Paleontological Journal

A new species of an unusual genus of stromatoporoids Stylostroma Gorsky, 1938, S. absurdum sp. nov., first identified in the sediments of the Middle Famennian of the Devonian system of the South Tatar arch of the Volga-Ural oil and gas bearing province, is described. The study of the host rocks revealed an increased content of organic carbon, which allows us to consider the sediments as analogs of oil-maternal rocks.

The study of the material from the Upper Carnian of Northern Kharalukah and the upper reaches of the Adycha River basin allowed us to clarify the species composition of the genera Yakutosirenites Tozer, 1994 and Orientosirenites Konstantinov, 2018. Based on the study of the shell shape, sculpture and lobe line features, the identification of new species Yakutosirenites (Yakutosirenites) selivanovae sp. nov. and Orientosirenites insolitus sp. nov. was substantiated. Their description is given. The new data allow us to supplement the taxonomic composition of the late Carnian ammonoids of Eastern Yakutia.

The species Kepplerites keppleri (Oppel), first described from southern Germany, is an index species of the lowermost subzone of the Callovian standard scale. This and the wide geographical distribution of this taxon determine its importance for interregional correlation. At the same time, K. keppleri is the ancestor of all the Callovian representatives of the genus Kepplerites (and the family Kosmoceratidae) in a vast territory of Boreal, Subboreal and Peri-Tethyan marine basins. The paper discusses the finds of this species in Central Russia (Middle Volga area) and their significance for systematics and biostratigraphy. The boundary between the Bathonian and Callovian on the Russian platform is proposed to be drawn along the first appearance of Kepplerites keppleri, as is customary in Southern Germany.

The historical development of main ray-finned fish taxa in the Permian and Early Triassic of the Kuznetsk Basin has been traced. Three faunal assemblages of ray-finned fishes, successively changing and having no continuity, have been identified: Permian, Indian and Olenekian. The first one is subdivided into five subassemblages. During the Permian, endemism among the ray-finned fish assemblages increased. In the Triassic, the faunal assemblages changed completely twice (without any continuity with earlier assemblages) - at the Permian-Triassic boundary and at the boundary of the Indian and Olenekian Stages.

The article describes a turtle assemblage from the Upper Cretaceous deposits of the Izhberda locality in the Orenburg Region of Russia. The assemblage contains at least four taxa of sea turtles: Protostegidae indet., Toxochelyinae indet. (the first reliable find in Eurasia), Ctenochelyidae indet., and Pan-Chelonioidea indet., similar to Corsochelys haliniches Zangerl, 1960. In addition, remains of Pan-Chelonioidea indet., which may belong to a wide range of taxa, and a fragment of a sculptured peripheral plate of Testudines indet., which may belong to a representative of the genus Peritresius (Ctenochelyidae) or a large representative of Nanhsiungchelyidae (previously not reported in Europe), are described.

Based on a representative faunal collection, including more than 30,000 bone remains, an assessment is made of the dynamics of the ecological composition of small vertebrate communities near Denisova Cave in the second half of the Middle- Upper Pleistocene. We reconstructed cold climate epochs that probably correspond to the beginning of the Samarovo (MIS 8), Taz (MIS 6) and Ermakovo (MIS 4) cooling periods in the climatostratigraphic scheme of the Pleistocene of Western Siberia. Relatively warm epochs probably correspond to the end of the Tobolsk (MIS 9), Shirta (MIS 7) and Kazantsevo (MIS 5) interglacials, as well as the Karga interstadial (MIS 3). Analysis of different ecological groups of small vertebrates allowed us to establish local features in the development of each epoch, characteristic directly of the cave environs.