A new baurusuchid crocodyliform (Archosauria) from the Late Cretaceous of Patagonia (Argentina)

A new baurusuchid, Wargosuchus australis gen. et sp. nov., coming from the Bajo de La Carpa Formation, Neuquén Province (Argentina), is described. This new taxon is based on a fragment of snout and a portion of the cranial roof. Wargosuchus differs from other crocodyliforms by possessing a deep median groove on the frontals, a contact between nasals and frontals extremely reduced, a large depression for the olfactory bulbs, three large foramina surrounding the large, smooth perinarial depression, and a hypertrophied, conical last premaxillary tooth followed by a large paracanine fossa. The finding of Wargosuchus in Patagonia (Argentina), a taxon with a strong resemblance to Brazilian baurusuchids, reinforces the hypothesis of a similar biota between both regions by the Late Cretaceous. Wargosuchus and Cynodontosuchus represent the only Argentinian mesoeucrocodylians to be included within Baurusuchidae. This finding extends the number of crocodyliforms from the Bajo de la Carpa Formation, which, in turn, corresponds to the most taxonomically diverse one in Argentina.     

A new primitive hadrosauroid dinosaur from the Early Cretaceous of Inner Mongolia (P.R. China)

The right dentary of a new hadrosauroid dinosaur, Penelopognathus weishampeli, has been discovered in the Bayan Gobi Formation (Albian, Lower Cretaceous) of Inner Mongolia (P.R. China). This new taxon is characterised by its elongated, straight dental ramus, whose lateral side is pierced by about 20 irregularly distributed foramina. Its dentary teeth appear more primitive than those of Probactrosaurus, but more advanced than those of Altirhinus, both also from the Lower Cretaceous of the Gobi area. Non-hadrosaurid Hadrosauroidea were already well diversified in eastern Asia by Early Cretaceous time, suggesting an Asian origin for the hadrosauroid clade. To cite this article: P. Godefroit et al., C. R. Palevol 4 (2005).     

Impact of the Gabcíkovo hydropower plant operation on planktonic copepods assemblages in the River Danube and its floodplain downstream of Bratislava

The structure of planktonic copepod assemblages in a by-passedDanube section, and in the adjacent floodplain water bodies,haschanged since the Gabcíkovo hydropower plant was putintooperation. The greatest change occurred in a former side arm(upstream of the village of Dobrohosí), which driedout.Changes were observed in the parapotamon-type side armssituatedbetween river km 1840 and 1820, fed artificially with waterfromthe head-race canal. The abundance of euplanktonic copepodspeciesdecreased, while that of tychoplanktonic species increased.Summerzooplankton biomass decreased. Definitive, but less extreme,changes occurred in the copepod assemblage in the open-waterareasof the former main channel of the Danube, and in theplesiopotamon-type side arms in the affected river section.These results suggest that the water supply provided to theby-passed floodplain is unable to maintain the previoushabitatdiversity, nor its planktonic assemblages speciesdiversity.     

Low community photosynthetic quotient in coral reef sediments

Fluxes of dissolved inorganic carbon and oxygen at the water-sediment interface were measured at eight coral reef stations (Indian Ocean) in summer and winter. The dark fluxes provided the community respiratory quotient (CRQ = dissolved inorganic carbon release / oxygen uptake) and the diurnal fluxes corrected from the dark fluxes gave the community photosynthetic quotient (CPQ = oxygen gross release / dissolved inorganic carbon gross uptake). The CRQ and the winter CPQ were not significantly different from 1. Summer CPQ (0.79; SD 0.02) was significantly lower than 1 due to the combined effect of the daily evolution of the community respiration and the discrepancy between the daily evolution in community oxygen respiration and community carbon respiration. These results highlight the importance of measuring simultaneously the benthic community production and respiration for long term integrated data sets, instead of the traditional daily or seasonal budget calculations from limited measures of community respiration. To cite this article: D. Taddei et al., C. R. Biologies 331 (2008).     

A Late Campanian sphenodontid (Reptilia, Diapsida) from northern Patagonia

The fossil record of sphenodontids in the Southern Hemisphere is much longer than in Laurasia, where they became extinct after Early Cretaceous times. Recent works demonstrated the persistence of at least eilenodontine sphenodontids until the ‘mid’-Cretaceous of Patagonia. Focused examination of the Los Alamitos Formation collections provided remains of Late Campanian sphenodontids. Although the phylogenetic position of these remains is still uncertain, they belong to a new, unrecorded species of sphenodontid perhaps related to opisthodontians or primitive, toothed sapheosaurs. To cite this article: S. Apesteguía, C. R. Palevol 4 (2005).     

Genetic determinism of parasitic circadian periodicity and subperiodicity in human lymphatic filariasis

The larval parasites of the pantropical lymphatic filariasis exhibit two types of circadian behaviour. Typically, they only appear in the human bloodstream at nighttime, synchronised with their mosquito vectors. In Polynesia and parts of Southeast Asia, free of nocturnal vectors, they are found at all hours, and each population biorhythm differs. Through a geometrical approach, we explain this circadian diversity by a single, dominant mutation: the clocks of individual parasites are set at midnight (ubiquitous) or at 2 p.m. Compared to other circadian genes, this mutation must be very old, as it is shared by four biologically remote genera of parasites. This seniority sheds new light on several theoretical and practical aspects of vector-parasite temporal relations.     

Model of interactions in biology and application to heterogeneous network in yeast

A major challenge for bioinformatics and theoretical biology is to build and analyse a unified model of biological knowledge resulting from high-throughput experiment data. Former work analyzed heterogeneous data (protein-protein interactions, genetic regulation, metabolism, synexpression) by modelling them by graphs. These models are unable to represent the qualitative dynamics of the reactions or to model the n-ary interactions. Here, MIB, the Model of Interactions in Biology, a bipartite model of biological networks, is introduced, and its use for topological analysis of the heterogeneous network is presented. Heterogeneous loops and links between synexpression pattern and underlying molecular mechanisms are proposed.     

Ant species diversity in the 'Grands Causses' (Aveyron, France): In search of sampling methods adapted to temperate climates

This study aimed at showing the applicability of using a combination of four sampling methods (i.e., Winkler extractors, pitfall traps, baiting and manual collection), something most often conducted in the tropics, to create an inventory of ant species diversity in temperate environments. We recorded a total of 33 ant species in the Grands Causses by comparing three vegetal formations: a steppic lawn ('causse' sensu stricto), which was the most species-rich (29 species), followed by an oak grove (22 species) and a pine forest (17 species). No sampling method alone is efficient enough to provide an adequate sampling, but their combination permits one to make a suitable inventory of the myrmecofauna and to obtain information on the ecology of these ant species.     

Steady-state kinetic behaviour of two- or n-enzyme systems made of free sequential enzymes involved in a metabolic pathway

The overall rate of functioning of a set of free sequential enzymes of the Michaelis–Menten type involved in a metabolic pathway has been computed as a function of the concentration of the initial substrate under steady-state conditions. Curves monotonically increasing up to a saturation plateau have been obtained in all cases. The shape of these curves is sometimes, but not usually, close to that of a hyperbola. Cases exist in which the overall rate of reaction becomes quasi proportional to the concentration of initial substrate almost up to the saturation plateau, which never occurs with individual enzymes. Increasing the number of enzymes sequentially involved in a metabolic pathway does not seem to generate any particularly original behaviour compared with that of two-enzyme systems. To cite this article: G. Legent et al., C. R. Biologies 329 (2006).     

The tonoplast proton—Translocating ATPase of higher plants as a third class of proton—Pumps

Taken together, all the data reported recently in the literature suggest that tonoplast ATPase belongs to a new class of proton pumps. To date, the most studied system is the proton-pumping ATPase from the tonoplast of Hevea latex. Its main characteristics are presented. It resembles the mitochondrial ATPase in its specificity, its substrate affinity, and its sensitivity to different inhibitors. However, for some aspects, it resembles the plasma membrane system in its response to other inhibitors tested (quercetin for example). It differs from both ATPases in its sensitivity to nitrate as well as by its molecular structure, i.e. a complex exhibiting a least 4 or 5 polypeptides. These results favor the existence of a third class of proton pumps, intermediate between the F1F0-class and the E1E2-class.     

New enantiornithine bird (Aves, Ornithothoraces) from the Late Cretaceous of NW Argentina

A new enantiornithine bird, Intiornis inexpectatus gen. et sp. nov, is described here. It is based on a partial hind limb found in beds of the Upper Cretaceous Las Curtiembres Formation (Campanian), North-West Argentina. The new taxon is referred to the family Avisauridae on the basis of its cranially convex third metatarsal. Several features suggest close relationships between Intiornis and the avisaurid Soroavisaurus, from the Lecho Formation (Maastrichtian; North-West Argentina). Intiornis was the size of a sparrow, thus representing the smallest Enantiornithes known from South America. The new species shows adaptations for a perching mode of life. Moreover, the hypothesis suggesting that the flying pterosaur reptiles decrease in taxonomic diversity due to competitive interaction with birds is discussed. The new species shows adaptations for a perching mode of life. Moreover, the hypothesis suggesting that the flying pterosaur reptiles decrease in taxonomic diversity due to competitive interaction with birds is discussed.     

Faunes et paléoenvironnements des principaux sites archéologiques plio-pléistocènes de la formation de Nachukui (Ouest-Turkana, Kenya)

Faunas and paleoenvironments from main archaeological Plio-Pleistocene sites of the Nachukui Formation (West Turkana, Kenya). The Nachukui Formation is currently under archaeological investigation, especially within the Kalochoro (2.35 – 1.9 Myr) and Kaitio (1.9 – 1.65 Myr) Members. Six main archaeological sites have been excavated from this time period, which yield rich vertebrate faunas collected in situ or in close vicinity to the site. Paleontological studies help to precise the specific diversity for each site and increase our documentation for each Member with the discovery of new taxa. They allow to provide new informations about the biotope diversities exploited by Hominids and show a climatic tendency towards more humid environment between the Members. To cite this article: J.-P. Brugal et al., C.R. Palevol 2 (2003).     

A basal Pachyrhizodontid fish (Actinopterygii, Teleostei) from the Lower Cretaceous of the Tlayúa Quarry, Central Mexico

Michin csernai gen. et sp. nov. from the Early Cretaceous (Albian) limestones of the Tlayúa Quarry, Puebla State, Central Mexico, is assigned to the Teleost clade Pachyrhizodontoidei as it possesses the enlarged inner premaxillary tooth, which is a unique synapomorphy of this clade. Additionally, the occurrence of relatively primitive characters (e.g., united parietals, angular and articular completely fused, caudal fin with five uroneurals) suggests that Michin csernai represents the most basal representative of the pachyrhizodontids.     

The Tortonian fish fauna of Gavdos Island (Greece)

Although the occurrence of fossil fishes is known since more than one century in the Neogene of Gavdos Island (Greece), its composition remained hitherto unknown. The present study demonstrates that, in the Tortonian of Gavdos, the most abundant species is Bregmaceros albyi (Sauvage), which constitutes two thirds of the collected material. This fish fauna is indicative of an environment of moderate depth, probably corresponding to the external edge of the neritic zone, or possibly to the upper part of the continental slope. To cite this article: J. Gaudant et al., C. R. Palevol 4 (2005).