PALEONTOLOGY OF INVERTEBRATES

Author: DIZ FERREIRO PAULA.
Year: 2003.
University: VIGO [www.uvigo.es].
Place of defense: FACULTAD DE CIENCIAS DEL MAR.
Place of preparation: FACULTAD DE CIENCIAS DEL MAR.

Summary: In this work we have studied benthic foraminifera in the Ria de Vigo from two points of view, the factors that determine the spatial distribution and vertical forms alive under conditions hildrodinámicas dip and outcrop and the parameters affecting the presence of forms killed in the fossil record. These two views are closely related and will permtir discuss those processes involved in the transition from a partnership to a living dead / fossil. In the area outside associations are dominated by small ways, whereas in the area of internal copies large gain more importance. This is because the quality of organic matter, the type of reproduction and comptencia with other species. Thus, the small size of foraminifera is a general feature of the Ria de Vigo and certainly highly productive coastal systems. The funds consisting of coarse sand and gravel clean the external sector, subject to a higher energy regime, partnerships are very different as a result of a highly predictable environment and the high resilience of the communities of foraminifera to energy environment, the type of food (communities bacterial biofilms, etc..), and also to the availability of microhabitats. The speed of the flow of fund determines the predominant way of life and the vertical distribution of foraminifera in the thick substrates. For funds under high flow velocities dominate life forms Stuck. The forms are stuck able to inhabit the thickness of sediment removilziado by currents. This fact suggests that conditions microenvironmental below the interface agua-sedimento are simejantes to the surface, which requires rethinking the concept of lifestyle epifaunal. Over the backbone of the estuary have been able to identify three associations foraminifera that are characteristic of certain sectors. These are: Association estuary external, internal estuary Association and Association of San Simon. The Association of external estuaries is characterized primarily by three species: B.spathulata, B.dilatata and S.fusiformis. Appears in relatively oxygenated sediments with a low organic carbon content (less 3.5%) but a high nutritional quality. The Association of internal estuary is characterized by the dominance of E.scaber, which are associated B.elegantissima and H.atlantica. This partnership is geared to high concentrations of organic carbon (higher 3.5%) but low quality, as well as conditions microenvironmental subóxicas and / or reductive inside the sediment. The Association de la Ensenada San Simon comprises A.beccarii and H.germánica, typical species of estuarine environments. The arrival of labile organic matter and high quality from anfloramiento summer mainly affects the composition of the partnerships. This fact is evident in the external sector. On the one hand, certain species, such as S.fusiformis, increase their abundance. Moreover, the medium is colonized by new species: funds high-energy, as channels, colonization is produced by species typical of the platform (G.praegeri, P.madeirae, C.obtusa). Stations shaft muddy external subjected sa better energy are colonized by N.stell, N.turgida, R.scotii and B.translucens. The quality of the food determines the vertical distribution of genetic benthic foraminifera. In some cases, the existence of concentrations of bacteria associated with inactive pipes at depths of polychaetes relatively large favors concentr 8 ation of 574 foraminifera at these levels. In other cases, foraminifera are concentrated in the superficial level, where they have migrated in response to the arrival of fresh food. The degradation of organic matter is the main parameters controlling the vertical extension of foraminifera in the internal affairs of the estuary. The comparison between live and dead partnerships has enabled tafonómicos differentiate the main processes involved in the generation of an association fossil / dead. Tafonómico The main process that takes place in areas of high energy is washing the forminíferos small, which means a significant loss of ecological information. At stations marginal areas located in areas of steep slopes are joining the association dead foraminifera from adjacent areas more shallow. In the muddy central shaft stations associations are dead, in general terms, similar to those alive.

Author: DIES ÁLVAREZ MARÍA EUGENIA.
Year: 2003.
University: ZARAGOZA [www.unizar.es].
Place of defense: FACULTAD DE CIENCIAS.
Place of preparation: FACULTAD DE CIENCIAS.

Summary: Formation Valdemiedes of the Iberian Chains is one of the most cited in literature for signing up for it to the limit Cambrian Inferior- East (Bilbiliense-Leoniense). This paper has revised its stratigraphy and paleontology in five sections, the study focused on the group of trilobites. Sections Rambla de Valdemiedes 1 and 2 of Murero (RV1 and RV2) and section Villafeliche 1 (Vi1) are located south and are characterized by the predominance of materials siliciclastic (facies slates with trilobites) during Bilbiliense (Lower Cambrian late ) and alternation of carbonate and siliciclastic (facies kinky) during Leoniense (early Middle Cambrian). Sections Ateca 16 (At16) and Jarque 1 (J1) are located north and characterized by the development of kinky facies in the Bilbiliense as in the Leoniense. In the section Ateca far to NOT are very frequent levels bioclastic limestone. This difference was already facial explained by the increased subsidence occurred in the southern part of the basin with respect to the north during the Bilbiliense higher. The nomenclature has been completed and the glossary of terms used by Liñán and Gozalo (1986), with the new terms appeared in Whittington and Kelly (1997). It has carried out the study and review of the trilobites Cambrian Inferio-Medio of traffic Chains Iberian determined that consists of the following taxa: Protolenus dimarginatus, Protolenus termierelloides, Protolenus interscriptus, Protolenus pisidianus, Protolenus jilocanus, Hamatolenus (Hamatolenus) ibericus , Hamatolenus (Myopsolenus) sp. A Hamatolenus (Lotzeia) lotzei, Hamatolenus (Lotzeia) sp. Alueva undulata, Alueva hastata, Alueva moratrix, Kingaspis (Kingaspidoides) sp. Kingaspis (Kingaspis) campbelli, Kingaspis (Kingaspis) sp. Acadoparadoxides mureroensis, Acadoparadoxides? Cf. Harlani, Eccaparadoxides sdzuyi, Onaraspis altus, Sdzuyia sanmamesi, Tonkinella sequei, Condylopyge cruzensis and Peronopsis aff. Longinqua. Of these, have been identified for the first time in Chains Iberian P. Dimarginatus, P. Termierelloides, P. Interscriptus, P. Pisidianus, K. (Kingaspidoides) sp. Kingaspis (K.) campbelli, Acadoparadoxides? Cf. Harlani and Peronopsis aff. Longinqua. There has been a morphometric study of the species with the largest number of copies (mostly adults), which has served to know the effect of deformation in different taxa with original relief, the kind of growth in the stadiums and support that adults taxonomic determination it is possible both in materials such as deformed without warp. It proposes a new zoning for the back end of Bilbiliense in Chains Iberian, areas interval Protolenus dimarginatus and Protolenus jilocanus and maintaining filozonación of paradoxídidos known to date areas Acadoparadoxides mureroensis and Eccaparadoxides sdzuyi to the principle of Cambrian East. The analysis of facial Training Valdemiedes indicates a deposit in a biome sublitoral where abundance and conservation of algal filaments suggests that photosynthesis was a normal process (infralitoral). The deposit was conducted primarily in media and calm below the basic wave (25-100 m) giving rise to a preservation of the fossils. One exception is the most northwestern outcrop (Ateca) where he was frequently the influence of waves produced bioclásticos accumulation levels in a more energetic and quick (1-25 min). This analysis also suggests for the Lower Cambrian terminal half infralitoral relatively deeper in the south with the development of slates with trilobites (recorded in Villafeliche) instead of curly facies and bioclastic limestone. The application of the sequential model of biofacies described by Liñán et al. (1993 a) materials has studied p 8 ermitido 62b establish a sequence that is repeated with slight variations in all sections of predominantly siliciclastic studied composition: algal filaments and brachiopod fosfáticos-braquiópodos calcíticos-trilobites polímeros-Evento Valdemiedes- brachiopod calcíticos- trilobites polymers. We have defined communities of trilobites of Protolenus dimarginatus, Kingaspis (K.) campbelli, Hamatolenus (H) ibericus and H. (H) ibericus + Alueva undulata for the Lower Cambrian and Acadoparadoxides mureroensis and Acadoparadoxides mureroensis + Alueva hastata for Cambrian East. Finally, this study confirms that the event paleoecológico more important in the formation Valdemiedes, and therefore around the limit Cambrian Inferior-Medio was the Event Valdemiedes. The new studies suggest that over the limit, there was a model of staggered extinction of trilobites which culminated in the Event Valdenmiedes.