The ammonite faunas of the Callovian-Oxfordian boundary interval in Europe and their relevance to the establishment of an Oxfordian GSSP

Kevin N. PAGE, Guillermo MELENDEZ, John K. WRIGHT

Abstract


The latest Callovian and Early Oxfordian are characterised by one of the highest levels of mixing of Boreal, Submediterranean and even Mediterranean faunas. In particular the massive expansion of Boreal Cardioceratidae from their original “home” in Arctic areas as far south as south-east France, brings them into contact with Mediterraneanstyle faunas rich in Phylloceratidae. This so-called “Boreal Spread” provides the framework within which highresolution inter-bioprovincial correlations are possible and hence the context for a successful GSSP designation for the base of the Oxfordian Stage within Europe (and hence the beginning of the Upper Jurassic). Associated with the Cardioceratidae, especially in more Tethyan areas is a great variety of Perisphinctoidea, including Aspidoceratidae, Periphinctinae, Grossouvrinae and rarer Pachyceratidae as well as frequent Hecticoceratinae and rarer Phylloceratidae. As several of these persist beyond Europe they therefore provide tantalising indications that a truly global correlation of any GSSP established in Europe will ultimately be possible. The stratigraphical, taxonomic and palaeobiogeographical context and significance of the trans Callovian-Oxfordian boundary faunas within Europe is here reviewed and the faunas of the candidate GSSP at Redcliff Point, Weymouth, SW England are described, including the basal Oxfordian species Cardioceras (Pavloviceras) redcliffense sp. nov.

Keywords


ammonites; stratigraphy; palaeobiogeography; Jurassic; Callovian; Oxfordian; GSSP; Cardioceratidae

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