Mid-Cretaceous Ammonite Sequence for Western New Mexico Iv
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Colonial Geology and Mineral Resources
COLONIAL GEOLOGY AND MINERAL RESOURCES VOLUME 4, NUMBER 3 LONDON: HER MAJESTY'S STATIONERY OFFIC 1954 P R I r. E 7.r fitl N F. T SOME NEW UPPER CRETACEOUS AMMONITES FROM NIGERIA1 By R. A. REYMENT, B.Sc. Geological Survey Department, Nigeria Abstract THREE NEW AMMONITE GENERA AND A NUMBER OF AMMONITE SPECIES ARE DESCRIBED from the Turonian and Coniacian of Nigeria. The new genera are Onitshoce,.as of Desmoceratidae, Kamerunoceras of Collignoniceratidae and Ezilloella of Vasco ceratidae. Some new species of Pseudaspidoceras Hyatt, Gombeoceras Reyment, Pachyvascoce,.as Furon and Solgerites Reeside are recorded. A discussion of the family Vascoceratidae appears. · Introduction IN A RECENT PAPER (Reyment, 1954) some new genera of Lower Turonian ammonites from Nigeria were established and their types and a few other species briefly described. The present paper contains descriptions of two further species of one of these new genera and of species of associated genera that have a wide distribution in both southern and northern Nigeria. Three new genera from the Turonian and Coniacian of southern Nigeria and the Cameroons are treated. This paper also includes a brief discussion of the family Vascoceratidae which provides an important element of the Lower Turonian faunas of many areas in Africa, Europe, Asia and North and South America. Both this and the previous work are preliminary to a larger review of the Upper Cretaceous-ammonites of southern Nigeria that is in active preparation;· but whose publication will in,evitably be delayed. Mean while, it is hoped that the new gehera described below and the informa tion on taxonomy and phylogeny becoming a\7ailable from studies of the Nigerian faunas will be of value both to palaeontologists and strati graphers. -
Handbook of Texas Cretaceous Fossils
University of Texas Bulletin No. 2838: October 8, 1928 HANDBOOK OF TEXAS CRETACEOUS FOSSILS B y W. S. ADKINS Bureau of Economic Geology J. A. Udden, Director E. H. Sellards, Associate Director PUBLISHED BY THE UNIVERSITY FOUR TIMES A MONTH, AND ENTERED AS SECOND-CLASS MATTER AT THE POSTOFFICE AT AUSTIN, TEXAS. UNDER THE ACT OF AUGUST 24. 1912 The benefits of education and of useful knowledge, generally diffused through a community, are essential to the preservation of a free govern m en t. Sam Houston Cultivated mind is the guardian genius of democracy. It is the only dictator that freemen acknowl edge and the only security that free men desire. Mirabeau В. Lamar CONTENTS P age Introduction __________________________________________________ 5 Summary of Formation Nomenclature_______________________ 6 Zone Markers and Correlation_______________________________ 8 Types of Texas Cretaceous Fossils___________________________ 36 Bibliography ________________________________________________ 39 L ist and Description of Species_________________________________ 46 P lants ______________________________________________________ 46 Thallophytes ______________________________________________ 46 Fungi __________________________________________________ 46 Algae __________________________________________________ 47 Pteridophytes ____________________________________________ 47 Filices __________________________________________________ 47 Spermatophytes __________________________________________ 47 Gymnospermae _________________________________________ -
Stratigraphy and Paleontology of Mid-Cretaceous Rocks in Minnesota and Contiguous Areas
Stratigraphy and Paleontology of Mid-Cretaceous Rocks in Minnesota and Contiguous Areas GEOLOGICAL SURVEY PROFESSIONAL PAPER 1253 Stratigraphy and Paleontology of Mid-Cretaceous Rocks in Minnesota and Contiguous Areas By WILLIAM A. COBBAN and E. A. MEREWETHER Molluscan Fossil Record from the Northeastern Part of the Upper Cretaceous Seaway, Western Interior By WILLIAM A. COBBAN Lower Upper Cretaceous Strata in Minnesota and Adjacent Areas-Time-Stratigraphic Correlations. and Structural Attitudes By E. A. M EREWETHER GEOLOGICAL SURVEY PROFESSIONAL PAPER 1 2 53 UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON 1983 UNITED STATES DEPARTMENT OF THE INTERIOR JAMES G. WATT, Secretary GEOLOGICAL SURVEY Dallas L. Peck, Director Library of Congress Cataloging in Publication Data Cobban, William Aubrey, 1916 Stratigraphy and paleontology of mid-Cretaceous rocks in Minnesota and contiguous areas. (Geological Survey Professional Paper 1253) Bibliography: 52 p. Supt. of Docs. no.: I 19.16 A. Molluscan fossil record from the northeastern part of the Upper Cretaceous seaway, Western Interior by William A. Cobban. B. Lower Upper Cretaceous strata in Minnesota and adjacent areas-time-stratigraphic correlations and structural attitudes by E. A. Merewether. I. Mollusks, Fossil-Middle West. 2. Geology, Stratigraphic-Cretaceous. 3. Geology-Middle West. 4. Paleontology-Cretaceous. 5. Paleontology-Middle West. I. Merewether, E. A. (Edward Allen), 1930. II. Title. III. Series. QE687.C6 551.7'7'09776 81--607803 AACR2 For sale by the Distribution Branch, U.S. -
Les Vascoceratinae Et Les Pseudotissotiinae
LES VASCOCERATINAE ET LES PSEUDOTISSOTIINAE (AMMONITINA) D'ASHAKA (NE NIGERIA) : RELATIONS AVEC LEUR ENVIRONNEMENT BIOSÉDIMENTAIRE THE VASCOCERATINAEA AND PSEUDOTISSOTIINAEA (AMMONITINA) FROM ASHAKA (NE NIGERIA) : RELATIONSHIPS WlTH THE BIOSEDIMENTARY ENVIRONMENT Philippe COURVILLE COURVILLE Ph. (1992) - Les Vascoceratnae et es Pseudotssotinae (Ammonitina) d'Açhaka (NE Ngera) . relatons avec leur enviannement blosedimentare [The Vaçcoceia1,naea and Psetidotfssoti!naea jAmmon,ti.?s) fiom As,ba,ks (NE Nigeria) relationsh!ps with the biosedimentary enviionment] - Bull. Centres Rech Explof.- Prod EliAquitaine. 16. 2 407~457.8 f~y, 14 p.. Bo~ssensDecember 24, 19'32 - SSN : 0396~2687 CODEN. BCREDP A purdscpnary analyss groupng the sedtmentary yeo,ogy, the sequenta! stratgraphy. !he mcropaleonto1og;cal and nacropaeontologcal aspec!s. allows us 10 renterpret tbe marine çecton of the Gonga Formaton (hypostratotypc Ashaka sect~on).The paleartolag~cal successlonç (benthon~carganiçtrç and Ammonlte papulatons) and the sedmentary unis (ensembles mted by two d!scontinutes) cari now oe deçcrbed accurateiy A dynamc nterpretator of the seres of Ammonte papulatons s proposed for the local framework of the Ashaka ste some taxa coud beong to .. autochthonous ,, neages (Vascoceratnae and Pseudotsçatnae) others are corsdered ta be ., exo~ ric ,. elements (Fagesra and Pseodaspidoceras) The settements of the Cer,omanan and Turonan marne envronments seem to be w~th~na few steps reach. Fi'çt of a. tïe progreçslve settng of subplatycone 01 paty~spheroconetethysan Vascoceratds (Nigeiiceras and V gr cauv!ni) can be obçerved Ths ç folowed by the suaden .. appearance .. of cad-serperllcone Ammontes, whch quicky dr~fttowards cad-spherocone forms (frst morphologcal c:sls) Then a second morpnolagica crlsls occurç. -
Le Mans, France
High-resolution biostratigraphy and chemostratigraphy of the Cenomanian stratotype area (Le Mans, France) Delphine Desmares, Marc Testé, Bérengère Broche, Maxime Tremblin, Silvia Gardin, Loïc Villier, Edwige Masure, Danièle Grosheny, Nicolas Morel, Patrice Raboeuf To cite this version: Delphine Desmares, Marc Testé, Bérengère Broche, Maxime Tremblin, Silvia Gardin, et al.. High- resolution biostratigraphy and chemostratigraphy of the Cenomanian stratotype area (Le Mans, France). Cretaceous Research, Elsevier, 2020, 10.1016/j.cretres.2019.104198. hal-02328773 HAL Id: hal-02328773 https://hal.archives-ouvertes.fr/hal-02328773 Submitted on 23 Oct 2019 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Journal Pre-proof High-resolution biostratigraphy and chemostratigraphy of the Cenomanian stratotype area (Le Mans, France) Delphine Desmares, Marc Testé, Bérengère Broche, Maxime Tremblin, Silvia Gardin, Loïc Villier, Edwige Masure, Danièle Grosheny, Nicolas Morel, Patrice Raboeuf PII: S0195-6671(19)30086-2 DOI: https://doi.org/10.1016/j.cretres.2019.104198 Reference: YCRES 104198 To appear in: Cretaceous Research Received Date: 1 March 2019 Revised Date: 12 July 2019 Accepted Date: 31 July 2019 Please cite this article as: Desmares, D., Testé, M., Broche, B., Tremblin, M., Gardin, S., Villier, L., Masure, E., Grosheny, D., Morel, N., Raboeuf, P., High-resolution biostratigraphy and chemostratigraphy of the Cenomanian stratotype area (Le Mans, France), Cretaceous Research, https:// doi.org/10.1016/j.cretres.2019.104198. -
Towards a Phylogenetic Classification of the Cretaceous Ammonites V
N.Jb. Geo\. Palaont. Abh. Stuttgart, Januar 1997 Towards a phylogenetic classification of the Cretaceous ammonites V. Euomphaloceratidae By M. R. Cooper, Durban With 5 figures in the text COOPER, M. R. (1997): Towards a phylogenetic classification of the Cretaceous ammo nites. V. Euomphaloceratidae. - N. Jb. Geo\. Palaont., Abh., 203: 1-21; Stuttgart. Abstract: Phylogenetic analysis of Euomphaloceratinae COOPER, 1978, a group within highly diversified and heterogeneous Acanthocerataceae, indicates a fundamental dichotomy which suggests promotion of this taxon to family rank with recognition of two subfamilies. Nominate Euomphaloceratinae comprise E. (Euomphaloceras), E. (Kanabiceras), Burroceras, Paraburroceras, P. (Pseudaspidoceras), P. (Ampakabites), and Morrowites, and Romaniceratinae subfam. nov. is made up of Schindewo/fites, Kameruno ceras, Codazziceras, Proromaniceras (Proromaniceras), P. (Obiraceras), Neomphaloceras, Yubariceras and Romaniceras (?with Shuparoceras as a subgenus). Zusammenfassung: Die phylogenetische Analyse der Euomphaloceratinae COOPER, 1978, einer Gruppe der hoch diversifizierten und heterogenen Acanthocerataceae, weist auf eine fundamentale Dichotomie innerhalb der Unterfamilie hin. Der Gruppe wird daher Familienrang verliehen und zwei Unterfamilien abgegrenzt. Die Nominat-Unter familie Euomphaloceratinae umfaBt E. (Euomphaloceras), E. (Kanabiceras), Burroceras, Paraburroceras, P. (Pseudaspidoceras), P. (Ampakabites) und Morrowites. Zur zweiten Unterfamilie Romaniceratinae subfam. nov. gehiiren Schindewo/fites, -
Phylogeny, Diversity, and Ecology of the Ammonoid Superfamily Acanthoceratoidea Through the Cenomanian and Turonian
PHYLOGENY, DIVERSITY, AND ECOLOGY OF THE AMMONOID SUPERFAMILY ACANTHOCERATOIDEA THROUGH THE CENOMANIAN AND TURONIAN DAVID A.A. MERTZ A Thesis Submitted to the Graduate College of Bowling Green State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE August 2017 Committee: Margaret Yacobucci, Advisor Andrew Gregory Keith Mann © 2017 David Mertz All Rights Reserved iii ABSTRACT Margaret Yacobucci Both increased extinction and decreased origination, caused by rising oceanic anoxia and decreased provincialism, respectively, have been proposed as the cause of the Cenomanian Turonian (C/T) extinction event for ammonoids. Conflicting evidence exists for whether diversity actually dropped across the C/T. This study used the ammonoid superfamily Acanthoceratoidea as a proxy for ammonoids as a whole, particularly focusing on genera found in the Western Interior Seaway (WIS) of North America, including Texas. Ultimately, this study set out to determine 1) whether standing diversity decreased across the C/T boundary in the WIS, 2) whether decreased speciation or increased extinction in ammonoids led to a drop in diversity in the C/T extinction event, 3) how ecology of acanthoceratoid genera changed in relation to the C/T extinction event, and 4) whether these ecological changes indicate rising anoxia as the cause of the extinction. In answering these questions, three phylogenetic analyses were run that recovered the families Acanthoceratidae, Collignoniceratidae, and Vascoceratidae. Pseudotissotiidae was not recovered at all, while Coilopoceratidae was recovered but reclassified as a subfamily of Vascoceratidae. Seven genera were reclassified into new families and one genus into a new subfamily. After calibrating the trees with stratigraphy, I was able to determine that standing diversity dropped modestly across the C/T boundary and the Early/Middle Turonian boundary. -
CHAPTER I I I Sistematic DESCRIPTION
CHAPTER III SiSTEMATIC DESCRIPTION CIUPTER III systematic description Section I : Mortonlceratinae Introduction : The ammonoid species described by Stoliczka under the group of Ammonites crlstatl were sub divided by him into species 1, Ammonites blanfordianus, 2, Ammonites inflatus, condollianus. ootatoorensis and corruptus, 3, Amnionites propinquus. 4. Ammonites obesus, 5. Ammonites se rratocarlnatus. 6, Ammonite s subtricarinatus. These were transferred by later workers e.g. Kossmat to Schloenbachia and its subgenera as : Schloenbachla (Tropitoldes) . S. (Prlnotropis) . S. (Peroniceras). S, (Munerlceras) etc. According to present ideas the above mentioned species have undergone further transfers and except those of the Inflata group, are placed under different subfamilies, viz. Peroniceratlnae, Mune rice rat inae, etc. These species are, therefore, not considered under the present section; but those of the Inflata group which are now found to belong to the sub family Mortonlceratinae are dealt with here. The species which represent this subfamily in the present collection, viz. Mortoniceras (Mortoniceras) inflatum (Sow.); M. (M.) rostratum (Sow.), Mortonioeras (Peiradoceras) indicum spo nov., M. (Purnovarites) perinflatum Spath., M. (p.) - 17 - - 18 - subquadratum Spath, M. (d .) sp. Indet; ?Mortonicera8 (?Mortoniceras) deshpandel sp, nov., Prohysteroceras (Goodhallltes) stoliczkal sp. nov. are dealt with here., Of these eight species Mortonlceras (Mortonlceras) inflatum was described by Stoliczka and Kossmat from these rocks. Three species viz. Mortoniceras (M.) rostratum (Sow.), M. (Durnovarites) perlnflatum Spath., M. (D .) subquadratum Spath. are species already known and are recorded from outside South Indian basin; they are now recorded here for the first time. The remaining species described here are new to science. The subfamily Mortoniceratinae has an interesting history, being used in the first instance by Spath (1925) to comprise species of texanum group of Senonian. -
Sucesión De Amonitas Del Cretácico Superior (Cenomaniano – Coniaciano) De La Parte Más Alta De La Formación Hondita Y De L
Boletín de Geología Vol. 33, N° 1, enero-junio de 2011 SUCESIÓN DE AMONITAS DEL CRETÁCICO SUPERIOR (CENOMANIANO – CONIACIANO) DE LA PARTE MÁS ALTA DE LA FORMACIÓN HONDITA Y DE LA FORMACIÓN LOMA GORDA EN LA QUEBRADA BAMBUCÁ, AIPE - HUILA (COLOMBIA, S. A.) Pedro Patarroyo1 RESUMEN La sección de la quebrada Bambucá (Aipe - Huila) posee una buena exposición de los depósitos del Cretácico del Valle Superior del Magdalena. De la parte alta de la Formación Hondita se recolectaron Acanthoceras sp. y Rhynchostreon sp. del Cenomaniano superior. Dentro del segmento inferior de la Formación Loma Gorda se hallaron Choffaticeras (C.) cf. segne, Fagesia cf. catinus, Neoptychites cf. andinus, Mitonia gracilis, Morrowites sp., Nannovascoceras ? sp., Quitmaniceras ? sp., Benueites ? sp. junto con Mytiloides kossmati, M. goppelnensis y Anomia sp. del Turoniano inferior. Estratigráficamente arriba aparecen Paramammites ? sp., Hoplitoides sp. H. ingens, H. cf. lagiraldae, Codazziceras ospinae, Allocrioceras sp., que pueden estar representando entre el Turoniano inferior y medio. Para la parte alta de este segmento se encontraron Prionocycloceras sp. P. guayabanum, Reesidites subtuberculatum, Subprionotropis colombianus, Mytiloides scupini, Dydimotis sp., Gauthiericeras sp., Anagaudryceras ? sp., Eulophoceras jacobi, Paralenticeras sieversi, Hauericeras cf. madagascarensis, Peroniceras (P.) subtricarinatum, Forresteria (F.) sp., Barroisiceras cf. onilahyense, Ankinatsytes venezolanus que abarcan entre el Turoniano superior y el Coniaciano. Con base en la fauna colectada no es posible establecer los límites Cenomaniano/Turoniano y Turoniano/Coniaciano. Palabras clave: Amonitas, Cretácico superior, Valle Superior del Magdalena, Aipe-Huila-Colombia. UPPER CRETACEOUS AMMONITE SUCCESSION (CENOMANIAN – CONIACIAN) RELATED TO THE UPPER HONDITA AND LOMA GORDA FORMATIONS ALONG THE BAMBUCÁ CREEK, AIPE - HUILA (COLOMBIA, S.A.) ABSTRACT The Bambucá creek section (Aipe - Huila) shows a very good exposition of the Upper Magdalena Valley Cretaceous deposits. -
Rediscovery of the Holotypes of the Cenomanian (Upper Cretaceous) Ammonites Vascoceras Gamai Choffat, 1898, and Vascoceras Barcoicense (Choffat, 1898)
Cretaceous Research 56 (2015) 647e650 Contents lists available at ScienceDirect Cretaceous Research journal homepage: www.elsevier.com/locate/CretRes Short communication Rediscovery of the holotypes of the Cenomanian (Upper Cretaceous) ammonites Vascoceras gamai Choffat, 1898, and Vascoceras barcoicense (Choffat, 1898) * Fernando Barroso-Barcenilla a, b, , Jose Manuel Brandao~ c, Pedro Miguel Callapez d, e, Vanda Faria dos Santos e, f a Grupo de Investigacion IberCreta, Departamento de Geología y Geografía, Facultad de Ciencias, Universidad de Alcala de Henares, 28871 Alcalade Henares, Spain b Grupo de Investigacion Procesos Bioticos Mesozoicos, Departamento de Paleontología, Facultad de Ciencias Geologicas, Universidad Complutense de Madrid, 28040 Madrid, Spain c Instituto de Historia Contemporanea,^ Centro de Estudos de Historia e FilosofiadaCi^encia, Universidade de Evora, 7000-554 Evora, Portugal d Departamento de Ci^encias da Terra, Faculdade de Ci^encias e Tecnologia, Universidade de Coimbra, 3030-790 Coimbra, Portugal e Centro de Investigaçao~ da Terra e do Espaço, Universidade de Coimbra, 3000-134 Coimbra, Portugal f Museu Nacional de Historia Natural e da Ci^encia, Universidade de Lisboa, 1250-102 Lisboa, Portugal article info abstract Article history: The historical holotypes of the Cenomanian (Upper Cretaceous) ammonites Vascoceras gamai Choffat, Received 23 January 2015 1898 (type of the genus), and Vascoceras barcoicense (Choffat, 1898), thought to be destroyed by the fire of Received in revised form March 1978 at the National Museum of Natural History, Lisbon, Portugal, have been rediscovered in good 10 June 2015 state of preservation. Based on the study of the originals, these upper Cenomanian specimens can be Accepted in revised form 27 June 2015 rehabilitated as holotypes, maintaining and justifying the status of both taxa as well as of Vascoceras Available online 30 July 2015 cauvini Chudeau, 1909. -
Redalyc.SUCESIÓN DE AMONITAS DEL CRETÁCICO SUPERIOR (CENOMANIANO – CONIACIANO) DE LA PARTE MÁS ALTA DE LA FORMACIÓN HONDIT
Boletín de Geología ISSN: 0120-0283 [email protected] Universidad Industrial de Santander Colombia Patarroyo, Pedro SUCESIÓN DE AMONITAS DEL CRETÁCICO SUPERIOR (CENOMANIANO – CONIACIANO) DE LA PARTE MÁS ALTA DE LA FORMACIÓN HONDITA Y DE LA FORMACIÓN LOMA GORDA EN LA QUEBRADA BAMBUCÁ, AIPE - HUILA (COLOMBIA, S. A.) Boletín de Geología, vol. 33, núm. 1, enero-junio, 2011, pp. 69-92 Universidad Industrial de Santander Bucaramanga, Colombia Disponible en: http://www.redalyc.org/articulo.oa?id=349632022005 Cómo citar el artículo Número completo Sistema de Información Científica Más información del artículo Red de Revistas Científicas de América Latina, el Caribe, España y Portugal Página de la revista en redalyc.org Proyecto académico sin fines de lucro, desarrollado bajo la iniciativa de acceso abierto Boletín de Geología Vol. 33, N° 1, enero-junio de 2011 SUCESIÓN DE AMONITAS DEL CRETÁCICO SUPERIOR (CENOMANIANO – CONIACIANO) DE LA PARTE MÁS ALTA DE LA FORMACIÓN HONDITA Y DE LA FORMACIÓN LOMA GORDA EN LA QUEBRADA BAMBUCÁ, AIPE - HUILA (COLOMBIA, S. A.) Pedro Patarroyo1 RESUMEN La sección de la quebrada Bambucá (Aipe - Huila) posee una buena exposición de los depósitos del Cretácico del Valle Superior del Magdalena. De la parte alta de la Formación Hondita se recolectaron Acanthoceras sp. y Rhynchostreon sp. del Cenomaniano superior. Dentro del segmento inferior de la Formación Loma Gorda se hallaron Choffaticeras (C.) cf. segne, Fagesia cf. catinus, Neoptychites cf. andinus, Mitonia gracilis, Morrowites sp., Nannovascoceras ? sp., Quitmaniceras ? sp., Benueites ? sp. junto con Mytiloides kossmati, M. goppelnensis y Anomia sp. del Turoniano inferior. Estratigráficamente arriba aparecen Paramammites ? sp., Hoplitoides sp. -
Des Faunes D'ammonites Du Cenomanien Du Sud-Est De
Bull. Soc. géol. France, 1999, t. 170, n° 5, pp. 599-610 BIOCHRONOLOGIE QUANTITATIVE (ASSOCIATIONS UNITAIRES) DES FAUNES DAMMONITES DU CENOMANIEN DU SUD-EST DE LA FRANCE Claude MONNET* & Hugo BUCHER* Centre des Sciences de la Terre, CNRS - ERS 2042, Université Claude Bernard Lyon I, 27-43, boulevard du 11 Novembre, F-69622 VILLEURBANNE. Email: [email protected] Manuscrit déposé le 14 janvier 1999; accepté après révision le 7 avril 1999 Mots clés. - Ammonite, Cénomanien, Turonien, Associations Unitaires, Sud-est de la France (Bassin vocontien), Bassin Anglo- parisien, Diachronisme, Renouvellements fauniques Résumé. - La zonation dammonites du Cénomanien du sud-est de la France est révisée dans ce travail. Elle intéresse 138 espèces dammonites réparties sur 40 coupes. Ces données publiées par Thomel [1992] sont analysées au moyen de la méthode des associations unitaires [Guex, 1977, 1991]. Une suite logique danalyses, dont le but est doptimiser les données en soulignant les incohérences majeures de la documentation originelle, aboutit à la formation dune succession chronologique de 27 associations unitaires réunies en 7 zones dassociation latéralement reproductibles. Son application souligne les très rapides variations latérales de faciès même dans la partie distale du bassin et met en évidence un faible diachronisme des espèces (mais incluant certains index de zones). Cette analyse suggère également une diminution progressive des pulsations montrées par les taux de renouvellements fauniques durant le Cénomanien inférieur et moyen, jusquà ce quun état déquilibre soit atteint au Cénomanien supérieur et Turonien inférieur, sans changement apparent à la limite Cénomanien-Turonien. Cette tendance est accompagnée par un doublement rapide de la diversité spécifique durant la fin du Cénomanien inférieur et une décroissance progressive et prolongée à partir de la fin du Cénomanien moyen.