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1

Phylogeny of the ammonite family Aulacostephanidae Spath, 1924 during the Late Oxfordian and the Early Kimmeridgian in Europe: Main lineages, patterns of evolution and sedimentological to palaeogeographical controls on evolutionary development

Wierzbowski Andrzej

Volumina Jurassica

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2022

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Vol. 20

59--128

EN

The evolutionary history of the Aulacostephanidae presented here includes the interval of about 5 Ma of the Late Oxfordian and Early Kimmeridgian ranging from the origin of the family to is maximal development. The development and biogeographical distribution of aulacostephanids in Europe were related mostly to sea-level changes and tectonics. The appearance of the ancestor genus Decipia and the following genus Ringsteadia was controlled by marine transgressions during the Late Oxfordian which stimulated also the distribution of these ammonites in Subboreal and Submediterranean Europe. The main faunal turnover at the Oxfordian/Kimmeridgian boundary was related to allopatric speciation correlated to separation of the aulacostephanid assemblages: it resulted in the appearance of the main Ringsteadia-Pictonia-Rasenia lineage in NW Subboreal Europe and the side-lineages Ringsteadia-Vielunia-Eurasenia/Involuticeras and Ringsteadia-Vineta-Balticeras-Rasenioides in NE Subboreal and Central Submediterranean Europe. A strong development of the shallow-water carbonate platforms during the Early Kimmeridgian stimulated the development of still another Pictonia (Pomerania) - Rasenia (Pachypictonia) lineage. The main faunal turnover correlated to a large transgression at the end of the Early Kimmeridgian resulted in the sudden distribution of the new aulacostephanid faunas over large areas of northern and central Europe, and opened a new stage in the evolutionary development of the family.

2

Review of the Ordovician stratigraphy and fauna of the Anarak Region in Central Iran

Popov L. E., Hairapetian V., Evans D. H., Ghobadi Pour M., Holmer L. E., Baars C.

Acta Geologica Polonica

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2015

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Vol. 65, no. 4

403--435

EN

The Ordovician sedimentary succession of the Pol-e Khavand area, situated on the northern margin of the Yazd block, has important differences from those in other parts of Central Iran. It has been established that the presumably terminal Cambrian to Lower Ordovician volcano-sedimentary Polekhavand Formation, exposed in the Pol-e Khavand area, has non-conformable contact with greenschists of the Doshakh Metamorphic Complex. The succeeding, mainly siliciclastic Chahgonbad Formation contains low to moderately diverse faunal assemblages, including brachiopods, cephalopods, trilobites and tentaculitids. The Darriwilian age of the lower part of the formation is well established by the co-occurrence of brachiopod genera Camerella, Phragmorthis, Tritoechia and Yangtzeella. The associated rich cephalopod fauna is different from the Darriwilian cephalopod associations of the Alborz terrane and may show some affinity with warm water faunas of North China and South Korea. It is likely that the Mid Ordovician fauna recovered from the lower part of the Chahgonbad Formation settled in the area sometime during a warming episode in the late Darriwilian. By contrast the low diversity mid Katian brachiopod association includes only three taxa, which occur together with the trilobite Vietnamia cf. teichmulleri and abundant, but poorly preserved tentaculitids questionably assigned to the genus Costatulites. This faunal association bears clear signatures linking it to the contemporaneous cold water faunas of the Arabian, Mediterranean and North African segments of Gondwana. Four brachiopod species recovered from the Chahgonbad Formation, including Hibernodonta lakhensis, Hindella prima, Lomatorthis? multilamellosa and Yangtzeella chupananica are new to science.

3

Upper Cretaceous (Maastrichtian) charophyte gyrogonites from the Lameta Formation of Jabalpur, Central India: palaeobiogeographic and palaeoecological implications

Khosla A.

Acta Geologica Polonica

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2014

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Vol. 64, no. 3

311--323

EN

A charophyte gyrogonite assemblage consisting of Platychara cf. sahnii, Nemegtichara grambastii and Microchara sp. is reported herein from two localities (Bara Simla Hill and Chui Hill sections) of the Lameta Formation at Jabalpur. The Lameta Formation locally underlying the Deccan traps has been shown to be pedogenically modified alluvial plain deposits containing one of the most extensive dinosaur nesting sites in the world. They are associated with dinosaur bones and freshwater ostracod assemblages that suggest a Late Cretaceous (Maastrichtian) age. This is the first detailed systematic account of charophyte gyrogonites from the Lameta Formation. This charophyte assemblage is compatible with the biostratigraphic attribution provided by the ostracods. From a biogeographic viewpoint, it exhibits considerable similarity to other infratrappean assemblages of the Nand, Dongargaon, and Dhamni-Pavna sections (Maharashtra), and some intertrappean assemblages of Kora in Gujarat, Rangapur in Andhra Pradesh and Gurmatkal in South India. Globally, the genus Microchara is well distributed throughout Eurasia, whereas the genus Platychara occurs richly in the Upper Cretaceous deposits of Europe, Asia, America and Africa. However, at the specific level, Platychara cf. sahnii shows close affinities with charophytes from the Maastrichtian of Iran whilst Nemegtichara grambastii shows distinct affinities with two species of Early Palaeogene deposits of China and Mongolia. The presence of charophyte gyrogonites in the Lameta sediments is attributed to local lacustrine and palustrine conditions within a flood plain environment.

4

Ewolucja zespołów trylobitowych z drugiego i trzeciego oddziału kambru Gór Świętokrzyskich i ich znaczenie biogeograficzne

Żylińska A.

Przegląd Geologiczny

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2013

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Vol. 61, nr 1

30–-39

EN

Deposits of the Cambrian Series 2 and 3 of the Holy Cross Mountains, comprising sandstones, and silty and clayey mudstones, are located on the Małopolska Block which is part of the Trans-European Suture Zone. Most recent geophysical data point to the proximal nature of this structural element with regard to the Baltica palaeocontinent. The trilobite assemblages are dominated by Ellipsocephalidae, generally accompanied by Holmiidae in the lower part, and by Paradoxididae in the upper part of the studied interval. They display a significant evolutionary trend, correlatable with the development of contemporary assemblages in Avalonia and Gondwana rather than those of Baltica. Discrepancies between the basement affinity and the dominant trilobites may be explained by the influence of strong larva-carrying currents from Avalonia and Gondwana.

5

The oldest Cambrian trilobites from the Holy Cross Mountains, Poland : taxonomic, stratigraphic and biogeographic reappraisal

Żylińska A.

Acta Geologica Polonica

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2013

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Vol. 63, no. 1

57-87

EN

Authorship issues are clarified, new photographic documentation is provided and emended systematic descriptions are presented for the oldest Cambrian trilobite taxa from the Holy Cross Mountains (Poland). Biostratigraphic analysis of the fauna allows correlation with the traditional Holmia kjerulfi-group Zone of Scandinavia, the Callavia Zone of Britain and Newfoundland, the lower and middle part of the Sectigena Zone of Morocco and the Marianian Stage of Spain. The trilobites display a strong biogeographic signal linked with West Gondwana and Avalonia and a suggestion is made that the TESZ margin of Baltica with the Malopolska Massif was liable to currents from those areas that distributed planktonic trilobite larvae.

6

Findings of Alona protzi Hartwig 1900 (Branchiopoda: Anomopoda. Chydoridae) in Finland

Nykanen M., Sarmaja-Korjonen K.

Studia Quaternaria

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2007

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Vol. 24

73-77

EN

Alona protzi is a rare species of Cladocera, occurring in lake littoral throughout Europe. However, little is known about this animal, and so far it has not been included in provisional lists of species found in Finland. In this short report we present our findings of Alona protzi, both recent and subfossil material, as well as one previous, unpublished finding site of the species in Finland. We found three subfossil shells of this species in the bottom sediments of two lakes. In a third lake we found intact animals, an ephippial female and a male, while sampling stony bottom of lake littoral.

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Charakterystyka jurajskich mszywiołów południowej Polski w aspekcie warunków paleooerodowiska i biogeografii

Hara U.

Przegląd Geologiczny

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2007

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Vol. 55, nr 1

54-54, 60

EN

A few distinctive bryozoan assemblages have been recognized in the Middle and Upper Jurassic sediments of southern Poland. The biota moderately rich in bryozoan taxa are generally restricted to a few cyclostome genera and dominated respectively by tubuloporines among which the majority form a fan-shaped or discoidal [bereniciform], encrusting colonies previously called "Berenieca", a bryozoan ubiquitous in the Jurassic. The Lower and Upper Callovian epifaunal bryozoan community of the vicinity of Cracow at Zalas in the Cracow Upland is represented by well-known Jurassic Stomatopora Bronn, Hyporosopora Canu & Bassler and Microeciella Taylor & Sequeiros, genera, as well as the other undeterminated, numerous bereniciform colonies. In terms of the species richness the most diversified is the Early Oxfordian bryozoan assemblage of the Ćmielów area [NW margin of the Holy Cross Mts], associated with an open shelf biohermal sedimentation, which was replaced later [during the transversarium and bifurcatues zones] by the shallow-water, soft-bottom coral buildups, among which the bryozoans are well-represented and described from Bałtów. The presence of the ?Late Tithonian–Berriasian bryozoan fauna has been documented in the thin-sections of the Stramberk limestones of the Polish Flysch Carpathians. Palaeoecological aspects of the studied bryozoan biotas are related to the nature and relative abundance of the colonial growth forms, the substrate type and other ecological factors. The moderately rich occurrence of the bryozoans in the Late Middle and Upper Jurassic sequences of Poland shows a different pattern of distribution than the biotas of the northwestern Europe which display the greatest species diversity in the Middle Jurassic [Bathonian]. The taxonomical and biogeographical studies of the Jurassic bryozoan biotas of Poland, in spite of the great patchiness in the global distribution of the Jurassic cyclostomes, has a key significance for the evolutionary radiation pattern and may add new data, whether this fauna originated and started to radiate in the Late Middle or the Upper Jurassic, or this event was mostly connected with the facies migration from west to east.

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Upper Oxfordian – Lower Kimmeridgian ammonite succession (Amoeboceras, Suboxydiscites) in the Nordvik section (northern Siberia)

Rogov M., Wierzbowski A.

Volumina Jurassica

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2006

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Vol. 4, no. 1

211-212

EN

Nordvik Peninsula situated at the Laptiev Sea, east of Taimyr Peninsula provides one of the most fossiliferous Jurassic - Lower Cretaceous successions of northern Siberia. The succession consists of clays and mudstones with numerous levels of phosphatic and calcareous concretions. The Mesozoic deposits of the area were discovered at the beginning of XX century, but more detailed studies were undertaken by Russian geologists from sixties to eighties of the century: see Zakharov et al. (1983) and earlier papers cited therein. The present study is based on the collection of ammonites gathered during joint field-trip of the Russian (Zakharov V., Rogov M.) and Czech geologists (Kostak M., Chadima M., Slechta S., Mazuch M.) in August 2003. The collection of Upper Oxfordian - Kimmeridgian ammonites consists of about 60 specimens carefully located in the 20 meters thick section. The most abundantly represented and zonally diagnostic are representatives of the genus Amoeboceras, whereas rarely encountered but palaeogeographically important are representatives of the genus Suboxydiscites. The Amoeboceras ammonites enable recognition of the standard Boreal ammonite zones of the Upper Oxfordian and Kimmeridgian. These of the Upper Oxfordian (cf. Sykes & Callomon 1979) include: the Glosense Zone with ammonites Amoeboceras transitorium Spath, A. glosense (Bigot et Brasil); the Serratum Zone with A. serratum (Sowerby), A. koldeweyense Sykes et Callomon, A. nunningtonense Wright; the Regulare Zone with A. freboldi Spath, A. regulare Spath; the Rosenkrantzi Zone with A. rosenkrantzi Spath. The Kimmeridgian ammonite zones (cf. Wierzbowski & Smelror 1993) include: the Bauhini Zone with A. lineatum (Quenstedt); the Kitchini Zone with A. subkitchini Spath below (Subkitchini Subzone), and A. kitchini Salfeld and A. modestum Mesezhnikov et Romm above (Modestum Subzone); the Elegans Zone with A. elegans Spath and A. decipiens Spath. The Kochi Zone is the only standard zone not recognized in the succession, but the interval possibly corresponding to this zone in the Kimmeridgian unfortunately has not yielded recognizable ammonites. The recognition of the standard Amoeboceras zones in the northern Siberia well known in NW Europe and the Barents Sea area indicates the uniform character of the Late Oxfordian to Kimmeridgian ammonite faunas in the Boreal Province. The ammonites of the genus Suboxydiscites appear for the first time in the studied succession in the upper part of the Kitchini Zone of the Kimmeridgian, and do occur in the younger interval of the Kimmeridgian. The ammonites represent the group of oppeliids of the Submediterranean roots (Ochetoceras(?), see Rogov 2001) that colonized the Boreal Province during Late Kimmeridgian. In the studied section Suboxydiscites are represented by both microconchs and macroconchs, belonging to the new species.

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Middle and Upper Jurassic bryozoan biota of the southern Poland – their diversity, palaeocology, evolution pattern and biogeography

Hara U.

Volumina Jurassica

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2006

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Vol. 4, no. 1

234-235

EN

A few distinctive bryozoan assemblages have been recognized in the Middle and Upper Jurassic sediments of the southern Poland. The Upper Callovian to Lower Oxfordian of the hardground character, epibenthic, bryozoan community at Zalas (the Kraków-Wieluf Upland) is restricted to a few cyclostomes, which are dominated by undeterminated, tubuloporinids of the fan-shaped or discoidal, bereniciform colonies, respectively (Fig. 1: 1-2), as well as to well-known Jurassic Hyporosopora and Microeciella genera. Much rarer are vine-like, uniserial runners of Stomatopora dichotoma Bronn. A moderately rich, the Early Oxfordian bryozoan biota of amielów (NW margin of the Holy Cross Mts.) occurs in the sponge biohermal facies, where the majority of colonies acquire an erect encrusting, massive, fungiform, as well as the branched colony-forms, among which the following taxa have been distinguished: Oncousoecia sp., Radicipora radiciformis (Goldfuss), Idmonea sp., Reptomultisparsa(?) sp., Mecynoecia sp., Ceriocava corymbosa (Lamouroux), Theonoa chlatrata Lamouroux and Apsendesia cristata Lamouroux. The most prolific is Radicipora radiciformis typically present in the high-diversified bryozoan assemblages, amongst marly facies, and is often accompanied by the numerous sclerosponges. The Middle-Upper Oxfordian bryozoan fauna of Ba.tów (NW of the Holy Cross Mts.), which colonizes the soft-bodied substrate, consists entirely of small, delicate, erect colonies and abundant, bereniciform, tubular-shaped zoaria (Fig. 1: 3) of the Hyporosopora baltovensis (see Hara & Taylor 1996). Palaeoecological aspects of the studied bryozoan biotas are related to the nature and relative abundance of the colonial growth forms, as well as to a substrate type, the orientation to substrate and methods of attachment. Evolution of the bryozoan biotas of Poland, during the late Middle and Late Jurassic was undoubtedly connected with the development of the favourable Callovian transgressive mostly sandy limestone facies (Calloviense-Lamberti chrons) and the shelf carbonate facies, which became prevalent in the Early Oxfordian (Cordatum Chron) as an open shelf sponge biohermal facies (amielów bryozoan biota), and replaced later during the Middle-Late Oxfordian (Transversarium-Bifurcatus chrones) by the shallower, soft-bottom coral facies (Ba.tów bryozoan fauna). Taxonomically, the Middle/Upper Oxfordian Jurassic bryozoans at Zalas show the similarities with the palaeogeographically distant Middle Jurassic shallow-water bryozoan fauna of the Carmel Formation (Utah), and the Early Oxfordian amielów bryozoans bear much of resemblance to the Middle Jurassic fauna the Saone-Rhine Basin (France) and the Swabian Basin of Germany. The moderately rich occurrence of the bryozoans in the Middle/Upper and Upper Jurassic sequences of Poland, shows the different pattern of distribution, than the biotas of the northwestern Europe which display the greatest species diversity in the Middle Jurassic (Bathonian). This fact has a great significance for an answer, weather the bryozoans of the southern Poland originated and started to radiate in the Late Jurassic, or this event was mostly connected with a facies migration from west to east. The Middle/Upper and Upper Jurassic bryozoan fauna of Poland has a key biogeographical significance, however, there is still a great patchiness in the global distribution of the Jurassic cyclostomes.

10

The microcrustacean fauna of Sicily and the central Mediterranean Sea area - current knowledge and gaps to be filled

Marrone Federico

Polish Journal of Ecology

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2006

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Vol. 54, nr 4

681-685

EN

The current knowledge of freshwater entomostracans from Sicily and some neighbouring central-Mediterranean countries is briefly reviewed. Data concerning different countries and different taxonomical groups are markedly inhomogeneous and often far from being representative of the real biota of the corresponding countries. This gap prevents a sound, biogeographical analysis of the freshwater microcrustacean fauna of the area. The major gaps that have to be filled are highlighted and the need for more surveys and monitoring is emphasised.

11

Checklist and annotated bibliography of Recent Foraminiferida from the German Baltic Sea coast

Frenzel P., Tech T., Bartholdy J.

Studia Geologica Polonica

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2005

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Vol. 124

67-86

EN

There are 96 Recent foraminiferal species reported from the German sector of the Baltic Sea. All are benthic taxa. Most species are agglutinated forms, reflecting the brackish water conditions of the southern Baltic Sea. Decreasing diversity is visible following the salinity gradient along the coast from the west to the east. The associations of the deeper water below the halocline and of shallow water above are very different with higher diversity in the deeper water. A complete species list and annotated bibliography for Recent foraminiferal species from the brackish water of the German Baltic Sea coast are presented.

12

An explanation for low endemism of Triassic crinoids fromthe epicontinental Germanic Basin, Poland

Salamon M. A., Niedźwiedzki R.

Geological Quarterly

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2005

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Vol. 49, No. 3

331--338

EN

A summary of known crinoid taxa in the Polish part of the Triassic Germanic Basin, including their presence elsewhere, is documented. At present, 13 taxa and 3 ecophenotypes of crinoids have been recorded from that area, only one of them being endemic. In the Lower Muschelkalk and lower part of theMiddleMuschelkalk, taxa widespread both in the Tethys and Germanic Basin, or Tethyan taxa, dominate. In the Upper Muschelkalk crinoids are very rare in Poland, being represented by Encrinus liliiformis and Holocrinus sp. Many of the species occurring in the central part of the Germanic Basin in the Upper Muschelkalk have not been recorded in the eastern part of the basin. The degree of endemism of the crinoid fauna in theMuschelkalk is markedly lower than the degree of endemism of the rest of the benthonic macrofauna. This probably resulted from huge number of crinoids forming "crinoid gardens" that produced large number of larvae, increasing the chances of successful geographical expansion of crinoids.

13

Middle Ordovician bryozoa from the Podlasie-Brest Depression (Belarussian part) : suborders Ceramoporina, Esthonioporina, Amplexoporina, Halloporina

Pushkin V.

Geological Quarterly

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2002

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Vol. 46, No 4

411-434

EN

Bryozoa (23 species) from many boreholes in the Belarussian part of the Podlasie-Brest Depression and some adjacent areas of the East European Platform are described. Only bryozoa from the orders Cystoporida (suborder Ceramoporina) and Trepostomida (suborders Esthonioporina, Amplexoporina and Halloporina) are represented. Four species and one family are described as new. The genera Anolotichiina Pushkin, 1992 and Minutolunaria Pushkin, 1992 are redescribed. The species described occur in the Llanvirn (Azeri-Kukruse Regional stages) and Caradoc (Idavere-Oandu Regional stages). The results support the hypothesis that the study area represented an independent biogeographical region of the Baltic province, corresponding to the Brest-Volyn confacies during the Llanvirn and Caradoc.

14

Stratigraphic and biogeographic significance of Late Cambrian trilobites from Łysogóry (Holy Cross Mountains, central Poland)

Żylińska A.

Acta Geologica Polonica

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2002

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Vol. 52, nr 2

217-238

EN

Revision of the Late Cambrian trilobites from Łysogóry in the Holy Cross Mountains, central Poland, enabled the application of a modified version of the Upper Cambrian biostratigraphic zonation established for the Baltica palaeocontinent. The following zones and subzones were recognised: Olenus scanicus and Parabolina brevispina subzones, Leptoplastus - Protopeltura praecursor Zone, Peltura minor Zone (Ctenopyge affinis subzones), Peltura scarabaeoides Zone (Ctenopyge linnarssoni and? Parabolina lobata subzones) and the Acerocare Zone sensu lato. Biogeographically the trilobites of Łysogóry show a distinct change, from a low diversity fauna with a predominance of Avalonian forms in the early Late Cambrian, to more diversified assemblages, characterised by the constant increase to dominance of Baltic elements by the end of the Cambrian.

15

Ammonites and stratigraphy of the uppermost Bajocian and Lower Bathonian between Częstochowa and Wieluń, Central Poland

Matyja B., Wierzbowski A.

Acta Geologica Polonica

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2000

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Vol. 50, no. 2

191-209

EN

A detailed biostratigraphical study of the black clays and siltstones with ironstone nodules of the Ore Bearing Częstochowa Clay Formation in the brick-pits at Częstochowa and Wieluń resulted in recognition of the following standard ammonite zones and subzones: the Parkinsoni and Bomfordi subzones of the Parkinsoni Zone of the uppermost Bajocian; the Convergens, Macrescens and Yeovilensis subzones of the Zigzag Zone, and the Tenuiplicatus Zone of the Lower Bathonian. The ammonite faunas are of Submediterranean character, although markedly impoverished when compared with those of the most classic areas of the province. This impoverishment is especially well seen in the uppermost Bajocian - lowermost Bathonian part of the succession, where the only numerous ammonites are these of the genus Parkinsonia, together with rare representatives of Cadomites; and in theuppermost part of the Lower Bathonian, where representatives of the corresponding macro- and microconchs- Asphinctites tenuiplicatus (BRAUNS), and Polysphinctites secundus (WETZEL) - predominate. In the palaeontological part of the paper 14 species belonging to the genera Oxycerites, Parkinsonia, Cadomites, Wagnericeras, Asphinctites and Polysphinctites are descibed. Of these, particular attention is paid to a form referred to as Parkinsonia (Parkinsonia) aff. dorni ARKELL from the uppermost Bajocian, represented by several specimens of various growth stages, which may be tentatively compared with the poorly diagnostic small, incomplete type-specimens of P. dorni.

16

Permian corals of the Cordilleran-Arctic-Uralian Realm

Fedorowski J., Bamber E., Stevens C.

Acta Geologica Polonica

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1999

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Vol. 49, no. 2

159-173

EN

Permian rugose corals of the Cordilleran-Arctic-Uralian Realm are abundant in shallow-water carbonates along the northwestern and western margin of Pangaea, from the Ural Mountains, area in Russia, through the Svalbard Archipelago and arctic and western North America, to Bolivia and Peru. The colonial forms are of particular interest for the biostratigraphy and reconstruction of the paleogeography of this extensive region. A revision of the systematics of these corals has shown that, although important differences exist between the assemblages in the areas listed, the faunas are recognizable throughout the entire realm. Almost all of the faunas in the realm, on cratonal Pangaea, are Cisuralian (Asselian to Artinskian) in age although younger faunas occur in rocks of terranes subsequently accreted to North America. The cratonal faunas show a general trend from a predominance of relatively simple, fasciculate species with open axial areas or weakly developed axial structures in the lowest Permian, to younger, more complex fasciculate and massive species with a variety of morphological elements in their axial structures and dissepimentaria. Suppression of the walls occurs commonly in the youngest faunas. As a result of the northward movement of Pangaea into cooler waters, colonial rugose corals were exterminated from the more northerly areas by early to mid-Artinskian time, but persisted throughout the Artinskian and possibly into the Kungurian and early Guagalupian in the cratonic successions of the western U.S.A. Similarities between the coral faunas of cratonal North America and the western allochthonous terranes indicate that faunal interchange occurred between these various coral faunas during the Cisuralian. The only colonial corals recovered from Wordian to Lopingian rocks in this region are waagenophyllid corals of tethyan affinity from the Cache Creek and Quesnellia terranes of British Columbia and the Hayfork and Eastern Klamath terranes of California.

17

Biostratigraphy and correlation of the Turonian - Coniacian succession and the Turonian - Coniacian boundary problem in the Far East Russia based on ammonites and inoceramids

Zonova T., Jazykova-Flidlider E.

Acta Geologica Polonica

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1998

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Vol. 48, no. 4

483-494

EN

The stratigraphy, ammonite and inoceramid content of the Turonian - Coniacian deposits of Far East Russia are presented. The evolution of North Pacific ammonites and inoceramids at the boundary of the two stages was studied and the levels of fundamental changes within the ammonite and inoceramid biota are recognized. The established palaeogeographic difference between the Sakhalin and the North-East region palaeobasins is reflected in the existence of two independent local zonal schemes. The main criteria of the Turonian-Coniacian stage boundary in the Far East of Russia were established on the basis of the two schemes. The Turonian/Coniacian (T/C) boundary is clearly marked by the change in the taxonomic diversity of the zonal inoceramid assemblages. It is defined at the base of the Inoceramus uwajimensis Zone. The appearance of the endemic ammonite species. Jimboiceras mihoense MATSUMOTO is the ammonite criterion for recognising the T/C stage boundary in Sakhalin. This is supported by occurrences of the cosmopolitan Coniacian genera Peroniceras and Forresteria.