|mhorn||Дата: Monday, 07.11.2011, 18:22 | Сообщение # 1|
|Mitta V.V., Sha J. (2011) Ammonite distribution across the Jurassic-Cretaceous boundary in central Russia // Paleontological Journal, Vol.45, no.4, P.379-389. |
The distribution of ammonites across the Jurassic–Cretaceous boundary of the central part of the Russian Platform is discussed. The nomenclature of Craspedites nodiger (Eichwald, 1962) and Hectoroceras tolijense (Nikitin, 1881) is updated. A new species, Craspedites ultimus sp. nov. [which is more close to Pseudocraspedites and Taimyroceras that to typical Russian Cr. (Trautscholdiceras)], is described from the basal horizons of the rjasanensis Zone (Ryazanian Stage). The Hectoroceras tolijense and Hectoroceras kochi faunal horizons lying between the nodiger and rjasanensis zones are united in the kochi Zone of the basal Ryazanian [but this zone is not the same Kochi zone as in the Siberian sections! - mhorn]. Previous opinions suggesting a hiatus between the Volgian and Ryazanian stages are reviewed and rejected.
Middle Jurassic - Lower Cretaceous ammonites & aptychi