Vol 52, No 7 (2018)

Data on global geographical and stratigraphic distribution of Permian nonmarine bivalves, which have not included in generalizing works are considered. The continental Permian beds of Euramerican, Angarian, Cathaysian, and Gondwanan paleozoogeographic realms are compared with reference to the nonmarine bivalve fauna from the Late Kungurian to Permian–Triassic boundary. It is concluded that the family Palaeomutelidae Lahusen, 1897 and also the genera Anadontella Betekhtina, 1987, Prilukiella Plotnikov, 1945, and Concinella Pogorevitsch in Betekhtina, 1966 are of the greatest significance for correlation of particular sections.

Marine–nonmarine correlations of the Permian of Laurussia are recently addressed using integrated sedimentological–palaeontological–geochemical signatures aiming to refine existing correlation schemes. However, for Gondwana such efforts are still in an early stage, with first studies on single localities and within distinct basins. Palynology is seen to be the key discipline to tackle this challenge and recent efforts to use climatic signatures recorded in palynomorph assemblages for cross-basin and interbasinal correlations of Karoo-aged basins in southern Africa are very promising. Their near continuous basin fill from the Pennsylvanian to the Early Jurassic captures the most prominent climate change in the Phanerozoic. Postglacial coal-bearing successions of Permian and Triassic age in the Main Karoo Basin of South Africa enable detailed studies of changing vegetation on land. Marine black shales capture changes in paleoceanographic conditions as reflected in marine phytoplankton assemblages and changing terrestrial input of pollen grains and spores, enabling precise correlation of terrestrial coals and marine shales. Ongoing research aims to establish the use of climate signals recorded in terrestrial and marine palynofacies for correlation on a Gondwana-wide, interregional scale.

Based on new extensive collections and revision of the previously known bivalve Inoceramus-like mollusks, the faunal characteristics of the Delendzhian–Dulgalakhian (Wordian–Capitanian) boundary beds of the Middle Permian of lower reaches of the Lena River (northern Verkhoyansk Region, northern Siberia) are amended. The upper part of the Delendzhian beds is characterized by abundant and diverse representatives of Inoceramus-like bivalves of the genera Kolymia, Evenia, and Okhotodesma. All of them became extinct at the Delendzhian–Dulgalakhian boundary. In the lower part of the Dulgalakhian Horizon, individual Maitaia bella Biakov occur; somewhat upward in the section, there is Atomodesma sp. From the upper part of the Delendzhian Horizon, a new species, Kolymia peregoedovi sp. nov., is described. Permian kolymiids are figured.

Large nonmarine bivalves, Permianaia gusevi gen. et sp. nov. (family Naiaditidae Scarlato et Starobogatov, 1979) from the terminal Permian (Zhukovian Regional Stage, Vyatkian Stage) of Vyazniki-1 and Sokovka localities (Vladimir Region) are described. The new genus is characterized by the Unio-like (oval rectangular), elongated, posteriorly expanded shell, duplivincular ligament, and absence of teeth in the hinge. This combination of characters distinguishes the genus Permianaia gen. nov. from nonmarine Naiaditidae and from Unio-like genera of Late Permian nonmarine bivalves, Palaeomutela and Palaeanodonta. Permianaia gusevi sp. nov. does not occur in the older Permian beds and, consequently, can be regarded as a biomarker of the terminal Permian deposits, the Zhukovian Regional Stage.

Taxonomy and stratigraphic distribution of the Early Kazanian gastropods of the Volga–Ural Region are studied. The material previously studied by Netchaev and collections from the northern areas of the paleobasin previously described by Licharew are reexamined. The Early Kazanian gastropod assemblages comprise 31 species, 20 genera, 16 families; of these four species and one genus are new; 67.7% species are in common with the Late Kazanian assemblages.