Palaeontological data about the climatic trends from Chattian to present along the Northeastern Atlantic frontage

Climatic changes that affected the Northeastern Atlantic frontage are analyzed on the basis of the evolution of faunas and floras from the late Oligocene onwards. The study deals with calcareous nannoplankton, marine micro- and macrofaunas, some terrestrial vertebrates and vegetal assemblages. The climate, first tropical, underwent a progressive cooling (North-South thermic gradient). Notable climatic deteriorations (withdrawal towards the South or disappearance of taxa indicative of warm climate and appearance of "cold" taxa) are evidenced mainly during the Middle Miocene and the late Pliocene. Faunas and floras of modern pattern have regained, after the Pleistocene glaciations, a new climatic ranging of a temperate type in the northern part.

Notes sur la géologie et la paléontologie du Miocène de Lisbonne. XXI Primeira caracterização de dinoflagelados dos níveis mais baixos da série miocénica de Lisboa

This is the first report on Dinoflagellata from lowermost Miocene beds in Portugal (Tagus basin, Lisbon region, exposure at Benfica). Some general data about Dinoflagellata are presented. Descriptions are provided for some forms: Gonyaulacysta tenuitabulata, Spiniferites ramosus, Achomosphaera sp., Hystrichokolpoma rigaudae, Homotriblium cf. pallidum, Cordosphaeridium sp, and Lingulodinium machaerophorum. Lithostratigraphical study of an important section along Circular highway at Benfica has shown that there is a hitherto unknown sedimentary cycle in Lisbon's lowermost Miocene (upper Oligocene?). Pollen and Ostracoda point out to an Lower Aquitanian or even Upper Chattian age for the first Neogene marine transgression in Portugal, previously considered as Upper Aquitanian or Lower Burdigalian.

Répartition des foraminifères benthiques dans les gisements de surface du Miocène d'Aquitaine (SW de la France)

The Aquitaine Basin (southwestern France) is known since long ago for its richness in marine miocene deposits of various facies. A few stratotypes concerning this period have been described in the investigated area. The stratigraphical framework has been recently revised and the study of new exposures completes our knowledge on these levels. In the present work, the authors produce a biostratigraphical distribution of about 160 species (larger and smaller foraminifera), found in the surface exposures of Aquitaine, from the topmost Oligocene (Chattian) through to Middle Miocene (including Serravallian). As a rule, the common species without significant ranges have not bcen mentioned. The microfaunas of several exposures have been thoroughly revised, which has allowed to precise the distribution of many species and induced a few modifications of the results previously produced. Synonymy problems and new taxonomical revisions have been taken into account. Of course, this work will be probably submitted to some changes according to new research on the already known exposures or other more recently discovered.

Etude de populations de Glycymeris (Bivalvia, Glycymerididae) du Miocène d'Aquitaine, Sud-Ouest de la France

Abundant crops of Glycymeris have been made in the neritic bioclastic deposits of the Aquitaine Basin. After an outline about the Chattian taxa, the 5 Lower Miocene lineages are presented; G. cor is plainly predominant. Then, the Middle Miocene faunas are also detaiIed, G. inflatus and G. bimaculatus being the most frequent taxa. A test of biometrical analysis about the G. cor species is presented.

Répartition des foraminifères benthiques dans les gisements de surface du Miocène d'Aquitaine (SW de la France)

The Aquitaine Basin (southwestem France) is known since long ago for its richness in marine miocene deposits ofvarious facies. A few stratotypes concerning this period have bccn described in the investigated area. The stratigraphical framework has becn recently revised and the study of new exposures completes our knowledge on these levels. In the present work, the authors produce a biostratigraphical distribution of about 160 species (Iarger and smaller foraminifera), found in the surface exposures of Aquitaine, from the topmost Oligocene (Chattian) through to Middle Miocene (including Serravallian). As a rule, the common species without significant ranges have not bcen mentioned. The microfaunas of several exposures have been thoroughly revised, which has allowcd to precise the distribution of many species and induced a few modifications of the results previously produced. Synonymy problems and new taxonomical revisions have been taken into account. Of course, this work will be probably submitted to some changes according to new research on the already known exposures or other more recently discovered.

Etude de populations de Glycymeris (Bivalvia, Glycymerididae) du Miocène d'Aquitaine, Sud-Ouest de la France Studyof Glycymeris (Bivalvia, G1ycymerididae) populations from the Aquitaine Miocene, SW France

Abundant crops of Glycymeris have been made in the neritic bioclastic deposits of the Aquitaine Basin. After an outline about the Chattian taxa, the 5 Lower Miocene lineages are presented; G. cor is plainly predominant. Then, the Middle Miocene faunas are also detaiIed, G. inflatus and G. bimaculatus being the most frequent taxa. A test of biometrical analysis about the G. cor species is presented.