Paleontologičeskij žurnal

The diversity of radiolarian species of the family Carpocaniidae Haeckel, 1881, emend. Riedel, 1967, from the surface sediments of the Emperor Seamount Chain (Nintoku, Jingū, Ojin, Koko and Yuryaku guyots) is analyzed. Five new species of the genus Carpocanium Ehrenberg, 1847, emend. nov.: C. rotundum sp. nov., C. fragaria sp. nov., C. alabastrum sp. nov., C. tulipa sp. nov., and C. fungus sp. nov. are described. The identification of the new species is based on their morphology, which differs from that of other species of the genus Carpocanium. It is proposed to restore Carpocanarium Haeckel, 1887 to a valid genus, and transfer it back into the family Carpocaniidae, based on the overall correspondence of its morphology to the diagnosis of this family.

The Toarcian species Simpsonibelus dorsalis (Phillips), first established outside Western Europe, is discussed. A single rostrum of this belemnite species was found in the clay flysch (not in situ) of the Upper Taurian (Yaman) formation of the Yaman ravine located in the vicinity of the village of Prochladnoe in the southern part of the Crimean Peninsula. Based on the revision and overview of the available data on the Lower Jurassic belemnites of the Crimea, it was found that the stratigraphic intervals to which their records are confined (Lower Pliensbachian, uppermost Lower Toarcian–Upper Toarcian) fall on the phases of the maximum taxonomic diversity of Early Jurassic belemnites in European seas. The mid-Bifrons chron (Fibulatum subchron) of early Toarcian appears to have been the most likely time for the migration of the S. dorsalis (Megateuthididae) to the Crimean margin of the Tethys Ocean.

Brachiopods are a group of animals known since the Early Cambrian and thrived in the Paleozoic. After the Permian–Triassic extinction, there was a significant reduction in the taxonomic diversity of brachiopods. According to one hypothesis, in the Mesozoic, brachiopods with blind gut could not reinstate their numbers due to the predominance of shelly plankton. We assume that the terebratulids, the most widespread group of modern brachiopods, were able to adapt to the changed composition of food due to a more efficient filtration mechanism of the plectolophous lophophore. Extant rhynchonellids have a blind–closed bulbus end of digestive tract, which is probably used for crushing and digesting shelly plankton.

A revision of the Late Ordovician ostracod species Isochilina punctata (Eichwald, 1860) was carried out, based on the original Eichwald specimens of the 19th century with the addition of numerous material from the Late Ordovician deposits of the Vruda and Izvara formations of the Leningrad region. A more precise description of the species is given. The lifestyle of Isochilina punctata in the conditions of a lagoon-like shallow basin has been reconstructed. It has been suggested that there was a special biofacies of Isochilina punctata, which lived in the Ordovician on the site of the current Izhora plateau.

A new member of the family Karpinskiosauridae (Tetrapoda, Seymouriamorpha), Volgerpeton exspectatus gen. et sp. nov., is described based on the material from the Monastyrsky Ovrag-D locality, which corresponds to the uppermost Urzhumian of the boundary stratotype of the Severodvinian Regional Stage in the Monastery Ravine sequence of Tetyushi District, Republic of Tatarstan, Russia. The holotype of the new species, a skull of 18 mm long, has the majority of skull roof bones preserved, and belonged to a larval indi vidual. The deep otic notches, absence of the interpremaxillary fenestra, extension of the squamosal into the marginal area of the parietal shield on the dorsal side of the skull, shape and orientation of the anterior edge of this bone, presence of a long anterolateral process in the nasal, a curved shape of the lateral edge of the supratemporal, a quadrangular shape of the postorbital portion of the jugal, a long-rectangular outline of the palatine, the specific pattern of dentition of the lateral elements of the palate, and presence of a long crista praequadrata of the quadratojugal are features that distinguish the genus Volgerpeton from Karpinskiosaurus. In terms of the cranial morphology, the genus Volgerpeton occupies an intermediate position between the known members of Discosauriscidae and Karpinskiosauridae, being similar to the former in the morphology of the otic and cheek regions of the skull, as well as in the shape of premaxillaria, and to the latter in the pattern of palatal dentition and the shape and enlarged size of the tabularia, which together confirms the assumption of the phylogenetic continuity of both the families. The finding of basal karpinskiosaurids in the upper Urzhumian agrees with the stratigraphic data, in particular, to the recent discovery of discosauriscids at the Kluchiki locality (Perm Region, Russia), which is Ufimian–Kazanian in age

The new bennettitalean species Otozamites meyenii sp. nov. is described from the Middle Jurassic deposits of the Mikhailovskii Rudnik open mine (Kursk Region). The new species is characterized by long finger-like papillae on the covering cells of the pinnae lower epidermis. The rachis vascular system of the new species possesses structure, characteristic of leaves of other Bennettitales: a ring, formed by two U-shaped rows of collateral vascular bundles with xylem faced toward interior. Unlike the Lower Cretaceous O. kerae Ohana et Kimura, possessing well defined bundles, the new species has indistinct boundaries between bundles. Our data also point on the presence in representatives of the genus Otozamites Braun of tracheids, characteristic of several angiosperms, whereas the presence of vessels in the vascular system of Otozamites leaves has not been confirmed.