Synthèse biostratigraphique du plio-pléistocène de Guadix-Baza (Province de Granada,Sud-Est de l'Espagne)

In the Guadix-Baza basin, a continental sequence 0214 ranging from the Upper Miocene (Upper Turolian) to the Middle Pleistocene (Cromerian) has been established. An essay of biozonation by means of the Rodent succession is proposed, based on the following biozones: Trilophomys castroi, Mimomys occitanus, Mimomys cappetai, Mimomys cf. reidi, Mimomys ostramosensis, Allophaiomys pliocaenicus, Mimomys savini and Arvicola cantiana.     

Suoidea du Miocène inférieur de Laugnac (Lot-et-Garonne, France)

The fossil vertebrate locality of Laugnac is the type locality of the Neogene mammalian zone MN2b. It has yielded many remains of Suoidea belonging to two different genera.Xenohyus venitor is characterized by its large size and especially its large central upper incisors, I1/ and I2/. It is quite difficult to know its phyletic relationships because the material is not abundant.Hyotherium cf.meisneri is more abundant with a quite good skull, pieces of skull, jaws and isolated teeth. It belongs to a peculiar lineage different from that ofH. major from Saint Gérand-le-Puy, France. It has some similarities withAureliachoerus aurelianensis from later geological levels (MN3-MN5).     

Une nouvelle espèce d'Apodemus (Rodentia,Mammalia)du Pliocène de la dépression de Guadix-Baza (Grenade,Espagne)

This paper describes a new species of Apodemus,A. agustii, a Middle Pliocene Muridae from the Guadix-Baza basin. Its morphology is far from that postulated as more frequent in Apodemus: its molars crowns are relatively high: there is no connection between t6 and t9 in M¹ and M². Taking in account this and its age, it is placed in an evolutionary branch, convergent with “Rhagapodemus” morphotype.     

Présence de collagène dans le proventricule des Syllidiens (Annélides Polychètes)

Résumé L'auteur décrit en particulier à l'aide du microscope électronique les différentes couches constituant la paroi du proventricule de Syllidiens (Annélides Polychètes) en insistant spécialement sur celles (zones sous-épithéliales) situées de part et d'autre de la couche des muscles radiaires caractéristique de cet organe. II est montré que, contrairement à ce qu'il était admis jusqu'à présent, les zones sous-épithéliales sont constituées par des fibres de collagène noyées dans un matériel granuleux vraisemblablement de nature mucopolysaccharidique. D'autre part, un système d'attache particulier entre zones sous-épithéliales et musculature radiaire est mis en évidence.Les fibres de collagène de périodicité 560 Å constituent, autour de la musculature radiaire, un réseau à mailles rectangulaires hautement organisé. Dans l'assise la plus interne de ce réseau, les fibres sont allongées parallèlement à l'axe antéro-postérieur du Ver; dans l'assise la plus externe, elles sont disposées circulairement dans des plans transversaux.La signification de la présence de ces fibres de collagène (les seules existant dans tout le corps des Syllis étudiés) est évoquée. Les problèmes de leur origine et du rôle possible de cellules différenciées (musculaires) dans la synthèse de ce collagène sont analysés.

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Presence of collagen in the proventriculus of Syllids

Summary The layers of the wall of the proventriculus of Syllids (Annelids Polychetes) were studied, mainly with the aid of the electron microscope. The areas on both sides of the radial musculature (subepithelial zones) were given special attention. Contrary to previous views, it was shown that the subepithelial zones contain collagen fibrils within a granular material probably of mucopolysaccharide nature. Furthermore, a system of special attachment devices between subepithelial zones and radial musculature was demonstrated.The collagen fibrils (periodicity 560 Å) form a highly organized network with rectangular meshes around the radial musculature. In the innermost layer of this network, the fibers run parallel to the antero-posterior axis of the worm; in the outermost layer, they run circularly.The significance of the presence of these collagen fibers, the only in existence in the entire organism studied, is discussed. The problem of their origin, and the possible role played by differentiated (muscular) cells in the synthesis of this collagen are analyzed.

     

Révision de quatre espèces actuelles de Celleporaria (Bryozoa,Cheilostomata) décrites par de Lamarck en 1816

The bryozoa described by de Lamarck in 1816 are not well known. Four types of the Cellepora group have been found in the zoological collections of Museum d'Histoire naturelle in Paris: Celleporaria oculata, C. cristata, C. oliva and C. endivia. C. oculata is the type-species of the genus CelleporariaLamouroux, 1821. This revision confirms the synonymy of some species described subsequently.     

Étude palynologique du pliocène de la côte d'azur (France) et du littoral ligure (Italie)

Pollen analysis of Pliocene marine clays in coastal Alps paleogulfs is supported by biostratigraphic records according to foraminifers and accessorily to nannoplankton. From the seashore up to elevated areas, the region was occupied by forests mostly constituted by Gymnosperms (Taxodiaceae particularly). The Lower Pliocene vegetation was also characterized by local differences related to the substratum. Pollen assemblages changed in the Earliest Piacenzian; this event is probably to be related to a climatic fluctuation already evidenced in the Northwestern Mediterranean region.     

Contribution a la connaissancce des rhapydionininae (foraminifères, alveolinidae) crétacés

The formerly unknown microspheric form of Raadshoovenia salentina (Papetti and Tedeschi) and the new genus Cyclopseudedomia (type-species Cyclopseudedomia smouti n.g., n.sp.) are described from limestones of Campanian-Maastrichtian age from Gavrovo-Tripolitza zone in Greece. The new genus is distinguished from others of the sub-family RhapydionininaeKeijzer emend. Hamaoui and Fourcade by its almost entirely evolute test made of chambers tending to a cyclical stage (rapidly reached in the microspheric form).     

Première biozonation du Pléistocène Européen,principal résultat biostratigraphique de l'étude des Rhinocerotidae (Mammalia,Perissodactyla) du Miocène terminal au Pléistocène supérieur d'Europe Occidentale

For the Uppermost Miocene the already known zones MN 9 to MN 13 are used without any change; they prove to be particularly useful for the study of fossil rhinocerotids. The Plio-Villafranchian age corresponds to the zones 14 to 19, the definition of the first five being completed and the last being new. Middle to Upper Pleistocene age deals with the zones 20 to 26, all being new and defined following the same principles.     

Nouvelles interprétationsdes restes d'Équidés (Mammalia,Perissodactyla) de Nihowan (Pléistocène inférieur de la Chine du Nord): Equus teilhardi nov. sp.

The fauna yielded by the Nihowan lower pleistocene lacustrine deposits includes two species of Equus beside one Hipparion. Equus sanmeniensis was described in 1930 by Teilhard de Chardin and Piveteau; this species is characterized by its large size and the presence of cups on all incisors. Equus teilhardi nov. sp. is smaller and its lower incisors are devoid of cups. It is the first time that such an absence is noted among eurasiatic Equus; till now only some californian, south-american and african species were known to have lowers incisors without cups. The finding of several Equids in the same deposits and the significance of the lack of cups are briefly discussed.     

Nouveaux genres de Squaliformes (Chondrichthyes) du Paléogène des Landes (Sud-Ouest de la France)

Résumé  Parmi les nombreux squaliformes récoltés dans le Lutétien des Landes (SO de la France), deux genres et espèces nouveaux ont été reconnus:Squaliodalatias weltoni n. gen. n. sp. etAngoumeius paradoxus n. gen. n. sp. La morphologie dentaire du premier permet de le rapprocher des Dalatiidae. Les relations phylétiques du second taxon sont pour 1’instant moins claires, en raison de sa denture supérieure inhabituelle pour un Dalatiiforme aussi évolué au niveau de la denture inférieure. Ces taxa nouveaux viennent enrichir nos connaissances sur un groupe encore mal connu à l’état fossile en raison de son habitat bathyal ainsi que sur la mise en place et la radiation, encore trop peu documentée, des faunes profondes.      

Phéromones agrégeant les ouvrières de Myrmica rubra

The workers of Myrmica rubra aggregate around a source of one of their secretions, which can be called ‘alarm pheromone’, and also around workers of Lasius flavus. The mechanism of these aggregations differ.Both L. flavus workers and a solution in liquid paraffin of 3-octanol, one of the mandibular gland compounds, act as an arrestant for the workers of M. rubra. Both Dufour's gland secretion and a source of 3-octanone, the major compound of the mandibular gland secretion, are true attractants.The poison gland secretion, a mixture of 3-octanone and 3-octanol in liquid paraffin and a solution in liquid paraffin of 3-nonanone, a minor mandibular gland compound, all induce klinokinesis. The secretion of the mandibular glands and the secretion of the venom apparatus both cause positive klinokinesis and taxis. These locomotory reactions increase the probability that an object, marked by nest mates with these secretions, will be detected by several workers.When presented alone, 3-octanone is the only attractive compound in the mandibular gland secretion. However, a mixture of 3-octanone and 3-octanol (15 per cent of 3-octanol in the vapour phase) is detected more easily by the ants. The diffusion coefficients of the two compounds are different, and a mixture of these substances creates not only a quantitative but also a qualitative odour gradient. This may explain the synergy of the mixture.     

Une nouvelle espèce du genre Bohlinia (Mammalia,Giraffidae) du Miocène supérieur de Toros-Menalla,Tchad

New Giraffidae specimens discovered from the Late Miocene fossiliferous sector of Toros-Menalla (northern Chad) are described. These specimens are assigned to Bohlinia, a genus known so far only in some Late Miocene localities of Eurasia. This is the first occurrence of the genus in Africa. Analysis of the material allows us to describe a new species of giraffid, Bohlinia adoumi n. sp., probably close to the Eurasian forms.     

Le Plio-Pléistocène de Camerota(Italie méridionale): Géomorphologie et Paléoflores

Geomorphological investigations have been carried out in Camerota surroundings where marine microfaunas have been discovered. So, we can separate the Late Pliocene deposits from Calabrian and post-Calabrian levels. Preliminary palynological results show a vegetational evolution in relation with the climate. Leaf-remains give informations on the structure of the vegetation.     

Une nouvelle sous-famille,les Poulpinae, et quatre nouvelles espèces de Saitoum radiolaires mésozoiques téthysiens

Studies of skeleton elements of several jurassic species of Saitoum allow to compare them with Poulpus from Trias. The sub-family Poulpinae is introduced, caracterised by three cephalic arcs and the collar position of the cephalic structure. Among the jurassic forms, 4 species are newly described: S. corniculum, S. elegans, S. levium and S. trichylum.     

Modification de la fonction antibiotique de deux diatomées marines, Asterionella japonica (Cleve) et Chaetoceros lauderi (Ralfs), par le dinoflagelléProrocentrum micans (Ehrenberg)

Two diatoms, Asterionella japonica (Cleve) and Chaetoceros lauderi (Ralfs), produced a similar lipidic antibiotic, whose activity increased after irradiation by visible light.In mixed cultures with the dinoflagellate Prorocentrum micans Ehrenberg, their cells contained higher amounts of the photoactivated antibiotic and a lower quantity of carotenoid pigments.These observations suggest the action of a chemical mediator released into the medium by P. micans, which inhibits the synthesis of pigments, thus leading to an increase of the photoactivation of the lipidic antibiotics in vivo. A similar inverse relationship between the concentration of carotenoids and the antibiotic activity was observed in several clones of Asterionella japonica isolated from different sea-water samples, and in cultures of the same diatom in the presence of diphenylamine. The importance of such phenomenon in a natural environment is discussed.