey)

The first report of silicified ostracodes of Thuringian Ecotype (sensu BECKER) from Early Devonian (Emsian) limestones of the Pelitli and Kartal formations in NW Anatolia (Yakacik area, Istanbul, Turkey) is presented. The poorly preserved faunas of only nine taxa indicate faunal relations of the Istanbul Terrane especially to Thuringia (Germany) and Morocco during the Emsian

Scarce ctenacanthiform sharks from the Mississippian of Austria with an analysis of Carboniferous elasmobranch diversity in response to climatic and environmental changes

The Carboniferous is characterized by drastic climatic and environmental fluctuations, which include multiple phases of glaciation resulting in an icehouse climate. Additionally, dynamic continental reconfigurations forced the contraction of the Rheic Ocean resulting in the closure of the Rheic–Tethyan Gateway, which precluded further faunal exchanges between the North American and Eurasian marine realms. Interestingly, cartilaginous fishes seem to be relatively immune to these drastic climatic and environmental changes. The Eurasian fossil record of Paleozoic sharks is strongly biased towards intensively sampled localities from England, Ireland, Scotland, and the Russian Platform. Here we present rare dental material from the Serpukhovian (early Carboniferous) of Austria, adding new information to the paleogeographic distribution of ctenacanthiform sharks. The new material revealed the first record of the genus Saivodus in Central Europe and allowed us to recognize a new species, Cladodus gailensis sp. nov., and a remnant of fossilized cartilage. In an attempt to identify possible linkages between climatic or environmental fluctuations on shark diversity throughout the Carboniferous, we provide a synopsis of the distribution and diversity of elasmobranchs based on primary literature. This preliminary assessment at genus level indicates two pronounced events of extinction, with the first one occurring during the latest Mississippian and the second one towards the end of the Pennsylvanian. The first extinction event distinctly correlates with the known diversity decline of other marine inhabitants and the second occurred during an unstable period of multiple phases of glaciation

Insight into the development of a carbonate platform through a multi-disciplinary approach - A case study from the Upper Devonian slope deposits of Mount Freikofel (Carnic Alps, Austria/Italy)

The development and behavior of Million year-scaled depositional sequences recorded within Palaeozoic carbonate platform has remained poorly examined. Therefore, the understanding of palaeoenvironmental changes that occur in geological past is still limited. We herein undertake a multi-disciplinary approach (sedimentology, conodont biostratigraphy, magnetic susceptibility and geochemistry) of a long-term succession in the Carnic Alps which offers new insights into the peculiar evolution of one of the best example of Palaeozoic carbonate platform in Europe. The Freikofel section, located in the central part of the Carnic Alps represents an outstanding succession in a fore-reef setting, extending from the latest Givetian (indet. falsiovalis conodont Zones) to the early Famennian (Lower crepida conodont Zone). Sedimentological analysis allowed to propose a sedimentary model dominated by distal slope and fore-reef slope deposits. The most distal setting is characterized by an autochthonous pelagic sedimentation showing local occurrence of thin-bedded turbiditic deposits. In the fore-reef slope, in a more proximal setting, there is an accumulation of various autochthonous and allochthonous fine- to coarse-grained sediments originated from the interplay of gravity-flow currents derived from the shallow-water and deeper-water area. The temporal evolution of microfacies in the Freikofel section evolves in two main steps corresponding to the Freikofel (Unit 1) and the Pal (Unit 2) Limestones. Distal slope to fore-reef lithologies and associate changes are from base to top of the section: (U1) thick bedded litho- and bioclastic breccia beds with local fining upward sequence and fine-grained mudstone intercalations corresponding, in the fore-reef setting, to the dismantlement of the Eifelian – Frasnian carbonate platform during the early to late Frasnian time (falsiovalis to rhenana superzones) with one of the causes being the Late Givetian major rift pulse; (U2) occurrence of thin-bedded red nodular and cephalopod-bearing limestones with local lithoclastic grainstone intercalations corresponding to a significant deepening of the area and the progressive withdrawal of sedimentary influxes toward the basin, in relation with late Frasnian sea-level rise. Magnetic susceptibility and geochemical analyses were also performed along the Freikofel section and demonstrate the inherent-parallel link existing between variation in magnetic susceptibility values and proxy for terrestrial input. Interpretation of magnetic susceptibility in term of palaeoenvironmental processes reflect that even though distality remains the major parameter influencing magnetic susceptibility values, carbonate production and water agitation also play an important role.Grants IGCP 580 and NAP0017 (DP, ACDS), the FWF P 23775-B17 (TS and EK