Vol 52, No 6 (2018)

Vendian (Ediacaran) tubiform organic-walled segmented microfossils from the East Siberian Platform, with no biological interpretation, were previously assigned to the Incertae sedis genus Kursovia Kolosov et Rudavskaja, 1984 and identified as Kursovia sp. 4. The re-examination of these fossils showed that these are new saarinid microorganisms that resemble Saarina juliae in the tubiform shape, segmented structure, presence of crenulae on free (upper) edge of segments and in the prominence of these features, but are smaller by one–two orders of magnitude. They are herein assigned to a new genus and species Saarinomorpha infundibularis Kolosov et Sofroneeva, gen. et sp. nov. in the family Saarinidae Sokolov, 1965.

Three species of incrusting bryozoans (Tubuliporida, Stenolaemata) from the Upper Callovian (Middle Jurassic) in the vicinity of the town of Kolomna, Moscow region, are described: Stomatopora dichotoma (Lamouroux, 1821), which was first discovered in the late Callovian of the Moscow region; Reptomultisparsa stratosa sp. nov.; and ?Microeciella sp. Some features of the interaction between S. dichotoma and ?Microeciella sp. the colonies of which developed side by side on the same substrate are discussed.

Fossil beetles of the families Asiocoleidae, Schizocoleidae, and Permosynidae, recently collected in the Aristovo locality (Upper Permian, northern European Russia, Malaya Northern Dvina River) are described. All fossils are isolated elytra, whose systematic position in the natural system is often hardly established; thus, they are described as formal taxa. Aristovo is the only locality dominated by both asiocoleids and permosynids; these insects started playing an important role at the end of the Permian. It could also have adephagians and polyphagyans, the main groups of Meso–Cainozoic beetles.

Amphibian remains from Sundyr-1 (Russia, Mari El Republic), the reference locality of the Sundyr Tetrapod Assemblage, are identified and described. The assemblage is assigned to the lower Upper Severodvinian Substage (Lower Putyatinian Subhorizon). It is shown that the taxonomic list of the Sundyr-1 locality includes five species, which belong to five genera and four families (Kotlassiidae, Dvinosauridae, Chroniosuchidae, and Enosuchidae). The aquatic tetrapod association of the Sundyr Assemblage occupies an intermediate position between Isheevo and Sokolki tetrapod communities and is mostly composed of genera and species from both of them. Archegosauroid temnospondyls are completely absent; the trophic niche of predominate piscivorous hunter of the community is occupied by the chroniosuchian Suchonica vladimiri. Except for the last taxon, amphibians of the Sundyr-1 locality are represented by pedomorphic, constantly aquatic taxa varying in trophic specialization.

The joint of the occipital skull region and two first cervical vertebrae of Psittacosaurus sibiricus from the Shestakovo locality (Barremian–Aptian), Kemerovo Region, Russia is described. The morphological differences in the atlas–axis complex between the infraorders Psittacosauria and Neoceratopsia connected with their functional features are revealed. The atlas–axis complex of P. sibiricus consists of two unfused vertebrae. The atlas includes the centrum, neural arch, and intercentrum. The axis consists of fused centrum, neural arch, and intercentrum, which is fused with its centrum. The cranial processes of the neural arch of the atlas are well developed, could have indicated the presence of a proatlas. The shape of the occipital condyle and anterior articular surface of the atlas are evidence that the occiput–atlas joint was only slightly flexible in the vertical plane. The atlas–axis complex and occipital condyle of P. sibiricus are similar in morphology to that of ornithopods.

New material from the Upper Kimmeridgian and Volgian of the Gorodishche section (Ulyanovsk Region, Russia) allows a more accurate definition of the tabulation formula and archeopyle morphology of the dinocyst genus Dingodinium. The partiform pattern of the antapex and morphological features of the epicyst indicate that the genus Dingodinium should be attributed to the family Cladopyxiaceae of the suborder Cladopyxiineae. The genus Dingodinium as well as the species D. albertii, D. jurassicum, and D. tuberosum are revised, and a new species, D. nequeas, is described. In addition, the published data on Jurassic and Cretaceous species of the genus Dingodinium are analyzed and morphological criteria allowing their identification are recognized. Many species have a wide geographic distribution. Some species can be regarded as stratigraphically important for certain intervals of the Jurassic and Cretaceous.