Bardin, J. and Rouget, I. and Benzaggagh, M. and Fürsich, F.T. and Cecca, F. (2015) Lower Toarcian (Jurassic) ammonites of the South Riffian ridges (Morocco): Systematics and biostratigraphy. Journal of Systematic Palaeontology, 13 (6). pp. 471-501.

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A rich ammonite fauna from the Lower Toarcian (Lower Jurassic) of the South Riffian ridges (northern Morocco), collected bed-by-bed from 14 new outcrops, is described. The fauna is nearly exclusively composed of already-known taxa, allowing correlation from the chronozone down to the zonule level. Fourteen species are described, among them the new species Dactylioceras (Dactylioceras) laticostatum sp. nov. The stratigraphical interval studied spans the first chronozone of the Toarcian, the Polymorphum Chronozone, but it remains unclear whether the Toarcian Oceanic Anoxic Event is represented in the studied succession. The Early Toarcian is mainly characterized by representatives of the family Dactylioceratidae, which are abundant but commonly crushed or deformed. Two new descriptors are proposed to describe the shell shape of crushed or incomplete specimens and have been used together with the classical ones for the taxonomic treatment of this group. A hypothesis about dimorphism in Dactylioceras (Orthodactylites) semicelatum (Simpson, 1843) and Dactylioceras (Dactylioceras) laticostatum sp. nov. is proposed. © 2014 The Trustees of the Natural History Museum, London.

Item Type: Article
Uncontrolled Keywords: ammonite; anoxic conditions; biostratigraphy; sexual dimorphism; species diversity; succession; taxonomy; Toarcian, Morocco, Ammonoidea; Dactylioceras; Dactylioceratidae
Subjects: Earth and Planetary Sciences
Divisions: SCIENTIFIC PRODUCTION > Earth and Planetary Sciences
Depositing User: Administrateur Eprints Administrateur Eprints
Last Modified: 31 Jan 2020 15:46

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