Search results for "ammonites"
showing 10 items of 45 documents
Les ammonites du Pliensbachien du jebel Bou Rharraf (Haut Atlas oriental, Maroc).
2011
60 pages; International audience; L'originalité des dépôts sédimentaires et des faunes d'ammonites du jebel Bou Rharraf repose sur la présence de faciès « Ammonitico Rosso », les plus occidentaux connus pour le Pliensbachien, une forte diversité des Phylloceratida (Phylloceras, Calaiceras, Zetoceras, Partschiceras et Juraphyllites) et une disparité morphologique importante chez les Galaticeras, Miltoceras et les Tauromeniceras. Si quelques formes, telles que Miltoceras taguendoufi et Mauretaniaceras elmii nov. gen., nov. sp. ont un cachet endémique très affirmé, les faunes du Pliensbachien du Haut Atlas oriental sont classiques pour la marge sud de la Téthys occidentale. Trois genres (Callo…
La faune ammonitique des marnes à fossiles ferrugineux de la région de Niort, France (Oxfordien inférieur, Zone à Cordatum, Sous-Zone à Cordatum)
2009
21 pages; Une nouvelle récolte d'ammonites dans les marnes à ammonites ferrugineuses de la région de Niort (France), autrefois étudiées par de GROSSOUVRE (1922), apporte de très nombreuses informations biostratigraphiques, paléoenvironnementales et paléobiogéographiques. La faune est datée de l'Oxfordien inférieur : Zone à Cordatum, Sous-Zone à Cordatum, partie inférieure probable. De plus, elle est unique en Europe occidentale 1) par les espèces trouvées -dont certaines ne semblent connues que dans ce gisement- 2) par la domination très atypique du binôme Taramelliceras - Creniceras qui représente les 2/3 des individus. Enfin, le spectre faunique plaide en faveur d'un milieu de plate-forme…
Apport des ammonites au cadre biostratigraphique et chronostratigraphique du Haut-Atlas de Rich au cours du Lias (Maroc).
2007
11 pages
Report on the 4th International Meeting of the IUGS Lower Cretaceous ammonite working group, the "Kilian Group" (Dijon, France, 30th August 2010).
2011
8 pages; International audience; The 4th Kilian Group meeting (Dijon, France, 30th August 2010) focused on the Aptian and Albian Stages. For the Aptian, a two-fold division of the stage was adopted for the Mediterranean area with a boundary between the Dufrenoyia furcata and Epicheloniceras martini Zones. The main changes to the zonal scheme concern the Lower Aptian with: the introduction of a Deshayesites luppovi Subzone in the upper part of the Deshayesites oglanlensis Zone; the replacement of Deshayesites weissi by Deshayesites forbesi as new indexspecies of the second interval zone; the introduction of a Roloboceras hambrovi Subzone in the upper part of the D. forbesi Zone; and the subd…
Ammonite diversity and its palaeobiogeographical structure during the early Pliensbachian (Jurassic) in the western Tethys and adjacent areas.
2009
14 pages; International audience; The early Pliensbachian (Early Jurassic) is known as a time of marked provincialism in the marine realm, notably between the Mediterranean Tethys and North–West Europe. In order to test this observation quantitatively, we compiled 104 locality-level species lists from those areas based on a comprehensive revision of early Pliensbachian ammonites. With this dataset, we also explore the relationship between ammonite richness and biogeography at the scale of the sub-chronozone during the early Pliensbachian. Using various multivariate statistics and rarefaction techniques, we show that: (i) there is a sharp contrast between the NW European (NWE) and the Medite…
Allometric space and allometric disparity: a developmental perspective in the macroevolutionary analysis of morphological disparity.
2008
8 pages; International audience; Here, we advance novel uses of allometric spaces--multidimensional spaces specifically defined by allometric coefficients--with the goal of investigating the focal role of development in shaping the evolution of morphological disparity. From their examination, operational measures of allometric disparity can be derived, complementing standard signals of morphological disparity through an intuitive and process-oriented refinement of established analytical protocols used in disparity studies. Allometric spaces thereby become a promising context to reveal different patterns of evolutionary developmental changes and to assess their relative prevalence and import…
Ammonite paleobiogeography during the Pliensbachian-Toarcian crisis (Early Jurassic) reflecting paleoclimate, eustasy, and extinctions.
2011
14 pages; International audience; The Pliensbachian-Toarcian crisis (Early Jurassic) is one of the major Mesozoic paleoecological disturbances when ca. 20% of marine and continental families went extinct. Contemporaneously, profound paleobiogeographical changes occurred in most oceanic domains including a disruption of ammonite provincialism during the Early Toarcian. Here, we quantitatively reappraise the structure and evolution of paleobiogeographical patterns displayed by ammonite faunas before, during, and after the biological crisis, over a time-interval including 13 biochronozones. The high-resolution study presented here involves the use of hierarchical Cluster Analyses, non-metric M…
Integrated stratigraphy of the Oxfordian global stratotype section and point (GSSP) candidate in the Subalpine Basin (SE France).
2014
44 pages; International audience; An integrated biostratigraphic approach, based on ammonites, calcareous nannofossils, dinoflagellates, combined with sedimentology, carbon-isotope and physical stratigraphy, is proposed for the Subalpine Basin (Thuoux and Saint-Pierre d'Argençon sections). Within the expanded marl deposits of the Terres Noires Fm., the Callovian-Oxfordian boundary is particularly well defined by ammonite taxa from different families (i.e. Cardioceratidae, Oppeliidae, Aspidoceratidae and Perisphinctidae), calcareous nannoplankton (first occurrence of large-sized Stephanolithion bigotii) and dinoflagellate cysts (first occurrence of Wanaea fimbriata). This precise biostratigr…
Atlas des fossiles caractéristiques du Lias portugais III a) Domérien (Ammonites).
2007
45 pages; International audience; Ce fascicule est le troisième de l'Atlas des fossiles caractéristiques du Lias portugais; il fait suite au fascicule I consacré aux faunes du Lias Inférieur (Hettangien-Sinémurien) et au fascicule II dédié aux faunes de la première partie du Lias Moyen (Carixien). Le fascicule III est consacré à la deuxième partie du Lias Moyen, le sous-étage Domérien. Contrairement aux publications précédentes, le présent travail se restreint aux seules ammonites. Une cinquantaine d'espèces sont brièvement décrites et figurées. Les autres taxons (nautiles, bélemnites, brachiopodes, lamellibranches...) feront l'objet d'un prochain fascicule. Le but de l'Atlas des fossiles c…
La transgression cénomanienne et l'âge des "Tourtias" du nord du bassin de Paris (F) et du bassin de Mons (B).
2010
29 pages; National audience