M. Cristina Cabral

Overview of Recent and Holocene ostracods (Crustacea) from brackish and marine environments of Portugal

An extensive overview of Recent and Holocene ostracods from brackish and marine environments of Portugal is presented for the first time. 178 species belonging to 75 genera have been found and all are listed and illustrated with SEM images. From those species only 30 were found alive, most of them living in marginal-marine environments. Some comments on the 30 species found alive and a summary of main results are also presented. The data come from unpublished notes, reports of several research projects, observations on Recent ostracods in sediments from different estuaries of the western coast of Portugal and from the western Algarve continental shelf and slope, Masters theses and published papers.

Calcareous nannofossil biostratigraphy of an outcrop section of Aptian sediments of west-central Portugal (Lusitanian Basin)

The present work is the first study of nannofossils from the Ponta Alta and Praia da Lagoa members of the Cresmina Formation and provides a new approach to establishing the age of these sediments. Nannofossil biostratigraphy improves previous age assignments: the Ponta Alta Member is placed within the latest Early Aptian, the passage between the Ponta Alta to the Praia da Lagoa members is assigned an early Late Aptian age and the Praia da Lagoa member is assigned an age not younger than the early Late Aptian. The lower half of the Rodísio Formation is assigned an age not younger than the Albian. The integration of the nannofossil results with isotope stratigraphy provides support for the age attributions and calibration with more open-marine sections. The low abundance of nannoconids observed within the Ponta Alta Member coincides with the OAE 1a carbon isotope excursion and is possibly a manifestation of the ‘nannoconid crisis’ event. The subsequent increase in the abundance of nannoconids in the upper Ponta Alta Member coincides with the highest values of the δ13C isotope anomaly and may reflect a position above the ‘nannoconid crisis’ event in the early Late Aptian.

Improving the Palaeoecological Understanding of the Lisboa–Sintra Region Cenomanian Units: The S. João Das Lampas Section

The S. Joao das Lampas section, in the Sintra region (Lusitanian Basin, Portugal), exhibits a highly fossiliferous marl–limestone Cenomanian succession and belongs to the Canecas Formation. In this work, we present data from ongoing studies on ostracods and microfacies to address palaeoecological issues within the regional framework. The fossil assemblage comprises ostracods (very abundant and represented mainly by brackish and marine littoral species), benthic foraminifers, dasycladalean and bryopsidalean algae, bivalves, gastropods, serpulids, and echinoderms. The succession consists predominantly of oyster-rich marls and marly limestones, interbedded with skeletal/microfossil-rich carbonate and marly layers and skeletal storm beds or lenses. Overall, the data point to a low- to moderate-energy marginal-marine setting with frequent variations in salinity.

Sieve-type pore canals in the Timiriaseviinae—A contribution to the comparative morphology and the systematics of the Limnocytheridae (Ostracoda, Crustacea)

Examination of normal pore canals, especially sieve-type pore canals, in living and fossil representatives of ten genera of the family Limnocytheridae, subfamily Timiriaseviinae, has revealed important diversity of structure. These complex pore canals have been studied via high-resolution scanning electron microscopy (the Cartographic Method) and analysed via the application of newly devised indices to assess patterns of consistency and variation in both detailed structure of individual pores and of their distribution on the calcified valve. The timiriaseviine taxa are compared with species of the genera Limnocythere, sub-family Limnocytherinae and Cyprideis (family Cytherideidae). The relationship between the living animal and its aquatic environment is discussed in the light of previous studies and of new evidence herein. The importance of normal pore canals for systematics is highlighted by the recognition and definition of the new tribe Gomphodellini Danielopol, Cabral Lord nov. tribe, subfamily Timiriaseviinae, family Limnocytheridae.