149 research outputs found
Une occupation de la fin du Dernier Maximum Glaciaire dans les Pyrénées : le Magdalénien inférieur de la grotte des Scilles (Lespugue, Haute-Garonne)
International audienceThe excavations by R. and S. Saint-Périer at the Grotte des Scilles (Lespugue, Haute-Garonne, France) in 1923-1924 yielded archaeological material attributed to the Magdalenian. The re-examination of this old collection now allows a more precise characterization of it, in light of recent research on this period. This article presents the different artefact types found (lithic and osseous tools, faunal remains, personal ornaments, portable art items and one sandstone lamp) in order to consider all activities documented at the site. Particular attention is given to typological and technological data, the analyses of which point to a Lower Magdalenian chronological attribution. A SMA 14C date shows that occupation took place around 16,000 years BP (19,400 years cal BP) at the Grotte des Scilles. The identification, for the first time, of a Lower Magdalenian presence in the Pyrenees raises new questions concerning Magdalenian occupation at the end of the Last Glacial Maximum in southwestern France and northern Spain.Les fouilles menées par R. et S. Saint-Périer dans les années 1920 à la grotte des Scilles (Lespugue, Haute-Garonne) ont livré un ensemble de vestiges attribués au Magdalénien. L'étude de cette collection ancienne offre désormais la possibilité de préciser cette caractérisation à la lumiÚre de travaux récents sur cette période. La présentation des différentes catégories de vestiges (industries lithique et osseuse, faune, parure, art mobilier et lampe) permet d'appréhender l'ensemble des registres d'activités documentés sur le site. En particulier, cet article présente les éléments typo-technologiques qui fournissent des arguments pour rattacher l'occupation de cette cavité au Magdalénien inférieur. Une date 14C par SMA situe cette période autour de 16 000 BP (19 400 cal BP) à la grotte des Scilles. La mise en évidence de ce premier jalon pyrénéen conduit ensuite les auteurs à discuter du peuplement magdalénien à la fin du dernier maximum glaciaire dans le sud-ouest de la France et le nord de l'Espagne
Recent Laborian of the Peyrazet cave-rock shelter (Creysse, Lot, France). New data for the end of Lateglacial in Quercy
DĂ©couverte en 1990, la grotte-abri de Peyrazet (Creysse, Lot, France) se situe dans le Haut-Quercy en bordure du causse de Martel, Ă quelques centaines de mĂštres du cours actuel de la Dordogne. Les fouilles menĂ©es depuis 2008 livrent une archĂ©osĂ©quence du Tardiglaciaire qui permet de combler certaines lacunes documentaires rĂ©gionales et plus largement du Sud-Ouest de la France. Au MagdalĂ©nien supĂ©rieur succĂšde un niveau ayant donnĂ© des indices dâun Azilien sensu lato stratigraphiquement sĂ©parĂ© du Laborien, ensemble supĂ©rieur qui fait lâobjet de cet article. Jusquâalors ce technocomplexe de la fin du PlĂ©istocĂšne et des dĂ©buts de lâHolocĂšne demeurait mal connu dans la rĂ©gion. En effet, seuls des travaux anciens menĂ©s dans deux gisements permettaient de noter sa prĂ©sence en Quercy. La dĂ©couverte dâun ensemble laborien rĂ©cent (ou Ăpilaborien) Ă Peyrazet est lâoccasion de conduire une Ă©tude collective des divers vestiges dans un cadre archĂ©ostratigraphique mieux maĂźtrisĂ©. Lâanalyse gĂ©oarchĂ©ologique met en Ă©vidence lâaction conjointe du ruissellement et de lâĂ©boulisation comme principaux responsables de la mise en place des dĂ©pĂŽts. Dans la partie S-O du site, un lithofaciĂšs de remaniement indique une bioturbation importante en lien avec le creusement de terriers. Bien que leur origine ne soit pas liĂ©e aux activitĂ©s humaines, les rongeurs, les oiseaux, les poissons et les mĂ©somammifĂšres (exceptĂ© le liĂšvre) apportent des donnĂ©es concernant lâenvironnement des chasseurs-cueilleurs. La grande faune est dominĂ©e par le cerf dont les carcasses pourraient avoir Ă©tĂ© introduites incomplĂštes sur le site puis traitĂ©es pour en extraire la viande et la moelle. Nous avons bĂ©nĂ©ficiĂ© dâune analyse fonctionnelle croisĂ©e Ă lâĂ©tude typo-technologique des vestiges lithiques composĂ©s pour lâessentiel de silex locaux et rĂ©gionaux. Ce double regard a permis de mettre en Ă©vidence une diversitĂ© dâactivitĂ©s mise en Ćuvre dans la cavitĂ©. Une piĂšce dâocre rouge, quelques vestiges dâindustrie osseuse et des Ă©lĂ©ments de parure participent Ă©galement Ă la description dâune large gamme de tĂąches effectuĂ©es lors dâun sĂ©jour prolongĂ© ou de plusieurs occupations successives. La comparaison des pointes de chasse microlithiques avec dâautres gisements sur une vaste Ă©chelle gĂ©ographique conduit Ă discuter lâattribution de cet ensemble supĂ©rieur Ă diffĂ©rentes phases du Laborien. LâhypothĂšse dâun Laborien rĂ©cent (ou Ăpilaborien) conduit Ă rĂ©flĂ©chir Ă une perduration de morphotypes ancestraux parallĂšlement Ă de nouveaux types dâarmatures, observation dĂ©jĂ rĂ©alisĂ©e notamment Ă La Borie del Rey dans le Haut-Agenais mais qui demande encore des prĂ©cisions et de nouvelles dĂ©couvertes.Discovered in 1990, Peyrazet cave-rock shelter (Creysse, Lot) lies in the Haut-Quercy region at the limits of the Martel limestone plateau, several hundred meters from the current Dordogne River valley. Excavations begun in 2008 produced a Late Glacial archaeo-sequence that sheds new light on several still poorly understood aspects of the archeological record in both the Haut-Quercy region and southwestern France in general. The level overlying the Late Magdalenian occupation produced limited evidence for the Azilian and is stratigraphically separated from the Laborian. This latter techno-complex, dated to the end of the Pleistocene and early Holocene, remains poorly documented in the region, having only been previously identified from two sites in the Quercy. The discovery of a recent Laborian (Epilaborian) occupation at Peyrazet presented the ideal occasion for a collaborative study of the diverse archaeological material recovered from this well-understood archaeo-stratigraphic context. A geoarchaeological analysis produced evidence for both surface runoff and the accumulation of coarse deposits (Ă©boulis) as the principal site formation processes. In the southwest area of the site, a reworked lithofacies demonstrates substantial bioturbation in connection with animal burrowing. Although the presence of rodent, bird, fish, and medium-sized mammals (except hare) cannot be definitively connected to human activity, they nevertheless provide important information concerning the environments exploited by hunter-gatherer groups. Larger species are dominated by red deer whose carcasses were partially processed before being introduced to the site, where meat was subsequently removed and marrow consumed. A functional analysis combined with a typo-technological study of the primarily locally- and regionally-procured lithic material revealed evidence for diverse activities having taken place on-site. An ochre fragment, several bone tools and ornaments equally indicate a large variety of tasks to have been carried out during a single, long occupation or several successive visits. A typo-technological comparison of hunting weaponry (microliths) from sites across a substantial area suggests the assemblage to represent either a Laborian/Epilaborian mix or a unique Epilaborian occupation. This latter case would indicate the persistence of older morphotypes alongside the development of new tools forms, a situation already identified at Borie del Rey in the Haut-Agenais but which requires more detailed study supported by new discoveries
Photography-based taxonomy is inadequate, unnecessary, and potentially harmful for biological sciences
The question whether taxonomic descriptions naming new animal species without type specimen(s) deposited in collections should be accepted for publication by scientific journals and allowed by the Code has already been discussed in Zootaxa (Dubois & NemĂ©sio 2007; Donegan 2008, 2009; NemĂ©sio 2009aâb; Dubois 2009; Gentile & Snell 2009; Minelli 2009; Cianferoni & Bartolozzi 2016; Amorim et al. 2016). This question was again raised in a letter supported
by 35 signatories published in the journal Nature (Pape et al. 2016) on 15 September 2016. On 25 September 2016, the following rebuttal (strictly limited to 300 words as per the editorial rules of Nature) was submitted to Nature, which on
18 October 2016 refused to publish it. As we think this problem is a very important one for zoological taxonomy, this text is published here exactly as submitted to Nature, followed by the list of the 493 taxonomists and collection-based
researchers who signed it in the short time span from 20 September to 6 October 2016
DĂ©terminants Ă©cologiques dâun peuplement prairial de colĂ©optĂšres Scarabaeoidea Laparosticti (Manche, France)
Summary. â Ecological determinants of a meadow community of Coleoptera Scarabaeoidea Laparosticti (Manche, France). â Beetles belonging to the group of Scarabaeoidea Laparosticti represent an important component of grazed meadows, particularly in contributing to their structural biodiversity. They are indeed functioning elements that recycle organic matter coming from herbivore dejections. This study aimed at characterizing the whole assemblage of Coleoptera Scarabaeoidea Laparosticti and at determining respective influence of two main ecological factors, i. e. the type of herbivore (cow or horse) and the type of grazed meadow (meso-hygrophilous or xerophilous), on the distribution (in terms of presence/ absence and abundances) of coprophagous beetles. Sampling were carried out in the â RĂ©serve naturelle nationale du Domaine de Beauguillotâ (Manche, France) during 2005 by using the standard trapping â Cebo-Superficie-Rejillaâ. A total of 12,621 individuals belonging to 26 species were collected. A strong effect of herbivore type was highlighted, as numerous species were found to be exclusively or mainly present in cow dung. The effect of meadow type slightly occurred, being important only in case of statistical interactions with herbivore type.RĂ©sumĂ©. â Les ColĂ©optĂšres Scarabaeoidea Laparosticti forment une composante importante des milieux prairiaux pĂąturĂ©s, Ă la fois comme Ă©lĂ©ments constitutifs de leur biodiversitĂ© et en tant que maillons essentiels de leur fonctionnement (recyclage de la matiĂšre organique issue des fĂšces dâherbivores). Les objectifs de cette Ă©tude furent dâune part de caractĂ©riser globalement le peuplement de ColĂ©optĂšres Scarabaeoidea Laparosticti et dâautre part dâĂ©valuer lâinfluence de deux facteurs Ă©cologiques majeurs, le type dâherbivore prĂ©sent (vache ou cheval) et le type de prairie pĂąturĂ©e (mĂ©so-hygrophile ou xĂ©rophile) sur la rĂ©partition (en termes de prĂ©sence/ absence et dâabondances) des espĂšces de ColĂ©optĂšres coprophages. LâĂ©chantillonnage a Ă©tĂ© menĂ© dans la RĂ©serve naturelle nationale du Domaine de Beauguillot (Manche, France) durant lâannĂ©e 2005 au moyen du piĂ©geage standard Cebo-Superficie-Rejilla. Au total, 12 621 individus appartenant Ă 26 espĂšces ont Ă©tĂ© rĂ©coltĂ©s. Nous avons pu mettre en Ă©vidence un effet marquĂ© du type dâherbivore, un grand nombre dâespĂšces Ă©tant notamment infĂ©odĂ©es ou prĂ©fĂ©rentielles des bouses de vache. Lâeffet du type de prairie est apparu faiblement, plus fortement dans le cas dâinteractions statistiques avec le type dâherbivore.Elder Jean-François, PĂ©tillon Julien. DĂ©terminants Ă©cologiques dâun peuplement prairial de colĂ©optĂšres Scarabaeoidea Laparosticti (Manche, France). In: Revue d'Ăcologie (La Terre et La Vie), tome 65, n°3, 2010. pp. 225-233
Reactions of the Ό-alkyne-dicobalt complexes [Co2(CO)6(Ό-CF3-CC-R)] (R=CF3, H) with [Co2Cp2(Ό-SMe)2]: Substitution and insertion leading to novel thiolato-alkyne tetra- and tricobalt clusters
cited By 9International audienceThe bis(ÎŒ-thiolato)dicobalt complex [Co2Cp2(ÎŒ-SMe)2] (1) reacts with alkyne-cobalt complexes [Co2(CO)6(ÎŒ-F3CCCR)] (2) to give tri- and tetranuclear cobalt cluster compounds. When R=CF3 the main product is [Co2(CO)4(ÎŒ-CF3C2CF 3)ÎŒ-Co2Cp2(ÎŒ-SMe)2] (3) but the trinuclear cluster [Co3Cp(CO)4(ÎŒ-SMe)2(ÎŒ-CF 3C2CF3)] (4) is also obtained in low yield. When R=H the products are the isomeric clusters [Co3Cp(CO)4(ÎŒ-SMe)2(ÎŒ-CF 3C2H)] (5 and 6), [Co3Cp2(CO)3(ÎŒ-SMe)(ÎŒ-CF 3C2CH)] (7) and [CpCo(CO)2]. The solid state structures of 3, 4, 5 and 7 have been established by X-ray analysis. The 50 electron triangular cluster 4 has weak Co-Co bonds [2.573(1), 2.800(1), 2.838(1) Ă
]. The alkyne ligand bridges the shortest of these bonds in perpendicular fashion. 5 and 7 contain open chain tricobalt units [Co-Co 2.39-2.57 Ă
] more typical of 50 electron M3 species. In these complexes the alkyne is Ï-bonded to the central metal atom and Ï-bonded to both terminal cobalt atoms. Variable temperature NMR indicates that 5, 6 and 7 each exist in solution as interconverting isomers which differ in the configuration at one sulphur atom. For 5 the activation parameters [ÎHâĄ=64 kJ mol-1 and ÎSâĄ=-85 J K-1 mol-1] were obtained spectroscopically. In the solid, molecules of 7 contain an asymmetrically bridging carbonyl [Co-C 1.833(4) and 2.050(3) Ă
] which is not detectable in the solution spectra. © 2001 Elsevier Science B.V
Electrochemical oxidation and protonation of a bridging amide ligand at a dinuclear metal-sulfur site
International audienceThe electrochemical oxidation of the amide complex [Mo2(cp)2(Ό-SMe)3(Ό-NH2)] 1 (cp = η5-C5H5) has been investigated in tetrahydrofuran (thf) and MeCN electrolytes by cyclic voltammetry, controlled-potential electrolysis and coulometry. The two-electron oxidation of 1 leads to the release of a proton and to the formation of the imide derivative [Mo2(cp)2(Ό-SMe)3(Ό-NH)]+ 2. In MeCN, this reaction is reversible. The protonation of 1 has been shown to produce a complex in which a NH3 ligand is bound to a Mo centre; the protonated complex is stabilized by co-ordination of the anion of the acid, of the solvent or of a substrate to the neighbouring metal centre. The protonation performed in thf in the presence of chloride produces [Mo2(cp)2(Ό-SMe)3(Ό-Cl)] which is the precursor of the amide complex 1. The final protonation product formed in MeCN is [Mo2(cp)2(Ό-SMe)3(MeCN)2]+, which also is a precursor of 1. Therefore, these experiments allow the construction of a hydrazine disproportionation cycle
Electrochemical oxidation and protonation of a bridging amide ligand at a dinuclear metal-sulfur site
International audienceThe electrochemical oxidation of the amide complex [Mo2(cp)2(Ό-SMe)3(Ό-NH2)] 1 (cp = η5-C5H5) has been investigated in tetrahydrofuran (thf) and MeCN electrolytes by cyclic voltammetry, controlled-potential electrolysis and coulometry. The two-electron oxidation of 1 leads to the release of a proton and to the formation of the imide derivative [Mo2(cp)2(Ό-SMe)3(Ό-NH)]+ 2. In MeCN, this reaction is reversible. The protonation of 1 has been shown to produce a complex in which a NH3 ligand is bound to a Mo centre; the protonated complex is stabilized by co-ordination of the anion of the acid, of the solvent or of a substrate to the neighbouring metal centre. The protonation performed in thf in the presence of chloride produces [Mo2(cp)2(Ό-SMe)3(Ό-Cl)] which is the precursor of the amide complex 1. The final protonation product formed in MeCN is [Mo2(cp)2(Ό-SMe)3(MeCN)2]+, which also is a precursor of 1. Therefore, these experiments allow the construction of a hydrazine disproportionation cycle
Identification fine du processus d'isolation Ă©lectrique de la poudre de fer par action de l'acide phosphorique. Ătude de l'influence des paramĂštres physico-chimiques du milieu sur la qualitĂ© des matĂ©riaux isolĂ©s
Contrat SAPHYR (1992-1993
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