Le « Mégalosaure » (Dinosauria,Sauropoda) de Saint-Agnant (Charente-Maritime,France) : description et origine stratigraphique

The “Megalosaur” remains from Saint-Agnant (Charente-Maritime, France), reported as early as 1881 by Boissellier, are here described and figured for the first time. These bones, as well as a few additional specimens from the nearby locality of Soubise, belong in fact to an indeterminate sauropod. The stratigraphical position of these remains unambiguously indicates an infra-Cenomanian age. However, the presence in this area of continental deposits with Purbeckian and Wealden facies does not allow to decide between an earliest or late Early Cretaceous age.     

Correlation between spatial distributions of pollen data, archaeological records and physical parameters from north-western France: a GIS and numerical analysis approach

New methodologies using Geographical Information Systems (GIS) and statistical tools were developed to provide new elements to the interpretation of fossil pollen records on the large spatial scale of north-western France. The originality of these methods lies in the analysis of the spatial distribution of the archaeobotanical data in order to identify correlations with other spatial parameters such as geological, climatic, pedological, topographical and archaeological characteristics. 218 pollen analyses from north-western France and a series of thematic maps (geological, archaeological, climatic, etc.) were used. The application of numerical analyses makes it possible to describe the spatial distribution of pollen data at a regional scale, and to identify spatial correlations between pollen data and other environmental parameters, and between archaeobotanical groups, archaeological and abiotic parameters simultaneously. Two examples are presented and discussed: (A) The spatial distributions of the predominance of hazel over oak between 6700 and 5700 cal b.p. and of modern precipitation are shown to be positively correlated, i.e. hazel is dominant in the most humid areas of the region. (B) The pollen data from the Bronze Age show associations of (1) pollen groups ascribed to meadows, shrubland, and forests with cooler temperatures, higher altitudes and northern latitudes, and (2) pollen groups ascribed to moor environments and anthropogenic vegetation with warmer temperatures, southern latitudes and lower altitudes. The latter implies that the agricultural landscapes of the Bronze Age were mainly confined to southern latitudes and low altitudes of the region, while the areas characterised by high altitudes and low temperatures were characterised by extensive activities such as grazing by cattle. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Les industries acheuléennes de la France septentrionale

The excavations of several open air sites in Northern France and, especially in the Somme basin, have given numerous data concerning the age and the environment of the human occupations for the period from MIS 12 to MIS 8. The quality of the raw material and the function of the different sites have a great effect on the composition of the lithic assemblages as it has been seen for the different sites located near the confluence of the Somme and Avre (Cagny-la Garenne, Cagny-l’Épinette, Ferme de l’Épinette, Gentelles). The characteristics of the lithic industries of Gouzeaucourt show the complexity of the transition from Lower to Middle Palaeolithic.     

Comparative ecological analysis of Toarcian (Lower Jurassic) benthic faunas from southern France and east-central Spain

Toarcian (Lower Jurassic) argillaceous-marly sediments of southern France (Causses) and east-central Spain (Barranco de la Puta section) were deposited in mid to lower shelf settings. They contain a low to moderately diverse, autochthonous fauna of benthic macroinvertebrates dominated by bivalves and gastropods, in the case of the Causses, and by bivalves and brachiopods in the Barranco de la Puta section. Five benthic associations are recognized at the latter locality and four at the former. In the Causses, low species diversity, evidence of seasonal mass mortality, presence of the opportunistic bivalve Parvamussium pumilum, local dominance of the soft bottom coral Thecocyathus mactrus and the dark-grey, fine-grained sediment point to high rates of sedimentation, high turbidity, intermittently lowered oxygen values and soft to soupy substrate conditions. These factors, together with eutrophic water masses, were the main environmental parameters governing faunal distribution. Soupy substrate conditions are thought to be largely biologically produced by the activity of infaunal depositfeeders, chiefly nuculoid bivalves. In the Barranco de la Puta section, abundant brachiopods, higher carbonate content of the sediment, and evidence of intermittent in-situ reworking and winnowing point to an influence of storm-induced currents, a shallower depositional depth, lower turbidity, a lower rate of sedimentation, and a somewhat firmer substrate. As a consequence, the fauna is largely dominated by epifaunal suspension-feeders. Compared with maximum and average sizes from elsewhere in the Jurassic, most bivalve species are distinctly smaller, a feature interpreted as stunting. Brachiopods, in contrast, reach normal size. The lack of nuculids, scarcity of deposit-feeders in general, and stunting are interpreted as evidence of an oligotrophic environment. Lowered oxygen conditions appear to have played only a very limited role in shaping the distribution pattern. Many of the differences between both areas can be explained by the different trophic regimes that reflect considerably higher run-off and consequently higher input of terrigenous sediment and dissolved nutrients to the basin in the case of the Causses. This in turn is thought to possibly reflect differences in regional climate; humid in southern France and more arid in eastcentral Spain.     

La limite Oligocène-Miocène en Limagne : changements fauniques chez les mammifères, oiseaux et ostracodes des différents niveaux de Billy-Créchy (Allier, France)

The lacustrine sequence of Billy-Créchy (Allier) yielded four superposed fossiliferous levels that can be precisely dated for the first time and represent the upper part of the Oligocene and the basis of the Miocene. The age of the localities is given by mammals and particularly by the Rodent and Lagomorph faunas: three are ascribed to the Paleogene mammalian levels MP 29-MP30 and the upper one to the Neogene MN 1. The Paleogene faunas evidence a high degree of similarity with those of the Oligo-Miocene Lower Freshwater Molasse of Switzerland and the localities Créchy 1 and 2 correspond particularly well to the Swiss locality Brochene-Fluh 53, to which a magnetostratigraphic calibration ascribed an age between 24.1 and 23.6 Ma, the date of the Oligo-Miocene boundary being fixed at 23.8 Ma. Changes in the Rodent composition and abundance in these faunas document the impact of the Oligo-Miocene crisis, the uppermost fauna being very impoverished. The avifaunas differ from those of the Aquitanian localities of the Saint-Gérand-le-Puy area by the presence of two forms which are no longer found in the more recent deposits. These birds are mainly aquatic and indicate the proximity of shallow to moderately deep lakes, along the edge of which the Flamingo-related Palaelodidae were nesting. In Ostracod assemblages - numerous along the sequence but in most cases crushed or completely encrusted -, small-sized specimens are abundant, well-preserved, and among them Cypridopsis sp. is dominant; they are represented by adults and juveniles: they indicate shallow-water environmental conditions and unstable environment. Among large specimens, freshwater and brackish species occur; all of them are broken, coated by CaCO3: they belong to different biocenoses and attest some transport.     

Invertébrés remarquables du Callovien inférieur de la Voulte-sur-Rhône (Ardèche, France)Remarkable Invertebrates from the Lower Callovian of la Voulte-sur-Rhône (Ardèche, France)

Remarkable Invertebrates from the Lower Callovian of la Voulte-sur-Rhône (Ardèche, France). The four-excavating field expeditions from 1983 to 1986 led to collect a considerable amount of new data from this exceptional paleontological site, which was neglected, and unexplored for the essential, until now. This paper presents a synthesis of the main available results. For the first time, the succession of the lithofacies is precised from all preserved deposits thick about 12 m. These observations reveal, on the whole, a great homogeneity of lithologic, paleobiologic or taphonomic characteristics, which denote a rather great constancy of the global environmental conditions. The lithofacies are schistous marls revealing former uncemented paleosubstrates, with clay very dominating (montmorillonite for 60–70%, calcium carbonate, siderite and limonite for less than 30% or 40%). The faunas are nearly exclusively composed of pelagic, nectopelagic or mesopelagic organisms (swimming in full water or dependent on free algal environments); they include very few benthic organisms. The marine water depth in this area would be estimated to have reached roughly 200 m. The surface and middle water strata, where lived the major part of organisms, must have been usually agitated, well oxygenated and illuminated. At the opposite side, the bottom water must have been very quiet and anoxic, in aphotic zona, which is responsible for the soft tissue mineralisation.     

Home range area in the tortoise Testudo hermanni in relation to habitat complexity: implications for conservation of biodiversity

The tortoise Testudo hermanni is endangered by habitat fragmentation and loss in western Europe, where its high public profile and specific conservation projects make this a flagship species. Studies of movement in the peak reproductive season (June) showed that home ranges were substantially larger in France than in Greece. This difference was due to the intensity of use of the home range, not to the distance moved which was remarkably similar in the two areas. There was no sexual difference in home range area. The home range was therefore not large in France because of movement to nesting sites, but rather for utilization of the greater habitat complexity there. The need for reserves to include different vegetation types makes conservation of T. hermanni in France more difficult. Conversely, the need for large reserves increases its value as an umbrella species for conservation of biodiversity.     

Genetic variation of Sherardia arvensis L. – How land use and fragmentation affect an arable weed

The distribution of arable weeds extends over regions, where the species occur naturally in different kinds of habitats and regions, where they are mainly limited to arable fields.Here, we present a comparative study on the genetic structure of the arable weed Sherardia arvensis L. comprising populations from Mediterranean grasslands in Southern France and populations from arable fields in Germany. Enhanced by intensified land use since the 1960th, overall population density in Germany is very low compared to the density of populations in Southern France. We tested whether genetic variation within and among populations differ between France and Germany due to different patterns of distribution and land use. Therefore, we analysed 231 individuals of S. arvensis from 24 populations using AFLPs. Based on fragment analysis data we compared spatial genetic structure and genetic variation of populations from the two regions.Genetic variation within populations from the two regions (Shannon Index = 0.13 for both) and genetic variation among populations (26.8% and 30.0% in an analysis of molecular variance) were comparable. In both regions a drift-migration model supported the assumption of gene flow between populations. However, a clear correlation of geographical and genetic distances could only be reported for the indigenous populations from France (r = 0.46; P = 0.02), whereas in Germany a spatial genetic relationship between populations was missing (r = 0.16; P = 0.21).Our study revealed that neither French nor German populations are genetically impoverished. For French populations further the spatial genetic structure suggests that there is current gene flow between populations through pollinators and seed dispersal by cattle. For German populations comparable levels of genetic diversity and gene flow were detected, but gene flow was random. This can be traced back in all likelihood to diffuse dispersal by agriculture and the mechanical reshuffling of the individuals from the soil seed bank.     

New and poorly known Cenozoic clown beetle compressions from France (Insecta: Coleoptera: Histeridae)

Summary

Two French fossil Histeridae are described or revised, viz. Hister cerestensis n. sp. from the Oligocene of Céreste (Lubéron) and Plegaderus pitoni (Theobald, 1935), n. comb. from the Pliocene of Chambon Lake (Puy-de-Dôme). Morphometric data are used to compare fossil and extant taxa, with multivariate statistics. A list of the fossil Histeridae is given.