Global stratigraphy, palaeobiogeography and palaeoecology of Albian-Maastrichtian pithonellid calcispheres: impact on Tethys configuration

This study reviews the stratigraphy, palaeobiogeography and palaeoecology of some important Albian-Maastrichtian pelagic calcispheres: Bonetocardiella conoidea, Pithonella ovalis, P. perlonga, P. sphaerica and P. trejoi. It also presents a significant new data set on these organisms from the western South Atlantic Ocean. The group reached its acme simultaneously all over the world during the highest Cretaceous sea level in late Albian to Coniacian times. A strong association also existed between the maximum temperature and the salinity of the Tethyan water mass and the climax of these opportunistic microfossils. Their remarkable presence along the Brazilian and west African margins during the Albian, in association with other typical Tethyan pelagic biotic elements, indicates that during this period the northern South Atlantic was a long, narrow arm of the Tethys Sea. (C) 2000 Academic Press.

A new Coniacian-Santonian conchostracan genus from the Bauru Group, south-east Brazil: Taxonomy, palaeobiogeography and palaeoecology

Abundant conchostracans occur in Coniacian-Santonian dark grey, argillaceous, lacustrine sediments of the Sao Carlos Formation, Bauru Group, Parana Basin, in the central part of São Paulo State, south-east Brazil. They are ascribed to a new genus and species, Bauruestheria sancarlensis, included in the family Jilinestheriidae. The new taxon is similar to some Late Cretaceous species from China and Mongolia. It probably evolved from a Late Jurassic-Early Cretaceous ancestral form (Migransia), which first lived in West Gondwana, and later dispersed to Europe and Asia, originating distinct parallel lineages with increasing ornamental complexity. The conchostracans probably lived in oxygenated marginal areas of a very calm, perennial lake with an anoxic bottom, and were transported in suspension to the depositional site by weak turbidity currents or storm-induced flows. Great concentrations of juvenile conchostracans in some thin layers can be related to mass mortality, episodes caused by convection and dispersion of anoxic water during storms. (c) 2005 Elsevier Ltd. All rights reserved.

Commensal worm traces and possible juvenile thalassinidean burrows associated with Ophiomorpha nodosa, Pleistocene, southern Brazil

The Pleistocene Chui Formation at Osorio (Rio Grande do Sul, Brazil) consists of coastal marine and eolian sands, the former containing abundant and well-preserved Ophiomorpha nodosa burrow systems. Detailed ichnological study has revealed interesting features associated with them. Small-sized Ophiomorpha, here assigned to a new ichnospecies, O. puerilis, are interpreted as possible burrows of juvenile thalassinidean crustaceans probably belonging to the same species as the producers of larger O. nodosa. Additionally, helicoidal burrows with thick, concentrically laminated linings are associated with the walls of O. nodosa. They are assigned to the new ichnospecies Cylindrichnus helix, and they are interpreted as dwellings of commensal annelid worms. The association of these three icbnospecies constitutes a fossil example of the role of thalassinideans as ecosystem engineers able to modify their environment and to create new space and resources usable by other organisms. (c) 2005 Elsevier B.V. All rights reserved.

Microfacies and sequence stratigraphy of the Amapa Formation, Late Paleocene to Early Eocene, Foz do Amazonas Basin, Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Crowded Rosselia ichnofabric in the Early Devonian of Brazil: An example of strategic behavior

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)