The Turonian Stage and Substage Boundaries by Peter BENGTSON (Compiler) with Contributions by William A
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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. -
The Wunstorf Drilling Project
Progress Reports The Wunstorf Drilling Project: Coring a Global Stratigraphic Reference Section of the Oceanic Anoxic Event 2 by Jochen Erbacher, Jörg Mutterlose, Markus Wilmsen, Thomas Wonik, and the Wunstorf Drilling Scientific Party doi:10.0/iodp.sd..0.007 section. Disciplines involved include micropaleontology Introduction and Goals (calcareous nannofossils, planktonic foraminifera), macro- paleontology (ammonites, inoceramids), stable isotopes and The mid-Cretaceous greenhouse world (Albian–Turonian) cyclostratigraphy mainly based on borehole logging, multi was characterized by high atmospheric carbon dioxide sensor core logging���������������������������������������,�������������������������������������� and x-ray fluorescence (XRF) scanning levels, much higher global temperatures than at present�����,���� and data. The combination of geochemical, paleontological�����,���� and a lack of permanent ice caps at the poles (Bice et al., 2006; logging data will allow high resolution chemo- and biostra- Huber et al., 2002; Wilson et al., 2002). A characteristic tigraphy for the CTB�������������������������������������I������������������������������������ which may in ����������������������the future������������������ serve as an feature of this greenhouse world was the deposition of black international standard. shales during the Cenomanian / Turonian boundary interval (CTBI; Schlanger and Jenkyns, 1976; Arthur et al., 1990). The Wunstorf Core These carbon�����������������������������������������������-����������������������������������������������rich -
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. -
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. -
Mid-Cretaceous Ammonite Sequence for Western New Mexico Iv
iii Contents ABSTRACT 5 Genus Morrowites Cobban and Hook, n. gen. 9 Morrowites wingi (Morrow) 9 INTRODUCTION 5 M. depressus (Powell) 11 COMPOSITION OF MOLLUSCAN FAUNA 5 M. subdepressus Cobban and Hook, n. sp. 11 OCCURRENCE AND PRESERVATION OF FOSSILS 6 M. cf. M. dixeyi (Reyment) 12 STRATIGRAPHIC POSITION OF FOSSILS 6 Subfamily Euomphaloceratinae Cooper 13 COLLECTION LOCALITIES 7 Genus Kamerunoceras Reyment 13 Kamerunoceras turoniense (d'Orbigny) 13 FAMILY VASCOCERATIDAE H. Douvillé 14 SYSTEMATIC PALEONTOLOGY 7 Subfamily Vascoceratinae H. Douvillé 14 FAMILY BACULITIDAE GILL 7 Genus Neoptychites Kossmat 14 Genus Baculites Lamarck 7 Neoptychites cephalotus (Courtiller) 14 Baculites yokoyamai Tokunaga and Shimizu 7 Genus Fagesia Pervinquière 15 FAMILY MUNIERICERATIDAE WRIGHT 7 Fagesia superstes (Kossmat) 16 Genus Tragodesmoceras Spath 7 FAMILY C OLLIGNONICERATIDAE WRIGHT AND WRIGHT 16 Tragodesmoceras socorroense Cobban and Hook 7 Subfamily Barroisiceratinae Basse 16 FAMILY PLACENTICERATIDAE HYATT 8 Genus Cibolaites Cobban and Hook, n. gen. 16 Genus Placenticeras Spath 8 Cibolaites molenaari Cobban and Hook, n. sp. 16 Placenticeras cumminsi Cragin 8 REFERENCES 18 FAMILY ACANTHOCERATIDAE DE GROSSOUVRE 8 Subfamily Mammitinae Hyatt 8 Genus Mammites PLATES 1-14 21 Laube and Bruder 8 INDEX 50 Mammites nodosoides (Schluter) 8 TABLE 1—Mid-Cretaceous ammonite sequence for western New Mexico iv FIGURES 1—Location of study area 5 9—Histogram of size and body chambers of Neoptychites 2—External sutures of Mammites nodosoides (Schluter) 9 3— cephalotus (Courtiller) 14 Whorl sections of Morrowites wingi (Morrow) 10 4—External 10—Scatter diagram of breadth to diameter ratio of Neop- suture of Morrowites wingi (Morrow) 10 5—Whorl section and tychites 14 suture of Morrowites depressus 11—External sutures of Neoptychites cephalotus (Cour-tiller) 15 (Powell) 11 12—External suture of Fagesia superstes (Kossmat) 16 13— 6—External sutures of Morrowites subdepressus Cobban and Histogram of size of body chambers of Cibolaites molenaari Hook, n. -
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. -
Redalyc. SUCESIÓN DE AMONITAS DEL CRETÁCICO SUPERIOR (CENOMANIANO – CONIACIANO) DE LA PARTE MÁS ALTA DE LA FORMACIÓN HONDI
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 Available in: http://www.redalyc.org/articulo.oa?id=349632022005 Abstract The Bambucá creek section (Aipe - Huila) shows a very good exposition of the Upper Magdalena Valley Cretaceous deposits. To the upper part of the Hondita Formation were recollected Acanthoceras sp. and Rhynchostreon sp. of the upper Cenomanian. Related to the lower segment of the Loma Gorda Formation were found Choffaticeras ( C .) cf. segne , Fagesia cf. catinus , Neoptychites cf. andinus , Mitonia gracilis , Morrowites sp., Nannovascoceras ? sp., Quitmaniceras ? sp., Benueites ? sp., Paramammites ? sp. togheter with Mytiloides kossmati , M . goppelnensis and Anomia sp. of the lower Turonian. Following by Hoplitoides sp. H . ingens , H . cf. lagiraldae , Codazziceras ospinae , Allocrioceras sp. that can be representing between the lower and middle Turonian. To the upper part of this segment were collected Prionocycloceras sp. P . guayabanum , Reesidites subtuberculatum , Subprionotropis colombianus , Mytiloides scupini , Dydimotis sp., Gauthiericeras sp., Anagaudryceras ? sp., Eulophoceras jacobi , Paralenticeras sieversi , Hauericeras -
Upper Cenomanian–Lower Turonian Ammonoids from the Saxonian Cretaceous (Lower Elbtal Group, Saxony, Germany)
Upper CenomanianLower Turonian ammonoids from the Saxonian Cretaceous (lower Elbtal Group, Saxony, Germany) MARKUS WILMSEN & EMAD NAGM The Upper Cenomanian to Lower Turonian ammonoid fauna of the Saxonian Cretaceous (Elbtal Group, Saxony, Ger- many) has been revised based on the study of 270 specimens hosted in the Museum für Mineralogie und Geologie (MMG) of the Senckenberg Naturhistorische Sammlungen Dresden. In total, 12 species have been identified and, based on this revision, a number of ammonoids are now reported and/or illustrated for the first time from the Elbtal Group of Saxony: Euomphaloceras septemseriatum, Neocardioceras juddii barroisi, Watinoceras coloradoense, Spathites (Jeanrogericeras) reveliereanus, Sciponoceras gracile and Scaphites equalis. The study demonstrated the presence of all Upper Cenomanian and Lower Turonian standard ammonite biozones in the lithostratigraphic succession of the lower Elbtal Group: the lower Upper Cenomanian Calycoceras naviculare Zone (represented by the Oberhäslich For- mation), the mid- and upper Upper Cenomanian Metoicoceras geslinianum and Neocardioceras juddii zones (repre- sented by the Dölzschen Formation), and the Lower Turonian Watinoceras coloradoense and Mammites nodosoides zones (represented by the Brießnitz Formation). The ammonoid fauna from the Saxonian Cretaceous is dominated by strongly ornamented and widely distributed Acanthoceratidae. • Key words: Upper Cretaceous, Saxo-Bohemian Creta- ceous Basin, ammonites, taxonomic revision, biostratigraphy. WILMSEN,M.&NAGM, E. 2013. Upper Cenomanian–Lower Turonian ammonoids from the Saxonian Cretaceous (lower Elbtal Group, Saxony, Germany). Bulletin of Geosciences 88(3), 647–674 (18 figures). Czech Geological Sur- vey, Prague. ISSN 1214-1119. Manuscript received September 26, 2012; accepted in revised form January 25, 2013; published online July 3, 2013; issued July 3, 2013. -
Stratigraphy and Biostratigraphy of an Upper Cretaceous Outlier Near Roy, Harding County, New Mexico
New Mexico Geological Society Guidebook, 52nd Field Conference, Geology ofthe Llano Estacado, 2001 251 STRATIGRAPHY AND BIOSTRATIGRAPHY OF AN UPPER CRETACEOUS OUTLIER NEAR ROY, HARDING COUNTY, NEW MEXICO SPENCER G. LUCASI AND ANDREW B. HECKERT2 INew Mexico Museum of Natural History, 1801 Mountain Rd NW, Albuquerque, 87104; 2Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, NM 87131-1116 Abstract.-Upper Cretaceous strata exposed as outliers near Roy in Harding County, New Mexico, are assigned to the Graneros Shale and the overlying Greenhorn Formation. The Greenhorn Formation locally consists of three members (in ascending order): Lincoln, Hartland, and Bridge Creek. The Lincoln Member is 8.3 m thick and dominated by yellowish gray and very pale orange calcareous shale and characteristic persistent beds of calcarenite. The Hartland Member is 11.0 m thick and consists mostly of medium and brownish gray bentonitic shale. The Bridge Creek Member here is erosionally truncated by the Neogene Ogallala Formation 4.1 m above its base and consists of interbeds ofledge forming limestone and calcareous shale. Fossils from the Lincoln Member include numerous specimens of the bivalve Ostrea beloiti Logan and of the selachian Ptychodus anonymus Williston. The Hartland Member lacks biostratigraphic ally significant fossils. The Bridge Creek Member produces the ammonites Euomphaloceras sp. and Sciponoceras gracile (Shumard) near its base and Watinoceras coloradoense (Henderson) and Vascoceras birchbyi Cobban and Scott near its top. These fossils can be assigned to the upper Cenomanian Sciponoceras gracile ammonite zone and the lower Turonian Vascoceras birchbyi ammonite zone. Younger ammonite zones normally present in the Bridge Creek Member are not present at Roy, having been stripped offby Neogene erosion.