Upper cenomanian ammonites from the environs of Saumur,and the provenance of the types of Ammonites vibrayeanus and Ammonites geslinianus |
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| Authors: | WJ Kennedy P Juignet |
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| Institution: | Geological Collections, University Museum, Parks Road, Oxford, U.K.;Université de Rouen, Département de Géologie, Faculté des Sciences et Techniques,76130 Mont-Saint-Aignan, France |
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| Abstract: | Ammonite faunas consisting of Neolobites vibrayeanus (d'Orbigny), Calycoceras (Calycoceras) naviculare (Mantell), C. (Lotzeites(?)) sp., Pseudocalycoceras lattense Thomel, Metoicoceras geslinianum (d'Orbigny) and Euomphaloceras septemseriatum (Cragin) from Saumur, within the type area of the Turonian stage, are described from the collections of the Château de Saumur. They allow the recognition of two Upper Cenomanian horizons at Saumur, the one equivalent to the Sciponoceras gracile/Metoicoceras geslinianum Zone as developed in the Sables à Catopygus obtusus/Sables de Bousse of the Cenomanian stratotype; the other, older assemblage equates with the Calycoceras naviculare/Eucalycoceras pentagonum Zone fauna known from the Marnes à Ostracées of the type Cenomanian. From lithological comparisons it is suggested that this area is the source of the types of both Metoicoceras geslinianum and Neolobites vibrayeanus, which are redescribed. |
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| Keywords: | Calycoceras Lotzeites Pseudocalycoceras Metoicoceras Ammonoidea Species Taxonomy Biostratigraphy Upper Cenomanian Middle Cretaceous Upper Cretaceous Saumur Touraine Anjou Western France |
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