Paleontologičeskij žurnal

A new organism with colonial organization, Olgunia bondarenkoae gen. et sp. nov., of sponge or coelenterate grade, is described from the Vendian deposits of the South-Eastern White Sea region. The new genus is characterized by a modular pattern and coordinated growth of neighboring individuals arranged in a fan-shape. The new genus has a combination of diagnostic characteristics of the genera Vaveliksia Fedonkin and Funisia Droser et Gehling, which makes it possible to combine all three genera into one new family Olgunidae with the type genus Olgunia gen. nov. The problem of coloniality in the Precambrian is discussed.

New information has been obtained regarding the systematic composition of ammonoids and conodonts from the Shimanskyites shimanskyi Zone of the lower (Smithian) Substage of the Olenekian Stage in South Primorye. This is based on the material from the Lower Triassic sections of the Kamenushka River basin, specifically from the Kamenushka-2 and Perevalny sections. In light of the correlation data pertaining to these sections, it is proposed that the Scythogondolella milleri conodont Zone in this region corresponds to two ammonite zones (Anasibirites nevolini and Shimanskyites shimanskyi) of the Smithian Substage in South Primorye. The new species of the genera Owenites (O. golozubovi sp. nov.) and Preflorianites (P. lelikovi sp. nov.) are described herein. The clarification and emendation of the diagnosis of the genus Submeekoceras, in conjunction with the results of its comparison with other genera of the family Arctoceratidae, permit a reconsideration of the generic affiliation of the majority of forms currently attributed to the genus Arctoceras. The obtained results make it possible to outline the phylogenetic relationships of a number of genera belonging to the families Lanceolitidae and Ussuritidae (order Prolecanitida Miller et Furnish, 1954), as well as Proptychitidae and Arctoceratidae (order Ceratitida Hyatt, 1884). The prevalence of diverse ostracod species in the Shimanskyites shimanskyi Zone, coupled with a relatively diverse ammonoid community, suggests that anoxia, which is assumed to have been present in other marine basins in other regions of the world at that time, was absent in the bottom waters of the late Smithian sea marine basin of South Primorye.

An analysis of the isotopic composition of chitin (oxygen and nitrogen) was made for the terrestrial and freshwater Pleistocene arthropods for the first time for the same paleolocality, the Old Crow River in northwestern Yukon, representing layers from Middle Pleistocene to Holocene. About a hundred fragments of arthropods were tested among the fossils, including the weevils Lepidophorus lineaticollis (Coleoptera, Curculionidae), some ground beetles (Coleoptera, Carabidae), as well as the ephippia of freshwater crustacean Daphnia cf. pulex (Branchiopoda, Daphniidae). An isotope analysis of modern representatives of the same arthropods from different regions of the Yukon was made for comparison. Isotopic lines show differences between terrestrial and freshwater animals. The isotopic composition of freshwater crustaceans allows to see the difference between cold and warm time intervals. Herbivorous beetles show a more complex picture, possibly associated with the adaptation to different biotopes and host plants, which allowed the species to survive during climate and environment fluctuations.

New Early Frasnian conodonts of the genus Icriodus – I. aqua sp. nov. and I. lacrima sp. nov. from the Ust’-Yarega Formation of the Southern Timan are described. These species are characterized by a rather wide platform. The mass appearance of taxa with such a platform is most likely related to the abrupt change of environments in the Early Sargaevian time, which caused the emergence of new food resources.

The article describes remains of sea turtles (clade Pan-Chelonioidea) from three Upper Cretaceous localities of the Penza Province of Russia: Malaya Serdoba 1 and 2 (Campanian) and Penza (Maastrichtian). The distal part of the humerus of Pan-Chelonioidea indet. from the Malaya Serdoba 1 locality is similar to the humerus of Terlinguachelys fischbecki (Protostegidae) from the Campanian of USA. The turtle assemblage from the Malaya Serdoba 2 locality includes Protostega gigas (Protostegidae) and Pan-Chelonioidea indet. similar to T. fischbecki and representatives of the clade Ctenochelyidae, and resembles in systematic composition the sea turtle assemblage from the Campanian Beloe Ozero locality, Saratov Province of Russia. The outer surface of the costal plates of turtle from the Penza locality has a sculpture similar to Peritresius ornatus (Ctenochelyidae) and Glyptochelone suyckerbuycki.

Loons (genus Gavia; family Gaviidae of the order Gaviiformes) are highly specialized diving birds with an incompletely understood evolutionary history. In the Early to Middle Miocene, the earliest small species of the genus Gavia were part of the warm-climate faunas of southern Europe, but as the climate cooled in the Late Miocene, loons virtually disappeared from the fossil record of Eurasia, which may be explained by a shift in their nesting range to high latitudes. The coracoid of a fossil loon from the Upper Miocene of the Hyargas Nuur 2 locality in western Mongolia described in this paper represents the oldest find of the family Gaviidae in the fossil record of Asia and the first in the continental Neogene of the region. In size, the loon from Hyargas Nuur 2 corresponds to modern G. stellata, but is morphologically closer to G. arctica and may represent an ancestral form of this modern species. This find is within the modern breeding range of G. arctica and is also interpreted as belonging to the breeding range of loons in the Late Miocene.