The results of comparative morphological and ontogenetic analyses of the ostracods Bathoniella Tesakova (East European Platform (EEP) and Northern Germany, Bathonian–lower Callovian) and Parabathoniella Tesakova (Scotland, lower–middle Bathonian) suggested their origin from representatives of the genus Glyptocythere Brand et Malz with reticulate ornamentation (Europe, Bajocian–Bathonian). The West European Parabathoniella evolved from G. comes Br. et Malz, while East European Bathoniella evolved from G. tuberosa (Khabarova). Both ancestral taxa evolved from the West European G. concentrica Br. et Malz, which migrated to the EEP with formation of the allopatric G. tuberosa in the late Bajocian. A replacement name G. pseudotuberosa Tesakova, nom. nov. is proposed for G. tuberosa Br. et Malz, 1962 from the lower Bathonian of Germany, a junior homonym. The development of ornamentation and linear dimensions in the lineage of reticulate Glyptocythere demonstrates a complete cycle of morphogenesis with paedomorphosis and magnification in Bajocian species and subsequent gerontomorphosis and minification in Bathonian representatives and their descendants Bathoniella in the Bathonian and early Callovian. The stratigraphic continuity of successive species made it possible to recognize new lineage zones in the EEP: G. tuberosa in the terminal upper Bajocian–lower Bathonian (Michalskii–Besnosovi zones), B. prima in the terminal lower Bathonian–upper Bathonian (Ishmae Zone–lower part of the Calyx/Infimum Zone), B. milanovskyi in the upper Bathonian (presumably the upper part of the Calyx/Infimum Zone)–lower Callovian (Elatmae Zone), B. paenultima in the lower Callovian (Subpatruus Zone, C. surensis, C. subpatruus, C. uzhovkensis biohorizons) and B. ultima in the lower Callovian (Subpatruus Zone, Ch. saratovensis Biohorizon–Calloviense Zone). Additionally, the B. milanovskyi Zone is recognized in Northern Germany. The species Parabathoniella elongata (Wakefield) from the lower and middle Bathonian of Scotland appears to have been the only member of the West European genus. Its homologous acquisition of bathoniellid sexual dimorphism at the same time as B. prima Tesakova allows a pan-European correlative level based on the first appearance of these species in the geological record to be drawn.

This is the second part of the paper on the Cretaceous of the Mountainous Crimea. A lot of new data has been received during last ten years. This paper summarizes the state of knowledge of the Upper Cretaceous stratigraphy, selected biostratigraphic groups (ammonites, belemnites, ostracods, foraminifers, gilianelles, nannoplankton) and magnetostratigraphy. Ammonite and belemnite biostratigraphic subdivisions are proposed for the first time for the Crimean Upper Cretaceous. Foraminifera-based biostratigraphy is updated, and new biostratigraphic units are proposed and correlated with the European scale. Stratigraphic hiatuses are recognised in the succession of southwestern Crimea: the base and the top of lower Cenomanian, upper Coniacian–lower Santonian, Campanian/Maastrichtian and Cretaceous/Paleogene boundary intervals.

The stratigraphically important ostracod taxa Palaeocytheridea milanovskyi Lyubimova, 1955 and P. nikitini Lyubimova, 1955 from the lower Callovian of the East European Platform and Northern Germany are revised. P. nikitini is reduced to a synonymy of P. milanovskyi. The latter one is proposed as the type for the new genus Bathoniella from the lower Bathonian–lower Callovian (Ishmae–Calloviense zones). Three more species: B. prima sp. nov., B. paenultima sp. nov. and B. ultima sp. nov. are included in Bathoniella gen. nov. A new – bathoniellid – subtype of sexual dimorphism is described. This is also characteristic of another new genus, Parabathoniella, with the type species Acantocythere elongata Wakefield, 1994 from the lower–middle Bathonian (Tenuiplicatus–Progracilis zones) of the Inner Hebrides, Scotland, as well as the genus Mandelstamia from the Upper Jurassic and lower Cretaceous of Europe.

This paper contains refined and extended descriptions of two ostracod genera of the family Cytheru-ridae: Pseudohutsonia Wienholz, 1967 and Procytherura Whatley, 1970, based on material from the Upper Bajocian (Michalskii ammonite Zone) and Lower Bathonian (Besnosovi ammonite Zone) of the Russian Plate from the Sokur composite Section (Saratov Region) and from the Obval Borehole (Penza Region). The genus Pseudohutsonia is revised and the evolution of two parallel lineages in the Middle Jurassic is proposed. Five stratigraphically significant ostracod species are described. For Pseudohutsonia clivosa (Khabarova, 1955), a neotype is designated herein; four others, Procytherura iyae, Acrocythere sokurensis, Nanacythere octum, and Trachycythere peculiaris, are described as new. For four taxa identified in open nomenclature (Nanacythere sp. 1, N. sp. 2, Ljubimovella sp. 1 and Gen. et sp. 8), information on the material and distribution in the studied sections is given, which will facilitate their use for stratigraphy and correlation in the future.

The ostracod genera Camptocythere Triebel and Procytherura Whatley from the Lower and Middle Callovian of TETs-5 reference Section (Saratov Region) and Middle Callovian–Lower Oxfordian of Mikhailovtsement reference Section (Ryazan Region) have been studied. The genus Camptocythere is revised; genus Aparchitocythere Swain et Peterson is considered as a separate genus (rather than a subgenus of Camptocythere), whereas the genus Palaeoloxoconcha Dreyer is for the first time included as a subgenus. New species are described: C. (Camptocythere) quinta Tesakova, sp. nov., C. (Palaeoloxoconcha) caudata Tesakova, sp. nov. (with the subspecies C. (P.) caudata caudata Tesakova, subsp. nov. and C. (P.) caudata nuda Tesakova, subsp. nov.), C. (P.) ryazanica Tesakova, sp. nov. and Procytherura ippolitovi Tesakova, sp. nov. Within the East European Platform (EEP), two ostracod concurrent-range zones have been recognized. The A. milanovskyi–P. cinicinnusa Concurrent-range Zone is recognized in the Lower Callovian (Subpatruus ammonite Zone, Subpatruus–Saratovensis biohorizons) of Ukraine, Kursk Region, and Volga Region. The Pr. wartae–Pl. kurskensis Concurrent-range Zone is recognized in the Lower Callovian (Subpatruus ammonite Zone, Saratovensis Biohorizon)–Middle Callovian (Jason Zone) of Ukraine, Belarus, Central Chernozemye, Kursk Region, and Middle Volga Region. Based on the evolution of the subgenus C. (Palaeoloxoconcha), new lineage zones are proposed. The C. (P.) bathonica Lineage Zone is recognized in northwestern Europe in the Upper Bajocian–Bathonian. The C. (P.) caudata Lineage Zone is recognized on the EEP (Belarus, Kursk and Saratov regions) in the Lower Callovian (Subpatruus Zone, Saratovensis Biohorizon)–lower part of the Middle Callovian (Jason Zone). The C. (P.) ryazanica Lineage Zone is recognized in the Ryazan Region in the upper part of the Middle Callovian (Coronatum Zone)–Lower Oxfordian (Mariae Zone).

A new species Camptocythere (Anabarocythere) triangula Tesakova, sp. nov. is described from the Upper Bajocian (Michalskii ammonite Zone) and the Lower Bathonian (Besnosovi ammonite Zone) of the Russian Plate (Sokur Borehole, Saratov Region). This species is presumed to be the ancestor of C. (A.) muricata Gerke et Lev, sp. nov. from the upper Bathonian–Callovian of northern Siberia, Timan-Pechora Province and the Barents Sea shelf, the first description of which is also published in this paper. The publication of the original description by O.M. Lev, expanded and supplemented by the author of this study, confers availability and validity of this species from the date of the present publication, and eliminated shortcomings in the stratigraphic literature, where until now C. (A.) muricata was a nomen nudum. The possible phylogenetic relationship between these species allows them to be considered indices of the corresponding lineage zones in the scale of evolution of the subgenus C. (Anabarocythere) Nikitenko. The species Procytheridea? bajociensis (Khabarova, 1955) is re-studied from the same deposits of the Sokur Borehole and the Lower Bathonian of the Obval Borehole (Penza Region). P. concinna Permjakova, 1974 and P. ljubimovae Permjakova, 1974 from the synchronous deposits in Ukraine were synonymized with this species after its revision. A neotype is designated for P.? bajociensis and an expanded and supplemented redescription is provided. The monospecific assemblages (or with the dominance of this taxon) with P.? bajociensis, are restricted to the Late Bajocian–Early Bathonian of the Russian Plate and Western Kazakhstan and suggest an extremely shallow coastal setting, possibly with unstable salinity.

The stratigraphically important ostracod genera Plumhoffia Brand, 1990 (family Cytheruridae) and Aaleniella Plumhoff, 1963 (family Eucytheridae) from the Upper Bajocian and Lower Bathonian of the Volga Region (Sokur Section, Saratov Region) and central Russia (Obval Borehole, Penza Region) are revised, and updated and expanded descriptions are provided. Four species are described. A neotype is designated for Plumhoffia tricostata (Khabarova, 1955); three others: Aaleniella franzi, A. volganica, and A.? ovoidea are described as new. Their distribution along the Sokur reference section of the Upper Bajocian (Michalskii ammonite Zone)–Lower Bathonian (Besnosovi ammonite Zone) of the Volga Region allows development of detailed ostracod-based biostratigraphy and correlation of the sections studied with synchronous deposits of Western Europe.

The results of micropaleontological analysis of the boundary interval of the lower–middle Callovian in the TETs-5 section (Saratov) are presented. The taxonomic composition and distribution of foraminifera and ostracods in the section are studied. The ranges of the biostratigraphic units inferred from microfauna and their correlation with the ammonite scale are refined. Two foraminiferal zones of the East European Platform are established: Haplophragmoides infracalloviensis–Guttulina tatarensis and Lenticulina cultratiformis–Lenticulina pseudocrassa. The volume of the Lenticulina cultratiformis–Lenticulina pseudocrassa Zone ranges from the upper part of the lower Callovian (the upper part of the Koenigi Zone and the Calloviense Zone) to the middle Callovian. Two biostratigraphic units by ostracods are established: (1) the Acantocythere milanovskyi–Procytheridea cinicinnusa Zone corresponding to the Subpatruus Zone of the lower Callovian, to the lower part of the Ch. saratovensis biohorizon, and (2) Beds with Praeschuleridea wartae–Pleurocythere kurskensis corresponding to the terminal part of the Subpatruus Zone (the upper part of the Ch. saratovensis biohorizon), the Koenigi and Calloviense zones of the lower Callovian, and the lower part of the Jason Zone of the middle Callovian. The images of typical taxa are provided.

An extended and updated redescription of the stratigraphically important species Glyptocythere aspera (Khabarova, 1955) from the Upper Bajocian–Lower Bathonian of the Russian Plate (RP), Western Kazakhstan and Uzbekistan was made as a result of a revision, and a neotype was designated. The species G. bathonica from the Lower Bathonian of the RP and Western Kazakhstan was described as new. The lineage G. tuberodentina Brand et Malz in Brand et Fahrion (bj 2 , Parkinsoni ammonite Zone) → G. aspera (bj 2 -bt 1 , Michalskii ammonite Zone and lower part of the Besnosovi ammonite Zone) → G . bathonica sp. nov. (bt 1 , upper part of the Besnosovi Zone) has been reconstructed on the RP, which developed by paedomorphosis, with the advancing evolution of males. Species characters (shell outline, linear parameters, hinge, and sculpture) evolved in females and males at different rates, in males with retardation, which led to the convergence of the shells of both sexes in G. bathonica sp. nov. That is, the lineage evolved with a weakening of sexual dimorphism. The species G. tuberodentina appeared and developed in northern Germany in the Late Bajocian ( Parkinsoni Phase) and at the same time migrated across the Polish Sea to the seas of RP. The north German G. tuberodentina taxon-range Zone (b 2 , Parkinsoni Zone, the upper part of the Truellei Subzone and the Bomfordi Subzone) was traced for the first time in Poland and the Dnieper–Donets Depression (DDD). In the DDD, its range was reduced due to the recognition of a new ostracod lineage-zone in the Michalskii Zone. Based on the reconstructed lineage, the following new ostracod lineage-zones were established: G. tuberodentina Zone (b 2 , Parkinsoni Zone) for the DDD, G. aspera Zone (bj 2 -bt 1 , the zones Michalskii and Besnosovi with the O. mojarowskii and O. sciticum biohorizons) for the DDD, Central Russia, the Volga Region, and Western Kazakhstan, and G. bathonica Zone (bt 1 , Besnosovi Zone, O. issae–A. excentricum biohorizons) for Central Russia, the Volga Region, and Western Kazakhstan.

Впервые в келловее (аммонитовые зоны Calloviense, Jason, Coronatum и Athleta) Центрального Дагестана выявлены и изучены остракоды. Комплекс насчитывает девять видов, один – Pleurocythere khapissovi sp. nov. – описан как новый. Для ранее известных форм приведены изображения.

On the basis of detailed, combined rock-magnetic, lithological, and micropaleontological study of the Mikhailovtsement section of the Moscow syneclise (Ryazan region), the fluctuations in Central Russian Sea level in Callovian–Early Oxfordian were reconstructed. According to the variations of rock-magnetic parameters over the section, seven rock-magnetic intervals were established which correspond to different stages of basin evolution. These stages are compared with sea level fluctuations established on the basis of changes in the lithology of rocks and the ostracod complexes. In general, the nature of sea level change in Callovian–Oxfordian, revealed by combination of the methods during the study of Mikhailovtsement section coincides with global trend.

The genus Lophocythere in Late Callovian of the Russian Plate includes the following species: L. karpinskyi (Mandelstam in Lyubimova, 1955), L. sp. A, L. sp. B and L. acrolophos Whatley, Ballent, Armitage, 2001. Based on similarities in sculpture and hinge structure, the first two species belong to the same phyletic lineage; the third belongs to the other lineage, L. propinqua Malz, 1975 (J2bt3) → L. scabra Triebel, 1951 (J2cl1–2) →? → L. sp. B. L. karpinskyi and L. sp. B invaded the sea of the Russian Plate from Western Europe during a transgression in J2cl1 (Koenigi Phase), and L. sp. A appeared there during J2cl3 (Athleta Phase). L. acrolophos also appeared in the same phase, but it probably originated from L. interrupta Triebel, 1951 (J2cl1-2). These species are the markers of transgression and indices of Pan-European correlative levels.

Based on a detailed integrated petromagnetic, lithological, and micropaleontological study of the Mikhailovtsement reference section of the Moscow syneclise (Ryazan Region), the fluctuations in the Middle Russian Sea level in the Callovian–Early Oxfordian were reconstructed. According to the variations of petromagnetic parameters through the section, seven petromagnetic intervals corresponding to different stages of the paleobasin evolution were established. These stages are correlated with sea level fluctuations established on the basis of changes in the rock lithology and the ostracod complexes. In general, the character of sea level change in the Callovian–Oxfordian that was revealed during the study of the Mikhailovtsement section is in agreement with the global trends.

Various methods of ostracod analysis with reference to paleobathymetric and paleotemperature reconstruction are considered in detail, using Callovian–Lower Oxfordian ostracod assemblages from the Mikhailovtsement reference section (Ryazan Region) as an example. Based on generalization of the data obtained by different methods, seven transgressive–regressive events are reconstructed, five of which had a pan-European scale and were accompanied by the intensified boreal effect. For the Upper Callovian of the East European Platform, ostracod index species of paleotemperatures, paleoeutrophication, and paleodepths on the upper subtidal depths are recognized for the first time.

Abstract Previous studies made in different parts of the world have shown that Barremian–Aptian times imply many difficulties in deciphering the biostratigraphy, microfossil evolution and correlation of bioevents. In an attempt to improve our knowledge of this period in a particular area of the Tethyan realm, we present the first integrated study of microbiota (including planktonic foraminifera, calcareous nannofossils, ostracods and palynomorphs) and magnetostratigraphy of the upper Barremian–Aptian sediments from south-eastern Crimea. The nannofossils display the classical Tethyan chain of bioevents in this interval, while the planktonic foraminifera demonstrate an incomplete succession of stratigraphically important taxa. Our study enabled the recognition of a series of biostratigraphic units by means of four groups of microfossils correlated to polarity chrons. The detailed analysis of the microfossil distribution led to a biostratigraphic characterization of the Barremian/Aptian transition and brought to light an interval, which may correspond to the OAE1a.

Results of clumped isotope, oxygen isotope and elemental (Mg/Ca, Sr/Ca) analyses of exceptionally well-preserved belemnite rostra and ammonite shells from the uppermost Callovian-Upper Kimmeridgian (Lamberti-Mutabilis zones) of the Russian Platform are presented. Despite a significant decrease in belemnite delta O-18 values across the Upper Oxfordian-Lower Kimmeridgian, the clumped isotope data show a constant sea-water temperature (ca. 16 degrees C) in the studied interval. The decrease in belemnite delta O-18 values and lower delta O-18 values measured from ammonite shells are interpreted as a result of the salinity decline of the Middle Russian Sea of ca. 1 2 parts per thousand, and salinity stratification of the water column, respectively. The postulated secular palaeoenvironmental changes are linked to the inflow of subtropical, saline waters from the Tethys Ocean during a sea-level highstand at the Middle-Late Jurassic transition, and progressive isolation and freshening of the Middle Russian Sea during the Late Oxfordian-Kimmeridgian. The obtained clumped isotope data demonstrate relative stability of the Late Jurassic climate and a paramount effect of local palaeoceanographic conditions on carbonate delta O-18 record of shallow epeiric seas belonging to the Subboreal Province. Variations in Mg/Ca and Sr/Ca ratios of cylindroteuthid belemnite rostra, which are regarded by some authors as temperature proxies, are, in turn, interpreted to be primarily dependent on global changes in seawater chemistry. The paleoenvironmental variations deduced from clumped and oxygen isotope records of the Russian Platform correspond well with changes in local cephalopod and microfossil faunas, which show increasing provincialism during the Late Oxfordian and the Early Kimmeridgian. Based on the review of literature data it is suggested that the observed salinity decrease and restriction of Subboreal basins during the Late Jurassic played a major role in the formation of periodic bottom water anoxia and sedimentation of organic rich facies.