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International audience; Vertebrate microremains, particularly teeth, represent a substantial part of known vertebrate biodiversity. Many groups, such as Mesozoic mammals, are known mostly through isolated teeth. Classical imaging techniques of such complex millimetric to inframillimetric objects are most often limited by problems of manipulation, depth of focus or limited orientation. The methods generally used are stereomicroscopy (including in-focus z-series reconstruction) and Scanning Electron Microscopy (SEM), which provide good images. Nevertheless, both provide 2D static images or partial and directional 3D data, making complete observation difficult. Propagation phase contrast synchrotron X-ray microtomography is a powerful technique alleviating these limitations. Thanks to submicron resolution and to the edge detection effect, it rapidly provides 3D data from minute samples with levels of quality and detail unattainable using conventional microtomographs. Complex morphology of small specimens can be studied with unlimited orientation possibilities and, when coupled with 3D printing, it allows enlarged 3D reproductions of such small and fragile fossils. (C) 2010 Academie des sciences

19 pages; International audience; The Subphylum Blastozoa represents more than one third of the early Palaeozoic echinoderm fauna. A comprehensive database including all records of blastozoans was built to provide quantitative analyses of palaeogeography and diversity patterns and processes, for the 10 classes currently included in this subphylum during the early Palaeozoic. The global pattern of taxonomic diversity shows two peaks during the Cambrian Series 3 and the Late Ordovician intervals. In Cambrian times, the high taxonomic diversity seems to be related with a high turnover rate and a high endemicity of blastozoan genera, whereas in Ordovician times, the rise in diversity is associated with a low endemicity and a low turnover rate. The gradual increase of Ordovician diversity can be explained by the progressive geographic extension of blastozoan genera onto most palaeocontinental margins, associated to the long-term gradual sea level rise. This global pattern is subdivided into local trends to compare the relative influence of regional distributional patterns. Blastozoans occurred mainly on Gondwanan and Laurentian margins during the Cambrian. In both Ordovician and Silurian times, blastozoans colonised different provinces, characterised by varied latitudinal position and environmental conditions: the Laurentian province was mainly located in the equatorial latitudes (temperate to warm waters, mainly carbonate platforms), and both the northwestern peri- Gondwanan and Asian provinces, in the intermediate to high latitudes (temperate to cold water, mainly siliciclastic environments). After the Hirnantian mass extinction, blastozoans finally recovered chiefly on Laurentian margins, where climate and environmental conditions were probably more favourable. The two diversification events recorded for blastozoans in the early Palaeozoic concerned two distinct evolutionary faunas (Cambrian Evolutionary Fauna vs. Palaeozoic Evolutionary Fauna). They were driven by distinct processes, even if the Ordovician diversification had indeed started during the middle Furongian with a medium origination event. Difference in processes might be related to the evolution of global environmental/ climatic conditions coupled with the position of continental masses.

International audience; The major evolutionary events that characterize the Precambrian-Cambrian transition are accompanied by profound ecological changes in the composition of benthic communities, the nature of the substrate, and the occupation of marine ecospace. The increased animal activity on and within the substrate is attested to by numerous trace fossils, such as the cosmopolitan Treptichnus pedum whose first appearance is used as the global stratotype section and point (GSSP) to mark the base of the Cambrian. In spite of its major importance in biostratigraphy, the maker of Treptichnus trace fossils, and more generally of treptichnids, has long remained an enigma. Treptichnids were subhorizontal burrow systems produced in the subsurface and had a worldwide distribution throughout the Cambrian. Here we show, by using experimental ichnology, that the treptichnid burrow systems were most probably produced by priapulid worms or by worms that used the same locomotory mechanisms as the Recent priapulids (e. g., Priapulus). Their typical three-dimensional morphology with repeated arcuate probing branches suggests that their function was related to the feeding strategy of the worm such as predation or scavenging upon small epibenthic or endobenthic invertebrates. This interpretation is strongly supported by the preserved gut contents of Cambrian priapulids from the Burgess Shale Lagerstatte that contain effectively a variety of small epibenthic prey. The antiquity of treptichnids would designate priapulids as one of the earliest infaunal colonizers of the substrate that possibly interacted with epibenthic communities, thus playing a leading role (1) in the construction of the early marine food chain, and (2) as important subhorizontal bioturbators in the early stages of the "Cambrian Substrate Revolution."

International audience; renelopsis teixeirae Alvin et Pais is reported from the Lower Cretaceous (Hauterivian) of the Vale Cortico clay pit, Santa Susana Formation, near Torres Vedras, western Portugal. This is the second occurrence of F. teixeirae, previously known from a single specimen from the Valanginian of the Vale de Lobos Formation exposed at the beach cliff near Sesimbra. The diagnosis is emended and the description is completed based on well preserved leafs and twigs compressions. The specimens consist of leafy axes with whorls of either two or three leaves, each of the abaxial and adaxial surfaces showing a central horseshoe-shaped notch at the base, a trichome of both long hairs and massive papillae covering both outer cuticle surfaces, and stomata also borne on the adaxial cuticle. The dark grey mudstone bed with F. teixeirae is interpreted as a tidal-flat to estuarine deposit. In Portugal Frenelopsis species are known from a wide variety of deposits from the Valanginian to the Maastrichtian reflecting specific habitats.

International audience; The Sr/Ca and Ba/Ca ratios in inorganic apatite are strongly dependent on the temperature of the aqueous medium during precipitation. If valid in biogenic apatite, these thermometers would offer the advantage of being more resistant to diagenesis than those calibrated on biogenic calcite and aragonite. We have reared seabreams (Sparus aurata) in tanks with controlled conditions during experiments lasting for more than 2 years at 13, 17, 23 and 27 degrees C, in order to determine the variations in Sr and Ba partitioning relative to Ca (D(Sr) and D(Ba), respectively) between seawater and fish apatitic hard tissues (i.e. teeth and bones), as a function of temperature. The sensitivity of the Sr and Ba thermometers (i.e. partial derivative D(Sr)/partial derivative T and partial derivative D(Ba)/partial derivative T, respectively), are similar in bone (partial derivative D(b-w)(Sr)/partial derivative T = 0.0036 +/- 0.0003 and partial derivative D(b-w)(Ba)/partial derivative T = 0.0134 +/- 0.0026, respectively) and enamel (partial derivative D(e-w)(Sr)/partial derivative T = 0.0037 +/- 0.0005 and partial derivative D(e-w)(Ba)/partial derivative T = 0.0107 +/- 0.0026, respectively). The positive values of partial derivative D(Sr)/partial derivative T and partial derivative D(Ba)/partial derivative T in bone and enamel indicate that D(Sr) and D(Ba) increase with increasing temperature, a pattern opposite to that observed for inorganic apatite. This distinct thermodependent trace element partitioning between inorganic and organic apatite and water highlights the contradictory effects of the crystal-chemical and biological controls on the partitioning of Ca, Sr and Ba in vertebrate organisms. Taking into account the diet Sr/Ca and Ba/Ca values, it is shown that the bone Ba/Ca signature of fish can be explained by Ca-biopurification and inorganic apatite precipitation, whereas both of these processes fail to predict the bone Sr/Ca values. Therefore, the metabolism of Ca as a function of temperature still needs to be fully understood. However, the biogenic Sr thermometer is used to calculate an average seawater temperature of 30.6 degrees C using the Sr/Ca compositions of fossil shark teeth at the Cretaceous/Tertiary boundary, and a typical seawater Sr/Ca ratio of 0.02. Finally, while the present work should be completed with data obtained in natural contexts, it is clear that Sr/Ca and Ba/Ca ratios in fossil biogenic apatite already constitute attractive thermometers for marine paleoenvironments.

volcanic ash ; trace element leaching ; kinetic experiments ; chlorophyll-alpha; International audience; The eruption of Etna in Sicily on 13 July 2001 marked the most intense activity of the volcano in the last 300 years. The eruption occurred while the oceanographic cruise ANSIC 01 was being conducted to the east of Sicily, presenting a unique opportunity for the investigation of the chemical effects on the marine system during a period of significant (similar to 1 g m(-2)) ash deposition. Comparison of trace element data with measured concentrations from the oceanographic cruise JUVENILE 99, carried out two years before, indicates large enrichments of V. Cr, Mn, Fe, Co, Cu and Pb. We attribute this behaviour to leaching of freshly-erupted volcanic ash, according to trace element concentrations measured in suspended particulate matter (SPM). The exception is Pb, which is likely to be influenced by another, possibly anthropogenic, source. Trace element behaviour in the water column and during leaching experiments suggests that trace element distributions are driven by the occurrence of alteration minerals on glass surfaces, given that the main trace element source in seawater appears to come from the soluble-ash fraction. Trace element solubility is likely to be increased by organic complexation, which accelerates the alteration of ash particles. Organic substances suitable for complex trace elements are probably formed during the lysis of phytoplankton cells, produced during an increase in marine primary productivity associated with the volcanic fertilisation of surface waters

International audience; Quantitative analysis of Early Jurassic calcareous nannofossil assemblages from the Peniche section in Portugal have been performed in order to interpret palaeoenvironmental changes occurring in the Lusitanian Basin during the Late Pliensbachian Davoei, Margaritatus and Spinatum Ammonite Zones. Nannofossil data are compared to already published carbon and oxygen stable isotope data, organic matter content (wt\%Total Organic Carbon, TOC), and biomarker analysis. A significant change in calcareous nannofossil assemblages and species diversity at the transition between the Margaritatus and Spinatum Ammonite Zones matches with the pattern shown by geochemical data. This suggests that a profound change in environmental conditions occurred at that time. In the Davoei and Margaritatus Ammonite Zones, in a context of general sea-level rise, the Lusitanian Basin was characterized by water column stratification that favoured the sedimentation and preservation of organic matter. Biomarkers and oxygen isotope trends suggest that stratification of water masses occurred because of low salinity in surface waters. The shallowest part of the water column, characterized by oligotrophic conditions, was inhabited by the (probable) calcareous dinocyst Schizosphaerella spp., while the deep-dweller Crepidolithus crassus flourished in the lower photic-zone layers. In the Spinatum Ammonite Zone, a regressive trend occurred and a salinity increase is inferred on the basis of oxygen isotope values. Water masses were probably less stratified at that time. The upper photic-zone nannofossil assemblages were still dominated by Schizosphaerella spp. whilst, in the deep photic-zone. Mitrolithus jansae (a Mediterranean taxon) replaced C crassus (a taxon with NW-European affinity). This pattern may indicate a change in palaeoceanographic conditions related to surface current circulation. The sea-level fall occurring during the Spinatum Ammonite Zone may have resulted in the partial isolation of the Lusitanian Basin from the NW-Europe basins because of the creation of a threshold. Alternatively, tectonic drowning of North African carbonate platforms in the late Pliensbachian may have promoted better exchanges of nannoplankton between the Lusitanian Basin and the Mediterranean Tethys via the creation of new seaway connections. (C) 2010 Elsevier B.V. All rights reserved.

International audience; Data collected during this study indicate that dissolved Y and REE (rare earth element) behaviour can be monitored through shale-normalised ratios. Relationships occurring between these ratios suggest that leaching from lithogenic materials is the main source of REE in the studied area. This process involves riverine detrital matter in the inner area of the Gulf of Palermo. Features of shale-normalised patterns and the relationship recognised between dissolved Fe and Y/Ho suggest that REE are released from Fe-rich coatings of atmospheric dust. Observed similarities between dissolved Fe and chlorophyll- content suggest that leaching of Fe-rich atmospheric particulates induces a fertilisation of shallow water layers influencing the dissolved organic content. In turn, the increasing chlorophyll- content causes a progressive decrease in amplitude of the negative Ce anomaly in seawater that is also observed in water in the Central Mediterranean Sea, suggesting that organic matter generally plays a key role in REE behaviour at the solid-liquid interface. Shale-normalised REE features recognised in suspended particulate matter (SPM) indicate the occurrence of three different fractions from lithogenic matter, biogenic carbonates and authigenic components, respectively. The latter is formed during REE scavenging onto the surface of detrital biogenic particles and is mainly recognised in inner gulf waters

International audience; The exceptional record of well-preserved wood remains from the Middle Jurassic of Svalbard is studied from the taphonomic point of view. These remains were recovered from the Brentskardhaugen Bed, a conglomerate with phosphatic nodules, which constitutes the record of the eroded deposits corresponding to the Toarcian-Early Bathonian gap. The wood remains occur in the cores of these nodules. These wood fragments are preserved as phosphate (francolite) and as charcoals. The well preservation allows us to identify xenoxyloid cross-field pits and xenoxylean pitting on the radial wall of tracheid, characterizing the species Xenoxylon phyllocladoides. Phosphatic nodules originated as the result of early phosphate precipitation filling the inter-particle pore space of the sandy quartz sediment around the wood fragments (and other organic-rich nucleation centers) below the sediment-water interface. This phosphatization involved a sudden burial of the wood remains in the sea-bottom, the subsequent decay of the lignin, and a fast growth of carbonate fluorapatite forming phosphatic inner moulds. Fossil microbial biofilms induced the phosphatization. The dissolution/decay of the lignin is not possible in charcoal, and phosphatic casts did not develop in charcoalified parts. Some remains were not totally charred, with the lignin preserved only in reduced relicts that were later replaced by phosphate. The phosphate precipitation occurred in recurrent episodes during the Toarcian-Callovian as a result of distinct sea-level rises and the associated nutrification of the shelf. The phosphatic nodules were developed and reworked during the transgressive-regressive cycle of the Toarcian-Early Bathonian, as well as during the final transgression of the Late Bathonian-Earliest Callovian, which resulted in the Brentskardhaugen Bed

The aim of this contribution is to describe and interpret the fossil rodents from the Vallesian spelean breccias of the Sheikh Abdallah paleocave system, Western Desert, Egypt. Among the 1239 rodent teeth studied, there are three new genera and five new species. The fauna contains the earliest known murine in the world (four specimens), the earliest recorded hystricid in Africa and Europe (one specimen) and a primitive lophiomyine (15 specimens). The assemblage is dominated by Myocricetodon, of which there are four species comprising more than 1000 specimens, followed by a new genus of gerbilline (80 teeth), Africanomys (30 specimens), two genera of dendromurines (45 specimens), the squirrel Atlantoxerus (two specimens), glirids (five specimens), the gerbil Protatera (three specimens) and an indeterminate murid (two specimens). No lagomorphs were found in samples. New rodent taxa described are Faraframys heissigi, Ameuromys grandis, Steatomys bartheli, Saharamys misrensis and Africanomys bahariyaensis.

International audience; The objective of this study is to estimate changes in feeding preferences of the proboscidean species Gomphotherium subtapiroideum (Schlesinger 1917) by means of dental microwear analyses. The dietary changes are first evaluated through the ontogeny of this species, between juveniles and adults, and are then studied through geological time, from early Middle Miocene (MN5) to middle Late Miocene (MN8-9) localities of the German Molasse Basin. The microwear patterns of juvenile and adult individuals of G. subtapiroideum from Sandelzhausen (MN5) differ merely by the variable "length of scratches", emphasizing longer jaw movements during mastication in adults. The microwear signatures of G. subtapiroideum do not vary significantly between the two geological time periods studied, but reflect mixed feeding preferences in both cases. These results imply that, despite an important environmental change at that time (drying and opening), the ecology of G. subtapiroideum and, especially, its feeding habits were not affected. Its dental microwear pattern is then compared with those of other species of Proboscidea from the Middle-Late Miocene of Germany, namely Deinotherium giganteum and Gomphotherium steinheimense.

International audience; Quantitative analyses of Pliensbachian calcareous nannofossils have been carried out on a proximal-distal transect in the Lusitanian Basin (Portugal). The studied sections Vale Venteiro near Tomar and Peniche represent proximal and distal environments with respect to the emerged land of the Iberian Meseta (to the East). The upper portion of the Vale das Fontes Fin (Davoei and Margaritatus ammonite Zones) is studied in both sections and correlated by means of ammonite and nannofossil integrated biostratigraphy. A careful analysis of the preservation state of nannofossils is performed. Preservation state is moderate to good in the two settings; changes in nannofossil assemblages are therefore considered as primary. Samples were analysed for nannofossil absolute and relative abundances, species diversity and wt\%CaCO3. The analysis of calcareous nannofossils (absolute abundance, percentage, average abundance) shows changes in the community structure in space (i.e., from proximal to distal), and vertically within the water column. This pattern suggests a partitioning of habitats within the photic zone, and with respect to emerged lands. Proximal environments within the Lusitanian Basin were probably more eutrophic, because of the proximity of emerged lands to the East (Iberian Meseta). This was the source area for nutrients delivered into the basin by river transport. Distal environments were likely characterized by a greater water depth and by a deeper light penetration leading to it relatively more expanded photic zone. The assemblages recorded in the proximal setting exhibit high mean relative abundance of placolith-bearing coccolithophorids (Lotharingius spp., Biscutum spp. and Similiscutum spp.) and of Schizosphaerella spp., while distal assemblages are dominated by Crepidolithus crassus and Schizospharella spp. Crepidolithus crassus is interpreted as a deep-dweller coccolithophorid, inhabiting preferentially distal and deeper settings in the Lusitanian Basin. Placolith-bearing coccolithophorids were more abundant in proximal settings with respect to emerged lands, under relatively elevated trophic conditions. The probable calcareous dinocyst Schizospharella spp. proliferated in surface waters of both proximal and distal environments. (C) 2009 Elsevier Masson SAS. All rights reserved.

International audience; The marine Messinian deposits of Tunisia cover a narrow littoral strip some 300 km long between the northern Bizerte and Cap Bon areas and the central-eastern Sahel region. Litho- and biofacies analysis of six stratigraphic sections reveals the distinctive features of these deposits.;The lower Messinian deposits are characterized by ubiquitous siliciclastics and abundant oolitic/bioclastic limestones organized in an eastward facing ramp. Westward (landward), this ramp changes into coastal lagoons, sometimes containing evaporites. Eastward, the ramp passes to the reefal Pelagian Platform extending as far as Lampedusa.;Two main sedimentary cycles are distinguished: 1) an early Messinian siliciclastic retrogradational then oolitic/bioclastic progradational cycle (Beni Khiar Formation and lower Oued bel Khedim Formation): 2) a late Messinian brackish to continental cycle that probably accumulated in rapidly subsiding lagoons (Cued el Bir Formation and upper Oued bel Khedim Formation). The Tunisian early Messinian cycle is partly eustatically controlled, but the late Messinian cycle cannot be confidently correlated to other well-known Messinian series because of tectonic movements.;The lower Messinian deposits of Tunisia are also characterized by abundant suspension-feeding organisms (molluscs and bryozoans) and rare corals, calcareous algae, echinoids, and larger benthic foraminifers. The proposed palaeoenvironmental model shows that the lower Messinian ramp of Tunisia was located on a current-protected margin and subjected to continent-derived sediment and nutrient supply. Eastward, nutrient influx diminished and a shallow-water isolated carbonate platform with coralgal facies developed between the western and the eastern Mediterranean basins. The main hydrological connection between these two basins occurred through a narrow seaway situated to the northeast of the Pelagian Platform, south of Sicily and Malta.

A new component of the Early Palaeozoic arthropod fauna is described from a monospecific accumulate of carapaces in a Late Ordovician (Katian) hemipelagic mudstone from the Cardigan district of southwest Wales (UK). Its non-biomineralized carapace is preserved as a carbonaceous residue, as is more labile anatomy (soft-parts) including the inner lamella and sub-ovate structures near its antero-dorsal margin, which we interpret to be putative eyes. The depositional context and associated fauna indicate that the arthropods inhabited an area of deep water and high primary productivity above a pronounced submarine topography. The preserved density of carapaces suggests the arthropods may have congregated into shoals or been transported post-mortem into depressions which acted as detritus traps. The accumulate provides a rare example of soft-part preservation in hemipelagic mudstones and highlights the role of organic material as a locus for authigenic mineralization during metamorphism.

International audience; The study of eight stratigraphic sections at the margin of the semi-enclosed Zsambek Basin (Hungary) allows the sedimentary anatomy of oolitic-bioclastic systems in the Sarmatian of the Central Paratethys to be reconstructed. The mollusc, foraminiferal and ostracod associations indicate that the carbonate systems are Latest Badenian to Late Sarmatian in age. The Lower-Upper Sarmatian deposits are organized in superimposed subaqueous dunes prograding towards the basin on a low-angle ramp. During the Late Sarmatian, the ramp underwent subaerial erosion linked to a moderate relative fall in sea-level. Lagoonal deposits were later formed and microbial-nubeculariid-bryozoan-serpulid buildups were emplaced. The 'abnormal' marine conditions of the Sarmatian, conducive to the development of a poorly diversified flora and fauna and dominant non-skeletal grains, are linked to fluctuating salinities, mesotrophic to eutrophic conditions and perhaps high alkalinity.

International audience; Eucalyptolaurus depreii gen. et sp. nov. is proposed for angiosperm leaves newly collected from uppermost Albian ­ lowermost Cenomanian of Charente-Maritime (western France). They consist of simple, narrow, elongate laminas with entire margins and intramarginal veins. The epidermal cells of adaxial cuticle shows small, rounded, blunt papillae outward that protrude inward and fuse together as rolls along and parallel to the margins, while the adaxial cuticle bears brachyparacytic stomatal apparatus that exhibit sunken guard cells and hair bases consisting of a thick-walled pore surrounded by radially arranged differentiated cells. Resin bodies occur inside the mesophyll. These characters closely resemble the lauroid taxa 'Myrtophyllum' and Pandemophyllum from the Cenomanian of the Czech Republic and Dakota (USA) respectively. The narrow angle of basilaminar secondaries and the whole suite of features in the guard cells (sunken guard cells embedded into subsidiary cells and stomatal ledges) strongly support close affinity with the Lauraceae. From the Cenomanian lauraceous reproductive organs and their related leaves already showed high disparity and diversity. In addition they displayed a broad ecological range from freshwater floodplains to brackish swamps. This combined to high diversity of reproductive organs suggest ecological radiation of Lauraceae by the Cenomanian.

International audience

International audience; Outcrops, offshore wells, electric logs and seismic profiles from northern Tunisia provide an opportunity to decipher the Messinian Salinity Crisis in the Strait of Sicily. Messinian deposits (including gypsum beds) near the Tellian Range reveal two successive subaerial erosional surfaces overlain by breccias and marine Zanclean clays, respectively. In the Gulf of Tunis, Messinian thick evaporites (mostly halite) are strongly eroded by a fluvial canyon infilled with Zanclean clays. The first erosional phase is referred to the intra-Messinian tectonic phase and is analogous to that found in Sicily. The second phase corresponds to the Messinian Erosional Surface that postdates the marginal evaporites, to which the entire Sicilian evaporitic series must refer. The Western and Eastern Mediterranean basins were separated during deposition of the central evaporites.

Extant species of Muridae occupy a wide array of habitats and have diverse dietary habits. Consequently, their dental microwear patterns represent a potential clue to better understand the paleoecology of their extinct relatives, which are abundant in many Old World Neogene localities. In this study, dental microwear is investigated for specimens of 17 extant species of murine and deomyine rodents in order to test the reliability of this method and infer dietary preferences on the fossil species Saïdomys afarensis. This extinct form comes from a mid-Pliocene site (AL 327) located at the Hadar Formation (Ethiopia) known to have delivered many hominid specimens of Australopithecus afarensis. A significant correlation between microwear patterns and diet is detected. Thus, grass, fruit, and insect eaters display, respectively, high amounts of fine scratches, wide scratches, and large pits. Moreover, some aspects of the paleoecology of S. afarensis, including feeding habits, could be assessed in regard to its dental microwear pattern. Indeed, it probably had feeding habits similar to that of living grass eaters. These results concur with the presence of open to woodland areas covered by an herbaceous vegetal layer, including monocotyledons, in the vicinity of this mid-Pliocene locality.

Phosphatic remains (tooth enamel, turtle shell fragments and fish scales) of continental vertebrates (freshwater fish, crocodilians, turtles, and theropod and sauropod dinosaurs) recovered from eight localities of NE Thailand ranging in age from the Late Jurassic to the late Early Cretac- eous have been analysed for their oxygen isotopic compositions (d 18 Op). From these preliminary data, local meteoric water d 18 Ow values estimated using d 18 Op values of crocodilians and turtles range from 24.1+ 2‰ at the end of the Jurassic to 28.3+ 2‰ during the Early Cretaceous, suggesting a transition from dry to wetter climates with increasing amount of seasonal precipitation from several hundred millimetres per year to several thousand millimetres. Measurable offsets in d 18 Op values observed between dinosaur taxa (the spinosaurid theropod Siamosaurus, other ther- opods and nemegtosaurid sauropods) are interpreted in terms of differences in water strategies, and suggest that Siamosaurus had habits similar to those of semi-aquatic vertebrates such as crocodi- lians or freshwater turtles.

International audience; The oxygen isotope composition of human phosphatic tissues (delta18OP) has great potential for reconstructing climate and population migration, but this technique has not been applied to early human evolution. To facilitate this application we analyzed delta18OP values of modern human teeth collected at 12 sites located at latitudes ranging from 4 degrees N to 70 degrees N together with the corresponding oxygen composition of tap waters (delta18OW) from these areas. In addition, the delta18O of some raw and boiled foods were determined and simple mass balance calculations were performed to investigate the impact of solid food consumption on the oxygen isotope composition of the total ingested water (drinking water+solid food water). The results, along with those from three, smaller published data sets, can be considered as random estimates of a unique delta18OW/delta18OP linear relationship: delta18OW=1.54(+/-0.09)xdelta18OP-33.72(+/-1.51)(R2=0.87: p [H0:R2=0]=2x10(-19)). The delta18O of cooked food is higher than that of the drinking water. As a consequence, in a modern diet the delta18O of ingested water is +1.05 to 1.2 per thousand higher than that of drinking water in the area. In meat-dominated and cereal-free diets, which may have been the diets of some of our early ancestors, the shift is a little higher and the application of the regression equation would slightly overestimate delta18OW in these cases.

International audience; In insects, biogenic amines have been shown to play an important role in olfactory plasticity. In a first attempt to decipher the underlying molecular mechanisms, we report the molecular cloning and precise expression pattern of a newly identified octopamine/tyramine-receptor-encoding gene in the antennae of the noctuid moth Mamestra brassicae (MbraOAR/TAR). A full-length cDNA has been obtained through homology cloning in combination with rapid amplification of cDNA ends/polymerase chain reaction; the deduced protein exhibits high identities with previously identified octopamine/tyramine receptors in other moths. In situ hybridization within the antennae has revealed that MbraOAR/TAR is expressed at the bases of both pheromone-sensitive and non-sensitive olfactory sensilla and in cells with a neurone-like shape. In accordance with previous physiological studies that have revealed a role of biogenic amines in the electrical activity of the receptor neurones, our results suggest that biogenic amines (either octopamine or tyramine) target olfactory receptor neurones to modulate olfactory coding as early as the antennal level.

Zn isotopic fractionation caused by sorption on 2-Lines ferrihydrite (Fh2L) and goethite was investigated to assess the role of reactions at the Fe-oxyhydroxide/water interface in changes of the isotopic distribution of Zn. Since sorption reactions are ubiquitous in Earth’s surface environments, it is important to evaluate their influence on the isotopic distribution of Zn before it can be used to track and quantify contributions of various sources and/or biogeochemical processes involving this element. Our results show that Zn isotopes are fractionated upon sorption on Fe-oxyhydroxides with an enrichment of the heavy isotopes present on the solid’s surface. This fractionation appears to proceed through an equilibrium mechanism and yields different (Δ 66/64 Zn) sorbed–aqueous values for Zn sorption on goethite [(Δ 66/64 Zn) sorbed–aqueous around +0.29‰] and Fh2L [(Δ 66/64 Zn) sorbed–aqueous around +0.53‰]. These different magnitudes of Zn fractionation are related to structural differences between Zn complexes existing on the surface of goethite (octahedrally coordinated Zn by oxygen atoms) and Fh2L (tetrahedrally coordinated Zn by oxygen atoms), as evidenced by Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy and CD-MUSIC modeling. These results show the importance of accounting for reactions at the Fe-oxyhydroxide/water interface when dealing with the isotopic distribution of Zn at the Earth’s surface. Considering the large range of other possible sorbents (Mn or Al oxides, phyllosilicates, carbonates, biologic surfaces, etc.) and the importance of reactions at sorbent/water interfaces for other non-traditional stable isotopes (i.e. Cr, Fe, Ni and Cu) that are increasingly used in environmental studies, these results emphasize the need for further experimental studies that are needed to quantify the isotopic fractionation of these elements possibly accompanying their sorption.

The Moresby Seamount located in the Woodlark Basin is a fragment of oceanic crust (dolerites and gabbros) generated 66.4 ± 1.5 My ago before being obducted during the Eocene on the Australian margin. Since 8 My, the motion of a normal fault related to the opening of the Woodlark Basin is responsible for the unroofing of the Moresby seamount. The latter was sampled during the ODP campaign Leg 180 in 1998. Geochemical compositions of dolerites can be explained by a process of fractional crystallization in which the magnesian spinel was involved. Therefore fractionation processes took place at relatively high pressure (>1 GPa), most likely during the upward migration of deep magmas throughout the mantle. The Fe-rich gabbros, more differentiated than the dolerites, could have derived from an early differentiated magma evolving in the crust at relatively low pressures. The trace element content of dolerites indicates that their source was a depleted oceanic mantle slightly influenced by arc-related magmas. This study suggests that the ophiolites fragment of the Moresby seamount was created in the vicinity of a subduction zone; this model being in agreement with the regional tectonic setting of SE Asian since the Cainozoic.

International audience; The important question of early angiosperm growth habit (i.e., trees, shrubs or herbs?) remains unanswered. Various theories have been based on data from both living and fossil plants. The Early Cretaceous fossil wood record, however, was seldom used to investigate early angiosperm habit. We set up a database for the Early Cretaceous and Cenomanian of Europe, as this area has the most complete and stratigraphically well-constrained record. The database has 170 entries, based on a bibliographical survey and on the examination of more than 600 new fossil wood specimens from a wide range of palaeoenvironments. In our record the woody characteristic in angiosperms appeared during the Albian, whereas most of the angiosperm's early evolution took place earlier, during the earliest Cretaceous. From the European fossil wood record for the Early Cretaceous and Cenomanian, the global extension and dominance of angiosperms in the Cenomanian is concomitant with a sharp increase in heteroxylous wood diversity. It appears that small stature and weak wood limited the angiosperm ecological radiation for some time.

The Stripe Field Mouse lineage ( Apodemus agrarius ) was present in the Late Pleistocene in southwestern France (locality of Bouzies-Q, Quercy), according to the age of ca. 17,417–17,044 BC of the collected sample (AMS 14 C dating of collagen extracted from small mammal bones). This occurrence demonstrates that a much western expansion of the Stripe Field Mouse lineage than believed occurred at the end of the last cold phase of the Pleistocene, the few fossil populations up to now known being both younger and located inside the present-day distribution area of the lineage. The AMS 14 C date supports the hypothesis of the late migration of this species into Europe. If tooth morphology indicates clear differences with respect to Apodemus sylvaticus or A. flavicollis , there are appreciable ones between the Bouzies-Q population and the present-day Apodemus agrarius of western Europe, likely indicating evolution at the sub-specific level despite the short time period involved.

New precise zircon U–Pb ages are proposed for the Triassic–Jurassic (Rhetian–Hettangian) and the Hettangian–Sinemurian boundaries. The ages were obtained by ID-TIMS dating of single chemical-abraded zircons from volcanic ash layers within the Pucara Group, Aramachay Formation in the Utcubamba valley, northern Peru. Ash layers situated between last and first occurrences of boundary-defining ammonites yielded 206Pb/238U ages of 201.58 ± 0.17/0.28 Ma (95% c.l., uncertainties without/with decay constant errors, respectively) for the Triassic–Jurassic and of 199.53 ± 0.19 / 0.29 Ma for the Hettangian–Sinemurian boundaries. The former is established on a tuff located 1 m above the last local occurrence of the topmost Triassic genus Choristoceras, and 5 m below the Hettangian genus Psiloceras. The latter sample was obtained from a tuff collected within the Badouxia canadensis beds. Our new ages document total duration of the Hettagian of no more than c. 2 m.y., which has fundamental implications for the interpretation and significance of the ammonite recovery after the topmost Triassic extinction. The U–Pb age is about 0.8 ± 0.5% older than 40Ar–39Ar dates determined on flood basalts of the Central Atlantic Magmatic Province (CAMP). Given the widely accepted hypothesis that inaccuracies in the 40K decay constants or physical constants create a similar bias between the two dating methods, our new U–Pb zircon age determination for the T/J boundary corroborates the hypothesis that the CAMP was emplaced at the same time and may be responsible for a major climatic turnover and mass extinction. The zircon 206Pb/238U age for the T/J boundary is marginally older than the North Mountain Basalt (Newark Supergroup, Nova Scotia, Canada), which has been dated at 201.27 ± 0.06 Ma [Schoene et al., 2006. Geochim. Cosmochim. Acta 70, 426–445]. It will be important to look for older eruptions of the CAMP and date them precisely by U–Pb techniques while addressing all sources of systematic uncertainty to further test the hypothesis of volcanic induced climate change leading to extinction. Such high-precision, high-accuracy data will be instrumental for constraining the contemporaneity of geological events at a 100 kyr level.

The Chay Peninsula (western France) succession corresponds to a Kimmeridgian shallow and low-energy ramp system that developed in the northeast of the Aquitaine Basin. The sedimentation shows a transition from a carbonate-dominated to a mixed carbonate–siliciclastic depositional environment that takes place at the base of a major, third-order sea-level transgression. Facies partitioning and coral-microbialite reef levels (i.e., reef windows) suggest higher-frequency (fourth-order) sea-level oscillations. Reef-growth phases (i.e., high-frequency reef windows) are interpreted to have been controlled by fifth-order sea-level oscillations. In the mixed siliciclastic–carbonate system, successive prograding units of shoreface sediments pass into thick marl–limestone alternations over a distance of tens of metres. Such remarkable short-distance lateral facies variations suggest a complex sedimentary system made of juxtaposed deposits that rapidly shift through time. Terrigenous fluxes, in modifying the light intensity and the nutrient level in the water column strongly controlled the facies distribution and notably the reef composition and growth. Identified coral genera suggest mixed photo-heterotrophic mode of nutrition and low-mesotrophic conditions in marine waters. For each reef-growth phase, nutrient increase favoured large amounts of microbialites to develop, forming a crust that entirely capped the coral reef surface. Thus, high-frequency fluctuations in nutrient input in tune with fifth- (or higher) order sea-level fluctuations controlled the reef development at a millennial scale. The Chay Peninsula reef distribution and development provide insight into understanding the response of reef communities under climatically-induced environmental changes.

Small (50e200 nm), calcium phosphate (apatite)-covered organic particles called nanobacteria or calcifying nanoparticles (CNP) seem to be ubiquitous in kidney stones and are thought to be involved in stone formation. Although initial claims that these particles are the smallest known life forms have been somewhat softened, much controversy remains as to their involvement in kidney stone formation as well as in other pathological calcifications. I suggest that such particles are non-living and may be formed during the normal living activities of bona-fide bacteria which inhabit the kidneys. This hypothesis is based on previous observations that bacteria immersed in a supersaturated fluid produce organic globules which calcify when released to the surrounding fluid, forming CNP-like particles. The possibility that this process is responsible for the formation of CNP associated with pathological calcifications deserves greater scrutiny.

FR2116; International audience; Observed patterns of species richness at landscape scale (gamma diversity) cannot always be attributed to a specific set of explanatory variables, but rather different alternative explanatory statistical models of similar quality may exist. Therefore predictions of the effects of environmental change (such as in climate or land cover) on biodiversity may differ considerably, depending on the chosen set of explanatory variables. Here we use multimodel prediction to evaluate effects of climate, land-use intensity and landscape structure on species richness in each of seven groups of organisms (plants, birds, spiders, wild bees, ground beetles, true bugs and hoverflies) in temperate Europe. We contrast this approach with traditional best-model predictions, which we show, using cross-validation, to have inferior prediction accuracy. Multimodel inference changed the importance of some environmental variables in comparison with the best model, and accordingly gave deviating predictions for environmental change effects. Overall, prediction uncertainty for the multimodel approach was only slightly higher than that of the best model, and absolute changes in predicted species richness were also comparable. Richness predictions varied generally more for the impact of climate change than for land-use change at the coarse scale of our study. Overall, our study indicates that the uncertainty introduced to environmental change predictions through uncertainty in model selection both qualitatively and quantitatively affects species richness projections.

This study reopens the discussion on the AP/NAP ratio that contrasts the total number of Arboreal Pollen grains (AP) to that of the Non-Arboreal Pollen grains (NAP), and its meaning in terms of vegetation land-cover. Based on a set of 52 present-day pollen assemblages (mostly moss polsters) from continental France and black- and-white aerial photographs of these localities, we perform statistical analyses to clarify the meaning of the AP/NAP ratio. Short- and long-distance transported pollen grains, possible over-representation of Pinus, and distortion of cultivated plants are among the biases explored here and for which answers are given. Grey level analysis of the aerial photographs provides direct estimates of the Tree Surface/Herb Surface (TS/HS) ratio for a radius of 1000 m around the sampling point. Statistical estimates of the AP/NAP and TS/HS cut-off values separating tree- and herb-prevalent landscapes are computed. Such results obtained from modern pollen records have been applied to a Late Pliocene small maar locality from southern France characterized by a very weak pollen transport and provide the basis to further distinguish tree- and herb-prevalent landscapes in past pollen records.

International audience; Many techniques have been developed to estimate species richness and beta diversity. Those techniques, dependent on sampling, require abundance or presence/absence data. Palaeontological data is by nature incomplete, and presence/absence data is often the only type of data that can be used to provide an estimate of ancient biodiversity. We used a simulation approach to investigate the behaviour of commonly used similarity indices, and the reliability of classifications derived from these indices, when working with incomplete data. We drew samples, of varying number and richness, from artificial species lists, which represented original life assemblages, and calculated error rates for classifications of the parent lists and samples. Using these results, we estimated the Minimum Sample Richness (MSR) needed to achieve 95% classification accuracy. Results were compared for classifications derived from several commonly used similarity indexes (Dice, Jaccard, Simpson and Raup-Crick). MSR was similar for the Dice, Jaccard and Simpson indices. MSR for the Raup-Crick index was often much lower, suggesting that it is preferable for classifying patchy data, however the performance of this index was less stable than the other three in the simulations, which required an even lower MSR. MSR can be found for all presence/absence data from the contour graphs and equations as long as the absolute species richness and the beta diversity can be estimated.

International audience; Since the 1970s, radiolarians have been used extensively to study and characterize basin successions from the peri-Mediterranean regions. However, no data was ever produced in Tunisia in spite of the occurrence of Jurassic siliceous series previously described by many authors. Our study presents the biostratigraphical results obtained on sections from the Jédidi Formation, which characterizes the basinal series of the Tunisian Trough. We provide new direct age determinations from the base, the middle part and the top of the formation, which ranges from the latest Bajocian–middle Bathonian to the Oxfordian (Tethyan biozones UAZ 5-6 to 8-9). The onset of these radiolarianbearing series of the Tunisian Trough, adjacent to partly coeval Ammonitico Rosso successions, is interpreted as resulting from regional palaeotopographical gradient and palaeoceanographical conditions. Inaccurately interpreted as “true” radiolarites, theses series are different from coeval radiolarites of the Maghrebian “Dorsale calcaire” and from more recent homologous deposits of the Flysch domain. They are instead correlative with series exposed in the Babors and the west-Numidian ranges of northern Algeria that belonged to the same Jurassic North African margin of western Tethys. During Alpine convergence s.l., this external domain was overthrust by nappe complexes of the Maghrebide inner zones and the Flysch domain units.

International audience; Pollen and paleomagnetic analysis of the Rubielos de Mora-1 core (Rubielos de Mora basin, NE Spain) has been carried out with the aim of reconstructing floral, vegetational and climatic changes within an accurate time framework. Based on biostratigraphic information, the magnetostratigraphy (ATNTS04) resulting in an age of Early Miocene for the cored sedimentary sequence. The high percentages of thermophilous taxa and the diverse subarid flora in the pollen spectra points to a very dry subtropical climate with a marked seasonality, reflecting the onset of the Miocene climatic optimum. On the other hand, taxa with high water requirements (riparian) are also abundant. Alternation in pollen taxa (thermophilous vs. mesothermic–riparian), coincide with sedimentological changes, which are related to lake level fluctuations and vegetation changes. In turn, the vegetational pattern indicates cyclic changes in temperature and precipitation which is controlled by astronomically forced obliquity cycles.

International audience; What actually is the expected pattern relating to molecular and morphological divergence? A phylogenetic correlation is expected; however, natural selection may force morphological evolution away from this expected correlation. To assess this relationship and the way it is modulated by selection, we investigated the radiation of the murine rodents, also called as Old World rats and mice. Regarding their diet, they are diversified as they include many omnivorous as well as specialist taxa. The size and shape of the mandible, a morphological character involved in the feeding process, was quantified and compared with an estimate of molecular divergence based on interphotoreceptor retinoid binding protein (IRBP) sequences. Size and shape of the mandible appeared to be related by an allometric relationship whatever the ecology of the taxa. Small size characterizes most murines, causing a dominance of low size distances; still, the frequency of important size differentiation increases with molecular distances. Regarding shape changes, the pattern is much contrasted between omnivores and specialists. A pattern of phenotypic drift characterizes the mandible evolution of taxa sharing an omnivorous diet. Little saturation occurs over more than 10 million years with regard to the shape of the mandible that appears as a valuable marker of phylogenetic history in this context. In contrast, important morphological distances can occur when specialist taxa are involved, even when the molecular divergence is small. Ecological specialization thus triggers an uncoupling of molecular and phenotypic evolution, and the departure from a phenotypic drift pattern.

Des plantes fossiles du Jurassique supérieur rapportées aux Gymnospermes s.l. provenant du massif Manamana, au sud-ouest de Madagascar, ont été étudiées. Elles sont attribuées aux Ptéridospermales et aux Coniférales. Une nouvelle espèce, Brachyphyllum madagascariense nov. sp. est décrite, avec l'aide des caractères épidermiques observés au microscope électronique à balayage (MEB). Il s'agit de la première description d'une telle paléoflore dans le Jurassique supérieur de Madagascar. Des comparaisons de composition systématique sont faites avec d'autres paléoflores de même âge du Gondwana.

The diverse and exceptionally well-preserved pycnogonids described herein from the Middle Jurassic La Voulte Lagerstätte fill a 400 Myr gap of knowledge in the evolutionary history of this enigmatic group of marine arthropods. They reveal very close morphological and functional (locomotion, feeding) similarities with present-day pycnogonids and, by contrast, marked differences with all Palaeozoic representatives of the group. This suggests a relatively recent, possibly Mesozoic origin for at least three major extant lineages of pycnogonids (Ammotheidae, Colossendeidae, Endeidae). Combined evidence from depositional environment, faunal associates and recent analogues indicate that the La Voulte pycnogonids probably lived in the upper bathyal zone ( ca 200 m). Our results point to a remarkable morphological and ecological stability of this arthropod group over at least 160 Myr and suggest that the colonization of the deep sea by pycnogonids occurred before the Jurassic.

International audience; The characterization and distribution of the microfacies and the microfossil assemblages of a Middle Oxfordian section from Jura Mountains composed by thick oolitic–coral limestones is analyzed. Six microfacies types(mainly grainstones) are differentiated mainly composed by ooids, intraclasts and bioclasts. Foraminiferal assemblages are dominated by agglutinated forms. Benthic microbial communities and sessile foraminifera are the main components of the encrustations. The whole set of microfossil assemblages is typical of shallow subtidal environments rich in “algae” (Cayeuxia, “Solenopora”, Thaumatoporella, Bacinella, Girvanella and Terquemella) and foraminifera such as Nautiloculina oolithica, Redmondoides lugeoni, Ammobaculites coprolitiformis, Troglotella incrustans and Rectocyclammina. The increasing upward record of debris of algae and Nautiloculina, and the decrease of serpulids, bryozoans, nodosariids and ophthalmidiids indicate a shallowing- upward trend. The stratigraphic distribution of microfacies and microfossil assemblages lead to diVerentiate two main successive phases. The Wrst is a deeper subtidal environment in an open shelf, while the second is a shallow subtidal environment with evolution from winnowed to more restricted conditions. Microfabrics of radial to concentric ooids upwards in the section correspond to higher energy environments related to an oolitic shoal. This study shows how a very detailed analysis of microfacies, which integrates oolitic features, microfossil assemblages and microtaphonomy is potentially a useful tool for interpreting hydrodynamism and sequence evolution in marine carbonate shallow environments.

International audience; The siliceous sponges and crinoids from the Chénier Ravine (France, Lower Callovian) are used here as biological markers to characterize the palaeoenvironment of the adjacent and contemporaneous La Voulte Lagerstätte that is remarkable for its unique soft-bodied fauna (e.g. worms, cirrate octopods, vampire squids). Sponges are abundant with dominant hexactinellids (80%) and lithistids (20%). Four lines of fossil evidence, supported by Recent analogues, indicate that this sponge community inhabited deepwater setting under dysphotic or aphotic conditions: (1) the dominance of hexactinellids; (2) the prevalence of cone-shaped and erect morphologies that usually characterize Recent bathyal sponges; (3) the close similarities with Recent hexactinellids from the continental slope and; (4) the lack of encrustation by photophilic organisms. Attachments of sponges on hard substrate (e.g. crystalline basement) and their preservation in soft sediments (e.g. muds) indicate heterogeneous bottom conditions. The Chénier fauna also contains small stalked, asymmetric cyrtocrinid crinoids that are known to live on hard substrates in bathyal environments such as the SW Pacific steep seamounts. Convergent palaeoenvironmental clues obtained from both crinoids and siliceous sponges support the notion that the La Voulte area, including the La Voulte Lagerstätte, was situated in the upper part of the bathyal zone near the slope-basin transition with a water depth most probably exceeding 200 m. Supporting evidence from heterogeneous substrates and complex fault systems indicate a depositional environment along the external part of the slope where steep topographies and blocks usually favour the settlement of cyrtocrinid crinoids and hexactinellid sponges. La Voulte may therefore be one of the rare and extremely precious Mesozoic Lagerstätten to have fossilized a deep marine environment

Hydrological conditions prevailing before, during and after the Messinian salinity crisis in Sicily have been approached using dinoflagellate cyst records. The synthetic sequence considered is based on five classical sections from the Caltanissetta Basin. Our interpretations are based on the recognition of autochthonous, allochthonous and reworked population among the dinocyst assemblages. For the first time, sea-surface temperatures and seasonal salinity contrasts were tentatively reconstructed using a “Mutual Climatic Range Method”. Sicilian late Tortonian deposits correspond to marine environment with significant terrestrial inputs favourable to eutrophic dinocyst species. Immediately after the beginning of the Messinian Stage, euryhaline assemblages took place, followed by meso-hyperhaline taxa, within a general trend to shallowing. At the end of the Tripoli diatomitic Formation, environment appears confined, with regular oceanic inflows. Such marine inflows remain persistent during the deposition of the salt Member, witnessing the probable persistence of nearby normal marine sea-surface water conditions in the Mediterranean Sea but with possible reduced hydrological circulation and/or low nutrient component. Such inflows are slightly decreasing up to the top of the Sicilian Upper Evaporites. At the same time, river inputs appear weak during the salt deposition, as the consequence of a rather dry climatic context. As shown by reworking activity, terrestrial inputs increase progressively from the base of the Upper Evaporites. During the Lago Mare period, while climate remains rather dry (absence of freshwater algae inputs, very low amount in trees requiring humid conditions), local deposition environment is confined with mesohaline to hypohaline sea-surface waters, in a context with relatively high seasonal sea-surface salinity contrast (up to 6‰). The very high reworking observed in the Arenazzolo silts, in addition to slightly increasing water depth, led us to consider the presence of a discontinuity between the Lago Mare and the Arenazzolo Fms. We consider the Arenazzolo Formation as a transgressive facies following a deep downcutting period. The Arenazzolo Formation presents a two-step development. The first one, correlative with the presence of a G. etrusca (a species with Paratethyan affinities), corresponds to a relative high-stand sea-level with oceanic influxes, low seasonal sea-surface salinity contrast and probable more humid context, as revealed by the important freshwater algal inputs. During the second step, salinity becomes much more variable, with a clear increase of seasonal sea-surface salinity contrast, a possible slight mean sea-surface temperature increase (only few degrees) and a clear weakening of the river inputs. Taking the proposed Zanclean position of the Arenazzolo Fm. into consideration, we state that mean sea-surface temperature did not change significantly from the base of the Messinian to the earliest Zanclean. At 5.33 Ma, the suddenly achieved flooding restored a fair, deep oceanic environment characterized, at the beginning, by a clear mean sea-surface temperature cooling (up to 6–7 °C) and a nutrient depletion, associated with the basins starvation. Sea-surface salinities were normal, with very low seasonal contrast. Hydrodynamics then nutrient supply became then quite normal from c.a. 5.08 Ma. The status of the Sicilian Caltanissetta Basin as a marginal basin although fastly deepening and the stratigraphical location of the Messinian discontinuity at the base of the Arenazzolo is the scenario that best matches our dinocyst record.

International audience; Patterns of change in the structure of bacterial communities monitored by ribosomal intergenic spacer analysis (RISA) in oil contaminated sediments inhabited or not by the marine polychaete Nereis diversicolor were studied during 45 days under laboratory conditions. Results supported by principal component analysis showed a marked response of the bacterial communities to the oil contamination and to the presence of N. diversicolor. Phylogenetic affiliation of specific RISA bands showed that, in the contaminated sediments, the presence of the marine polychaetes favoured the development of bacteria which may play an active role in natural bioremediation processes of oil polluted environments.

International audience; In order to better understand the parameters that drove evolution of actinopterygian fishes from the Late Jurassic to the Late Cretaceous (this being the time of diversification of crown group teleosts, by far the dominant fish group today), we define three environmental indicators, which are detectable as concordant patterns in the geological and fossil records. These are 1) freshwater radiations, 2) vicariant events and 3) sea temperature. We mapped the indicators onto a phylogeny of the Late Jurassic–Palaeocene actinopterygian taxa, and plotted the variations against time for each of the indicators. Our results show that for several of the marine clades, diversity is positively correlated with sea temperature and for one clade negatively correlated with sea temperature. The marine radiation is very important in the mid-Cretaceous, especially in the Tethys, which may have been a centre of origin for some clades. Vicariant events occurred in both marine and freshwater groups, and are abundant during the opening of the south Atlantic in the Early Cretaceous. Freshwater radiations, forming in some cases species flocks, are especially evident in the basal Cretaceous in Asia. Although these results are affected by biases related to the fossil record and to its study, we propose that these global patterns are genuine and reflect the strong impact of the Earth system on the evolution of fishes in the Late Mesozoic.

International audience; We describe a new species of lungfish, Ferganoceratodus martini sp. nov. , based on a single specimen discovered in the Late Jurassic - Early Cretaceous of the Phu Nam Jun locality, north-eastern Thailand. The material comprises an almost complete skull roof with associated upper and lower jaws, as well as some postcranial remains. F. martini shows characters unexpected and/or unknown in other Mesozoic lungfishes, such as pieces of a 'hard snout'. The microstructure of the 'hard snout' provides support to the Bemis and Northcutt interpretation of the cosmine tissue of Palaeozoic lungfishes as homologous to the complex cutaneous vasculature of the living Neoceratodus . Because the homologies of the ossifications of the skull roof among lungfishes and among piscian sarcopterygians are unsatisfactorily understood, we use a topological nomenclature in the description of the specimen and in the discussion of post-Devonian dipnoan skull roof characters. We define a few characters for the cladistic analysis only, but these are regarded as less theory-laden. We propose a hypothesis of phylogenetic relationships for most of the post-Devonian forms known by skull remains. The main feature is the ancient dichotomy between the Neoceratodus lineage and most of the other Mesozoic forms, including the Lepidosirenids. The palaeobiogeographical pattern shows a series of vicariant events between Laurasia and Gondwana in the Late Triassic - Early Jurassic, followed by a vicariant event between Africa and South America

International audience; The palynological analysis in the Karpatian–Sarmatian (late Early-Middle Miocene) interval of the cores Tengelic-2 and Hidas- 53 (Hungary) reveals the existence of a forest organized in altitudinal belts, developed in a subtropical–warm temperate humid climate, reflecting the so-called Miocene climatic optimum. Pollen changes from the late early Miocene to the late middle Miocene have been observed and are related to climatic changes. The vegetation during the Burdigalian and the Langhian was dominated by thermophilous elements such as evergreen trees and Engelhardia, typical of a present day rain and evergreen forest at low altitudes (i.e. SE China). During the Serravallian several thermophilous elements strongly decreased, and some of them disappeared from the central European area. Thus, the rain and evergreen–deciduous mixed forest suffered a great transformation due to the loss and decrease in the abundance of several evergreen plants. This kind of vegetation was progressively substituted by deciduous and mesothermic plants such as deciduous Quercus, and Fagus, Alnus, Acer, Carpinus, Ulmus, Zelkova, etc. At the same time, the presence of altitude coniferous trees increased. This climatic cooling is correlated with global and regional climatic changes.

International audience; Abundant and diverse trace fossils occur in deposits, recording an Early Devonian transgression in Bolivia. The very well-exposed Presto-El Peral section is located in the Interandean Belt 50 km northeast of Sucre. Trace fossils can be assigned to five associations from nearshore to offshore environments (namely Skolithos, Diplocraterion, Altichnus, Palaeophycus, and Zoophycos associations). They clearly illustrate the different colonization phases of the benthos with increasing marine influence. A deeper-water Helminthopsis association occurs in other complementary sections on the Eastern Cordillera. Variation of bioturbation intensity, ichnodiversity, and preservation potential is evaluated. The morphology of traces, mainly deep burrows, shows a significant gradient related to the behavior of tracemakers and the environmental changes. Main trends are consistent with the Seilacherian bathymetric model which is detailed here and/or emended with a well-exposed field example. A precise correlation is proposed with fossil benthic associations dominated by brachiopods. The whole gives an accurate model for benthos colonization and benthic marine zonation

International audience; To test the influence of both civilization and volcanism on the chemical composition of ostracod carapaces, 32 wellpreserved valves from Kagoshima Bay (Kyushu Island, South Japan) were analysed by means of spark source mass spectrometry. In Kagoshima Bay, the extent of pollution corresponds to human activities. Kagoshima Bay is also an area of important volcanic activity: emissions from Sakurajima volcano are very frequent. The species analysed were Argilloecia hanaii , Callistocythere undulatifacialis , Pontocythere subjaponica and Loxoconcha tosaensis . Twenty-three chemical elements were detected. Among them, 11 were always above the limit of detection: Al, B, Cl, F, Fe, K, Na, P, S, Si and Zn. The correlation between Zn and Fe was characteristic of the volcanic environment. Two discriminant analyses were performed using either the location area or the species as grouping variables. An association between Zn and S is possible; it could be related to volcanic activity. The chemical composition of carapaces is ascribed to taxonomic units rather than the environment.

International audience; L'étude de spécimens dentaires attribués à la famille Amphilemuridae apporte de nouvelles données sur ce groupe très spécialisé de petits mammifères placentaires de l'Éocène. Reconnus comme des Lipotyphla érinacéomorphes, cinq genres et 17 espèces étaient jusqu'à présent décrits sur les continents européen et nord-américain : Macrocranion, Gesneropithex, Amphilemur, Alsaticopithecus et Pholidocercus. Le matériel objet de notre étude, en grande partie inédit, provient de plusieurs localités européennes, de contexte endokarstique ou de bassin continental. La morphologie dentaire est utilisée pour la détermination ou, dans certains cas, la révision d'anciennes déterminations. Il est possible de proposer un nouveau genre, Echinolestes n. gen., et six nouvelles espèces, concourant à augmenter la diversité connue des amphilémuridés, notamment au sein du genre Macrocranion.

22 pages; International audience; Ammonoids recovered much faster than other marine shelly invertebrates after the end-Permian mass extinction. Based on a refined global data set at the basin level, we investigate the paleobiogeographical global latitudinal and longitudinal diversity patterns in terms of climatic changes during the Early Triassic. Such analysis differs from already published qualitative or quantitative studies in that it estimates faunal patterns and endemicity at an ecologically meaningful level of spatial resolution, i.e. at the basin level. During the Early Triassic, the global first order trend in increasing ammonoid diversity was accompanied by a progressive change from cosmopolitan to latitudinally-restricted distributions. This led to the emergence of a clear latitudinal diversity gradient during most of the Smithian and Spathian stages, which entails increased steepness of the Sea Surface Temperature gradient during the late Early Triassic. However, two brief episodes of ammonoid cosmopolitanism combined with low global diversity interrupted the first order increasing trend at the very beginning of the Smithian and at its very end. The longitudinal analysis of Smithian distributions indicates a westward decrease of diversity within the Tethys, which faded away during the Spathian. Analysis of endemicity indicates a rapid biogeographical maturing and structuring of faunas concomitant with the edification of the latitudinal diversity gradient.

International audience; The coccolithophore species Watznaueria britannica is dominant in Middle-Upper Jurassic calcareous nannofossil assemblages and presents morphological variation, including different coccolith size, shape and length of the central area and of the bridge. Six morphotypes can be recognized in the polarizing light microscope. The aim of this work is to better understand the morphological variability of W. britannica and determine if this variability is controlled by paleoecological factors. In order to investigate the potential paleoecological controls on W. britannica morphology and abundance, we carried out a biometric study on a restricted temporal interval: the Late Oxfordian, in the Swabian Alb (southern Germany), characterized by increasing carbonate production linked to climatic changes. The Balingen–Tieringen section, where previous works on sedimentology, nannofossil assemblage composition, and δ18O and δ13C analyses were performed,was selected for this study. The variations in morphology and abundances ofW. britannicawere studied on 40 samples of the Balingen–Tieringen section, presenting variable lithologies and calcium carbonate contents. For each level, seven biometric parameters (coccolith length, width and ellipticity, central area length, width and ellipticity and central area proportion with respect to the coccolith) were measured or calculated on digitally captured images of the first 100 W. britannica coccoliths observed in the light microscope. The relationships between the different biometric variables were described using bivariate and Principal Component Analyses. Biometric parameters and Principal Component factors extracted from nannofossil assemblages as well as other paleoenvironmental proxies, were investigated using regression, and their stratigraphic trends were compared. Principal component analysis of the six biometric variables (3938 measurements) on W. britannica coccoliths shows a reduced morphological variability compared to a significant size gradient. An allometric trend recognized on the total placolith and on the central area within theW. britannica assemblages suggests that the different morphotypesmay represent intra-specific variability rather than different species.The general trend through Late Oxfordian shows an increase in size ofW. britannica coccoliths,mainly driven by an increase in the contribution of the largemorphotypes. Increasing placolith size is associated with drier and warmer climatic conditions during the latest Oxfordian.

International audience; Repetitive changes in Early Pliocene marine and continental sediments were forced by astronomical cycles (eccentricity, precession) and related to low amplitude climatic fluctuations as demonstrated at Capo Rossello and Monte San Nicola (Sicily). This work aims to establish if such climatic fluctuations have also controlled changes in the vegetation during the warm Early Pliocene. High-resolution pollen analysis of the Lupoaia section (SW Romania) provides evidence of a clear response owing to its location within a delta system which constitutes a reliable area for pollen deposition near the Carpathians (i.e. capable of registering all the vegetation ecosystems from edaphic coastal associations up to the highest altitudinal belts), and owing to its Southeastern European longitude probably where warm–humid air masses arrived regularly, making the region a highly favourable refuge for thermophilous plants. Eccentricity appears to have controlled fluctuations in temperature (development of thermophilous elements during eccentricity minima, and descent of altitudinal trees during eccentricity maxima) while precession appears to have forced changes in humidity (expansion of cypress swamps related to precession maxima, and spread of herbaceous marshes requiring more humidity related to precession minima) with respect to increased precipitation and run-off.