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Том 51, № 11 (2017)
- Год: 2017
- Статей: 2
- URL: https://journals.rcsi.science/0031-0301/issue/view/10210
Article
Revision of the Cambrian Agnostina (Trilobita?) from Russia
Аннотация
Cambrian genera and species of Agnostina (?Trilobita) found in Russia are revised. Agnostid trilobite species are used as index taxa in chronostratigraphic subdivisions of the traditional Middle and Upper Cambrian in both regional and global stratigraphic scales. The correlation of the regional and international stratigraphic schemes largely depends on the state of knowledge of the regional agnostid fauna. Therefore, an up-to-date revision of this group based on the Russian collections taking into account their global diversity is very timely. For this study we reexamined the type collections of agnostids, including the holotypes of species described by Russian authors. This paper contains new photographic images of the holotypes housed in Russian museums. The compiled data offered solutions for some difficult taxonomic problems of the families Agnostidae, Ptychagnostidae, Peronopsidae, and some genera of Pseudagnostidae, Diplagnostidae. Apart from listing the diversity, this paper serves as the basis for studying the biogeography and evolution of this interesting arthropod group.
1167-1248
Middle Cambrian trilobites from Borehole Nizhny Imbak 219 (northwestern Siberian Platform)
Аннотация
Borehole Nizhny Imbak 219 is situated in the northwestern Siberian Platform. Paleontological material comes from the clayey–limestone series at a depth of 2333.3–2314.3 m referred to the Ovatoryctocara and Kounamkites zones of the Middle Cambrian Amgan Stage and from the overlying limestone series at a depth of 2264.1–2244.0 m referred to the upper part of the Kounamkites Zone and an unnamed zone of the Amgan Stage and also to the Solenopleura patula and Dorypyge olenekensis–Corynexochus perforatus zones of the Middle Cambrian Mayan Stage. The questions of the traditional Lower–Middle Cambrian boundary and the role of Siberian sections in the construction of the International Chronostratigraphic Chart are considered. The trilobites collected are described.
1249-1292