|mhorn||Дата: Tuesday, 11.11.2014, 16:40 | Сообщение # 1|
|Bonnot A., Boursicot P.-Y. & Ferchaud P. (2014) Les genres Subgrossouvria Spath et Orionoides Spath (Ammonitina, Perisphinctidae) de l'Horizon à Leckenbyi (Callovien supérieur, Zone à Athleta) de Montreuil-Bellay (Maine-et-Loire, France) // Carnets de Géologie [Notebooks on Geology], Brest, vol. 14, nº 17, p. 351-399. |
The genera Subgrossouvria Spath and Orionoides Spath (Ammonitina, Perisphinctidae) from the Leckenbyi Horizon (Upper Callovian, Athleta Zone) of Montreuil-Bellay (Maine-et-Loire, France).- In the Montreuil-Bellay area (Maine-et-Loire, France), the lowermost bed of the Upper Callovian (Leckenbyi Horizon) contains a very abundant ammonite fauna (N=3275). The Family Perisphinctidae is represented by Choffatia isabellae Bonnot et al., the genus Pseudopeltoceras Spath, the genus Subgrossouvria Spath, which includes S. famula (Bean in Spath) and S. crassa Gérard & Contaut, and the genus Orionoides Spath, which comprises O. indicus Spath. Thanks to the abundance and quality of the material, it was possible to describe and figure macroconchs and microconchs of these three species, including adult specimens with preserved peristome. The stratigraphical ranges of these taxa are also specified and their potential descendants can be considered. These species are unknown in the uppermost Middle Callovian, and we assume that they colonized the northwestern part of the European platform via the southern margin of the Tethys, as did Peltoceras marysae Bonnot et al. and Choffatia isabellae Bonnot et al.
Middle Jurassic - Lower Cretaceous ammonites & aptychi