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New palaeontological collections made from Upper Cretaceous strata exposed within the James RossBasin, Antarctica, include ten echinoid species. Five species are described for the first time from Antarctica, while four others, previously published by Lambert in 1910, are revised according to the new data. The described echinoids comprise two new species, Huttonechinus antarctica nov. sp. and Nordenskjoeldaster? australis nov. sp., specimens closely related to an European spatangoid, Micraster aff. regularis, and three taxa that cannot be named at the specific level owing to poor preservation. In total, the fauna comprises three species of regular echinoids, five holasteroids, and two spatangoids. The ten taxa range in age from Santonian to Early Maastrichtian. The richest faunas are those associated with the prolific Gunnarites antarcticus ammonite assemblage. Several forms show affinities with Australia, New Zealand, south-east Africa and South America. There are indications that this is an essentially deep shelf echinoid fauna.

Introduction and reworking of thanatofaunas in deep shelf sediments of the Western Channel Approaches. Macro- and micro-faunas are reported from six gravity cores collected at a mean depth of 150 m in the surfi- cial deposits of the Kaiser sand bank in the Southern Western Channel Approaches. These are bivalves (mainly), gas- tropods, echinids, crustaceans and foraminifers. These fauna present a very rich association of numerous, well preserved species from various ecological settings. Such an association is commonly reported from the continental shelf of the last transgressive cycle. In addition, the sediment comprises two imported fauna1 associations. The first one corresponds to thanatocaenoses of Pliocene/lowermost Pleistocene and Weichselian age, reworked respectively from the underlying Celtic incised valley fills and the Celtic Sand Banks. The absence of Quatemary fauna prior to the Weichselian suggests that the introduction of Pliocene sources occurred during the last climatic cycle. The second stage of importation took place after the last transgression in the Western Channel, and corresponds to the enrichment of the sediment in coastal fauna derived from western Brittany by the the predominant ebb tidal current. The variations of taxonomic diversity from core to core suggest a sediment transport around the bank that matches the one deduced from the study of tidal bedforms. At the present day, the wave action is highlighted by accumulation of species of the same shape, size and density inside storm beds. Wow- ever, the survival within these beds of very small, juvenile shells indicate that each storm reworking was short in duration. 0 Elsevier, Paris / Ifremer / CNRS / IRD continental shelf / thanatofauna / sea level / reworking / transport

La revision recente d’une riche faune d’ammonites du Cenomanien superieur-Turonien inferieur de la Hamada de Tinrhert (Sahara algerien) a permis d’etablir un cadre stratigraphique precis comprenant six intervalles. De plus, l’etude des echinides et des bivalves aide a caracteriser l’environnement de depot et a degager les grandes tendances de l’evolution de la faune benthique. Les calcaires correspondant au debut de la grande transgression du Cenomanien superieur (intervalles 1 et 2), dates de la Zone aC. naviculare, sont riches a la fois en ammonites et en benthos abondant et diversifie. Les intervalles 3 et 4, correspondant aux dernieres couches du Cenomanien, restent riches en cephalopodes, mais apparaissent pauvres ou meme tres pauvres en faune benthique, de meme que les intervalles 5 et 6 inferieur, dates du Turonien inferieur. Enfin, dans l’intervalle 6 superieur, l’ammonitofaune et le benthos redeviennent abondants seulement de facon tres locale. Ces caracteristiques environnementales suggerees par le contenu paleontologique peuvent alors etre comparees avec les conditions de depot des couches contemporaines du Maghreb oriental riches en matiere organique. En Tunisie centrale, les niveaux a matiere organique du Membre Bahloul sont les equivalents stratigraphiques des calcaires crayeux du Sahara central, encore riches en faune planctonique, mais partiellement amputes du benthos. Il y aurait donc eu, sur la plate-forme saharienne, un echo attenue des phenomenes responsables, dans les environnements de bassin, de la formation des couches a matiere organique de l’OAE 2. Mais la perturbation du milieu marin n’est pas allee jusqu’au developpement de facies anoxiques.

The existing definition of spatangoid fascioles as a narrow band of minute tubercles (miliaries) is inadequate. One reason is that many intermediates between the presence of indisputable fascioles and their total absence are known. Although fascioles are widely used in the classification of spatangoids, diversity of fasciole tuberculation has largely been ignored. We examine fascioles in about 100 spatangoid species, focusing on the earliest manifestations of fascioles (both developmentally and phylogenetically) and on their variable tuberculation. Qualitative observations are complemented by quantitative analyses (ANOVA and PCA) of 21 species. Three types of fascioles are defined according to tubercle pattern: protofascioles for localized concentrations of miliaries; parafascioles for bands of miliaries with a progressive transition to the surrounding tuberculation; orthofascioles for strongly differentiated, well-circumscribed bands of miliaries. Ontogenetic, architectural, ecological, and taxonomic variations of these three patterns are qualitatively and quantitatively investigated. We attempt to delineate plausible homologies, origins, and subsequent evolution of the different kinds of fascioles.

The study of well-preserved Pliocene and Pleistocene s from Emi from Emilia is used to analyze the morphological variations of Mediterranean populations, to depict the relationship between fasciole shape and other morphological characteristics and to describe previously unpublished pedicellar valves. These new data allow to be two species distinguished: s (Muller) a (Muller) and s Pomel; six s Pomel; six species closely related to s are synonymi are synonymized: s and it and s Pomel, i Pomel, i and itS. and s Checchia-R Checchia-Rispoli, x Simonelli a Simonelli and the recent species from Mediterranean, s Mortensen Mortensen. s can be disti can be distinguished from s by its hear by its heart-shaped subanal fasciole, when the s one is reni one is reniform. Moreover, the frontal groove of s is deeper, t is deeper, the primary tubercles of the interambulacra 1 and 4 are less numerous, the petals are shorter and narrower, the labrum is shorter. As far as pedicellariae are concerned, the jags of the large tridentate ones are stronger and the base of the globiferous ones is bigger. Palaeoecological observations on outcrops of the Stirone River, in Parme region, show similar environmental affinities between fossil populations and recent populations from Mediterranean. The s fossils fossils seem to be preserved within their life environment, that is to say in shore sandy substrates.

Cenomanian to Middle Turonian echinoid faunas from Nigeria are described for the first time on the basis of new collections sampled during recent geological investigations in the Benue Trough. Five Cenomanian species have been recognized: Tetragramma variolare, Heterodiadema libycum, Micropedina olisiponensis, Mecaster pseudofourneli, Mecaster sp. A. Two species, Mecaster cf. fourneli and Mecaster aff. scutiger, have been collected in the deposits of Middle Turonian age. Original palaeogeographical and stratigraphical data are provided with the taxonomic descriptions. Comparison with previous works in nearby regions is reviewed, and biogeographic outcomes are briefly discussed.

International audience; Amber fossils (microorganisms, arthropods, and plant remains) provide exceptionally well preserved data about past ecosystems, but amber itself was rarely used as a paleoenvironmental tool. Here we present geochemical analyses of mid-Cretaceous amber of southwestern France that demonstrate the preservation of a primary inorganic geochemical signal, especially the Cretaceous ocean strontium isotopic ratio. Our results indicate that inorganic chemical analyses present a potential to uniquely document the paleoenvironmental conditions such as processes of water extraction of amber-producing ecosystems.

International audience; Les mines de lignite du Cénomanien du Sarladais (Dordogne, France) étaient connues depuis longtemps sur le plan géologique. La présence d'ambre y avait été ponctuellement signalée, mais aucun échantillon n'était disponible. Les récentes investigations qui ont porté sur les anciennes exploitations ont permis de récolter des grains d'ambre de petite taille, surtout extraits des déblais de mines. Les grains présentent le plus souvent une forme de goutte plus ou moins allongée et apparaissent globalement translucides, les parties opaques des grains correspondant à des colonisations de micro-organismes filamenteux qui restent à étudier.

International audience; La commune d'Ecouflant (Maine-et-Loire, France) présente les seuls sites d'Anjou qui permettent d'étudier les lignites du Cénomanien inférieur et l'ambre qui y est associé. La carrière historique du Brouillard est celle qui a été la plus étudiée par le passé, mais est aujourd'hui en grande partie remblayée. Les échantillons d'ambre qui en proviennent ne contiennent pas d'arthropodes et sont très pauvres en microorganismes, à l'exception de filaments bactériens et de quelques microinclusions végétales. La carrière de Hucheloup présente encore de larges affleurements, pauvres en ambre, mais riches en plantes fossiles et en empreintes de mollusques bivalves. La série sédimentaire et le contenu fossile des argiles lignitifères témoignent de milieux de dépôt estuariens ou littoraux, à salinité variable.

International audience; The vertebrate remains from the early Cenomanian Lagerstätte of Puy-Puy (Tonnay-Charente, Charente- Maritime, France) are described. They consist of two hybodont shark egg capsules (Palaeoxyris sp.) and a single isolated body contour feather. The hybodont shark Tribodus is regarded as the most likely producer of the egg capsules, while the feather belonged to an indeterminate (avian or non-avian) theropod. These rare specimens are the first vertebrate fossils recovered from the plant-bearing clay of Puy-Puy and add to the short faunal list of the locality, thus providing important information for the palaeoecological reconstruction of this mid-Cretaceous paralic Lagerstätte. The fossils described here represent the first Cenomanian occurrence of Palaeoxyris and one of the very few records of Cenomanian feathers.

The Upper Cenomanian-Lower Turonian marine deposits of the Iullemmeden Basin and of the northern Chad Basin (Niger) consist of interbedded mudshales and fossil-rich limestones that formed on a ramp as a result of a Tethyan transgression. The faunal content of the limestone beds is characterized by (1) the absence of forms typically found on the Tethyan platforms: rudistids, corals and commonly associated forms (large benthic foraminifers, bryozoans, calcareous sponges, red and green algae); (2) the absence of pycnodonts and of brachiopods, and (3) the abundance of Gryphaeidae and Ostreidae, as well as the relative abundance of ammonites. This unusual faunal composition is ascribed to several factors. Rudistids, corals and associated forms may have failed to occur because of the general decrease in the diversity of these organisms in the Upper Cenomanian-Lower Turonian and because of the lack of suitable shoals on the Niger ramp for reefs to develop. Pycnodonts may have failed to gain a foothold in the face of severe competition from pioneer and opportunistic bivalves (Gryphaeidae, Ostreidae) that quickly colonized the ramp. The absence of brachiopods has not yet been explained satisfactorily; it could be due to several factors, including severe competition with pioneer bivalves and/or excessive turbidity of bottom waters.

Resume La forte dedendance des oursins envers leur milieu permet de les utiliser comme marqueurs ecologiques dans lecadre des reconstitutions paleoenvironnementales. Leur utilisation peut etre menee selon deux approches, l'une exploitant leur diversite morphologique intra- et interspecifique (analyse morpho-fonctionnelle), l'autre etant basee sur la diversite synecologique et biogeographique de leurs peuplements. D'une part, la taille, l'âge et la morphologie des individus varient en fonction de la profondeur du milieu et, plus localement, de la granulometrie du substrat. D'autre part, les modalites de dominance et d'association des differents groupes taxonomiques au sein d'un peuplement sont dependantes du contexte environnemental.

International audience; This paper documents for the first time microfossils in Upper Cretaceous (Santonian) amber from Martigues. Filamentous structures assigned to Prokaryotes and Eukaryotes are described. We show that the distribution of these filaments is closely related to the two types of amber encountered: red translucent, drop-shaped pieces and opaque to milky nuggets. The diversity and the constant occurrence of filaments in all studied pieces of amber reflect an exceptional filamentous resinicolous micro-world.

Hemiasterid echinoids form one of the oldest and most varied spatangoid groups. Current data on stratigraphical and geographical distribution pattern show that their biogeographical history is closely related to Mediterranean-Tethyan structural and climatic changes. The group first appeared in the Aptian in the central Tethys (southwestern Europe) and developed and diversified remarkably in the Late Cretaceous through the subgenera Hemiaster (Hemiaster), H. (Bolbaster) and H. (Leymeriaster). Marked morphological changes arose in the early Paleogene when new Tertiary forms H. (Trachyaster), Opissaster and Ditremaster, originating in the Caribbean and Madagascan regions, respectively, replaced H. (Bolbaster) which partly survived and H. (Hemiaster) and H. (Leymeriaster) which disappeared entirely. These new forms achieved their greatest diversity during the Eocenee and thrived in the Mediterranean basin until it was sealed off from the Indo-Pacific in the Middle Miocene. Then Late Neogene climatic and structural events reduced hemiasterids to only a few Mediterranean species. The survivors of modern groups persisted in refuge areas of the western Mediterranean until middle Messinian times before being reduced to only one species, the last fossil one, during the Pliocene. Then, the Cenozoic groups H. (Trachyaster) and Opissaster definitively disappeared. Outside the Mediterranean basin primitive H. (Bolbaster) and modern Ditremaster, which colonized deep-water Atlantic environments from the Late Cretaceous and Middle Miocene respectively, survived the Messinian and Plio-Pleistocene climatic crises. They flourished in the northern Atlantic where their present-day descendants Ditremaster (Sarsiaster) griegii and H. (Bolbaster) expergitus still survive. H. (Bolbaster) expergitus spread worldwide and colonized the western Mediterranean in the Plio-Pleistocene via the Straits of Gibraltar.

International audience; Over the past decade, the mid-Cretaceous amber deposits of Charentes (SW France) have been intensively studied. The fossils investigated were not only limited to arthropods preserved in amber, but also included microorganisms, plant debris and vertebrate remains. This plethora of analyses provided important data about the ecology of the overall system, including sources of litter input into the soil and of the above-ground ecology. More precisely, they showed that most of the microfossils were those of soil organisms or organisms that participated in the ecology of the forest soil. This new discovery provided the opportunity to study the ecology of the soil as preserved in the 100 million years old Charentes amber. Indeed, the trophic links of the fossil forest soil have been reconstructed on the basis of the fossil assemblage discovered in amber outcrops and overlayed on a model ecological forest soil food web. We relied on existing phylogenetic information to discuss the absence of certain taxonomic groups in the fossilized specimens. Our synthesis shows that although the organisms of this ancient forest of Charentes were different from those of modern soils, the soil food web was organized functionally the same as modern soils. It also demonstrated that trophic links of the soil community were already diverse, including various means of predation, parasitism and organic matter decomposition. The most obvious differences are the absence of evidence for symbiotic root nitrogen fixation and mycorrhizae.

International audience; New remains of an anuran and various squamate reptiles have been recovered from Cenomanian paralic deposits of Charentes (southwestern France). Remains are not abundant, yet they make up one of the most diverse Cenomanian assemblages and the most diverse one from Europe. Nine or 10 taxa are present. Precise taxonomic assignment of most of them is not always possible, even at family level; however, the mosasauroid Carentonosaurus mineaui, the snake Simoliophis rochebrunei, as well as a possible dolichosaurid lizard are identified. At least two taxa are new, but they cannot be named on the basis of the available material. Among the fossils are an anuran and terrestrial lizards that rank among the very scarce ones from the Cenomanian. In addition, three distinct snakes are among the oldest ones. The faunas from the Cenomanian of Charentes are mixtures of terrestrial and predominantly marine taxa.

International audience; This paper presents fossil faecal pellets - also named coprolites or frass - attributed to termites, which were found in amber and lignitic clay from the Wealden (Hauterivian-Barremian?), Late Albian and Early Cenomanian of south-western France. These coprolites have a characteristic subcylindrical shape and hexagonal transverse section and are assignable to Microcarpolithes hexagonalis Vangerow. The termite families that possibly produced these coprolites are discussed. The noticeable lack of termite attacks on the fossil wood associated with amber and lignitic clay is taphonomically analyzed in relation with the palaeoflora and palaeoclimate of these amber forests. The different medium where coprolites were found (amber, wood, sediments) suggests that primitive Cretaceous termites had already developed various biologies, such as wood or cryptic foraging, but probably not yet soil-feeding.

Resume Des restes d'Asterides (plaques infero- et superomarginales) ont ete trouves dans les sediments du Cenomanien deCharente-Maritime (Sud-Ouest de la France). Ils appartiennent a 17 taxons, dont la nouvelle espece Calliderma moreaui nov. sp., et correspondent a 5 familles differentes: Goniasteridae, Pycinasteridae, Stauranderasteridae, Sphaerasteridae et Astropectinidae. Leur description est suivie d'une breve analyse de leurs repartitions stratigraphique et paleobiogeographique.

International audience; Two mammalian hairs have been found in association with an empty puparium in a ¡"100-millionyear-old amber (Early Cretaceous) from France. Although hair is known to be an ancestral, ubiquitous feature in the crown Mammalia, the structure of Mesozoic hair has never been described. In contrast to fur and hair of some Jurassic and Cretaceous mammals preserved as carbonized filaments, the exceptional preservation of the fossils described here allows for the study of the cuticular structure. Results show the oldest direct evidence of hair with a modern scale pattern. This discovery implies that the morphology of hair cuticula may have remained unchanged throughout most of mammalian evolution. The association of these hairs with a possible fly puparium provides paleoecological information and indicates peculiar taphonomic conditions.

International audience; Some isolated teeth of theropod and sauropod dinosaurs from the Cenomanian (Late Cretaceous) of Charentes are described. Two new teeth of Troodontidae confirm the presence of this theropod family, previously based on a single specimen. New dental morphotypes are recognized within Dromaeosauridae and Brachiosauridae in comparison with those already known from Charentes. Lastly, a very small tooth is tentatively assigned to an embryonic or neonatal sauropod. The palaeobiogeographical history of European hadrosauroids is briefly discussed. This history was probably more complex than it appears, involving exchanges with both North America and Asia as early as the mid-Cretaceous (Albian­Cenomanian).

International audience; Over the past six years, organic inclusions preserved in amber samples from outcrops worldwide have been discovered and imaged in 3D using propagation phase contrast based X-ray synchrotron imaging techniques at the European Synchrotron Radiation Facility (ESRF). A brief description of the techniques and protocols used for detecting and 3D non-destructive imaging of amber inclusions is provided. The latest results from the major amber projects in the ESRF are given, illustrating the increasing utility of the imaging capabilities of X-ray synchrotron phase contrast microtomography.

Resume De nombreux fragments d’echinides spatangues ont ete decouverts dans le Pliocene de Challans, en Vendee (Ouest de la France). Malgre l’etat fragmentaire des echantillons, la cartographie d’un test complet a pu etre reconstituee a partir de differents elements et de leur symetrisation. La forme generale du test, ainsi que ses caracteres architecturaux et ornementaux permettent d’etablir la presence du genre Spatangus dans l’Ouest de la France a la fin du Neogene. Il s’agit la d’un jalon important pour comprendre l’histoire biogeographique du genre Spatangus et du groupe morphologique S. (S.) purpureus sur les cotes atlantiques apres la crise messinienne. Cette forme pliocene est comparee a l’espece miocene Spatangus (Phymapatagus) brittanus , abondante en Anjou, en Bretagne et en Touraine. Cette espece plus ancienne etait rattachee au sous-genre Phymapatagus sur la base d’une absence presumee de tubercules primaires sur l’interambulacre posterieur. La decouverte de specimens parfaitement preserves, munis de tubercules majeurs sur l’ensemble du test, dans le Miocene moyen d’Ille-et-Villaine permet d’invalider cette distinction subgenerique et de restituer l’espece brittanus dans le sous-genre Spatangus ( Spatangus ). La presence de ce sous-genre dans l’Ouest de la France est ainsi attestee tant pour le Miocene moyen que pour le Pliocene.

International audience; The investigation of microorganisms preserved in amber from Charente- Maritime (southwestern France) provides new insights into the mid-Cretaceous amber forest ecology. Amber from the localities of Archingeay-Les Nouillers and Cadeuil is unique due to the plethora of microinclusions and macroinclusions as well as the preservation of litter organisms. Soil microorganisms such as actinomycetes, sheathed prokaryotes, carnivorous fungi (Ascomycota), algae, testate amoebae and nematodes indicate that the resin solidifi ed in terrestrial or limnetic- terrestrial microhabitats on the forest fl oor. Furthermore, arboreal and even marine micro organisms are preserved in the amber. This micro-assemblage suggests that the amber forest was located close to the sea shore or was at least temporarily under marine infl uence.

International audience; Arcantipsocus courvillei n. gen., n. sp. is described from the Cretaceous amber of Archingeay (France). It is placed within the suborder Psocomorpha, and in the Mesozoic extinct family Arcantipsocidae n. fam. characterized by 14- segmented antenna; legs with tarsi 3-segmented; forewing setose with evanescent veins; pterostigma dark, thickened and setose; M 2-branched; areola postica free; nodulus present; hind wing with M bifurcated, without basi-radial cell; claws with a preapical tooth. A cladistic phylogeny for Psocomorpha is given including the new fossil taxon. Th e discovery of this new taxon demonstrates the necessity of a deep phylogenetic redefi nition of the currently admitted major subdivisions of this suborder.

International audience; Les échinides (oursins) sont apparus au Paléozoïque inférieur et, après une première phase de diversification au Paléozoïque, ont été les acteurs d'une radiation évolutive très intense au cours du Mésozoïque et du Cénozoïque. Sur la base d'une reconsidération des homologies de la paroi du corps des échinodermes, sont présentés quelques aspects majeurs de l'évolution des oursins : l'origine de l'irrégularité et de la symétrie bilatérale ; un modèle de radiation, celle des spatangues ; la diversification des modes de reproduction. Ces exemples permettent de prendre la mesure des capacités d'innovation dont ont fait preuve les oursins au cours de leur radiation postpaléozoïque.

International audience; One of the best ways to obtain data about the ecology of past forests is to study amber fossils. Meso- and macroinclusions in amber have been intensively studied for a long time, however microinclusions have been largely neglected despite their high potential of fossilization in amber. Because of their abundance in recent forest ecosystems, many microorganisms are prone to be trapped in tree resin and thus fossilized in amber. According to their tiny size, from a statistical point of view we should find more microfossils in amber than arthropods. From this observation, investigations of microorganisms in the mid-Cretaceous amber of SW France have been performed. Studies of this material since 1999 already allowed the discovery of a rich arthropod fauna. From first investigations rich microfauna and microflora were also found: they were mainly composed ofcyanobacteria and actinomycetes but also included green algae, protists, nematodes. The most spectacular was the discovery of a rich diatom flora composed of both freshwater and marine taxa. More detailed studies of these inclusions revealed that a non-quantifiable part of these microorganisms was only contaminants and biased our estimation of the microcoenosis of mid-Cretaceous amber forests of SW France. This paper details the different types of amber contamination by modern microorganisms (particularly modern diatoms) highlighted during the study. A simple and accessible decontamination protocol, inexpensive enough to be used routinely in the laboratory, has been developed accordingly. This protocol comprises three main steps: (1) ultrasonic cleaning, (2) oxidation byH2O2 to eliminate organic contaminants, and (3)HFacid attack to dissolve inorganic contaminants such as siliceous skeletons. SEM observations controlled for the efficiency of our protocol. The contamination of samples is one of the most important sources of error in science, particularly in microbiology and paleomicrobiology. Mid-Cretaceous ambers found in Charentes (SW France), due to their outcropping conditions, are excellent tools for the investigation of such phenomenon of sample contamination and showed how this problem could bias paleoecological interpretation from erroneous amber preserved microcoenosis. We suggest that this protocol should be applied as a preliminary step when studying microorganisms embedded in amber to avoid erroneous scientific results.

Combined sedimentological, palaeontological and palaeographical data from the north Castilian platform (Spain) during the Late Cretaceous show that the spatial distribution of echinoids reflects a palaeoecological zonation in which the morphological groups of hemiasterid spatangoids characterize different environments: (1) Mecaster with large and conspicuous petaloid ambulacra (like M. cenomanensis) inhabit shallow environments of the inner platform; (2) Mecaster with narrow and more or less open ambulacra (like M. verneuili) characterize deeper environments of the outer platform; (3) Hemiaster with a globular test and reduced posterior petals (like H. (Bolbaster) gauthieri) populate the deepest part of the outer platform. Palaeogeographical maps for Cenomanian, Early and Late Turonian, and Coniacian periods are used to illustrate the relationships between this zonal distributions of hemiasterids and the morphology of the north Castilian and Navarro-Cantabrian platforms. When only a single morphological group of hemiasterids (Hemiaster or Mecaster) is present at the northern (deep) and southern (shallow) areas of the platform during the entire Late Cretaceous, the central part of the platform shows an alternation of Hemiaster and Mecaster through a vertical section. This alternation represents the geographical depth changes related to transgression-regressional events. Thus, the environmental variations lead to repetitive cycles of echinoid distribution in which Hemiaster stratigraphically substitutes Mecaster, the two groups living within the same region at the same time, but in different environments. Globular Hemiaster, considered typical for the cold water faunas of Northern Europe, and Mecaster, which characterize the warmer conditions of Northern Africa, coexist in intermediate areas such as Northern Spain where their geographical provincialism gives way to a bathymetric one. A regional ecological zonation overlaps the larger scale climatic and geographical provincialism.

The analysis of size-frequency spatial distribution of three species of Cenomanian echinoids in a single fossil assemblage shows both intraspecific and interspecific horizontal segregation of the individuals parallel to the variations in silt and organic matter levels of the substrate. The exceptional preservation of echinoids. fossilized in the living position with part of their spines. and their multimodal size-frequency distribution, with no evidence of physical transportation. suggest that a catastrophic event resulted in the fossilization of the demographic structure of the populations. The assemblage. being the result of mass mortality of a community, corresponds to a census assemblage. Thus the patchy segregation of echinoids could not primarily be influenced by size-selective taphonomy (current winnowing, biological or mechanical destruction) but more likely determined by biological phcnomena like mortality and recruitment patterns, high juvenile growth, substrate selection and herd mode of life. Recent examples of spatial separation of adults and juveniles. given for different species of echinoids. show that these patchy distributions are widespread, and therefore may be a privileged source of fossil preservation of cohort's size-frequency distribution in catastrophic mortality. □Palaeoecology, size-frequency distribution, demography, echinoids. spatangoids, cassiduloids, Mecaster, Catopygus, Nucleopygus.

A significant portion of Mesozoic amber is fully opaque. Biological inclusions in such amber are invisible even after polishing, leading to potential bias in paleoecological and phylogenetic studies. Until now, studies using conventional X-ray microtomography focused on translucent or semi-opaque amber. In these cases, organisms of interest were visualized prior to X-ray analyses. It was recently demonstrated that propagation phase contrast X-ray synchrotron imaging techniques are powerful tools to access invisible inclusions in fully opaque amber. Here we describe an optimized synchrotron microradiographic protocol that allowed us to investigate efficiently and rapidly large amounts of opaque amber pieces from Charentes (southwestern France). Amber pieces were imaged with microradiography after immersion in water, which optimizes the visibility of inclusions. Determination is not accurate enough to allow precise phylogenetic studies, but provides preliminary data on biodiversity and ecotypes distribution; phase contrast microtomography remains necessary for precise determination. Because the organisms are generally much smaller than the amber pieces, we optimized local microtomography by using a continuous acquisition mode (sample moving during projection integration). As tomographic investigation of all inclusions is not practical, we suggest the use of a synchrotron for a microradiographic survey of opaque amber, coupled with microtomographic investigations of the most valuable organisms.

A significant portion of Mesozoic amber is fully opaque. Biological inclusions in such amber are invisible even after polishing, leading to potential bias in paleoecological and phylogenetic studies. Until now, studies using conventional X-ray microtomography focused on translucent or semi-opaque amber. In these cases, organisms of interest were visualized prior to X-ray analyses. It was recently demonstrated that propagation phase contrast X-ray synchrotron imaging techniques are powerful tools to access invisible inclusions in fully opaque amber. Here we describe an optimized synchrotron microradiographic protocol that allowed us to investigate efficiently and rapidly large amounts of opaque amber pieces from Charentes (southwestern France). Amber pieces were imaged with microradiography after immersion in water, which optimizes the visibility of inclusions. Determination is not accurate enough to allow precise phylogenetic studies, but provides preliminary data on biodiversity and ecotypes distribution; phase contrast microtomography remains necessary for precise determination. Because the organisms are generally much smaller than the amber pieces, we optimized local microtomography by using a continuous acquisition mode (sample moving during projection integration). As tomographic investigation of all inclusions is not practical, we suggest the use of a synchrotron for a microradiographic survey of opaque amber, coupled with microtomographic investigations of the most valuable organisms.

International audience; The exploitation of a third part of the sand quarry of Font-Benon (Archingeay­Les Nouillers, southwestern France) has exposed a clay lens bearing a massive accumulation of plant macro- and mesoremains. From the stratigraphic point of view, this lens corresponds to sub-unit A2sm1­2 dated as Lowermost Cenomanian in age. The plant assemblage is remarkable by lowfragmentation, association of vegetative and reproductive organs of the same taxa, and by the quality of histological cuticle preservations. The plant remains were accumulated close to the producing plants and deposited in paralic, calm and brackish environment, probably of conifer-dominated type mangrove.

International audience; Wagner's Parsimony Method, a grouping method used in phylogeny and synecology, is applied for the first time to taxon lists of fossil plant assemblages from the Albian­Cenomanian of Europe. When compared to a "classical" Correspondence Analysis, WPM allows for a higher resolution, using taxa named in "cf." or "aff." and points out both clusters and gradients. WPM results in a tree in which localities order according to their species content and minimizes the number of changes of character states (presence/absence), whereas Correspondence Analysis plots the localities along axes and maximizes the inertia ("variance" explaining most differences between localities). Close relationships exist between the plant palaeobiocenoses and palaeobiotopes, the latter being inferred from taphonomical data (especially the salinity and the clastic size). The space/time working scale can be very fine, up to the landscape ecology level.

International audience; Recent studies on the ant phylogeny are mainly based on the molecular analyses of extant subfamilies and do not include the extinct, only Cretaceous subfamily Sphecomyrminae. However, the latter is of major importance for ant relationships, as it is considered the most basal subfamily. Therefore, each new discovery of a Mesozoic ant is of high interest for improving our understanding of their early history and basal relationships. In this paper, a new sphecomyrmine ant, allied to the Burmese amber genus Haidomyrmex, is described from mid-Cretaceous amber of France as Haidomyrmodes mammuthus gen. and sp. n. The diagnosis of the tribe Haidomyrmecini is emended based on the new type material, which includes a gyne (alate female) and two incomplete workers. The genus Sphecomyrmodes, hitherto known by a single species from Burmese amber, is also reported and a new species described as S. occidentalis sp. n. after two workers remarkably preserved in a single piece of Early Cenomanian French amber. The new fossils provide additional information on early ant diversity and relationships and demonstrate that the monophyly of the Sphecomyrminae, as currently defined, is still weakly supported.

Ants are one of the most studied insects in the world; and the literature devoted to their origin and evolution, systematics, ecology, or interactions with plants, fungi and other organisms is prolific. However, no consensus yet exists on the age estimate of the first Formicidae or on the origin of their eusociality. We review the fossil and biogeographical record of all known Cretaceous ants. We discuss the possible origin of the Formicidae with emphasis on the most primitive subfamily Sphecomyrminae according to its distribution and the Early Cretaceous palaeogeography. And we review the evidence of true castes and eusociality of the early ants regarding their morphological features and their manner of preservation in amber. The mid-Cretaceous amber forest from south-western France where some of the oldest known ants lived, corresponded to a moist tropical forest close to the shore with a dominance of gymnosperm trees but where angiosperms (flowering plants) were already diversified. This palaeoenvironmental reconstruction supports an initial radiation of ants in forest ground litter coincident with the rise of angiosperms, as recently proposed as an ecological explanation for their origin and successful evolution.

International audience; Trichomyia lengleti, sp. nov., is described from the Lower Cenomanian amber of La Buzinie, Charente (southwest France) from a piece of fully opaque amber. The Upper Albian Trichomyia swinhoei Cockerell, 1917 is transferred from the Trichomyiinae to the Sycoracinae incertae sedis, stat. nov. Trichomyia lengleti, sp. nov. is the oldest representative of the subfamily Trichomyiinae, supporting at least a Cretaceous diversification for the Psychodidae. The discovery of this fossil fly and its study (thanks to propagation-phase-contrast synchrotron X-ray imaging) improves our knowledge of the biodiversity and the historical evolution of psychodoid flies. A checklist of fossil trichomyiine species is given.

International audience; The new aeshnopteran family Enigmaeshnidae is proposed for Enigmaeshna deprei gen. et sp. nov., the first fossil insect collected as imprint in the Earliest Cenomanian clay of the Puy-Puy quarry at Tormay-Charente (Charente-Maritime, SW France). The bed bearing E. deprei was previously known for its highly diversified fossil plant assemblage. Although this taxon belongs to the much derived clade Aeshnodea, it is characterized by several unique hind wing venation characters, never found in other Aeshnoptera, viz. part of MAb distal of the trigonal planate very long, and presence of five posterior branches of AA directed towards posterior wing margin.

International audience; Amber usually contains inclusions of terrestrial and rarely limnetic organisms that were embedded in the places were they lived in the amber forests. Therefore, it has been supposed that amber could not have preserved marine organisms. Here we report the first known amber-preserved marine microfossils. Diverse marine diatoms as well as radiolarians, sponge spicules, a foraminifer, and a larval spine of a sea urchin were found in Late Albian and Early Cenomanian amber samples of southwestern France. The highly fossiliferous resin samples solidified ca. 100 million years ago on the floor of coastal mixed forests dominated by conifers. The amber forests of southwestern France grew directly along the coast of the Atlantic Ocean and were influenced by the nearby sea: shells and remnants of marine organisms were probably introduced by wind, spray or high tide from the beach or the sea onto the resin flows.

International audience; Bugs of two new genera and species are described as Buzinia couillardi and Tanaia burmitica. They are preserved in mid-Cretaceous amber from south-west France and northern Myanmar (Burma), respectively (c. 100 Ma). These are the first formally described fossils of the heteropteran family Schizopteridae. Both belong to the subfamily Hypselosomatinae and are very similar to the extant genus Hypselosoma Reuter, providing evidence for the antiquity and morphological stability of this small bug family and the infraorder Dipsocoromorpha. Given the putative ecology of the fossils, a discussion is provided on the French and Burmese amber forest ecosystems. The geological setting of La Buzinie, a new amber deposit in south-west France that yielded the two specimens of Buzinia couillardi, is outlined.

International audience; Newly collected specimens of an uncommon and poorly known irregular echinoid, Nucleopygus (Jolyclypus) jolyi, are recorded from Cenomanian strata in Charentes (western France). The first examples of this echinoid to have been described date back to the late nineteenth century; those specimens (i.e., the types) appear to have been lost. What particularly distinguishes this taxon from other Cenomanian echinoids is the singular combination of derived and plesiomorphic morphological characters, the latter being reminiscent of Jurassic irregular echinoids. Derived features concern the appendages, employed in locomotion and feeding, whereas ancestral characters involve the apical system and periproct. This peculiarity has led previous workers to include this echinoid in the stem-group Galeropygidae, which would imply a >40-myr gap in the stratigraphic range of this group or, alternatively, challenge the stratigraphic provenance of the taxon. A detailed examination of newly collected material has now allowed us to resolve the apparent discrepancies, describe a reversal and document sexual dimorphism as well. A phylogenetic analysis was carried out in order to revise the systematic position of the taxon, now transferred to the Cretaceous genus Nucleopygus. A neotype is designated.

Resume Le Cretace represente une periode cruciale dans l’evolution des vertebres, avec notamment l’emergence des groupes modernes de mammiferes (Metatheriens et Eutheriens). En Europe, les formations continentales se limitent au Cretace basal (facies wealdien) et terminal (Campano-Maastrichtien). Pour ce qui est de la partie moyenne du Cretace, les faunes de vertebres continentaux ne sont connues que tres incompletement, a travers certains assemblages formes dans des environnements paraliques et souvent composes de microrestes. Un gisement de ce type, recemment decouvert dans le Cenomanien inferieur de Fouras (site de Fouras-Vauban, Charente-Maritime, Sud-Ouest de la France), a livre une riche association et offre ainsi l’opportunite de completer nos connaissances. Aux cotes des nombreux restes de poissons littoraux, les tetrapodes sont representes par des cheloniens, crocodiliens, ophidiens, plesiosaures, pterosaures et dinosaures. La presence a Fouras-Vauban de formes particulieres typiquement gondwaniennes (le requin dulcaquicole Tribodus et un crocodile zyphodonte proche de Hamadasuchus ) permet de discuter les affinites paleobiogeographiques des faunes peuplant l’archipel europeen durant la partie moyenne du Cretace et les voies de communication trans-tethysiennes entre l’Europe occidentale et l’Afrique du Nord. Pour citer cet article : R. Vullo et al., C.R.Palevol 4 (2005) .

Three specimens of gerromorphan bugs in Late Albian amber from south-west France are described. One is regarded as an incertae sedis within the Gerromorpha, the other two are assigned to Cretogerris albianus gen. et sp. nov., the oldest representative of the aquatic bug family Gerridae. The discovery confirms the great antiquity of the Gerridae, until now only inferred from an Early Cretaceous representative of the sister family Veliidae. The phylogenetic affinities of Cretogerris within the Gerridae are still rather uncertain, but this fossil taxon shows highly specialized body and leg structures that are very similar to those of the marine Halobatinae, suggesting that it was possibly a marine surface skater. The Gerridae and the Chresmodidae, another extinct group of Mesozoic surface skaters, were contemporaneous during at least the early Cenomanian. The discovery of these gerromorphan bugs in the Albian amber supports the hypothesis of a selective trap of a litter fauna, originating from a beach environment, for this resin.

Synopsis Guyotemaimetsha enigmatica, a new genus and species of evaniomorphan wasp, is described from the French Albian amber. Its phylogenetic affinities are discussed. It has strong similarities with the genera Maimetsha and Cretogonalys, which are attributed to the Maimet‐shidae and Trigonalidae, respectively. The exact relationships of these Cretaceous taxa remain enigmatic.

Integrated studies and revisions of sedimentary basins and associated magmatism in Peru and Bolivia (8–22°S) show that this part of western Gondwana underwent rifting during the Late Permian–Middle Jurassic interval. Rifting started in central Peru in the Late Permian and propagated southwards into Bolivia until the Liassic/Dogger, along an axis that coincides with the present Eastern Cordillera. Southwest of this region, lithospheric thinning developed in the Early Jurassic and culminated in the Middle Jurassic, producing considerable subsidence in the Arequipa basin of southern Peru. This ∼110-Ma-long interval of lithospheric thinning ended ∼160 Ma with the onset of Malm–earliest Cretaceous partial rift inversion in the Eastern Cordillera area. The lithospheric heterogeneities inherited from these processes are likely to have largely influenced the distribution and features of younger compressional and/or transpressional deformations. In particular, the Altiplano plateau corresponds to a paleotectonic domain of “normal” lithospheric thickness that was bounded by two elongated areas underlain by thinned lithosphere. The high Eastern Cordillera of Peru and Bolivia results from Late Oligocene–Neogene intense inversion of the easternmost thinned area.

International audience; The Late Messinian of the Sorbas Basin (Betic Cordillera, SE Spain) has been sampled to estimate (1) the paleoenvironmental changes recorded by the benthic foraminifers in pre-evaporitic and evaporitic units, and (2) the impact of the`Messinian Salinity Crisis' on the foraminiferal biodiversity. In the pre-evaporitic unit, foraminifers indicate a circalittoral to bathyal environments and show significant changes in bottom-water oxygenation. Simultaneously, the occurrences of epiphytic damaged foraminifers and the blocks of Porites point out the presence of plant substrates and coral-reefs on the infralittoral zone. The overlying evaporitic unit is characterized by four subaqeous selenitic gypsum layers and three marine fossiliferous intercalations. Each episode of gypsum deposition ends with a desiccation event. Each fossiliferous intercalations traduce a rapid reflooding of the basin by marine waters corresponding to infralittoral to upper bathyal environments with normal marine conditions. During the evaporitic period, the ecological conditions in the water column were intermittently favorable to the development of marine organisms, and moreover, the marginal basins of the Betic Cordillera were not continuously desiccated during the Messinian. The low percentage of extinct species (5%) at the Messinian^Pliocene boundary and the occurrences of benthic foraminifers in the evaporitic unit indicate that the infralittoral to upper bathyal environments have not been completely modified and/or barren during the`Messinian Salinity Crisis', i.e. the`Messinian Salinity Crisis' is not associated with a biological crisis.

International audience; Morphological and palaeoecological changes in irregular echinoid diversity during the Late Miocene Messinian stage have been analysed at the scale of the Sorbas Basin of southeast Spain. Biometrical and statistical analyses established the validity of species differentiation. An example is given for Messinian, Pliocene and Recent Schizaster species: S. saheliensis and S. canaliferus. Palaeoecological analyses show that irregular echinoid faunas record environmental changes, especially sea-level variations, with contrasting ecomorphological gradients for deepening and shallowing trends. Deepening is indicated by the stratigraphic succession of Clypeaster altus, associated Clypeaster marginatus^Spatangus^Schizaster and then Brissopsis species whereas shallowing is indicated by the opposite succession. The survival of Brissopsis, typically a stenohaline and relatively deep marine organism, in the marls interbedded within the uppermost Messinian gypsum of the Sorbas Basin testifies to the existence of marine connexions between this basin and other Mediterranean marine areas during the end of the evaporitic episode. Tabulation of irregular echinoid species diversity at eight time intervals between the Tortonian/Messinian boundary and the present-day (inclusive) for the Mediterranean Basin as a whole indicates a progressive increase in diversity from the latest Tortonian to the upper part of the pre-evaporitic Messinian before a fall in diversity during the salinity crisis. However, survivals after the crisis are very numerous, representing 78% of the maximum pre-evaporitic value.

International audience; De récentes investigations menées sur les niveaux fossilifères interstratifiés dans les gypses messiniensde Los Yesos (bassin de Sorbas, Andalousie) ont permis la récolte d'une macrofaune et d'une microfaune marinesdiversifiées avec au total plus de 80 espèces identifiées représentant principalement des bivalves, des échinides, desforaminifères, des ostracodes, des crustacés décapodes et des bryozoaires... L'assemblage est caractéristique d'unmilieu de plate-forme de type infralittoral inférieur ~ circalittoral supérieur. Sur le plan stratigraphique, la fauneprésente un net cachet messinien, mais contient des espèces qui survivront du Pliocène ~ l'Actuel au sein du bassinméditerranéen. Ces résultats pèsent de nouveau le problème de l'influence réelle de la crise messinienne sur les peuplements littoraux méditerranéens.