40 research outputs found

    New early devonian charophyta from Gondwana

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    Early Devonian charophytes are reported from Australia (Buchan, Victoria) and Europe (Landeyran, southern France): Moellerina australica n. sp. Feist and Pinnoputamen occitanicum n. sp. Feist. Sedimentological data and associated faunas from these localities accord with both species having inhabited lacustrine or estuarine environments. A critical review of Devonian biotopes confirms that, as with present day species, Mid Palaeozoic charophytes could not have lived in open marine habitats. Originating in Baltica during the Silurian, charophytes appeared in Gondwana in the earliest Devonian.<br /

    The IMAM case. Additional investigation of a micropaleontological fraud

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    International audienceStarting in 1996 and for almost a decade, M.M. IMAM contributed to twelve papers published in international geological journals. These papers dealt with the micropaleontology and biostratigraphy of Cretaceous to Miocene series from Egypt and Libya. They were abundantly illustrated in order to support the author's findings and interpretations. However most photographic illustrations (189 at least) were fabricated with material lifted from the publications of other authors, commonly from localities or stratigraphic intervals other than those indicated by M.M. IMAM

    L'affaire IMAM. Compléments d'enquête sur une fraude micropaléontologique

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    À partir de 1996 et pendant près d'une décennie, M.M. IMAM a contribué à douze articles parus dans des revues géologiques internationales. Ces publications traitent de la micropaléontologie et de la biostratigraphie de séries d'âge Crétacé à Miocène d'Égypte et de Libye. L'iconographie abondante était sensée renforcer la validité des découvertes et interprétations de l'auteur. Or la plupart des illustrations photographiques (189 au moins) ont été fabriquées à partir de photos "empruntées" à des publications d'autres auteurs, le plus souvent provenant de localités ou d'intervalles stratigraphiques autres que ceux indiqués par M.M. IMAM.Starting in 1996 and for almost a decade, M.M. IMAM contributed to twelve papers published in international geological journals. These papers dealt with the micropaleontology and biostratigraphy of Cretaceous to Miocene series from Egypt and Libya. They were abundantly illustrated in order to support the author's findings and interpretations. However most photographic illustrations (189 at least) were fabricated with material lifted from the publications of other authors, commonly from localities or stratigraphic intervals other than those indicated by M.M. IMAM

    Mosaic Convergence of Rodent Dentitions

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    BACKGROUND:Understanding mechanisms responsible for changes in tooth morphology in the course of evolution is an area of investigation common to both paleontology and developmental biology. Detailed analyses of molar tooth crown shape have shown frequent homoplasia in mammalian evolution, which requires accurate investigation of the evolutionary pathways provided by the fossil record. The necessity of preservation of an effective occlusion has been hypothesized to functionally constrain crown morphological changes and to also facilitate convergent evolution. The Muroidea superfamily constitutes a relevant model for the study of molar crown diversification because it encompasses one third of the extant mammalian biodiversity. METHODOLOGY/PRINCIPAL FINDINGS:Combined microwear and 3D-topographic analyses performed on fossil and extant muroid molars allow for a first quantification of the relationships between changes in crown morphology and functionality of occlusion. Based on an abundant fossil record and on a well resolved phylogeny, our results show that the most derived functional condition associates longitudinal chewing and non interlocking of cusps. This condition has been reached at least 7 times within muroids via two main types of evolutionary pathways each respecting functional continuity. In the first type, the flattening of tooth crown which induces the removal of cusp interlocking occurs before the rotation of the chewing movement. In the second type however, flattening is subsequent to rotation of the chewing movement which can be associated with certain changes in cusp morphology. CONCLUSION/SIGNIFICANCE:The reverse orders of the changes involved in these different pathways reveal a mosaic evolution of mammalian dentition in which direction of chewing and crown shape seem to be partly decoupled. Either can change in respect to strong functional constraints affecting occlusion which thereby limit the number of the possible pathways. Because convergent pathways imply distinct ontogenetic trajectories, new Evo/Devo comparative studies on cusp morphogenesis are necessary

    Etude floristique et biostratigraphique des Charophytes dans les séries du Paléogène de Provence

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    An analysis is given of the floral distribution in the Upper Eocene and Oligocene of the South of France, in the areas of Apt-Forcalquier, Mormoiron-Pernes, Aix, Marseille, Pertuis, Montélimar and Barrême. The age of several of these formations is established especially that of the "Argiles des Milles" (near Aix-en-Provence) previously considered as Middle Oligocene and now attributed to the Upper Oligocene on the basis of charophyte data. Close similarities with the South of England (Isle of Wight) have been recognized for the Eocene-Oligocene transitional zones. A relationship with vertebrate (Rodent) biostratigraphy is suggested for the localities from the "Stampian" and "Aquitanian". From a systematic standpoint, the new sub-genus Microstomella of Nitellopsis Hy, and six new species, N. (M.) aptensis, Sphaerochara davidi, Stephanochara oodea, Harrisichara tumidula, Rhabdochara raibocarpa, R. altilis, are created. Two previously described form, Sphaerochara inconspicua n. comb, and Stephanochara ungeri n. sp. (= Croftiella escheri Horn af Rantzien) are revised. The non valid genus Croftiella Horn af Rantzien is replaced by Stephanochara Grambast.La répartition des flores récoltées dans l'Eocène supérieur et l'Oligocène des bassins d'Apt-Forcalquier, Mormoiron-Pernes, Aix, Marseille ainsi que dans les secteurs de Pertuis, Montélimar et Barrême est analysée. La datation de plusieurs formations est précisée, notamment celle des argiles des Milles (près Aix -en-Provence), considérées comme stampiennes et attribuées, sur la base des Charophytes, à l'Oligocène supérieur. Pour les niveaux de passage de l'Eocène à l'Oligocène (Bartonien-Lattorflen), des affinités très étroites avec le Sud de l'Angleterre (lie de Wight) sont établies. Une corrélation avec l'échelle biostratigraphique des Vertébrés (Rongeurs) est proposée pour les gisements du Stampien et de l'Aquitanien. Du point de vue systématique, le nouveau sous-genre de Nitellopis Hy, Microstomella, et 6 espèces nouvelles, N. (M.) aptensis, Sphaerochara davidi, Stephanochara oodea, Harrisi-chara tumidula, Rhabdochara raibocarpa, R. altilis, sont créés. Deux formes anciennement décrites sont révisées : Sphaerochara inconspicua n. comb et Stephanochara ungeri n. sp. (= Croftiella escheri Horn af Rantzien). Le genre Crof-tiella Horn af Rantzien, non valide, est remplacé par Stephanochara Grambast.Feist Monique. Etude floristique et biostratigraphique des Charophytes dans les séries du Paléogène de Provence. In: Géologie Méditerranéenne. Tome 4, numéro 2, 1977. pp. 109-138

    Evolution of the charophyte floras in the Upper Eocene and Lower Oligocene of the Isle of Wight

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    Volume: 20Start Page: 143End Page: 15

    Nouvelles charophytes de l'Eocène continental de l'Algérie

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    Six new species from non-marine Tertiary localities of Algeria are described and situated in their stratigraphie context. Five of them come from Oued Meguerchi (Saharian Atlas) and the sixth one from Gour-Lazib and Glib-Zegdou (north-western Saharian Hammada). The affinities of the flora as a whole suggest that relationships between North Africa and northern mesogean regions as well as, but to a less extant, with Asia.Six nouvelles espèces de Charophytes provenant de l'Eocène continental de l'Algérie sont décrites et situées dans leur contexte strati-graphique. Cinq d'entre elles proviennent du gisement de Oued Meguerchi dans l'Atlas saharien et la sixième du gisement des Gours Lazib et du Glib Zegdou dans la Hammada du Dra (Sahara nord-occidental). Les affinités de l'ensemble de la flore suggèrent que des relations existaient, dès l'Eocène inférieur, entre le Nord de l'Afrique et les régions mésogéennes et, à un degré moindre, avec l'Asie.Mebrouk F., Feist Monique. Nouvelles charophytes de l'Eocène continental de l'Algérie. In: Géologie Méditerranéenne. Tome 26, numéro 1-2, 1999. pp. 29-45
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