Signification stratigraphique du « Niveau des Monstres » du Frasnien Franco-Belge

The various interpretations of the « niveau des monstres » and of the beds which are supposed to contain the species Spirifer orbelianus ABICH, H., 1858 are considered. The conditions allowing to maintain some of the numerous terms that have been used so far to define this level or these beds are outlined. The Franco-Belgian late Givetian and early Frasnian species erroneously confused with the Famennian species from Armenia is (are) not described, but belong(s) either to the genus Uchtospirifer LIACHENKO, A.I., 1957, or to a related genus. The taxonomic status of the species Cyrtiopsis orbeli... Mehr ...