Contributions à la paleontology du Miocène moyen continental du basin du Tage; (IV) Charophytes - Póvoa de Santarém, Pero Filho et Tremês

This study on middle Miocene Charophytes from the Tagus' basin indicates the presence of two species, hitherto undescribed from these strata in Portugal. Correlation diagrams of height and width of gyrogonite demonstrate that the populations of Nitellopsis (Tectochara) etrusca from the localities Póvoa de Santarém and Pêro Filho are identical to that from La Grenatière (Hérault, France), The population of Lychnothamnus duplicicarinatus from Tremês is identical to that already known from Anwill (Switzerland). The age of this flora is therefore suggested as being the upper part of the middle Miocene. The results of Charophyte studies are in accordance with stratigraphical conclusions from previously conducted mammalian studies (Antunes and Mein). A table showing the distribution of species in the three portuguese localities is given.

Charophytes from Silveirinha (?Upper Paleocene - Lowermost Eocene) according to Janine Riveline

Charophytae gyrogonites are common among the washing/sieving residues from the important ?Upper Paleocene or lowermost Eocene site of Silveirinha (lower Mondego, Portugal). The whole Charophyte material has been submitted to Janine Riveline, who recognized but Nitellopsis (Tectochara) dutemplei (Watelet)Grambast & Souliè-Marsche minor Riveline. This form has been found in the lacustrine marls overlying the "Conglomerat de Cernay" that is rich in late Thanetian vertebrates. Taking into account the presence of the above referred form, the age of the concerned sediments may be (not basal) Sparnacian, Peckichara disermas Charophyte zone.

Contributions à la paleontology du Miocène moyen continental du basin du tage

This study on middle Miocene Charophytes from the Tagus'basin indicates the presence of two species. hitherto undescribed from these strata in Portugal, Correlation diagrams of height and width of gyrogonite demonstrate that the populations of Nitellopsis (Tectochara) etrusca from the localities Póvoa de Santarém and Pêro Filho are identical to that from La Grenatière (Hérault, France), The population of Lychnothamnus duplicicarinatus from Tremês is identical to that already known from Anwill (Switzerland). The age of this flora is therefore suggested as being the upper part of the middle Miocene. The results of Charophyte studies are in accordance with stratigraphical conclusions from previously conducted mammalian studies (Antunes and Mein), A table showing the distribution of species in the three portuguese localities is given.

Les plus anciens mammifères terrestres du Miocène marin de Lisbonne - le gisement du Km 10

For the first time, small mammals were found at the earliest marine level in the northeastern part of the lower Tagus basin, to the NE of Lisbon. At this new locality, at the 10 kilometer of the Lisbon-Oporto A1-IP1 highway,conglomerates yielded, along with marine fossils, more or less abraded teeth and bones from insectivores,lagomorphs, rodents and small artiodactyls (sec Tableau 1). Age may he ascribed to the lower Miocene, MN 2b Neogene mammal unit (about 22 My), but an early MN 3 age cannot be entirely excluded. That corresponds to latest Aquitanian (or less probably earliest Burdigalian) (sec Tableau 2). This is the first hitherto found locality with small mammals of this age as far as Portugal is concerned, as well as the oldest locality so far known in the Tagus basin. Km 10 is somewhat older than the localities of Universidade Católica and Avenida do Uruguay in Lisbon (ANTUNES & MEIN, 1986). Hence we can rather accurately date the age of the first marine transgression in the northeastern part of the lower Tagus basin. This shows that in this region there are no marine equivalents of the "Venus ribeiroi beds" (Aquitanian,Division 1 of the Lisbon Miocene series). Correlation between this unit and the uppermost levels of the essentially paleogene "Complexo de Benfica" may be possible. Fossils at km 10 point out to shallow, coastal, highenergy marine environments. Sedimentological features are compatible with this model. Dry land and swamps with brackish (or ev en fresh) waters were present nearby. From those areas came remains of mammals, crocodylians, as well as oysters and charophytes that were later transported to the sea. Sea was warmer than the extant Atlantic at the same latitudes, even if conditions were not strictly tropical then. These conditions surely influenced climate in the nearby regions. Ecological data concerning mammalian faunas distinctly point out to nearby forest-rich environments, much more so than for Universidade Católica and Avenida do Uruguay localities, from where drier, even steppe environment forms largely prevail.

On the Upper Cretaceous age and affinities of Neocyprideis lusitanicus (Ostracoda)

Guernet & Lauverjat (1986) described a new species, Neocyprideis lusitanicus, from sediments deposited near Aveiro, Portugal. For these authors, some associated fossils (Molluscs, planktonic Foraminifera) indicated a Pliocene age. That seemingly was the first record of Neocyprideis in post-Miocene sediments in Europe. A recent study of Upper Cretaceous material from the same region showed an abundant Neocyprideis fauna, associated with Charophyta. These Neocyprideis could be assigned without any doubt to N. lusitanicus. Therefore, N. lusitanicus appears as an Upper Cretaceous species, reworked in much later sediments, not Pliocene but Quaternary, as indicated by the planktonic Foraminifera assemblage. This interpretation is supported by: 1 - the incompatibility of the Neocyprideis (restricted to lacustrine-lagoonal environments) with abundant planktic Foraminifera; 2 - the occurrence of N. lusitanicus with Charophytes and non marine, cretaceous vertebrates but without the same Foraminifera. Neocyprideis lusitanicus is a valid species, clearly different from the other late Cretaceous species (N. coudouxensis and N. murciensis) as well as the Early Miocene described species (N. aquitanica, N. janoscheki).

Limnic ostracoda from Silveirinha, Portugal (? Late Paleocene - Lowermost Eocene)

Silveirinha, a rich site for mammals and other vertebrates, yielded some molluscs, charophytes and ostracods. The latter are described here. Eight species were recognized. Two of them, Ilyocypris lusitanicus n. sp. and Cypris silveirinhaensis n. sp. are new. Other, unnamed species may be ascribed to Cyclocypris? and Cypria? besides a further four undeterminate Cypridacea. The Ostracod association is typical for limnic environments and is compatible with intertropical conditions. Cypris silveirinhaensis suggests an Eocene, and especially a lower Eocene age.