0000000000680256
AUTHOR
Didier Marchand
showing 39 related works from this author
Homéomorphies et canalisations évolutives: Le rôle de l'ontogenèse.Quelques exemples pris chez les Ammonites du Jurassique
1989
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…
Proposal for the Thuoux section as a candidate for the GSSP of the base of the Oxfordian stage.
2012
20 pages; International audience; The Thuoux section, located in South-Eastern Basin of France (coordinates: 44°30'55"E; 5°42'25"N), is a section that satisfies numerous demanding criteria as reference section (GSSP) for the base of the Oxfordian stage. Sedimentation was continuous in that the abundant ammonitic fauna yields no detectable hiatuses. The stratigraphic boundary is located between the Lamberti Zone and the Mariae Zone or more precisely between the Paucicostatum horizon (MARCHAND, 1979) and the Thuouxensis horizon (FORTWENGLER & MARCHAND, 1994a). In this section, there is a perfect mixing bet-ween Boreal ammonites (Cardioceratinae) whose species are used as stratigraphic markers…
Note sur l'ontogenèse crânienne et les hétérochronies chez Gorilla gorilla et Pan troglodytes
2001
Resume La comparaison par les methodes Procrustes de l'ontogenese crânienne de Pan troglodytes et de Gorilla gorilla precise la dynamique et la chronologie de leur developpement. Les arbres phenetiques confirment un gradient morphologique du nouveau-ne a l'adulte, avec un dimorphisme d'origine sexuelle plus accuse chez le gorille. La quantification des changements morphologiques par des champs vectoriels permet de visualiser et de comparer l'organisation spatiale de la croissance cranio-faciale des deux especes. On en deduit que des heterochronies du developpement (acceleration, pre-deplacement, hypermorphose par acceleration et hypermorphose par post-deplacement) sont a l'origine des varia…
A solution to the human paradox: fundamental ontogenies and heterochronies
1999
Solving the human paradox means explaining how a genetic difference of a mere 1% can be consistent with 5 million years of anatomical transformation from great apes to present-dayHomo sapiens. The solution proposed here is that of the internal history of ontogenetic change. A concept of “fundamental ontogeny” is developed and deduced from comparison between living and fossil primates. The fossil human lineage can be summarized into five fundamental ontogenies corresponding to successive skull plans (bauplans) resulting from five major phases of craniofacial contraction: prosimians (adapiforms), monkey apes (propliopithecidae), great apes (dryopithecidae), australopithecines andHomo. The mor…
Characterization and correlation of Upper Jurassic (Oxfordian) bentonite deposits in the Paris Basin and the Subalpine Basin, France
2003
Explosive volcanic activity is recorded in the Upper Jurassic of the Paris Basin and the Subalpine Basin of France by the identification of five bentonite horizons. These layers occur in Lower Oxfordian (cordatum ammonite zone) to Middle Oxfordian (plicatilis zone) clays and silty clays deposited in outer platform environments. In the Paris Basin, a thick bentonite (10–15 cm), identified in boreholes and in outcrop, is dominated by dioctahedral smectite (95%) with trace amounts of kaolinite, illite and chlorite. In contrast, five bentonites identified in the Subalpine Basin, where burial diagenesis and fluid circulation were more important, are composed of a mixture of kaolinite and regular…
Heterochronic differentiation of sexual dimorphs among Jurassic ammonite species
1997
Ontogenetic and then heterochronic approaches are used here to analyze sexual differentiation within two well-known Jurassic dimorphic species. This analysis compares two ways of determining the relative biological age of ammonites, one using size (diameter) and the other the number of septa as a proxy of age. The shape standard is established from factor analysis of morphological and growth parameters. Size-age-shape relationships are analyzed on the basis of a new heterochronic representation. When diameter is used as a proxy of age, microconch morphs are globally considered to be progenetic compared with macroconch morphs. When size and age are determined separately and shape is included…
Le genre Nucleolites (Echinoidea, Cassiduloidea) du Bajocien à l'Oxfordien dans le Bassin de Paris : apport des données architecturales à la systémat…
2005
International audience; La classification des espèces du genre Nucleolites de l'intervalle BajocienOxfordien du bassin de Paris est révisée. Une vision classique, jusqu'alors utilisée par les auteurs et fondée principalement sur la morphologie générale du test, est tout d'abord présentée. Elle est ensuite modifiée à partir de nouvelles données architecturales se référant au modèle extraxialaxial concernant la structure de l'appareil apical ainsi que la présence de plaques supplémentaires et de plaques caténales. Ces données architecturales sont considérées comme prioritaire vis-à-vis de la morphologie générale du test. Cette approche conduit à une nouvelle vision de la classification des …
Milankovitch and sub-Milankovitch forcing of the Oxfordian (Late Jurassic) Terres Noires Formation (SE France) and global implications
2010
ABSTRACT High‐resolution analysis (2277 samples) of magnetic susceptibility (MS) was performed on ∼700‐m‐thick Early–Middle Oxfordian marine marls of the Terres Noires Formation, SE France. MS variations within these sediments record sub‐Milankovitch to Milankovitch frequencies with long‐term eccentricity (405 kyr and ∼2 Myr) being the most prominent. The 405 kyr cycle was used as a high‐resolution geochronometer for astronomical calibration of this poorly constrained interval of Late Jurassic time. The estimated duration of this Early–Middle Oxfordian interval concurs with the current International Geologic Time Scale GTS2004 (∼4 Myr), but the estimated durations of the corresponding ammon…
La notion d'espace morphologique,outil d'analyse de la morphodiversité des organismes
1997
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…
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…
The logic of forms in the light of developmental biology and palaeontology.
2010
11 pages; If you ask palaeontologists, and indeed anyone interested in the theory of evolution, for the key words that encapsulate it, you will obtain the following results: adaptation, natural selection, speciation, but also ontogeny and phylogeny. The first three key words apply to the future of the individual and by extension to the future of the species: we are therefore dealing with adults of a reproductive age. The two other key words concern (i) the evolution of the morphology from the egg to the adult (individual ontogeny: short timescale) and especially what goes on in the black box called embryogenesis, and (ii) the modification of ontogenetic sequences over time, resulting in cha…
Coupures morphologiques et biochronologie chez les Kosmoceratinae de l'Est de la France (Callovien inférieur pp. à Callovien supérieur pp.)
1998
Abstract For the first time in eastern France, a detailed succession of the uppermost Lower Callovian to Lower Upper Callovian Kosmoceratinae is presented, according to the fossils collected in situ at Blye (Jura, France). It is compared with the abundant data from Champagne and Bourgogne. These ammonites may allow more accurate correlations between the subboreal and subtethysian biostratigraphical frameworks. They record numerous morphological changes, sometimes different from those generally accepted. They allow the precise recognition of the limits of the biostratigraphical units, and the definition of successive faunal units available in the lowermost Upper Callovian.
Biogéographie des ammonites jurassiques et reconstitution palinspastique de la Téthys
1987
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…
Le supra-occipital des Cétacés et des Rongeurs fouisseurs. Une convergence morphologique induite par le pôle post-céphalique ?
2000
A comparative study of the cranial morphologies of cetaceans and of rodents that use their incisors for burrowing brings out morphological convergences concerning the supra-occipital bone. These phyletically very remote groups are both subject to the same mechanical constraint, viz. the need for the spinal column to be aligned with the anteroposterior axis of the skull. This constraint, which is related to swimming in cetaceans and burrowing in rodents, entails three major points of convergence: 1) a clearly backward facing foramen magnum; 2) a shortened or even greatly shortened neck, sometimes with cervical vertebrae fused together; and 3) an uprighted or even forward tilted supra-occipit…
Chromosomes and the origins of apes and australopithecins
1996
Comparison of molecular data suggests that the higher apes (Gorilla, Pan) and humankind (Homo) are closely related and that they diverged from the common ancestor through two speciation events situated very closely together in time. Examination of the chromosomal formulas of the living species reveals a paradox in the distribution of mutated chromosomes which can only be resolved by a model of trichotomic diversification. This new model of divergence from the common ancestor is characterized by the transition from (1) a monotypic phase to (2) a polytypic phase of three sub-species — pre-gorilla, pre-chimpanzee and preaustralopithecine. The quadruped ancestors ofAustralopithecus appear to ha…
Contrôle géodynamique de la sédimentation argileuse du Callovien-Oxfordien moyen dans l'Est du bassin de Paris: influence eustatique et volcanique
1999
The Middle Callovian to Middle Oxfordian clay deposits drilled in the eastern Paris Basin (borehole HTM 102, ANDRA) show a strong mineralogical change occurring in the lowermost Oxfordian (Scarburgense subzone, Mariae zone). Such a change probably results from the initial development of connections between the young Atlantic Ocean and the Paris Basin. A bentonitic layer identified close to the boundary between Lower and Middle Oxfordian and also recognized in the subalpine Basin (South-East of France) at the same age, reflects a volcanic activity probably resulting from an extensional regime located in the North Sea.
Séries condensées et indice de préservation d'unité biostratigraphique: exemple de l'ennoiement de la plate-forme nord-bourguignonne (France) au Call…
1999
Abstract Several depositional environments associated with Callovian-Oxfordian condensed series of the southeast of the Paris Basin are defined. As sedimentation rates were very low, variations in palaeodepth, which were synchronous at regional scale, were taken to directly reflect fluctuations in accommodation potential. Within a major trend toward increased accommodation potential, five sharp upturns and one sharp downturn are detected. A biostratigraphic unit preservation index is denned to quantify and discuss the low preservation of sediments in these condensed series. This index is seen to vary with accommodation potential.
Tornquistes helveticus (Jeannet, 1951) (Ammonitina, Pachyceratidae) de l'Oxfordien inférieur du Jura Suisse; nom. nov. pro. “Herznachites” helveticus…
1994
Resume Le genre Herznachites Jeannet , 1951 est soumis a une revision. Il ne fait pas partie de la famille des Oppeliidae comme le pensait Jeannet. L'analyse morphologique montre que le seul echantillon du genre, a la disposition de Jeannet, doit etre rattache au genre Tornquistes de la famille des Pachyceratidae. L'holotype de Tornquistes helveticus ( Jeannet ) est un macroconque; un nouveau specimen, trouve depuis la description originale, est une forme microconque de la meme espece. Ce dernier collecte in situ , permet de fixer l'âge de l'espece de la sous-zone a Cordatum, de la zone a Cordatum, de l'Oxfordien inferieur.
Carbon and Oxygen Isotope Signals from the Callovian–Oxfordian in French Sedimentary Basins
2013
3 pages; International audience; High-resolution carbon and oxygen isotope data from the Paris Basin and the Subalpine Basin (France) are available in a precise biostratigraphic framework for the Callovian-Oxfordian stages. A biostratigraphically well-constrained δ13C curve, derived from bulk carbonates in the Paris Basin and the Subalpine Basin, is provided in order to document carbon-cycle evolution and to serve as a chemostratigraphic reference for the Callovian-Oxfordian in the Tethyan domain. Sea-temperature reconstructions, using diagenetically screened belemnite and oyster data, reveal major climate perturbations at the Middle-Late Jurassic transition.
The complex nature of progenetic species — examples from Mesozoic ammonites
1991
Several examples of progenetic species among Mesozoic ammonites are investigated. The ammonites are Middle Jurassic kosmoceratids, Upper Jurassic oppeliids, and Upper Cretaceous scaphites. As assessed through outgroup comparison, the progenetic species in each of these examples is characterized by small size at maturity and the presence of morphological features typical of those of the juveniles of more primitive species. However, in none of these examples is the progenetic species a duplicate form of the juvenile stage of more primitive species. There are at least three kinds of features of progenetic species that differ from those of the juveniles of more primitive species: (1) symplesiom…
Le dimorphisme chez Perisphinctes (Properisphinctes) cf. bernensis de Loriol (Oxfordien inférieur, région de Cracovie, Pologne)
2004
Resume Une population d'ammonites rapportee a Perisphinctes (Properisphinctes) cf. bernensis de Loriol 1898, d'âge Oxfordien inferieur (zone a Mariae), a ete trouvee dans la region de Cracovie, dans le Sud de la Pologne. L'etude de ces formes a permis de montrer l'existence, au sein de cette espece, d'un dimorphisme microconque/macroconque, qui etait soupconne, mais non encore demontre avec certitude. Cette espece, connue en Europe uniquement par des individus incomplets, precise notre connaissance des perisphinctides de la base de l'Oxfordien inferieur. Pour citer cet article : R. Tarkowski, D. Marchand, C. R. Palevol 3 (2004).
Fluctuations morphologiques et hétérochronies chez Toxaster (échinides, Crétacé inférieur)
2003
Resume Plusieurs etapes de la diversification du spatangue Toxaster au Cretace inferieur sont decrites a partir de l’analyse de six especes qui se succedent du Valanginien inferieur au Barremien sur la marge nord-ouest tethysienne. La description des variations morphologiques est fondee sur l’analyse de deux parametres angulaires qui permettent d’identifier trois modules sur le test. La comparaison des trajectoires ontogenetiques des especes T. granosus kiliani et T. retusus , prises comme references, suggere une interpretation heterochronique de type peramorphose. L’elargissement des comparaisons aux adultes des six especes demontre l’absence de peramorphocline, mais atteste que l’evolutio…
Les Pseudoperisphinctinae (Ammonitina, Perisphinctidae) de l'horizon à Leckenbyi (Callovien supérieur, zone à Athleta) de Montreuil-Bellay (Maine-et-…
2008
International audience; Dans la région de Montreuil-Bellay (Maine-et-Loire), de nombreuses coupes ont été réalisées au passage Callovien moyen-Callovien supérieur. Le premier banc attribué au Callovien supérieur a été daté de l'horizon à Leckenbyi. Il a fourni une très importante faune ammonitique (N=3125), dans laquelle les Perisphinctidae représentent 51% de l'effectif. À côté de formes plus ou moins bien connues comme Pseudopeltoceras leckenbyi (Bean), Orionoides pseudorion (Waagen), Subgrossouvria famulum (Bean) et S. crassa Gérard et Contaut, on trouve une espèce qui n'a jamais été ni décrite ni figurée : cette espèce fait l'objet du présent article. Choffatia isabellae n. sp. se disti…
Quantification de révolution morphologique du crâne des Hominidés et hétérochronies
1998
Abstract Comparisons of adult skulls of various species of great apes, fossil hominids and modern humans in the sagittal, Francfort and ortho-sagittal planes reveal a series of three separate organisation plans: ‘Great Ape’, ‘Australopithecine’ and ‘Homo’, the latter including primitive men ( Homo ergaster-erectus-neandertalensis ) and modern humans ( Homo sapiens ). Morphological changes between these plans are quantified for the first time here by vector fields. This study confirms the existence of cranio-facial contraction, which occurs as a series of leaps. The juvenile morphology of the great ape skull is broadly preserved in adult Homo sapiens, suggesting that numerous heterochronies …
Ammonoid morphological signal versus sea-level changes
1997
The morphological diversity, considered as a biological signal, of a series of four Upper Callovian (Middle Jurassic) ammonite populations of Côte-d’Or (France) is quantified. These populations fall within two third-order sequences of a second-order transgression. A sampling method that adheres as closely as possible to the morphological characteristics of the populations is established. It is valuable in that it eliminates the subjectivity related to taxonomy to allow more objective comparisons between the biological signal (shell morphology) and the physical signal (eustasy).
Paleoclimatic control of biogeographic and sedimentary events in Tethyan and peri-Tethyan areas during the Oxfordian (Late Jurassic)
2005
International audience; The paleobiogeographical distribution of Oxfordian ammonites and coral reefs in northern and Central Europe, the Mediterranean area, North and East Africa, and the Middle East and Central Asia is compared with the distribution in time and space of the most important lithofacies. Interest in the Oxfordian is focused on changes in facies and in biogeographical patterns that can be interpreted as the results of climatic events. Paleotemperature trends inferred from oxygen isotopes and paleoclimatic simulations are tested against fossil and facies data. A Late Callovian–Early Oxfordian crisis in carbonate production is indicated by the widespread absence of Lower Oxfordi…
Were climatic changes a driving force in hominid evolution?
2000
International audience; A comparison of externalist and internalist approaches in hominid evolution shows that the externalist approach, with its claim that climate was responsible for the appearance of bipedalism and hominization, now seems to be ruled out by the biological, palaeogeographical, palaeontological and palaeoclimatic data on which it was based. Biological data support the embryonic origin of cranio-facial contraction, which determined the increase in cranial capacity and the shift in the position of the foramen magnum implying bipedalism. In the internalist approach, developmental biology appears as the driving force of hominid evolution, although climate exerts a significant …
Faunal invasions as a source of morphological constraints and innovations? The diversification of the early Cardioceratidae (Ammonoidea; Middle Juras…
2005
Abstract Multivariate analysis of shell characters and quantification of morphological diversity (morphospace occupation and disparity) are used here to investigate the modes of morphological diversification of ammonites. We define five events in early cardioceratid history that connect geographical changes causing emigration or immigration phases with biodiversity dynamics: (1) the initial colonization of the Arctic Basin by the Cardioceratidae at the end of the Bajocian, Middle Jurassic; (2) the first appearance of the Kosmoceratidae clade in the Boreal Realm during the Bathonian; (3) the ensuing expansion phase of this clade in the Boreal Realm; (4) the first phase of migration of the Ca…
A revision of the rare genusCyclolampas(Echinoidea) using morphometrics with description of a new species from the upper Callovian of Burgundy (Franc…
2013
The discovery of a new species,Cyclolampas altusnew species in the upper Callovian of Burgundy (France) leads to the systematic revision of the rare echinoid genusCyclolampasPomel, 1883. Two morphometric approaches are used jointly to describe and quantify variations in test shape: the analysis of linear measurements and the Elliptic Fourier shape analysis. Both analyses yield congruent results that highlight the amplitude of within-species variations and quantify the part due to allometry. Along with the description ofC. altus, the systematic position of species formerly assigned to the generaPygorhytisPomel, 1883 andCyclolampasis amended. Previously attributed to the genusPygorhytis,Cyclo…
A sequence analyzed from the basin to the platform : the Middle Oxfordian calcareous succession in southeastern France
2004
Abstract Middle Oxfordian sedimentation is very homogeneous in southeastern France. It is characterized by a specific alternation of marls and fine-grained limestones (G. transversarium Zone). This work shows that sets of calcareous beds allow accurate stratigraphic correlations in various paleogeographic areas, from the shallow Jura platform to the deep Dauphinois basin. Following a rifting period, this sedimentation illustrates a doming period with decreasing subsidence and water depth. This corresponds to the establishment of a wide marine area more favourable to carbonate sedimentation. Considering sequence stratigraphy, some slight variations occur in the sediment record and lead to in…
Mature Modifications and Dimorphism in Ammonoid Cephalopods
1996
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.
Apparition d'une morphologie scaphitomorphe par miniaturisation chez une ammonite oxfordienne : Scaphitodites scaphitoides ()
1997
The pyritized fossil-bearing marls of the Jura (Lower Oxfordian) contain an ammonite that is remarkable because of its tiny adult size (less than 16 mm) and of the scaphitoidal coiling of its body chamber, which is similar to that of certain Cretaceous Scaphitaceae. Anatomical and ontogenetic analysis demonstrates that these individuals, which are ascribed to Scaphitodites scaphitoides (Coquand, 1853), formed a single species. We argue that the genus Scaphitodites derived from Taramelliceras by a complex process of progenesis (sensu Landman et al., 1991).
Integrated stratigraphy of the potential candidate Oxfordian GSSP at Thuoux and Saint-Pierre d'Argençon (France).
2013
5 pages; International audience; The Thuoux and Saint-Pierre d'Argençon sections (Subalpine Basin, southeastern France) are proposed as a potential GSSP candidate for the Callovian-Oxfordian boundary. Several aspects of stratigraphy that have recently been applied in the two selected sections are discussed, including ammonite and nannofossil biostratigraphy, palynology, physical stratigraphy, and cyclostratigraphy.
Les Oppeliidae (Ammonitina) de l'horizon à Collotiformis (Callovien supérieur, zone à Athleta) de la région dijonnaise (Côte-d'Or, France)
1999
Abstract In the Dijon area, the top of the Athleta zone contains rich ammonite fauna dominated quantitatively by two families: Perisphinctidae and Oppeliidae. The Oppeliidae are diversified and make up a numerically larger proportion of the ammonite fauna than in the underlying strata (up to 57 %). The exceptional state of preservation of the ammonites has permitted a precise study to be made of ontogenesis and intraspecific variability. Four sub-families are found (Oppeliinae, Hecticoceratinae, Distichoceratinae and Taramelliceratinae), within which sexual dimorphs have been recognised. One small form, characterized by lappets and a body chamber with ellipticoidal-trending coiling, is inte…
Thuoux and Saint-Pierre d’Argençon Sections (Subalpine Basin, Southeastern France): Case Studies of Ammonite Biostratigraphy for the Potential Candid…
2014
The Thuoux and Saint-Pierre d’Argencon sections (Subalpine Basin, southeastern France) display a thick silty–clayey sedimentation with abundant and diversified ammonite faunas, free of detectable hiatuses. The Callovian–Oxfordian boundary is biostratigraphically located between the Lamberti and the Mariae zones or, more precisely, between the Lamberti Subzone (paucicostatum horizon) and the Scarburgense Subzone (thuouxensis horizon). The mixing of Boreal–Sub-Boreal Cardioceratinae and Sub-Mediterranean–Tethyan Hecticoceratinae, Peltoceratinae, and Perisphinctinae in this basin allows reliable worldwide correlations that enhance the choice of the Thuoux and Saint-Pierre d’Argencon sections a…
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…
Synthesis of recent stratigraphic data on bathonian to oxfordian deposits of the eastern Paris basin
2007
International audience
L'approche paléontologique des concepts biologiques de l'espèce : défi pour l'étude de la paléobiodiversité. L'exemple des ammonites jurassiques.
2007
12 pages, publié sous l'égide de France Orchidées et de la Société Linnéenne de Lyon.; National audience
A revision of the rare genus Cyclolampas (Echinoidea) using morphometrics with description of a new species from the upper Callovian of Burgundy (Fra…
2013
18 pages; International audience; The discovery of a new species, Cyclolampas altus new species in the upper Callovian of Burgundy (France) leads to the systematic revision of the rare echinoid genus Cyclolampas Pomel, 1883. Two morphometric approaches are used jointly to describe and quantify variations in test shape: the analysis of linear measurements and the Elliptic Fourier shape analysis. Both analyses yield congruent results that highlight the amplitude of within-species variations and quantify the part due to allometry. Along with the description of C. altus, the systematic position of species formerly assigned to the genera Pygorhytis Pomel, 1883 and Cyclolampas is amended. Previou…