217 resultados para Paleontologia - Pleistoceno - Pleistoceno


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Abundant material of turtles from the early Oligocene site of Boutersem-TGV (Boutersem, Belgium), is presented here. No information on the turtles found there was so far available. All the turtle specimens presented here are attributable to a single freshwater taxon that is identified as a member of Geoemydidae, Cuvierichelys. It is the first representative of the ‘Palaeochelys s. l.–Mauremys’ group recognized in the Belgian Paleogene record. This material, which allows to know all the elements of both the carapace and the plastron of the taxon, cannot be attributed to the only species of the genus Cuvierichelys so far identified in the Oligocene, the Spanish form Cuvierichelys iberica. The taxon from Boutersem is recognized as Cuvierichelys parisiensis. Thus, both the paleobiogeographic and the biostratigraphic distributions of Cuvierichelys parisiensis are extended, its presence being confirmed for the first time outside the French Eocene record. The validity of some European forms is refuted, and several characters previously proposed as different between Cuvierichelys iberica and Cuvierichelys parisiensis are recognized as subjected to intraspecific variability.

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Fossil associations from the middle and upper Eocene (Bartonian and Priabonian) sedimentary succession of the Pamplona Basin are described. This succession was accumulated in the western part of the South Pyrenean peripheral foreland basin and extends from deep-marine turbiditic (Ezkaba Sandstone Formation) to deltaic (Pamplona Marl, Ardanatz Sandstone and Ilundain Marl formations) and marginal marine deposits (Gendulain Formation). The micropalaeontological content is high. It is dominated by foraminifera, and common ostracods and other microfossils are also present. The fossil ichnoasssemblages include at least 23 ichnogenera and 28 ichnospecies indicative of Nereites, Cruziana, Glossifungites and ?Scoyenia-Mermia ichnofacies. Body macrofossils of 78 taxa corresponding to macroforaminifera, sponges, corals, bryozoans, brachiopods, annelids, molluscs, arthropods, echinoderms and vertebrates have been identified. Both the number of ichnotaxa and of species (e. g. bryozoans, molluscs and condrichthyans) may be considerably higher. Body fossil assemblages are comparable to those from the Eocene of the Nord Pyrenean area (Basque Coast), and also to those from the Eocene of the west-central and eastern part of South Pyrenean area (Aragon and Catalonia). At the European scale, the molluscs assemblages seem endemic from the Pyrenean area, although several Tethyan (Italy and Alps) and Northern elements (Paris basin and Normandy) have been recorded. Palaeontological data of studied sedimentary units fit well with the shallowing process that throughout the middle and late Eocene occurs in the area, according to the sedimentological and stratigraphical data.

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The Museu Geológico collections house some of the first sauropod references of the Lusitanian Basin Upper Jurassic record, including the Lourinhasaurus alenquerensis and Lusotitan atalaiensis lectotypes, previously considered as new species of the Apatosaurus and Brachiosaurus genera, respectively. Several fragmentary specimens have been classical referred to those taxa, but the most part of these systematic attributions are not supported herein, excluding a caudal vertebra from Maceira (MG 8804) considered as cf. Lusotitan atalaiensis. From the material housed in the Museu Geológico were identified basal eusauropods (indeterminate eusauropods and turiasaurs) and neosauropods (indeterminate neosauropods, diplodods and camarasaurids and basal titanosauriforms). Middle caudal vertebrae with lateral fossae, ventral hollow border by pronounced ventrolateral crests and quadrangular cross-section suggest for the presence of diplodocine diplodocids in north area of the Lusitanian Basin Central Sector during the Late Jurassic. A humerus collected from Praia dos Frades (MG 4976) is attributed to cf. Duriatitan humerocristatus suggesting the presence of shared sauropod forms between the Portugal and United Kingdom during the Late Jurassic. Duriatitan is an indeterminate member of Eusauropoda and the discovery of new material in both territories is necessary to confirm this systematic approach. The studied material is in according with the previous recorded paleobiodiversity for the sauropod clade during the Portuguese Late Jurassic, which includes basal eusauropods (including turiasaurs), diplodocids and macronarians (including camarasaurids and basal titanosauriforms).

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O Algar da Manga Larga tem-se revelado uma das mais importantes cavidades verticais em Portugal e, apesar de ser já conhecido pelos espeleólogos desde há mais de trinta anos, continua a fornecer dados com relevante significado científico. No decurso de uma acção de pesquisa espeleológica promovida pela AESDA no referido Algar foi fotografado um conjunto de ossos de carnívoro, jacentes numa galeria a cerca de 95 metros abaixo da entrada da cavidade. As respectivas características morfológicas e biométricas indicavam tratar-se de um grande felídeo, remetendo para espécie actualmente extinta na Europa, nomeadamente o leopardo, Panthera pardus (L., 1758). A evidente importância paleontológica dos testemunhos ósseos levou a que se desencadeasse um conjunto de procedimentos com o objectivo de os salvaguardar adequadamente e de promover o seu estudo. Para esse efeito, realizaram-se os contactos necessários e procedeu-se ao registo e à recolha das peças em apreço atribuindo especial atenção à sua integridade e conservação. Seguiram-se as tarefas ligadas ao estudo biométrico comparativo dos restos osteológicos. A presença deste e outros vestígios faunísticos, nomeadamente de gato-bravo, em zonas profundas e de difícil acesso desta gruta, indiciam a existência de condutas que estão ou estiveram em contacto com o meio exterior, as quais não foram ainda referenciadas. Deste modo, para além do evidente interesse paleontológico da descoberta, é possível serem extrapoladas interpretações com aplicação no âmbito da exegese da própria cavidade, situação que levou já à descoberta de uma galeria não registada. Este trabalho tem vindo a ser amplamente divulgado junto da comunidade espeleológica nacional e internacional, inclusivamente no 14º Congresso Internacional de Espeleologia que se realizou em 2005 na Grécia. O estudo paleontológico está concluído e a aguardar publicação em revista da especialidade (CARDOSO & REGALA, no prelo).

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ICHNOFOSSILS (PALEO-BURROWS and CROTOVINES) ATTRIBUTED TO EXTINCT MAMMALS IN SOUTHEASTERN and SOUTH BRAZIL. This work presents information regarding tunnels which are attributed to large extinct mammals. These structures can be found in several places in southeastern and southern Brazil, in different types of substrate, occurring as hollow structures (paleo-burrows) or those filled with sediments (crotovines). The dimensions and osteoderm and claw imprints found along the internal walls of the paleo-burrow found on aluvial fan deposits near the town of Cristal (Rio Grande do Sul State) suggest that a dasypodid xenarthran might have dug this structure. Comparison with similar structures found in Argentina can provide more detailed information regarding the paleoecology and biostratigraphy of the organisms that made these burrows.

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Tese de doutoramento em Paleontologia. Faculdade de Ciências do Mar e do Ambiente, Univ. do Algarve, 2005