11 research outputs found
Calcitization of aragonitic bryozoans in Cenozoic tropical carbonates from East Kalimantan, Indonesia
© The Author(s) 2016. Open Access. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The file attached is the published version of the article
Ground-based absolute magnetic survey on the backbone network of points of the secular passage in Ukraine for the era of 2005
The results of the geomagnetic field components on renewed Ukrainian repeat stations (RS) network are considered. The methods of absolute geomagnetic and astro-geodetic measurements are described, as well as methods of geomagnetic field reduction to certain epoch. The reduction of geomagnetic field components are carried out to 2005 year epoch. The catalogue of RS is created. The maps of magnetic declination for Ukraine are constructed and comparison with results calculated by model IGRF-2005 has been done. It is shown that in spatial structure of magnetic declination one can distinguish several regional anomalies with intensity 1-2 °
Case history: The âmadeleinesâ instable slope near Dakar (Senegal): Analysis, hazards mapping
Le âcontinental terminalâ, sa place dans l'Ă©volution gĂ©odynamique du bassin sĂ©nĂ©galo-mauritanien durant le CĂ©nozoĂŻque
Phosphatherium escuillieidu Thanétien du Bassin des Ouled Abdoun (Maroc), plus ancien proboscidien (Mammalia) d'Afrique
International audienceWe detail here the study of Phosphatherium escuilliei from the Paleocene of the Ouled Abdoun Basin, 040 Morocco. This fossil is both the oldest proboscidean and the oldest modern ungulate. The species, known by two specimens, is dated as Thanetian on the basis of the foraminifera and the selachians identified in the matrix. P. escuilliei shows several derived proboscidean features, especially the true lophodont pattern of the molars, but also remarkable primitive features such as a vestigial dilambdodonty and a very small size, the smallest reported in the order. The vestigial dilambdodonty is interpreted here as a reminiscence of the pantomesaxonian super-group. Primitive tethythere features are also noticed, especially the orbit in anterior position and the occurrence of a postentoconule. Numidotherium koholense from El Kohol (late Early Eocene of Algeria) is the most closely related proboscidean to P. escuilliei, and the two species are included in the same family Numidotheriidae. However, the available material shows only one possible synapomorphy: the absence of lingual cingulum in the upper molars. P. escuilliei is the most primitive known lophodont proboscidean. The dP4/ of P. escuilliei strongly recalls the single known tooth of the enigmatic species Khamsaconus bulbosus from the Ypresian site of N'Tagourt 2, Morocco. Shared features such as the occurrence of a postentoconule and the incipient bilophodonty indicate affinities of K. bulbosus with tethytheres, and others such as the absence of conules are even possibly suggestive of affinities with lophodont proboscideans. The K. bulbosus morphology remains however clearly more primitive than that of P. escuilliei, especially in being more bunodont. Phosphatherium, Numidotherium, Barytherium and even Khamsaconus raise the problem of a lophodont ancestral proboscidean morphotype, which is in accordance with the recent hypothesis of Court (1995) regarding Moeritherium as more derived than Numidotherium. P. escuilliei supports the early age of the radiation of modern orders of mammals, which was earlier than the late Paleocene, as well as its âexplosiveâ pattern if it is closely connected to the extinctions of the K/T boundary. It shows also, more clearly than the taxa from the Adrar Mgorn fauna (late Paleocene of Morocco), the old age of the eutherian presence in the Arabo-African domain. It also supports the African origin of true proboscideans.Nous dĂ©taillons ici l'Ă©tude de Phosphatherium escuilliei (ThanĂ©tien du Bassin Ouled Abdoun, Maroc), plus ancien proboscidien, mais aussi plus ancien ongulĂ© moderne dĂ©couvert. L'espĂšce, connue par deux spĂ©cimens trouvĂ©s de seconde main, est datĂ©e du ThanĂ©tien sur la base de la microfaune de foraminifĂšres et sĂ©laciens identifiĂ©e dans la gangue sĂ©dimentaire de l'holotype. P. escuilliei montre plusieurs traits dĂ©rivĂ©s de proboscidiens, spĂ©cialement la lophodontie vraie des molaires, mais aussi des caractĂšres archaĂŻques notables tels qu'une dilambdodontie vestigiale et une trĂšs petite taille, la plus petite observĂ©e dans l'ordre. La dilambdodontie vestigiale est interprĂ©tĂ©e ici comme une rĂ©miniscence du super-groupe des pantomesaxoniens. Des traits gĂ©nĂ©raux de tĂ©thythĂšres sont Ă©galement relevĂ©s tels que l'orbite en position antĂ©rieure et la prĂ©sence d'un postentoconule. Numidotherium koholense de la localitĂ© d'El Kohol (AlgĂ©rie, EocĂšne infĂ©rieur tardif) est l'espĂšce la plus proche de P. escuilliei; les deux formes sont intĂ©grĂ©es dans la mĂȘme famille des Numidotheriidae. Cependant, une seule synapomorphie possible est relevĂ©e sur la base du matĂ©riel disponible: l'absence de cingulum lingual aux molaires supĂ©rieures. P. escuilliei est le plus primitif des proboscidiens lophodontes. La dP4/ de P. escuilliei Ă©voque fortement l'unique dent connue de l'espĂšce Ă©nigmatique Khamsaconus bulbosus du site de N'Tagourt 2 (Maroc, YprĂ©sien). Des traits de Khamsaconus tels la prĂ©sence d'un postentoconule et la bilophodontie naissante tĂ©moignent d'une affinitĂ© avec les tĂ©thythĂšres, et d'autres tels l'absence de conules semblent mĂȘme suggĂ©rer une parentĂ© avec les proboscidiens lophodontes. La morphologie de Khamsaconus reste cependant nettement plus primitive que celle de P. escuilliei, notamment dans la bunodontie marquĂ©e. Phosphatherium, Numidotherium, Barytherium et mĂȘme Khamasaconus posent le problĂšme d'un morphotype ancestral lophodonte des proboscidiens, lequel s'accorde avec la rĂ©cente conclusion de Court (1995) sur la position dĂ©rivĂ©e de Moeritherium comparativement Ă Numidotherium. Phosphatherium escuilliei Ă©taye la grande prĂ©cocitĂ© de la radiation des ordres modernes d'euthĂ©riens, d'Ăąge antĂ©rieur au PalĂ©ocĂšne supĂ©rieur, et son caractĂšre âexplosifâ si elle est Ă©troitement corrĂ©lĂ©e aux extinctions de la limite K/T. Il tĂ©moigne en outre, plus nettement que les taxons de la faune de l'Adrar Mgorn (PalĂ©ocĂšne supĂ©rieur du Maroc), de l'anciennetĂ© du peuplement euthĂ©rien du domaine arabo-africain. Il vient enfin Ă l'appui de l'origine africaine des proboscidiens vrais