Trilobite faunal dynamics on the Devonian continental shelves of the Ardenne Massif and Boulonnais (France, Belgium)

During the Devonian the sedimentation on the continental shelves of Ardenne Massif and Boulonnais has changed from a mixed siliciclastic-carbonate ramp (Eifelian), through a carbonate barrier reef (Givetian) and then to a detritic influx with local mud-mounds (Frasnian). Here we analysed the faunistic dynamics of the trilobite associations through the changing environment. We used multivariate analyses (clustering and ordering) to discriminate the trilobite associations within 67 different samples. Three previously known communities and one new were recognised: the Eifelian Mixed association, the Givetian Dechenella association and the two Frasnian Bradocryphaeus and Scutellum-Goldius associations. These trilobite faunas present a progressive ecological specialisation. The Mixed association occurs both in the ramp or carbonated (local reef developed on the ramp) facies without any significant difference in its composition. The Dechenella fauna occurs preferentially close to barrier reefs, but can also survive during short periods of detrital input. The two Frasnian communities show a strong relationship with their environment. The Scutellum-Goldius association is only found in reef systems, whereas the Bradocryphaeus flourishes exclusively in lateral facies.Fil: Bignon, Arnaud Marcel Jacques. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; ArgentinaFil: Crônier, Catherine. Universite Lille 3; Franci

FRASNIAN (UPPER DEVONIAN) BRACHIOPODS FROM ARMENIA: BIOSTRATIGRAPHIC AND PALAEOBIOGEOGRAPHIC IMPLICATIONS

An assemblage of seven brachiopod species belonging to the orders Rhynchonellida, Atrypida and Spiriferida are studied from three localities (Ertych, Djravank and Noravank) of Central Armenia. The examined material is recovered from shallow water nodular limestones and provides insights into the diversity of Frasnian brachiopods on that part of the northern margin of Gondwana preserved within the South Armenian Block. The revision of Atrypa (Planatrypa) ertichensis, a biostratigraphically significant species for the Frasnian of the Lesser Caucasus (Armenia and Nakhichevan), revealed the presence of frills, an ornamental feature rarely observed in Atrypa (Planatrypa) representatives and considered as unknown in this species. Taxonomic discussion also involves the selection of neotypes for Ripidiorhynchus gnishikensis and A. (P.) ertichensis. The newly described taxon, Angustisulcispirifer arakelyani n. gen., n. sp., appears to be one of the most biostratigraphically important species for the Frasnian of Armenia. The size variability of Cyphoterorhynchus koraghensis and Desquamatia (Seratrypa) abramianae is documented quantitatively for the first time and it shows a continuous and progressive growth without any distinct groupings; the former is a palaeobiogeographically important species for the Frasnian strata of the northern Gondwana margin. Pending the revision of the Pakistani and Iranian material ascribed to C. koraghensis, that may include several subspecies, a plaster cast of its lectotype from the Frasnian of Kuragh in Chitral (northwest Pakistan) and the holotype as well as one of the paratypes of Cyphoterorhynchus koraghensis interpositus from the Frasnian Bahram Formation of the Ozbak-Kuh region in eastern Iran are illustrated herein. Finally, a new Frasnian brachiopod zone, namely the Ripidiorhynchus gnishikensis–Angustisulcispirifer arakelyani assemblage Zone is here introduced for the studied sections. Although its base and top cannot be identified, it is constrained to the Frasnian based on conodonts identified in the Djravank section. It may be considered as a partly lateral equivalent of the Cyrtospirifer subarchiaci–Cyphoterorhynchus arpaensis brachiopod Zone established in Nakhichevan

Fossiles cambriens de la région barrandienne (République tchèque) conservés au Musée d'Histoire Naturelle de Lille

A complete list of fossils originating from the Cambrian of the Barrandian area and housed in the Musée d'Histoire Naturelle de Lille is compiled. The collection includes two agnostids, ten trilobites, one brachiopod and one echinoderm species, all collected at ten outcrops in the Buchava Formation of the Skryje-Týřovice Basin and most probably also at two outcrops in the Jince Formation of the Příbram-Jince Basin. A large part of the material was collected by Prof. Charles Barrois and Dr. Louis Dollé (both University of Lille) during the excursion organised before the Ninth International Geological Congress in Vienna in 1903. Other, poorly documented specimens were purchased from the enterprise Krantz towards the end of the 19th century and in the first years of 20th century. The geographic position and stratigraphy of outcrops, from which the material originates, are briefly discussed.Une liste complète des fossiles provenant du Cambrien de la région barrandienne déposés au Musée d'Histoire Naturelle de Lille a été établie. La collection comprend deux espèces d'agnostidés, dix trilobites, un brachiopode et un échinoderme ; les fossiles récoltés dans dix affleurements proviennent tous de la Formation Buchava du bassin de Skryje-Týřovice et probablement également de deux affleurements de la Formation Jince du bassin de Příbram-Jince. Une grande partie du matériel a été récoltée par le Professeur Charles Barrois et par le Dr. Louis Dollé (de l'Université de Lille) au cours de l'excursion organisée avant le VIIIème Congrès géologique national à Vienne en 1903. Les autres spécimens, mal documentés, ont été achetés à l'entreprise Krantz à la fin de 19ème siècle et dans les premières années du 20ème siècle. La situation géographique et la stratigraphie des affleurements d'où provient le matériel sont brièvement discutées

Ontogeny of an ordovician trinucleid (Trilobita) from Armorica, France: a morphometric approach

8 fig., 2 tabl.A large number of well-preserved immature exoskeletons enable the first detailed quantitative description of the ontogeny of the trinucleid Marrolithus bureaui (Oehlert, 1895) from the Lower Caradoc of the Armorican Massif (Armorica, northwest France). For the accurate description of cephalic features, a landmark-based approach was adopted in order to recognize ontogenetic instars and to establish the patterns of size increase and shape change during ontogenetic development. The quantitative analysis permitted the demonstration of a progressive shape change in agreement with ontogenetic ordination and a comparison of the timing of size and shape changes. Changes that took place during the meraspid period included, in particular, the development of a more pronounced sub-quadrangular cephalic outline, a compression (sag.) of the glabella and a size decrease until disappearance of the alae in late stages. This quantitative ontogenetic reconstitution of Marrolithus bureaui might be considered as a reference for the better understanding of phylogenetic affinities between other trinucleid species

La diversité morphologique du porc en tant qu’indicateur des mécanismes de gestion de l’élevage porcin et de l’approvisionnement des villes romaines: Apport de l’analyse du contour des troisièmes molaires inférieures du porc

Revue du Nord, Hors série. Collection Art et Archéologie, N° 21. Université Charles-de-Gaulle Lille 3, 201

Les hétérochronies du développement : un outil pour l'étude de la variabilité et des relations phylétiques ? Exemple de <i>Nigericeras</i>, Ammonitina du Crétacé supérieur africain

L\u27ontogenèse de  Nigericeras  gadeni (Crétacé supérieur saharien)  est caractérisée par trois stades ornementaux : multituberculé dans les tours internes, bituberculé puis lisse en fin de croissance. Les Hétérochronies du Développement permettent de décrire sa variabilité adulte, entre un type orné–épais pédomorphique et un type lisse-mince péramorphique. Cette espèce s\u27enracine au sein du genre Pseudocalycoceras. Une dérive péramorphique marque l\u27évolution de ces ammonites et de leurs descendants, aboutissant à des taxons morphologiquement très comprimés, différents au Niger et au Nigéria. Les taxons paraissent en adéquation avec des milieux très peu profonds. Le contexte transgressif général induit une raréfaction progressive de leurs niches écologiques.The Nigericeras gadeni ontogenesis (Saharian Upper Cretaceous) is characterized by three ornamental stages: multi-tuberculate inner-whorls, ombilical bi-tuberculate medium-whorls, then finally smooth adult stage. Ontogenetic Heterochonies account for their adult variability, which extends between both paedomorphic (thick/ornamented) morphotype, and peramorphic (thin/smooth) morphotype. That species may take root in the older Pseudocalycoceras. A peramorphocline characterizes the evolution of these ammonites and their younger relatives, leading to different Nigerian and Nigerien, highly compressed taxa. Such morphologies seem to be related to shallow-water palaeo-environments. The general transgressive context leads to the progressive scarcity of their supposed ecological niches.</p

Morphology and ontogeny of an Early Devonian Phacopid Trilobite with reduced sight from Southern Thailand

International audienc

The systematics and phylogeny of the Devonian subfamily Asteropyginae (Trilobita: Phacopida)

Traditionally, the evolutionary scenarios of Asteropyginae have been organized in two major clades involving four pygidial patterns. The first cladistic analysis performed on the subfamily maintained the organization in two clades, though the phylogenetic relationships between genera were unexpected compared to the traditional scenarios. Moreover, the previous systematic scheme based on pygidial segmentation was rendered obsolete. In this study, we performed a new phylogenetic analysis from well-known taxa and recent discoveries. Sixty species assigned to 36 genera have been analysed from a dataset of 72 characters. Three more species are used as the outgroup. The 79 most parsimonious trees have a length of 492 steps and a retention index of 0.735. Our analysis confirms the monophyly of Asteropyginae excluding the genus Protacanthina. The phylogenetic pattern is unconventional in that a largely pectinate topology is resolved, rather than two clades corresponding to formerly delimited pygidial morphs. Nevertheless, most relationships between genera suggested in the traditional evolutionary scenarios of the subfamily have been recovered, the main differences being the origin of the group. Whereas Treveropyge was usually considered as the origin of the remaining Asteropyginae, the present results instead identify Destombesina as the sister group to all remaining members of the subfamily. From the new phylogenetic pattern, the diagnoses of genera are rewritten in a standard way and to delimit clades more accurately. This work implies modified generic assignments for some species and the erection of four new genera: Minicryphaeus gen. nov., Gandlops gen. nov., Morzadecops gen. nov. and Pennarbedops gen. nov. The systematic position of Erbenochile is also discussed, the genus no longer being assigned to Asteropyginae.Fil: Bignon, Arnaud Marcel Jacques. Université Lille 1; Francia. University of Yale; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Crônier, Catherine. Université Lille 1; Franci