Ostracodes et stratigraphie du néogène et du quaternaire méditerranéens

A stratigraphical chart of marine ostracoda from Lower Miocene to Recent is established. Selected species (approximatively 220) are those morphologicaly well characterized and known from different parts of the Mediterranean area. It appears that: • lower Miocene ostracodes are still poorly known; • specific diversity is high during the Tortonian and the Lower Messinian before the complete disappearance of marine Mediterranean species during the Upper Messinian évaporitic episodes; • during the early Pliocene, about half of the Upper Miocene marine species are reintroduced with the Atlantic waters; other species migrate for the first time in the Mediterranean Sea by the same way; • at the end of the Pliocene or at the beginning of the Pleistocene several species known in Mediterranean since the Middle Miocene or before, such as Cytherella sp. gr. transversa and Ruggieria tetraptera, as well some “nordic guests” such as Hemicythere villosa and Cythere lutea, appear. This work is an opportunity to confirme a Late Miocene age for the Neogene of Skyros (Aegean Sea), to assign the “Upper Pliocene” of Terquem to the Lower Pleistocene and to refute the existence of a pliocene psychrosphere.     

Climatic control on vegetation and sedimentary dynamics during the Miocene (Burdigalian to Langhian) in northeastern Tunisia

Palynological and sedimentological analyses were performed on Miocene sediments of North-East Tunisia in order to detect the changes in depositional environments, including those linked to eustasy, along with changes in vegetation and climate. The specific integration of palynological (pollen and dinocysts) and sedimentological (including facies analysis) data indicate that shallow marine settings persisted until the early Burdigalian–Langhian, and that open marine environments developed progressively in the late Langhian. Since the early Serravallian, deltaic environments developed under a fluctuating, but predominantly warm climate. The palynological data support a subtropical climate during the Burdigalian, with tropical conditions prevailing at the Langhian–Serravallian transition. The observed high frequency values of megathermic and mega-mesothermic pollen taxa represent the vegetation response to the Miocene climatic optimum (MCO).     

Nouvelles observations sur les Miogypsinidés du Miocène inférieur et moyen de Provence et de Corse (France) et de Sardaigne septentrionale (Italie)

The detailed study of the Miocene strata of Bonifacio has revealed an atypical Miogypsinid assemblage. In addition to the three already cited genera, Miogypsinoides, Miogypsina and Miolepidocyclina from this region, Miogypsinodella is for the first time represented by two new species (Mdella corsicana nov. sp. et Mdella pillaria nov.sp.). The stratigraphical ranges of each genus in the Miogypsinidae are not verified here. However, Mdes bantamensis is still present in the Upper Burdigalian and the genus Miogypsinoides is also present in the Lower Langhian. Six species of Miogypsina coexist in the Upper Burdigalian (M. tani, M. globulina, M. intermedia, M. cf. sabahensis, M. cushmani, M. mediterranea) and two species are present in the Lower Langhian (M. antillea, M. digitata). This distribution is apparently an example of palaeoendemism resulting from the geographic isolation and the rotation of the Corso-Sardinian block and also from the palaeogeographical and palaeoecological favourable environment during that time.     

Les foraminifères du Burdigalien moyen à supérieur de la région sud-aquitaine (golfe de Saubrigues, SW France)

Many exposures assigned to the Miocene formation of “Marnes de Saubrigues” (southwestern Aquitaine Basin) have been studied. Their revised stratigraphical allocation has made it possible to recognize mainly Middle to Late Burdigalian age deposits which have been widely sampled. They have been correlated with planktonic zones N6 pars-N7 and NN3-NN4 and locally dated 17.7 Ma with Sr isotopes. It is noteworthy that this chronological interval is only known in the southern Basin. An inventory of the rather abundant microplankton is provided, including series crossed by drillings in the Gulf of Biscay. These deposits yield a large diversity of benthic foraminifera, nearly 400 taxa, which can be considered as a reference fauna for western Europe Burdigalian. From a geographic point of view, it has been possible to subdivise the exposures into groups according to their bathymetry. Let us point out the first discovery of Borelis in the Burdigalian of France and in the northeastern Atlantic Miocene as well. Very rare specimens of Cycloclypeus are also present in the Aquitaine Basin. Among smaller foraminifera, the occurrence of Rosalina aguayoi, Pavonitina styriaca, the last appearance of Falsocibicides aquitanicus and the persistance of the genus Almaena must be emphasized. Several assemblages supply diatoms, rare radiolaria and sometimes abundant sponge spicules; the presence of these organisms, seldom reported from the Aquitaine Tertiary, might be linked to upwelling-type currents. Bachmayerella (inc. sed.) is uncommon and cited for the first time in the Burdigalian. A few taxonomical remarks and short notes are given for some species of foraminifera, and palaeoecological details as well. Numerous taxa are represented and comparisons with the foraminifera faunas mainly from the Lower-Middle Miocene of Western Mediterranean and Paratethys are sketched.     

First discovery of the Miocene northern Atlantic sperm whale Orycterocetus in the Mediterranean

An incomplete mandible of a fossil sperm whale (Odontoceti; Physeteridae) is described. It is a portion of elongated and narrow symphysis with cylindrical and slightly curved teeth without enamel. The specimen, collected from the Miocene “Pietra leccese” sediments of South Italy, appears to represent a species of Orycterocetus, and is the first such record from the Mediterranean. Considering the wide diffusion of Orycterocetus in the North Atlantic, we believe its rare presence in the Mediterranean as occasional and due to a certain degree of interchange between the Mediterranean and the North Atlantic cetacean fauna during the Miocene.     

Die erste Wirbeltierfauna aus der miozänen Braunkohle der Niederrheinischen Bucht (Ville-Schichten, Tagebau Hambach)

This paper describes the first Miocene vertebrate fauna from the Ville Series of the Lower Rhine Embayment in western Germany. The fossil material was discovered in the vast Hambach open cast lignite mine ofRheinbraun. The numerous remains, mostly isolated teeth and disarticulated bones, were accumulated in a channel-fill within the main lignite seam. The fauna consists of chondrichthyans, teleosteans, amphibians, reptiles, and mammals which inhabited brackish-estuarine, lacustrine-fluviatile, and terrestrial environments. This is the first fauna to provide an insight into the diversity of vertebrates which lived in the forested peat swamps of the Rhenish Tertiary. Based on the rich association of more than 70 mammalian taxa, including about 30 rodent species, this late Orleanian fauna can be correlated with the upper part of the Mammalian Neogene biozone MN 5. Therefore the middle part of the main lignite seam (horizon 6C of the local lithostratigraphy) can be placed in the early middle Miocene. This means an age of 15.2-16.0 Ma (Langhian or Reinbekian of the stratigraphy of the NW German Tertiary). For some mammalian taxa (Lanthanotherium, Plesiosorex,Miopetaurista, Myoglis, Fahlbuschia, ‘Lartetomys’, Anchitheriomys, Dorcatherium), Hambach 6C is one of the richest European localities. In addition this assemblage contains some very rare mammals (‘Lartetomys’, Anchitheriomys, Orygotherium, Pliopithecus). The Hambach vertebrates are of great palaeobiogeographic importance as they represent the north westernmost outpost of terrestrial Miocene faunas in Europe.     

Les faunes de Scléractiniaires dans les faluns du Miocène moyen d'Atlantique-Est (bassins de la Loire et d'Aquitaine) : paléobiogéographie et évolution climatique

The Aquitaine and Loire basins show in the Middle Miocene numerous marine littoral deposits, often shelly or crag-type. Scleractinia are present, with a distribution and an abundance very variable according to the outcrops. A detailed study of all the available material, recently or historically cropped, allowed to draw up an accurate faunal inventory and to compare the distribution of taxa between the two basins. Out of 90 taxa in total, 62 are known in Aquitaine and 48 in Loire. In the Aquitaine Langhian, when is noted an obvious reduction of hermatypic taxa in comparison with the rich regional Burdigalian faunas, the association includes 44 species (25 reef-building ones). In the Serravallian, the reef-building taxa become significantly scarce and are residual (9 taxa out of 33 in Aquitaine, present in levels belonging to the lower sequence of the stage, and located in sheltered internal parts of the south-Aquitaine and central-Aquitaine gulfs). In the Loire basin, the corals are quite diversified in the Pontilevian facies (19 reef-building taxa out of 48), and much scarcer in the Lublean and Savignean facies. Globally, the Scleractinia are few abundant everywhere. If in the two basins hermatypic taxa persisted in the Langhian, indicating subreefal-type facies, varied factors have impeded permanently the settlement of reefs. In comparison with the Burdigalian, the thermic deterioration gradient, evidenced since the Chattian on the northeastern Atlantic frontage, had an important influence, and the Langhian waters were only subtropical. Other factors acted, at least locally, as the hydrodynamics, the bathymetry, the kind of substratum, the salinity pro parte. Moreover, a latitudinal gradient between the two basins is evidenced by the global species richness and by the ratio of hermatypicity, created here and defined as the fraction of hermatypic taxa reported to ahermatypic ones from a same basin. This ratio can be used at generic level or specific one as well. In the Serravallian, when the diversity was everywhere obviously lower, the influence of the climatic gradient went on, together with other unfavourable conditions (often abundant detritic supplies, high hydrodynamics, spatial biocompetition). Diverse biogeographic and paleogeographic data are also reported. A vast East-Atlantic coralline bioprovince, settled as early as the Chattian with a dispersion center located in Aquitaine, was still active in the Middle Miocene, when large transgressions favoured the faunal exchanges; its history was to be completed at the end of this period.     

Sur les Foraminifères benthiques de la base du Burdigalien dans les « Sables à Mactres » de Martillac (Gironde,SO France)

Northern Aquitaine exhibits highly fossiliferous type deposits of the Lower Burdigalian. They mainly consist of shallow crags of the Léognan and Saucats area. The levels of the earliest basis of the stage, little studied till now, are described in a new section, situated in the vicinity of the stratotype at Martillac (Gironde). They are fine blue-grey carbonated sands with rather abundant Bivalves, called “sables à Mactres”. Foraminifera are well represented (more than a hundred species) and generally in a good state of preservation. The whitish silty and sandy upper level yields a somewhat impoverished foraminiferal fauna. All taxa indicate a shallow infralittoral to near-shore environment, rather a quiet one with a normal salinity; porcelaneous and smaller hyaline foraminifera living in a silty and muddy substrate are common. Many taxa are thermophil; the existence of a tropical climate is confirmed by the associated macrofauna. The malacofauna evokes a sheltered bay submitted to tides (cf. Lesport and Cahuzac, 2005). From the biostratigraphic point of view, only the species Miogypsina globulina is present amongst the Miogypsinidae, it shows an early evolutionary stage and only sometimes exhibits a rudimentary second nepionic spiral. Therefore, the attribution to the Earliest Burdigalian is strengthened. The distribution of a few other species is precised; for example, Bolivina pseudoplicata (fide Hasegawa et al., 1990), already present in the Upper Burdigalian and in the Langhian of Aquitaine, is so observed in the lowermost Burdigalian stage, Elphidiella subnodosa is still existing in this level and the abundance of Neorotalia with supplementary equatorial chambers can be noticed, usually more frequent in the Chattian. So, these deposits corresponding to the beginning of the transgression in the type area are better characterized. These new data will allow to make comparisons with other, neighbouring formations of the same age.     

Les ostracodes continentaux au Néogène en Aquitaine (Sud-Ouest France). Répartition spatio-temporelle : le point sur la question

A systematic research of the non-marine ostracodes from the Aquitaine Basin Neogene shows that these animals were locally well represented and able to indicate palaeoecological and palaeoclimatic data, comparable in quality with such data as from Recent continental environments. We provide a list of the taxa, and the stratigraphical distribution during the Lower and the Middle Miocene is indicated, as well as the geographical location in comparison with the estimated shorelines. The recent stratigraphical revisions of some Miocene deposits, mainly marine, from the central, southern and northern parts of the Aquitaine Basin are used. The studied microfauna contains about 20 genera and slightly more than 30 species. Most of the found genera correspond to fresh to brackish ostracodes (particularly Cytheridae and Candonidae). Several genera can indicate environmental characteristics: Candonopsis and Sclerocypris (Upper Aquitanian in age) are intertropical dwellers. Vecticypris from the Lower Miocene could indicate (in analogy with Metacypris) relatively cooler waters existing in these environments.     

Deux nouveaux gisements a otolithes de teleosteens,dont une espece nouvelle,dans l'Aquitanien continental du Midi de la France

The continental Aquitanian of Southern France has yielded an otolith fauna containing seven species pertaining to the Umbridae and Cyprinodontoidei. One new species is here introduced: genus Cyprinodontidarum feistae. Such an assemblage indicates lacustrine deposition with possibly lagoonal influence. Two zones have been established: a first one, corresponding to the Lower and Middle Aquitanian is characterized by Prolebias praecursor; the second one, representing the Upper Aquitanian, is more diversified and characterized by genus Cyprinodontidarum angulosus.     

A new coral‐associated decapod assemblage from the Upper Miocene (Messinian) Upper Coralline Limestone of Malta (Central Mediterranean)

Abstract: A rich coral‐associated decapod assemblage is recorded from the ‘Depiru Beds’ of the upper part of the Upper Coralline Limestone (Messinian, Upper Miocene), from the island of Malta. Nineteen species within 17 genera have been discovered, where 14 genera are new for Malta. Four new species are described, namely Micippa annamariae sp. nov., Pilumnus scaber sp. nov., Panopeus muelleri sp. nov. and Herbstia melitense sp. nov. Herbstia melitense sp. nov. constitutes the first record of the genus from the fossil record in the Mediterranean region. This discovery more than doubles the number of known fossil decapod species from Malta. The fossil bivalve Jouannetia (J.) semicaudata Des Moulins, 1830 and the extant decapod Maja goltziana D’Oliveira, 1888, are also recorded for the first time from Malta. Other Neogene coral‐associated decapod assemblages are investigated and correlated with the new assemblage from Malta. The migration of taxa between the Mediterranean region and the Paratethys, particularly during the Lower Badenian (Langhian), is evidenced by the strong affinity of the Maltese decapod assemblage with that of the Middle Miocene Badenian assemblages from Hungary, Poland and Ukraine. Upper Miocene, Messinian assemblages from Spain, Algeria and Morocco are also similar to that from Malta.     

Neogene history of Sporolithon Heydrich (Corallinales,Rhodophyta) in the Mediterranean region

Most modern species of Sporolithon live in tropical and subtropical areas and only one species of the genus, S. ptychoides, occurs in the Mediterranean Sea. The scarce present-day populations of Sporolithon in the Mediterranean region are relics of a long history of the genus in this area since the Early Cretaceous. Analysis of data from the palaeontological literature, combined with the study of both fossil samples and Recent ones collected from Italy and Spain, shows that during the Miocene variations in the number of Sporolithon species in the Mediterranean region parallel changes in global temperature. After a maximum species richness in the Langhian (early Mid Miocene), coincident with the Miocene climatic optimum, the number of species decreased to just two before the Messinian Salinity Crisis. This marked decline follows the global cooling event that began at around 14 Ma. The closure of the connections of the Mediterranean region with the Indian Ocean during the Langhian left Mediterranean Sporolithon populations isolated from the main dispersal area of the genus. After the Messinian desiccation, a single species, S. ptychoides, re-invaded the Mediterranean Basin during the Early Pliocene and continues to inhabit this temperate sea today. The Atlantic Ocean is the most probable source of the re-invading Sporolithon plants.     

Oligocene and Early Miocene gastropods from Kutch (NW India) document an early biogeographic switch from Western Tethys to Indo-Pacific

Shallow marine gastropod assemblages from Chattian, Aquitanian and Burdigalian sections in the Indian Kutch Basin are described. They provide insight into the composition and biogeographic relations of the gastropod assemblages at this junction between the Western Tethys and Proto-Indo-Pacific Ocean. For the first time, an improved biostratigraphy allows a clear separation of the assemblages, especially for the hitherto undifferentiated Early Miocene faunas. Throughout the Oligocene, about one-third of the species are also frequently found in the Western Tethys, documenting a passable Tethyan Seaway for nearshore molluscs. A considerable provincialism is evident as well. The expected turnover during the Early Miocene, due to the closing of the Tethyan Seaway, is reflected in the Miocene assemblages. Surprisingly, however, the cut appears very early, i.e. already during the Aquitanian, when the West–East interrelation drops to zero despite the passage having been open during this interval. In contrast, the Burdigalian assemblages witness a minor re-appearance of Western Tethys taxa, suggesting the re-establishment of rather ineffective migration pathways prior to the final closure of the Tethyan Seaway. Cerithium bermotiense and Lyria (Indolyria) maniyaraensis are introduced as new species.     

Les gisements continentaux de Plaissan et de la Nouvelle Faculté de Médecine (Hérault) leur position stratigraphique

The study of Plaissan rodent fauna and the discoveryof a new fossiliferous locality, 〈Nouvelle Faculté Médecine〉, allow us to contribute to a more accurate biochronological mammalian scale, for the Bas-Languedoc Lower Miocene. Nouvelle Faculté Médecine, contemporaneous of La Paillade or slighthy older has a Aquitanian age; Plaissan, equivalent to Paulhiac, ist older than the oldest known interbedded marine level in the Languedocian marine Aquitanian (Les Cévennes); it should be contemporaneous with the ante-stratotypic Aquitanian of Carry-le-Rouet.     

Amphibians and reptiles from the Early Miocene of the Bardenas Reales of Navarre (Ebro Basin, Iberian Peninsula)

The Lower Miocene deposits of the Bardenas Reales of Navarre (NW Ebro Basin, northern Iberian Peninsula) have yielded a diverse vertebrate fauna, including remains of amphibians and reptiles. These remains occur in several localities in the Tudela Formation. The fossiliferous levels belong to the Biozones MN2b-3 (Biozones Z-A of the Ramblian, i.e., Late Aquitanian to Early Burdigalian in age). The amphibians and reptiles represent at least 13 out of 37 vertebrate species. Amphibians consist of a salamandrid urodele and two or three anurans. All the turtles are cryptodirans and consist of the chelydrid Chelydropsis apellanizi, the testudinids Ptychogaster (Temnoclemmys) bardenensis and Ptychogaster ronheimensis, and a Trionychinae indet. Squamates are represented by the anguid lizard Ophisaurus sp., a non-anguid lacertilian, an amphisbaenian, the erycine boid? Eryx sp., and indeterminate colubrids. Crocodilian remains are assigned to the basal alligatoroid Diplocynodon sp. The fossil associations of the Bardenas Reales of Navarre suggest that the vertebrates lived in the centre of an endoreic basin with stretches of water under intertropical to subtropical climatic conditions.     

Vegetation, climate and palaeoaltitude reconstructions of the Eastern Alps during the Miocene based on pollen records from Austria, Central Europe

Aim To reconstruct the flora, vegetation, climate and palaeoaltitude during the Miocene (23.03–5.33 Ma) in Central Europe. Location Six outcrop sections located in different basins of the Central Paratethys in Austria. Methods Pollen analysis was used for the reconstruction of the vegetation and climate. The altitude of the Eastern Alps that are adjacent to the Alpine Foreland and Vienna basins has been estimated using a new quantification method based on pollen data. This method uses biogeographical and climatological criteria such as the composition of the modern vegetation belts in the European mountains and Miocene annual temperature estimates obtained from fossil pollen data. Results Pollen changes from Early to Late Miocene have been observed. The vegetation during the Burdigalian and Langhian (20.43–13.65 Ma) was dominated by thermophilous elements such as evergreen trees, typical of a present‐day evergreen rain forest at low altitudes (i.e. south‐eastern China). During the Serravallian and Tortonian (13.65–7.25 Ma) several thermophilous elements strongly decreased, and some disappeared from the Central European region. This kind of vegetation was progressively substituted by one enriched in deciduous and mesothermic plants. Middle‐altitude (Cathaya, Cedrus and Tsuga) and high‐altitude (Abies and Picea) conifers increased considerably during the Langhian and later on during the Serravallian and Tortonian. Main conclusions Pollen changes are related to climatic changes and to the uplift of the Alpine massifs. The vegetation during the Burdigalian and Langhian reflects the Miocene climatic optimum. The decrease in thermophilous plants during the Serravallian and Tortonian can be interpreted as a climatic cooling and can be correlated with global and regional climatic changes. This study shows that the palaeoaltitude of the eastern part of the Eastern Alps during the Burdigalian was not high enough for Abies and Picea to form a forest. Therefore, we inferred that the summits of most of the mountains would have been less than 1800 m. The substantial increase of middle‐ and high‐altitude conifers in the pollen spectra suggests that the uplift rate increased during the Langhian in this region. Based on higher palaeoaltitude estimations for the pollen floras from the studied sections of Austria, we infer that the uplift of the easternmost part of the Alpine chain continued during the Serravallian and Tortonian.