Les mollusques de Bourgogne-Franche-Comté : vers un nouvel inventaire.

8 pages; National audience

Hettangian ammonites from the old iron mine of Beauregard (Thoste, Côte-d’Or, France).

The ammonite fauna of the old iron mine of Beauregard is reviewed. Only nine specimens from this locality are presently known. They are housed in the collections of the “Musée de Semur-en-Auxois”, of the “Muséum national d’Histoire naturelle” (Paris) and of the “Ecole Nationale Supérieuredes Mines” (Claude Bernard University, Lyon 1). The age, or possibly the ages, of these ammonites remain to precise in a coarsely defined time-span including the upper part of the early Hettangian and the middle Hettangian (pro parte?). These fossils, usually finely preserved, were collected during the nineteenth century thanks to intensive mining in the Thoste-Beauregard area. They are illustrated uniforml…

Homéomorphies et canalisations évolutives: Le rôle de l'ontogenèse.Quelques exemples pris chez les Ammonites du Jurassique

Resume La signification paleobiologique des homeomorphies et des processus evolutifs homologues qui les ont induits, sont analyses a partir de 7 exemples choisis parmi les ammonites du Jurassique. Les formes etudiees sont soit largement repandues soit endemiques dans les mers de plates-formes de l'Europe moyenne ou regnaient au cours du Jurassique des conditions ecologiques bien differentes de celles des regions mediterraneennes-plus oceaniques-ou vecurent la plupart des ancetres de ces formes. Il est montre que les tendances evolutives repetitives observees peuvent souvent etre comprises comme les resultats de strategies evolutives impliquant, au sein de chaque groupe analyse, l'adoption p…

Le visage du monde au Sinémurien.

9 pages; National audience

Breccias of the Adnet Formation: indicators of a Mid-Liassic tectonic event in the Northern Calcareous Alps (Salzburg/Austria)

Stratigraphy, lithology and depositional structures of Liassic red limestone-breccias of the Adnet Formation, including the ‘Adnet Scheck’, were studied at several outcrops of the Northern Calcareous Alps (NCA) south-east of Salzburg. A four-fold lithostratigraphic division is proposed for the Adnet Formation of the Osterhorn Mountains: the hemipelagic Schmiedwirt (Sinemurian) and Kehlbach (Carixian) members are separated from the pelagic Saubach Member (Toarcian) by a layer of amalgamated breccias (Scheck Member, probably Domerian to early Toarcian). Several other breccia beds occur locally from the base of the Kehlbach Member up to the lower Saubach Member. Although the sediments overlyin…

Evolution of ammonoid morphospace during the Early Jurassic radiation

The morphologic radiation of Early Jurassic ammonites following the near extinction at the end of the Triassic is analyzed from 436 species of 156 genera that form a representative sample of morphs occurring worldwide in the first three stages of the Jurassic (Hettangian, Sinemurian, Pliensbachian: 36 subzones, 24 m.y.). Morphologic diversity is analyzed independently of taxonomy by processing 18 shape parameters using multivariate analysis and clustering techniques. The morphospace thus defined indicates that morphs fall readily into two groups made up of four and five adjacent morpho-subsets. The temporal pattern of morphospace occupation in the 36 Lower Jurassic subzones displays diversi…

Geometric Measurement Analysis Versus Fourier Series Analysis for Shape Characterization Using the Gastropod Shell (Trivia) as an Example

Varied and efficient methods have been developed to describe and quantify natural objects. The most common ones use superimposition techniques (e.g. Procrustes methods; Bookstein, 1991), decomposition into harmonics (Fourier series and functions, wavelets; Anstey and Delmet, 1973; Christopher and Waters, 1974; Gevirtz, 1976; Lestrel, 1997; Toubin and others, 1999; Verrecchia, Van Grootel, and Guillemet, 1996; Younger and Ehrlich, 1977), analysis of spiral functions (e.g. Raup parameters; Raup, 1961, 1966; Tursch, 1998), and combinations of parameters from elementary geometry (e.g. circularity index, lengthening; Coster and Chermant, 1989; Schmidt-Kittler, 1986; Viriot, Chaline, and Schaaf, …

Colourblind taxonomy.

3 pages; International audience

Trajectoires ontogénétiques et hétérochronies complexeschez des ammonites (Harpoceratinae) du Jurassique inférieur (Domérien)

Evolutive transformations of ontogeny in the two main groups of Harpoceratinae which colonize the North-West Europe during the lower Domerian — Protogrammoceras (Matteiceras) and Protogrammoceras (Fieldingiceras) — are analyzed. Within P. (Matteiceras) these transformations belong to a strict heterochronical logic (translation of a standard ontogenetic trajectory). Within P. (Fieldingiceras) the alterations of the ontogeny cannot be placed in a same logic. Moreover, the P. (Matteiceras) heterochronical issues are complex: paedomorphic (neoteny) and peramorphic (acceleration) tendencies appear on both sides of critical point (inversion point) for a same feature, the ribs density.

Les ammonites de l'Hettangien, du Sinémurien et du Pliensbachien inférieur de la Dorsale de Grande Kabylie (Algérie).

Dommergues, Jean-Louis, Cattaneo, Gérard, Aïte, Ramdane, Gélard, Jean-Pierre (2008): Les ammonites de l'Hettangien, du Sinémurien et du Pliensbachien inférieur de la Dorsale de Grande Kabylie (Algérie). Geodiversitas 30 (3): 539-576, DOI: http://doi.org/10.5281/zenodo.5378393

The Jurassic ammonite Coelocerus: an atypical example of dimorphic progenesis elucidated by cladistics

Instances of convergence or parallelism among unrelated Lower Carixian ammonites are not uncommon. The case of polymorphitid-like ammonites is considered here, and the example of Coeloceras is investigated in detail. The small sexual dimorph (microconch) of Coeloceras pettos (Quensitedt) (Coeloceratidae), a progenetic species, provides a remarkable example of complex convergence with the microconch of Uptonia (Polymorphitidae). Homeomorphic morphology is here an amalgam of juvenile traits, of maturation-related transformations, and of completely new features bearing no obvious relation with either progenesis or maturation. A stratophenetic approach is hardly adequate for unravelling such an…

Alcide Dessalines d’Orbigny (1802-1857).

4 pages; National audience

Le cadre géographique et géologique.

2 pages; National audience

High-resolution dynamics of Early Jurassic marine extinctions: the case of Pliensbachian–Toarcian ammonites (Cephalopoda).

Abstract: The Pliensbachian–Toarcian interval was marked by major environmental disturbances and by a second-order mass extinction. Here, we reappraise the taxonomic, spatiotemporal and selective dynamics of extinctions over the whole interval, by analysing a high-resolution dataset of 772 ammonite species from NW Tethyan and Arctic domains. On average, 40–65% of ammonite species disappeared during each subchronozone, but higher extinction pulses (reaching 70–90%) prevailed from the Margaritatus to the Dispansum Chronozone. The main extinctions, corresponding to the Gibbosus, Pliensbachian–Toarcian boundary, Semicelatum, Bifrons–Variabilis, and Dispansum events, differed in their dynamics, …

Sinemurian to lowermost Toarcian ammonites of the Brescian Prealps (Southern Alps, Italy): preliminary biostratigraphical framework and correlations.

10 pages; International audience; A set of 28 ammonite biohorizons or faunal assemblages is proposed for the Sinemurian, the Pliensbachian and the lowermost Toarcian of the Brescian Prealps, in part based on the published data of the authors of this contribution and partly on new results, derived both from recent field investigations and from the study of the historical collection of Lower Jurassic ammonites preserved in the Museum of Natural Sciences of Brescia (Northern Italy). The biohorizons are present in the Liassic carbonate succession of the Brescian Prealps, cropping out between the eastern surroundings of Brescia (Botticino), to the east, and Lake Iseo, to the west. Since the Hett…

Size patterns through time: the case of the Early Jurassic ammonite radiation

The shell size of 1236 ammonite species representing all known Early Jurassic faunas is analyzed. Size patterns are studied for the entire period and then at the biozone scale for the first four stages of the Jurassic (28 Myr), during which ammonites recovered from the crisis at the Triassic/Jurassic (T/J) boundary. Our analysis reveals that (1) a size continuum (normal distribution from “dwarfs” to “giants”) exists for all Early Jurassic ammonites; (2) although there are no sustained trends (e.g., no Cope's rule), the succession is not monotonous and patterns may differ conspicuously from one biozone to the next; and (3) increases and decreases in size range are the most frequent evolution…

Stratotype Sinémurien.

320 pages; National audience

Deep-Time Phylogenetic Clustering of Extinctions in an Evolutionarily Dynamic Clade (Early Jurassic Ammonites)

7 pages; International audience; Conservation biologists and palaeontologists are increasingly investigating the phylogenetic distribution of extinctions and its evolutionary consequences. However, the dearth of palaeontological studies on that subject and the lack of methodological consensus hamper our understanding of that major evolutionary phenomenon. Here we address this issue by (i) reviewing the approaches used to quantify the phylogenetic selectivity of extinctions and extinction risks; (ii) investigating with a high-resolution dataset whether extinctions and survivals were phylogenetically clustered among early Pliensbachian (Early Jurassic) ammonites; (iii) exploring the phylogene…

Pseudoskirroceras, a remarkable but poorly known Early Pliensbachian Tethyan ammonite genus: New data from the High Atlas (Morocco).

13 pages; International audience; The discovery of new Early Pliensbachian ammonite faunas in Central High Atlas (Morocco) allows the re-examination of the taxonomic, stratigraphical and palaeogeographical framework of the genus Pseudoskirroceras, an intriguing but until now poorly known Tethyan taxon. For the first time, several specimens of Pseudoskirroceras mastodon (Fucini, 1935) the type species of the genus, have been collected in a well-known stratigraphical context. This material allows the evaluation of intra-specific variability and consequently the assessment of the taxonomical relevance of various geometrical and ornamental features. The best diagnostic features are the clearly …

Mollusca.

Early Jurassic normal faulting in a carbonate extensional basin: characterization of tectonically driven platform drowning (High Atlas rift, Morocco).

18 pages; International audience; This paper describes a tectonostratigraphic model of the synrift evolution of the Early Jurassic High Atlas rift of Morocco. The model is constrained by mapping of a set of inverted extensional blocks, by facies analysis of carbonate platform and turbiditic to hemipelagic synrift deposits, and by high-resolution (n 3 100 ka) biostratigraphy of the Early Jurassic succession. The chronostratigraphic packages of the High Atlas of Rich vary significantly in thickness, facies and architecture from one tectonic block to another. Our study shows how synrift strain varied in space and time over a long time interval (14 Ma) around the High Atlas rift. Initially, in …

Succession des faunes d'Ammonitesdu Sinémurien et du Pliensbachien dans les Préalpes médianes de Suisse romande (Vaud et Fribourg)

Resume L'analyse biostratigraphique et paleontologique des ammonites du Sinemurien et du Pliensbachien des Prealpes medianes de Suisse romande, permet de reconnaitre 15 horizons biostratigraphiques. Ils sont aisement correlables avec la zonation standard de l'Europe moyenne. Pour le Sinemurien superieur il existe des elements de comparaison tant avec la partie orientale de la nappe des Prealpes medianes (Langenegggrat, region de Thoune, Suisse) qu'avec sa partie meridionale (Chablais et klippes de Savoie, France). En effet, les faunes sont tres proches de celles de la region etudiee ici. Comme au Langenegggrat (Prealpes bernoises) et dans la plupart des gisements du Chablais (Savoie), les f…

Les ammonites du Pliensbachien du jebel Bou Rharraf (Haut Atlas oriental, Maroc).

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…

Le cadre stratigraphique.

5 pages; National audience

La notion d'espace morphologique,outil d'analyse de la morphodiversité des organismes

Resume L'analyse de la morphologie des organismes est une base essentielle dans la mise en evidence des changementsevolutifs. La morphologie est maintenant frequemment abordee par des procedures quantitatives, dont certaines permettent de construire de veritables cartes morphologiques ou les dissemblances et ressemblances de formes entre les organismes sont directement lisibles et quantifiees. La notion d'espace morphologique, illustree ici par differents exemples, se revele particulierement feconde pour comprendre comment la diversite morphologique d'un ensemble d'organismes (stades ontogenetiques, populations, clades) se structure, et par consequent pour interpreter en termes evolutifs ou…

Henri Tintant (1918-2002).

1 page; National audience

Ammonite diversity and its palaeobiogeographical structure during the early Pliensbachian (Jurassic) in the western Tethys and adjacent areas.

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…

Les ammonites du Sinémurien de Mandelot (Côte-D'or, France). Approches biostratigraphique, morphologique et ontogénétique

Resume L'etude des faunes d'ammonites du Sinemurien de la coupe inedite de Mandelot a permis d'apporter des precisions,pour une trentaine de taxons, soit sur l'ontogenese, soit la la variabilite ou la position stratigraphique. Ces especes qui, pour l'essentiel, sont des arietitides se rattachent essentiellement aux zones a Semicostatum, Turneri et Obtusum. Certains Coroniceras, Caenisites, Agassiceras, Asteroceras et Epophioceras , sont des formes souvent tres mal connues dont les positions stratigraphiques et les modalites ontogenetiques sont, ici, precisees pour la premiere fois. Ce travail est donc a la fois un element a la connaissance du Sinemurien de la Bourgogne, region du stratotype…

Fuciniceras paradoxus nov. sp. (Harpoceratinae, Ammonitina) du Domérien portugais. Réflexion sur le sens taxonomique d’un assemblage paradoxal de caractères

A new ammonite (Fuciniceras paradoxus) is described here. This Lower Domerian species is based on a recently revised collections which came from the Maria Pares section (Rabacal area, South of Coimbra, Portugal). Curiously, shell of F. paradoxus bears both diagnostic traits for the genus Protogrammoceras SPATH (e.g. acute ogival ventral area) and Fuciniceras HAAS (e.g. angulirursiradiate rib). Thus, the new species can be viewed as a morphological puzzle and as a challenge for taxonomists. The amazing collection of morphological traits previously suspected as highly improbable because of biomechanical constraints (1) confirms the inadequacy of the traditional use of the genera Protogrammoce…

Ammonite paleobiogeography during the Pliensbachian-Toarcian crisis (Early Jurassic) reflecting paleoclimate, eustasy, and extinctions.

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…

Biogéographie des ammonites jurassiques et reconstitution palinspastique de la Téthys

Resume— La distribution geographique des ammonites jurassiques est regie par deux causes fondamentales : l’ecologie et l’histoire evolutive (evenements vicariants). L’analyse conjointe de ces deux facteurs permet de reconnaitre : d’une part des taxons dont la distribution est essentiellement controlee par des contraintes ecologiques (Phylloce-ratinae et Lytoceratinae, lies a des environnements oceaniques profonds; Clydoniceratidae et Proplanulitinae lies a des plates-formes assez superficielles); d’autre part des taxons dont l’histoire evolutive est associee a des evenements vicariants (Ammonitina liasiques euro-boreales et Cardioceratidae-Kosmoceratidae boreaux du Jurassique moyen).Les exe…

Les ammonites du Sinémuriensupérieur du Jebel-Bou-Hamid (Haut-Atlas central, Rich, Maroc). Approches paléontologique et biostratigraphique

Resume L'etude des faunes d'ammonites - plus de 25 taxons - et de leur succession biostratigraphique dans unecoupe exceptionnellement complete et fossilifere du Haut-Atlas central de la region de Rich (Maroc) a permis la mise en evidence de 10 unites biochronologiques elementaires (=assemblages) pour une periode debutant au sein de la partie terminale du Sinemurien inferieur et s'achevant avec le Sinemurien superieur. Pour les zones a Oxynotum et Raricostatum, il s'agit des premieres donnees biostratigraphiques collectees avec une telle precision dans le Nord de l'Afrique. Pour le Sinemurien inferieur et la zone a Obtusum, les nombreuses donnees nouvellement acquises, completent, precisent …

Leptechioceras (Neomicroceras) Donovan, 1966 (Ammonitina, Echioceratidae, Sinémurien, Europe du Nord-Ouest): Taxon progénétique ou microconque?

Resume Des faunes d'ammonites inedites collectees banc par banc dans des series epaisses a dominante argileuse duSinemurien terminal du Bassin parisien (Cher, France) sont decrites. Certains des peuplements etudies sont esentiellement constitues d'ammonites de petite taille attribuees au sous-genre Leptechioceras (Neomicroceras) ; le rattachement de ces formes aux Echioceratidae, alors qu'elles etaient initialement interpretees comme des Eoderoceratidae, est base sur des arguments cladistiques et est confirme par les observations stratigraphiques. Une nouvelle espece, la plus tardive du sous-genre, Leptechioceras (Neomicroceras) sparsicosta est decrite. L'originalite en termes d'heterochron…

Croissance et miniaturisation de quelques Hildoceras (Cephalopoda) en liaison avec des environnements contraignants de la Téthys toarcienne

Resume La zone a Bifrons (Toarcien moyen) est une perode bien etudiee du point de vue stratigraphique tant en Europe occidentale (marge NW de la Tethys et plates-formes adjacentes) qu'en Italie et Afrique du Nord (marge sud de la Tethys). Dans ces regions, la succession zonale est basee sur l'evolution des Hildoceras. Cependant, on remarque que certains d'entre eux, quelle que soit leur place dans la lignee, presentent des particularites ornementales et dimensionnelles, manifestement liees au gisement dont ils sont, issus et aux conditions qui y regnaient. C'est particulierement le cas des sites d'Italie centrale et d'Algerie situes dans les fonds des ombilics de sedimentation crees par la …

La Dalle aux ammonites de Digne‑les‑Bains : un patrimoine d’âge Sinémurien de réputation mondiale.

6 pages; National audience

The recovery and radiation of Early Jurassic ammonoids: morphologic versus palaeobiogeographical patterns

Abstract The recovery and radiation of the Early Jurassic ammonoid morphospace, as represented by nine morphologic groups identified in an earlier study, are traced through the first 36 subzones of the Hettangian to Domerian time interval. A quantitative survey of the dispersion of 436 species over 15 palaeogeographical areas reveals seven palaeobiogeographical patterns, each corresponding to an exclusive set of species exhibiting similar characteristics in terms of distribution and abundance. This study combines morphologic, chronostratigraphical, and palaeobiogeographical data in an attempt to investigate possible connections between morphologic recovery and radiation patterns and the his…

The Global Boundary Stratotype Section and Point (GSSP) for the base of the Pliensbachian Stage (Lower Jurassic), Wine Haven, Yorkshire, UK

14 pages; International audience; Following votes by the Pliensbachian Working Group, the Jurassic Subcommission and the International Commission on Stratigraphy, IUGS ratified the proposed Global Boundary Stratotype Section and Point (GSSP) for the base of the Pliensbachian Stage (Lower Jurassic) at the base of bed 73b in the Wine Haven section, Robin Hood's Bay, Yorkshire Coast, UK. This level contains the characteristic ammonite association Bifericeras donovani Dommergues and Meister and Apoderoceras sp. Complementary data include: a) Strontium-isotope stratigraphy, based on analysis of belemnites which yield a calcite 87Sr/86Sr ratio for the boundary level of 0.707425 and data supportin…

Les ammonites.

Succession des faunes d'ammonites au Langenegggrat (Préalpes médianes, région de Thoune, Suisse): Une série de référence dans le Sinémurien supérieur

Resume Las succession detaillee des peuplements d'ammonites recoltes dans le Sinemurien superieur (Lotharingien) du Langenegggrat est presentee ici. Ces faunes, qui se repartissent en 5 associations stratigraphiquement distinctes, appartiennent a la partie superieure de la zone a Oxynotum et a la zone a Raricostatum. L'une de ces associations est particulierement originale; elle caracterise la base de la sous-zone a Macdonnelli et est largement dominee par Paltechioceras boehmi. Ces resultats conduisent a un affinement de la biostratigraphie du Sinemurien superieur de cette region et permettent une meilleure comprehension de la paleobiogeographie des regions alpines au cours du Lias inferie…

Jean-Jacques Collenot (1814-1892).

3 pages; National audience

Deux espèces sous un même masque. Le point de vue paléontologique piégé par les coquilles de deux espèces européennes de Trivia (Mollusca, Gastropoda).

16 pages; Lʼexpérience tentée dans ce travail a pour but dʼévaluer certaines conséquences des lacunes dʼinformation liées à la fossilisation sur la perception de lʼespèce en paléontologie. Cette expérience consiste à mener une étude de « type paléontologique » sur du matériel actuel puis à relire les résultats à la lumière des connaissances biologiques. Lʼobjet et le cadre de lʼétude ont donc été sélectionnés pour disposer dʼun matériel abondant et de bonne qualité dans un contexte spatio-temporel bien défini, et ainsi permettre de simuler ou non des lacunes dʼinformation. Trivia arctica et T. monacha, deux espèces proches de gastéropodes marins actuels vivant dans les eaux infra-littorales…

Succession des faunes d'Ammonites du Sinémurien supérieurdans le Chablais méridional et les Klippes de Savoie (Préalpes Médianes, Haute-Savoie, France)

Resume L'etude biostratigraphique et paleontologique des faunesd'ammonites du Sinemurien superieur et du Carixien basal dans le Chablais meridional (series reduites) et les Klippes de Savoie (series dilatees) permet de reconnaitre 9 horizons biostratigraphiques aisement correlables avec la zonation standard de l'Europe moyenne. Par leur contenu faunique les coupes etudiees sont tres proches de celles de la partie septentrionale des Prealpes medianes (Langenegggrat, region de Thoune, Suisse). En outre, les sequences reduites du Chablais presentent de remarquables analogies lithologiques avec celle du Langenegggrat. En termes paleobiogeographiques les faunes subbrianconnaises des Prealpes med…

L'approche paléontologique des concepts biologiques de l'espèce : défi pour l'étude de la paléobiodiversité. L'exemple des ammonites jurassiques.

12 pages, publié sous l'égide de France Orchidées et de la Société Linnéenne de Lyon.; National audience

Présence en Bourgogne d'Epideroceras hugi Donovan, 1958, une ammonite rare du Sinémurien supérieur : ontogenèse, statut spécifique et parenté.

9 pages; National audience; Un spécimen remarquablement bien conservé d'Epideroceras hugi Donovan, 1958, a été récolté dans le Sinémurien supérieur (chronozone à Raricostatum, sous-chronozone à Macdonnelli) de Drevin (Sâone-et-Loire). E. hugi est un Eoderoceratoidea de grande taille qui n'était jusqu'à présent connu avec certitude que dans un seul gisement des Préalpes médianes suisses. E. hugi est une forme qui appartient au groupe d'E. lorioli (Hug, 1899), taxon assez commun aux abords immédiats de la marge septentrionale de la Téthys occidentale et dans quelques régions relativement peu éloignées de cette marge : le Caucase, le domaine austro-alpin, le sud-ouest de l'Allemagne, l'est de …

Calculating the long-term displacement rates of a normal fault from the high-resolution stratigraphic record (early Tethyan rifting, French Alps)

Displacement rates of normal faults deduced from stratigraphic data are often unreliable. Here we calculate the velocity of motion on a normal fault from the variations in accommodation potential on both sides of the fault within a highresolution time-frame established by biostratigraphy and physical stratigraphy. Our example is the Ornon normal fault bounding the Early Jurassic Bourg-d’Oisans Basin formed during Tethyan rifting. We show that motion on the fault was discontinuous when examined at high resolution and over a long time interval. During a first interval (Hettangian to Sinemurian Arietites bucklandi zone) a low rate of displacement (= 202–423 m Myr -1 ) coeval with diffused exte…

Les sites complémentaires.

6 pages; National audience

Le site stratotypique.

6 pages; National audience

Les ammonites pliensbachiennes des nappes Lyciennes (Turquie méridionale). Description de faunes nouvelles, implications biostratigraphiques et paléobiogéographiques

Resume Le present travail est la premiere description de faunes d'ammonites d'âge Pliensbachien (Carixien moyen a superieur et surtout Domerien) issues de Turquie meridionale (Nappes lyciennes du Taurus occidental). Ces faunes proviennent de l'unite de Kisilka-Corak (gisement de Kizilca, region de Tavas) et de l'unite de Gumuslu (gisements d'Ayiburnu Tepe et du Koru Dag, region de Korkuteli). Elles comprennent 32 especes et caracterisent sept niveaux biostratigraphiques distincts. Deux formes nouvelles du Carixien sont decrites : Lytoceras kisilcus nov. sp. et Fuciniceras lycius nov. sp. Les peuplements lyciens sont essentiellement composes de Juraphyllitidae, Lytoceratoidea, Dactyliocerati…

Presence of the genus Bythinella Moquin-Tandon, 1856 (Gastropoda, Bythinellidae) and other hydrobioids in Saône-et-Loire (Burgundy, France): taxonomic considerations and conservation issues.

While listing spring-dwelling snails in the regionBourgogne Franche-Comté (eastern France), we found threelocalities with living representatives of the genus BythinellaMoquin-Tandon, 1856 in the department of Saône-et-Loire. Toour knowledge, they represent the only Bythinella -bearinglocalities currently known in this department. The sampledindividuals share several shell features with B. carinulata(Drouët, 1867), B. viridis (Poiret, 1801) and B. lanceleveiLocard, 1884. Pending a complementary genetic analysis, weidentify these specimens as Bythinella sp. Two of the threelocalities also yielded empty shells of Islamia andBythiospeum . They represent the westernmost occurrence ofthese stygob…

René Mouterde (1915-2007).

2 pages; National audience

Mature Modifications and Dimorphism in Ammonoid Cephalopods

The shell of an ammonoid is a kind of autobiography of the animal that once occupied it. Different parts of the shell tell different parts of the life history. The growth lines and the tiny intervals in between, along with the shape of the shell itself, record what was happening at the anterior end of the body. The septa and their sutures relate the tale of the other extremity.

Ammonites phylogenetic analysis: state of the art and new prospects

Abstract Two main types of data are available to resolve phylogenies using fossils data: (1) stratigraphic ordering of taxa, and (2) morphological characters. In most phylogenetic studies dealing with ammonites, authors have given priority to the stratigraphic distribution of taxa. This practice is classically justified by the fact that the ammonite fossil record is frequently outstandingly good. In practice, the level of integration of stratigraphic and morphologic information in a single analysis depends on the confidence that authors have in the quality of data. Besides, many evolutionary concepts, which could differ over time and between authors (e.g. anagenesis, cladogenesis, iterative…

Exploration of the Oxynoticeratidae ornamental morphospace using the discrete cosine transform (DCT) to analyze rib patterns.

The discrete cosine transform (DCT) is a Fourier-related transform widely used in signal processing and well suited to analyzing open outlines such as ammonite ribs. The method is applied here to depict and decipher the ribbing morphospace of a large group of Lower Jurassic ammonites composed of the Oxynoticeratidae and their close ancestors. Because they are clearly associated with buoyancy and/or swimming ability, the usually clearly involute, comparatively smooth and compressed shells of these ammonites may well be misleading taxonomic markers. In this context, quantitative analysis of the ribbing pattern using the DCT may significantly improve our perception of the ornamental patterns e…

Episodic deposition of the Lias in the Medianes nappe (western Switzerland): a record from mineralized ammonite-bearing beds

Abstract Sinemurian and Pliensbachian depositional sequences from the starved distal northern continental margin of the Tethys are preserved in the Medianes Nappe (Western Swiss Prealps). They contain mineralized beds which include a variety of facies. The northern continental margin of the Tethys was broken into blocks, less than 50 km wide, during an extensional phase. The Sinemurian and Pliensbachian sediments in the study are vary in thickness from less than 50 m in the north to more than 200 m in the south. Although the upper Sinemurian to Pliensbachian mineralized beds are thin, between 0.10 and 0.50 m thick, they commonly contain several distinct faunal horizons stacked one upon anot…

Gauging scale effects and biogeographical signals in similarity distance decay analyses: an Early Jurassic ammonite case study.

17 pages; International audience; In biogeography, the similarity distance decay (SDD) relationship refers to the decrease in compositional similarity between communities with geographical distance. Although representing one of the most widely used relationships in biogeography, a review of the literature reveals that: (1) SDD is influenced by both spatial extent and sample size; (2) the potential effect of the phylogenetic level has yet to be tested; (3) the effect of a marked biogeographical structuring upon SDD patterns is largely unknown; and (4) the SDD relationship is usually explored with modern, mainly terrestrial organisms, whereas fossil taxa are seldom used in that perspective. U…

Distribution of clay minerals in Early Jurassic Peritethyan seas: palaeoclimatic significance inferred from multiproxy comparisons.

13 pages; International audience; A set of published, unpublished, and new clay mineral data from 60 European and Mediterranean localities allows us to test the reliability of clay minerals as palaeoclimatic proxies for the Pliensbachian–Toarcian period (Early Jurassic) by reconstructing spatial and temporal variations of detrital fluxes at the ammonite biochronozone resolution. In order to discuss their palaeoclimatic meaning, a compilation of low-latitude belemnite δ18O, δ13C, Mg/Ca, and 87Sr/86Sr values is presented for the first time for the whole Pliensbachian– Toarcian period. Once diagenetic and authigenic biases have been identified and ruled out, kaolinite content variation is cons…

Adaptive radiation in the fossil record: a case study among Jurassic ammonoids

15 pages; International audience; Evolutionary radiations have been extensively studied especially in the fossil record and in the context of postcrisis recoveries. The concept of adaptive radiation that emerges from this very broad topic explicitly involves the effect of adaptation driven by ecological opportunity and is considered to be of the foremost importance. It is essential to be able to detect adaptive radiation because it points up factors that predispose a clade to radiate. Adaptive radiation has received much attention in recent decades based mostly on studies dealing with recent clades, but data from the fossil record are still scarce. This study begins to fill this gap with th…

La biodiversité au Sinémurien.

3 pages; National audience

Endemism as a palaeobiogeographic parameter of basin history illustrated by early- and mid-Liassic peri-Tethyan ammonite faunas

Abstract Episodes of endemism during Sinemurian–Pliensbachian times are described from synthetic data (publications and unpublished collections) about ammonite faunas of the western reaches of the Tethys. The Lusitanian, Sub-Betic and High Atlas basins receive special attention. The study shows that (1) endemism occurs principally in the Lusitanian and High Atlas basins, which are the most confined palaeogeographic structures; (2) it tends to occur synchronously in different basins but involving different taxa, i.e. it is independent of phylogeny; (3) it is not obviously correlated with relative sea-level at any given time. However, the fact that episodes of endemism coincide with second-or…

Origine du nom et situation de l’étage Sinémurien dans l’échelle des temps géologiques.

5 pages; National audience

La lumachelle à Cardinia (Bivalves) et Alsatites (Ammonites) du " Revers de Côte Dure " dans l'Hettangien de la couverture sédimentaire du Massif du Rochail (Oisans, Isère, France).

29 pages; International audience; Ce travail est consacré à l'étude d'une faune de l'Hettangien moyen (Chronozone à Liassicus, Sous-Chronozone à Laqueus) qui, relativement peu diversifiée, mais très abondante et bien préservée, caractérise un niveau lumachellique spectaculaire dans la série du Jurassique inférieur, globalement peu fossilifère, de la couverture sédimentaire, du massif du Rochail (Bassin subalpin, zone dauphinoise). Cette faune, qui provient du Revers de Côte Dure (Villard-Notre-Dame, Isère, France), est essentiellement composée de bivalves (e.g., Cardinia, " Astarte ") et d'ammonites (e.g., Alsatites, Saxoceras), mais elle livre aussi, surtout au sommet du banc lumachellique…

The shell matrix of the pulmonate land snail Helix aspersa maxima.

12 pages; International audience; In mollusks, the shell mineralization process is controlled by an array of proteins, glycoproteins and polysaccharides that collectively constitute the shell matrix. In spite of numerous researches, the shell protein content of a limited number of model species has been investigated. This paper presents biochemical data on the common edible land snail Helix aspersa maxima, a model organism for ecotoxicological purposes, which has however been poorly investigated from a biomineralization viewpoint. The shell matrix of this species was extracted and analyzed biochemically for functional in vitro inhibition assay, for amino acid and monosaccharides composition…

Le Sinémurien de la région de Semur-en-Auxois (Jurassique inférieur, Sud-Est du bassin de Paris, France), localité type historique de l’étage Sinémurien de d’Orbigny.

Oxyarietites boletzkyi n. gen., n. sp., nouveau genre et nouvelle espèce d'ammonite dans le Sinémurien inférieur de Bourgogne (France) : un rare précurseur des morphologies oxycônes pour le Jurassique.

13 pages; International audience; L'une des toutes premières ammonites à coquille presque oxycône observée dans les séries fossilifères après la crise faunique de la limite Trias/Jurassique est décrite. Elle provient du Sinémurien inférieur (chronozone à Semicostatum ou à Turneri) de Bourgogne (Mavilly-Mandelot, Côte-d'Or, France). Cette nouvelle forme, Oxyarietites boletzkyi n. gen., n. sp., possède une coquille involute, comprimée et carénée dont le type clairement suboxycône est nouveau pour le Sinémurien inférieur. En raison de son aire ventrale carénée, ce taxon se rattache probablement à la super-famille des Arietitoidea Hyatt, 1875 sensu Guex (1995) mais son attribution familiale est…

Introduction.

Early Jurassic (Sinemurian to basal Toarcian) ammonites of the Brescian Prealps (Southern Alps, Italy).

This work provides a more precise up-to-date biostratigraphical framework of the Early Jurassic ammonite succession of the Brescian Prealps with more than seventy taxa for the Sinemurian, Pliensbachian and basal Toarcian corresponding to a about 30 horizons or faunal assemblages rather well correlable with the NW European standard zonation. These results are supported with already published data, new data from recent field investigations, revised contributions of different authors and with the study of the historical collection of the Museum of Natural Sciences of Brescia (Northern Italy). The biohorizons are referred to the Lower Jurassic carbonate series of the Brescian Prealps, cropping …

Pierre Reynès (1829-1877).

1 page; National audience

Analysing disparity by applying combined morphological and molecular approaches to French and Japanese carabid beetles

The expression of morphological disparity within a clade is related to its history and to the environmental parameters within which it develops. Recent developments in geometric morphometries allow quantitative estimation of morphological disparity, and facilitate comparisons with genetic data intended to provide phylogenetic information. Such comparisons were made between two sets of ground beetle species from regions that differ biogeographically and environmentally: 12 post-glacial reinvading species from NE France; and 15 Japanese species less likely to be affected by the Pleistocene glacial events. Genetic relationships were inferred from mitochondrial DNA (ND5 gene). Morphological div…

Les faunes d'ammonites du Pliensbachien inférieur des séries dauphinoises de la Durance (Jurassique inférieur, barrage de Serre-Ponçon, Hautes-Alpes, France).

21 pages; Les faunes d'ammonites du Lias et particulièrement celles du Pliensbachien inférieur ont joué un rôle important pour la compréhension du cadre stratigraphique des séries dauphinoises des chaînes subalpines méridionales (dôme de Remollon). Ces faunes n'ont pourtant jamais fait l'objet d'études paléontologiques et elles sont décrites et illustrées pour la première fois dans le présent travail. Elles comportent une vingtaine d'espèces qui attestent de l'ensemble du Pliensbachien inférieur. Elles sont peu diversifiées et présentent un cachet euroboréal affirmé et sont surtout constituées de taxons en général abondants et largement répandus dans le Nord-Ouest de l'Europe. Malgré une po…

Data from: Gauging scale effects and biogeographical signals in similarity distance decay analyses: an Early Jurassic ammonite case study

In biogeography, the similarity distance decay (SDD) relationship refers to the decrease in compositional similarity between communities with geographical distance. Although representing one of the most widely used relationships in biogeography, a review of the literature reveals that: (1) SDD is influenced by both spatial extent and sample size; (2) the potential effect of the phylogenetic level has yet to be tested; (3) the effect of a marked biogeographical structuring upon SDD patterns is largely unknown; and (4) the SDD relationship is usually explored with modern, mainly terrestrial organisms, whereas fossil taxa are seldom used in that perspective. Using this relationship, we explore…

High-resolution dynamics of Early Jurassic marine extinctions: the case of Pliensbachian–Toarcian ammonites (Cephalopoda)

The Pliensbachian–Toarcian interval was marked by major environmental disturbances and by a second-order mass extinction. Here, we reappraise the taxonomic, spatiotemporal and selective dynamics of extinctions over the whole interval, by analysing a high-resolution dataset of 772 ammonite species from NW Tethyan and Arctic domains. On average, 40–65% of ammonite species disappeared during each subchronozone, but higher extinction pulses (reaching 70–90%) prevailed from the Margaritatus to the Dispansum Chronozone. The main extinctions, corresponding to the Gibbosus, Pliensbachian–Toarcian boundary, Semicelatum, Bifrons–Variabilis, and Dispansum events, differed in their dynamics, suggesting…