Ichthyosaurs from the Upper Triassic (Carnian–Norian) of the New Siberian Islands, Russian Arctic, and their implications for the evolution of the ichthyosaurian basicranium and vertebral column

ABSTRACT The first ichthyosaurian specimens discovered from the Upper Triassic of the Russian Arctic (Kotelny Island, New Siberian Islands) are described herein. They include the remains of large- to small-bodied ichthyosaurians originating from six stratigraphic levels spanning the lower Carnian to middle Norian. The material is mostly represented by isolated vertebrae and ribs, which are not possible to accurately diagnose, but also includes specimens comprising associated vertebrae and a fragmentary skeleton that preserves cranial remains (parabasisphenoid, fragmentary quadrate, partial mandible and hyoids). Based on vertebral and rib morphology, we identify the specimens as representatives of the following taxonomic groups: large-bodied shastasaurids, medium-sized indeterminate ichthyosaurians with a single rib facet in the presacral centra, and small euichthyosaurians with double rib facets present throughout the presacral vertebrae that likely represent toretocnemids and/or basal parvipelvians. In addition, the cranial and mandibular remains preserved in one of the specimens, ZIN PH 5/250, were studied using micro-computed tomography. Its mandible is highly similar to that of toretocnemids, whereas the parabasisphenoid demonstrates a peculiar combination of both plesiomorphic and derived character states, providing the first detailed data on this cranial element in a Late Triassic ichthyosaurian. Furthermore, the specimen also demonstrates a distinctive condition of rib articulation in the anteriormost presacral (cervical) vertebrae, which together with other features allows for the erection of a new taxon – Auroroborealia incognita gen. et sp. nov. Although the phylogenetic position of this taxon is uncertain due to its fragmentary nature, its anatomy, indicating toretocnemid or parvipelvian affinities, further supports the previously hypothesised sister-group relationships between these two clades. The morphology of the parabasisphenoid and vertebral column of the new taxon is discussed in broader contexts of the patterns of evolution of these skeletal regions in ichthyosaurs.

Russian Polar expedition and geopolitical interests at the turn of the XIXth and XXth centuries. Part 2. E.V. Toll’s expeditions and their geopolitical significance

Русская Полярная экспедиция (РПЭ) была важна с точки зрения геополитических интересов России: она имела широкий научный и общественный резонанс, находилась под Высочайшим покровительством президента Императорской Академии наук Великого князя Константина Константиновича. Оставшиеся в живых участники РПЭ и их последователи преодолели все сложности для того, чтобы спасти и сохранить геологические коллекции, собранные Э.В. Толлем на Таймыре и Новосибирских островах. Научные данные, полученные в ходе экспедиции, были столь значительны, что их обработка продолжалась вплоть до «дела Академии наук» (1929–1931 гг.) и ее реорганизации. Геологические образцы и некоторые документы Русской Полярной и других экспедиций с участием Э.В. Толля хранятся ныне в Рудно-петрографическом музее ИГЕМ РАН и доступны для дальнейших исследований. The Russian Polar Expedition (RPE) was important for Russian geopolitical interests: it had a broad social and academic resonance and was under the auspices of Grand Duke Konstantin Konstantinovich, the President of the Russian Imperial Academy of Sciences. The survived personnel of RPE and their followers managed to overcome the diffi culties to preserve the geological collections gathered by E.V. Toll at the Taimyr Peninsula and New Siberian Islands. The scientifi c results of the expedition were of paramount importance and were continuously studied and processes until the lawsuit of «The Plot at the Academy of Sciences of the USSR» was launched in 1929–1931, after which the Academy of Sciences of the USSR was reorganized. Geological samples and some documents of the Russian Arctic and other expeditions with the participation of E.V. Toll are now housed at the Ore and Petrographic Museum at IGEM RAS and are available for further studies.

Ordovician turbidites and black shales of Bennett Island (De Long Islands, Russian Arctic), and their significance for Arctic correlations and palaeogeography

Bennett Island stands alone in a remote part of the Arctic and information on its geology is essential to ascertain relations with other terranes in order to restore the early Palaeozoic Arctic palaeogeography. Lower Palaeozoic sedimentary rocks throughout the island were studied thoroughly for the first time. The Ordovician section (> 1.1 km thick) comprises three units: Tremadocian, lowest Floian black shale (130–140 m); Floian, lower Dapingian carbonate turbidite (> 250 m); and Dapingian, lower Darriwilian siliciclastic turbidite (> 730 m). Ordovician deposits conformably overlie Cambrian rocks deposited within the Siberian shelf, as shown earlier. Most of the Ordovician succession was formed in a deep trough that received carbonate debris from a nearby carbonate platform and silicate material from a distant landmass located to the NE (present coordinates). The Bennett Island Ordovician rocks have much in common with those of both the Central and Northern Taimyr belts. It could be tentatively suggested that both belts merged at their eastern continuation in the vicinity of De Long Islands. The whole system probably extends further eastwards. The Ordovician facies patterns and faunal assemblages in the New Siberian Islands are notably similar to those of northwestern Alaska, where the same lateral transition from turbidites to shelf limestones was reported.

New cryptogamic records. 6

First records of chrysophytes for the North-Western Russia and the Leningrad Region, fungi for the Pskov Region, lichens for Svalbard and the Altai Territory, bryophytes for the Far East, Arkhangelsk, Saratov, Voronezh and Sakhalin regions, the Karachayevo-Circassian Republic, Republic of North Ossetia – Alania, the Republic of Altai, the New Siberian Islands Archipelago, the Kuril Islands, the Republic of South Ossetia. The data on its localities, habitats and distribution are provided.

A new species of the genus Birisia (Dicksoniaceae) from the lower–middle Albian deposits of Southern Primorye, Far East of Russia

A new fern Birisia mandshurica, sp. nov. (Dicksoniaceae) from the lower–middle Albian Frentsevka Formation of southern Primorye, Far East of Russia is described. This species is characterized by short-creeping rhizomes with closely spaced stipes and bipinnate fronds with narrow linear pinnules. A reconstruction of B. mandshurica is proposed. It comes from the autochthonous locality of ferns and herbaceous angiosperms and was a part of pioneer open community, which occupied low flat plains between river channels. Revision of ferns, described as Acanthopteris gothanii Sze from China, shows, that these ferns belongs to Birisia alata (Prynada) Samylina. The name Acanthopteris Sze should be abandoned, due to absence of spore-bearing pinnules and poor preservation of sterile pinnules in type specimens. Based on Chinese and Russian material of good preservation, we provide emended diagnoses of the genus Birisia Samylina and its type species B. alata. Re-examination of various species of the genus Birisia revealed that this genus was widely distributed in the Cretaceous floras (from the Barremian to the Coniacian) of Eastern Siberia, New Siberian Islands, North-East and Far East of Russia, China, Japan, Alaska and Western Canada. B. alata is the most widespread species.

New cryptogamic records. 5

First records of Myxomycetes for the Republic of Belarus, Basidiomycetes for the Novosibirsk and Volgograd regions, the Republic of Altai, lichens and lichenicolous fungi for the Tver Region, the republics of Altai and Tyva, bryophytes for Novaya Zemlya, the Pskov, Tula and Saratov regions, the Republic of Ingushetia, the Khanty-Mansi Autonomous Area — Yugra, the Republic of Buryatia, the New Siberian Islands Archipelago, the Peninsula and excluded lichens for the Republic of Altai are presented. Data on localities, habitats, substrates and herbarium specimens of all species are provided.

Upper Cretaceous rhyolitic ashes in the Utes Derevyannykh Gor area (Novaya Sibir Island, the New Siberian Islands)

The article is concerned with the first finds of rhyolite ashes in Upper Cretaceous sediments of Novaya Sibir Island. In the course of the field work in the area of cape Utes Derevyannykh Gor in 2016, four layers of unlithified fine-grained ashes were found in the Turonian-Coniacian coal-bearing Derevyannye Gory Formation. The article presents the results of petrographic, X-ray diffractometric and microprobe analysis of pyroclastics from ash layers. A typification of volcanogenic-terrigenous deposits is proposed. Thin section of the samples were investigated on a polarizing microscope. X-ray phase analysis of the clay fraction was carried out using a DRON-3 diffractometer. X-ray microanalysis of vitroclasts were carried out on a scanning electron microscope “Jeol JSM-6480LV” with the microprobe analyzer “Oxford Instruments INCA-Energy 350”. It was established that Derevyannye Gory Formation is composed of rhyolitic tuffites, among which fine-grained crystal-vitroclastic and vitroclastic ashes of low and normal alkaline high-potassium rhyolites with thickness up to 2.5 m. Low pyroclastics sediments are not widespread. New data on the structure and composition of the Derevyannye Gory Formation confirm the hypothesis of previous researchers, that sedimentation in the Late Cretaceous in the area of Novaya Sibir Island was accompanied by explosive acidic volcanism. The main purpose of the article is to discuss the sources of pyroclastic material for the territory of the New Siberian Islands in the Turonian-Coniacian age. The conclusion is made about the territorial proximity of the paleovolcanic eruption center to the area of sedimentation. It is assumed that the paleovolcanic centers were located within the present territory of Kotelny, Zemlya Bunge, Faddeevsky islands and, probably, were inherited from the Early Albian stage.