New data on the extinct endemic rodents Tyrrhenicola and Rhagamys (Rodentia, Muridae) of Corsica (France) with special emphasis on their dental morphology and adaptation

S'estudien nous fòssils corsos de les localitats de Castiglione 1 i 3 (Oletta) i La Coscia (Rogliano) dels rosegadors recentment extingits Rhagamys i Microtus (Tyrrhenicola), un ratolí de camp i un talpó respectivament. Són comparats amb conjunts que ja s'havien estudiat prèviament, alguns revisats i completats gràcies a noves excavacions [Punta di Calcina (o Conca, Corse du Sud) i Corte (Haute-Corse)]. Una evolució morfològica suau d'ençà del Pleistocè Mitjà caracteritza M. (Tyrrhenicola), la qual es documenta per canvis en les proporcions de morfotipus dels primers molars, igual que per un increment en la mida, sent els exemplars més petits els que provenen de Punta di Calcina. Els índexs morfomètrics relatius a la primera meitat del primer molar inferior, així com els anàlisis multivariats, recolzen els resultats previs i permeten una distinció més precisa entre les poblacions successives. Per això, Microtus (Tyrrhenicola) es pot emprar per proposar cronologies relatives. D'altra banda, a les dues localitats més antigues es troben dues espècies de Rhagamys: R. minor i R. orthodon. El primer va viure durant un període curt, Punta di Calcina i Corte, al contrari que el darrer, que va viure fins l'Holocè. Tot i que les dues espècies difereixen considerablement en mida, l'evolució morfològica és suau en les dues espècies. La comparació de les morfologies oclusives dels molars a Rhagamys i les formes relacionades Rhagapodemus i Apodemus recolza la hipòtesi que Rhagamys, així com Rhagapodemus, es trobaven adaptats a una dieta abrasiva i que aquesta tendència evolutiva ja es trobava present al continent, abans de l'aïllament. Es discuteixen les grans similituds entre els patrons dentaris de Rhagamys i Tokudaia sota la perspectiva del seu origen comú amb les espècies d'Apodemus. Es proposa el murí japonès recent de l'arxipèlag de les Ryukyu com a model per a reconstruir Rhagamys, i per això s'hipotetitza que Rhagamys pot haver tingut un aspecte de talpó, una hipòtesi que es pot contrastar en base a l'estudi del material esquelètic. Lanàlisi de les dades de Còrsega du a la conclusió que l'evolució de Rhagamys i Microtus (Tyrrlienicola) va estar forçada per la competència en correlació amb esdeveniments d'immigració. Quan M. (Tyrrhenicola) va arribar, la línia evolutiva de Rhagamys es va dividir. Però M. (Tyrrhenicola) també va evolucionar, la mida es va incrernentar i el patró dentari es va fer més complex. Lesdeveniment evolutiu immediatament anterior a la línia de Rhagamys foula insularitat, que va comportar un gran canvi morfològic i de mida. Entre aquests esdeveniments i la seva extinció, l'evolució a aquestes espècies fou més aviat suau. Aquestes conclusions recolzen la interpretació de Sondaar (2000) sobre el paper de la competència a l'evolució insular.New Corsican fossils of the recently extinct endemic rodents Rhagamys and Microtus (Tyrrhenicola), respectively a field mouse and a vole, from the localities of Castiglione 1 and 3 (Oletta) and La Coscia (Rogliano) are examined. They are also compared to previously studied assemblages, some of which recently revised or completed by new excavations [Punta di Calcina (or Conca, Corse du Sud) and Corte (Haute-Corse)]. A slight morphological evolution since Middle Pleistocene characterises M. (Tyrrhenicola) which is supported by changes in proportions of morphotypes for first lower molars, as well as by a size increase, the smaller specimens being found at Punta di Calcina. Morphometric indexes relative to the anterior half of the first lower molar as well as multivariate analyses support previous results and allow a more precise distinction between the successive populations. Microtus (Tyrrhenicola) can thus be used to propose a relative chronology. Two species of Rhagamys are present aside in the two older localities, Punta di Calcina and Corte: R. minor and R. orthodon. The former had a short duration contrary to the latter that lived until Holocene times. If the two species differ considerably in size, morphological evolution is slight in both species. The comparison of the molar occlusal morphologies in Rhagamys and allied forms as Rhagapodemus and Apodemus supports the hypothesis that Rhagamys as well as Rhagapodemus where adapted to an abrasive diet and that this evolutionary trend was already present on the continent before isolation. Strong similarities between Rhagamys and Tokudaia dental patterns are discussed under the light of the common ancestry they share with Apodemus species. The extant Japanese murine rodent from Okinawa archipelago is proposed as a model to reconstruct the extinct Rhagarnys and consequently it is hypothesised that Rhagamys may have a vole-like morphology, such a hypothesis may be falsified by the study of skeletal material. The analysis of data from Corsica drives to the conclusion that evolution of both Rhagamys and Microtus iTyrrhenicolcú was forced by competit.ion in correlation with immigration events. When M. (Tyrrhenicola) settled, the Rhagamys lineage split. But M. (Tyrrhenicola) also evolved, size increased and the dental pattern became more complex. The immediate anterior evolutionary event in the Rhagamys lineage was insularity that induces a strong morphological and size change. Between these different events up to their extinction, evolution in these rodents was rather weak. Such conclusions support Sondaar's (2000) interpretation of the role of competition in insular evolution

Early Late Pliocene Paleokarstic Fillings Predating the Major Plio-Pleistocene Erosion of the Quercy Table, SW-France

Early late Pliocene rodent tooth remains, have been found in situ within Quercy paleokarstic fillings. They provide evidence of a sedimentary episode related to a high Pliocene marine level ca 3.5 Ma ago, that illustrates the situation predating the regional erosion phase and setting up of the hydrographic system

Méthodologies d'accès à des N-hydroxyphtalimides hautement substitués, vers de nouveaux catalyseurs d'oxydation aérobie

Dans un contexte industriel où les réactions d'oxydation sont réalisées dans des conditions qui ne satisfont pas toujours les principes de la chimie verte, notre groupe étudie des catalyseurs de structure N-hydroxyphtalimide (NHPI), pour l'oxydation aérobie de substrats organiques variés dans des conditions douces. Dans le but d'obtenir des catalyseurs plus actifs, deux familles d'analogues hautement substitués sur le noyau phtalimide ont été préparées, suivant deux nouvelles méthodologies de synthèse. La première consiste en la bis-ortho-métallation / silylation d'acides ortho-phtaliques non protégés, pour un accès très rapide à des analogues silylés du NHPI. Les premiers tests en catalyse d'oxydation aérobie montrent une influence intéressante des groupements silyles sur la stabilité de l'espèce active, via leur encombrement stérique, cela permettant une amélioration de l'activité catalytique. La seconde stratégie inclut une cyclotrimérisation [2+2+2] totalement intramoléculaire d'ène-diyne diesters, pour la construction d'un squelette bis-ortho-lactone pentacyclique innovant. Ces intermédiaires sont aisément transformés en 3,6-bis(2-hydroxyphényl)-4,5-diarylphtalimides, ces composés présentant une symétrie C2 et deux axes d'atropoisomérie. Le dédoublement des énantiomères a été effectué, dans la perspective d'obtenir des catalyseurs d'oxydation aérobie potentiellement énantiosélectifs.In the chemical industry, oxidation reactions are not often performed in green chemistry conditions. Our group has been studying N-hydroxyphthalimides (NHPI) catalysts for the aerobic oxidation of various organic substrates in mild conditions. In order to obtain more active catalysts, two families of analogs, showing high substitution on the phthalimide core, have been prepared, following two new synthetic methodologies. The first one consists of the bis-ortho-metalation / silylation of unprotected ortho-phthalic acids, for the efficient access to silylated analogs of NHPI. Preliminary tests in aerobic oxidation catalysis show an interesting influence of the bulkiness of the silyl groups towards the active species, because of increases in catalytic activities. The second strategy includes a totally intramolecular [2+2+2] cyclotrimerization of ene-diyne diesters, affording an innovative pentacyclic bis-ortho-lactone scaffold. These intermediates are easily converted to 3,6-bis(2-hydroxyphenyl)-4,5-diarylphthalimides, which present C2 symmetry and two atropoisomeric axis. The resolution of both enantiomers has been performed, in order to access aerobic oxidation catalysts with potent enantioselective activity.SAVOIE-SCD - Bib.électronique (730659901) / SudocGRENOBLE1/INP-Bib.électronique (384210012) / SudocGRENOBLE2/3-Bib.électronique (384219901) / SudocSudocFranceF

Mid-Neogene Mediterranean marine-continental correlations: an alternative interpretation

Recent revised magnetostratigraphic and astrochronologic calibrations of several calcareous planktonic microfossil datum events (in particular Coccolithus miopelagicus and Neogloboquadrina acostaensis) combined with our magnetobiostratigraphic investigation of a 10 m-thick section at Ecotet, near Lyon (France), in which terrestrial micromammals (Vallesian Zone MN9) are intercalated with calcareous nannoplankton and planktonic foraminifera belonging to Zones NN6-NN8 and N14-15 (=M11 and M12), respectively, lead us to question the recent recalibration by Krijgsman et al. [(1996) Eart Planet. Sci. Lett. 142, 367-380) of the Aragonian/Vallesian (MN7-8/MN9) boundary with Chron C5r.1r (~11.1 Ma) and the lower/upper Vallesian (MN9/10) boundary with Chron C4Ar.2n (~9.6-9.7 Ma). Ecotet, with a uniform reverse polarity, is shown to be assignable uniquely to Chron C5r. Interregional correlation of Ecotet with Mediterranean terrestrial stratigraphies indicates that Progonomys (whose First Occurrence (FO) has been traditionally placed in Mediterranean Mammal Zone MN10) was already present in Mediterranean Zone MN9 at ~11.4 Ma and did not experience a 2 million-year delay in its putative prochoresis from Asia