Wyniki wyszukiwania - BazTech

1

Integrated biostratigraphy and palaeoenvironments of the Upper Cretaceous in the Petrich section (Central Srednogorie Zone, Bulgaria)

Pavlishina Polina, Dochev Docho, Wagreich Michael, Koukal Veronika

Acta Geologica Polonica

|

2023

|

Vol. 73, no. 1

33--62

EN

The Upper Cretaceous succession (Coniacian to lowermost Maastrichtian, with focus on the Campanian) at Petrich, Central Srednogorie Zone in Bulgaria, is described and calibrated stratigraphically based on nannofossils, dinoflagellate cysts and inoceramids. The following standard nannofossil zones and subzones are identified: UC10-UC11ab (middle to upper Coniacian), UC11c-UC12-UC13 (uppermost Coniacian to Santonian), UC14a (lowermost Campanian), UC14bTP-UC15cTP (lower Campanian to ‘middle’ Campanian), UC15dTP-UC15eTP (upper Campanian), UC16aTP (of Thibault et al. 2016; upper part of the upper Campanian), and UC16b (Campanian-Maastrichtian boundary). The base of the Campanian is defined by the FO of Broinsonia parca parca (Stradner) Bukry, 1969 and Calculites obscurus (Deflandre) Prins and Sissingh in Sissingh, 1977 (a morphotype with a wide central longitudinal suture). The Areoligera coronata dinoflagellate cyst Zone (upper lower Campanian to upper upper Campanian) is identified, corresponding to the UC14bTP-UC16aTP nannofossil subzones. The inoceramid assemblage indicates the ‘Inoceramus’ azerbaydjanensis-‘Inoceramus’ vorhelmensis Zone, correlated within the interval of nannofossil subzones UC15dTP-UC15eTP. The composition of the dinoflagellate cyst assemblages and palynofacies pattern suggest normal marine, oxic conditions and low nutrient availability within a distal shelf to open marine depositional environment during the Campanian.

2

Palynostratigraphy of dinosaur bone-bearing deposits from the Upper Cretaceous of Western Bulgaria

Pavlishina Polina, Dochev Docho, Nikolov Vladimir, Yaneva Marlena, Konyovska Ralitsa

Acta Geologica Polonica

|

2019

|

Vol. 69, no. 4

617--626

EN

Palynological investigation of the Vrabchov dol locality (Western Bulgaria) which recently yielded fragmentary dinosaur bones attributed to the clade Titanosauria, reveals well-preserved sporomorph assemblages dominated by angiosperm pollen from the Normapolles group, spores and rare gymnosperms. The age assessment of the studied sequence is based on the diagnostic Normapolles species, such as Oculopollis orbicularis Góczán, 1964, Oculopollis zaklinskaiae Góczán, 1964, Krutzschipollis spatiosus Góczán in Góczán et al., 1967 and Krutzschipollis crassus (Góczán, 1964) Góczán in Góczán et al., 1967. The concurrent presence of these pollen species suggests a late Santonian–early Campanian age for the succession. The sporomorph association is encountered in a palynofacies dominated by continental elements, including translucent phytoclasts (tissues, wood remains and plant cuticles). The sedimentary succession shows no evidence of marine elements and a very low proportion of AOM that attests to deposition within a lagoonal to foreshore marine environment, with high continental input and short transportation. The vegetation in the studied area was primarily composed of a range of Normapolles-producing angiosperms and secondarily of pteridophyte spore-producing plants. Gymnosperms were rare. Such a vegetation pattern reflects a warm, seasonally dry climate during the late Santonian–earliest Campanian in the studied area. The dinosaurs inhabited a wet lowland area, probably rich in herbaceous plants.

3

The Upper Campanian - lower Maastrichtian cephalopod fauna of Botellos, Nuevo León: a key to understand faunal turnover across the Campanian-Maastrichtian boundary in NE Mexico

Ifrim C., Lara de la Cerda J. E., Peña Ponce V. H., Stinnesbeck W.

Acta Geologica Polonica

|

2017

|

Vol. 67, no. 1

145--162

EN

A new cephalopod collection from the Campanian-Maastrichtian boundary interval of NE Mexico, consisting of 1076 individuals assigned to 29 species and 22 genera is presented. This collection is a mix of ammonoids, one coleoid and one nautilid, which originate from at least three ammonoid biozones: The upper Campanian Exiteloceras jenneyi and Nostoceras (Nostoceras) hyatti zones, and the lower Maastrichtian Pachydiscus (Pachydiscus) neubergicus Zone. The age of the collection is thus middle late Campanian to late early Maastrichtian, and it closes a stratigraphic gap between faunas described formerly from this region. The specimens are nuclei collected from the desert pavement. The abundance of specimens allows for a comparison to other Campanian-Maastrichtian ammonoid records from Mexico, North America and Europe.

4

Revision of Hamites wernickei Wollemann, 1902 (Cephalopoda, Ancyloceratina) from the classic Lüneburg section (Upper Cretaceous, northern Germany)

Niebuhr B., Jagt J. W. M.

Acta Geologica Polonica

|

2016

|

Vol. 66, no. 4

627--644

EN

A re-examination of heteromorph ammonites of late Campanian age from the Zeltberg section at Lüneburg has demonstrated that the type series of Hamites wernickei in fact comprises two different species that are here assigned to the nostoceratid Nostoceras Hyatt, 1894 and the polyptychoceratid Oxybeloceras Hyatt, 1900. Nostoceras (Didymoceras) wernickei (Wollemann, 1902) comb. nov., to which three of the four specimens that were described and illustrated by Wollemann (1902) belong, has irregularities of ribbing and tuberculation and changes its direction of growth at the transition from the helicoidal whorls to the hook, which is a typical feature of members of the subfamily Nostoceratinae. Torsion of body chambers is not developed in hairpin-shaped ammonite species, which means that the species name wernickei is no longer available for such polyptychoceratine diplomoceratids. Consequently, the fourth specimen figured and assigned to Hamites wernickei by Wollemann (1902) is here transferred to Oxybeloceras and considered conspecific to material from the Hannover area (Lehrte West Syncline) as O. aff. crassum (Whitfield, 1877). In addition to the "Heteroceras-Schicht des Mucronaten-Senons" of Lüneburg (bipunctatum /roemeri Zone, upper upper Campanian), the geographic range of N. (D.) wernickei probably includes Upper Austria, Tunisia and the Donbass region, while O. aff. crassum is known from the Hannover area (northern Germany), southern France, northern Spain and Upper Austria.

5

Porosphaera globularis (Phillips, 1829) (Porifera, Calcarea) in the Campanian (Upper Cretaceous) of extra-Carpathian Poland

Jurkowska A., Świerczewska-Gładysz E., Dubicka Z., Olszewska-Nejbert D.

Acta Geologica Polonica

|

2015

|

Vol. 65, no. 1

121--139

EN

The stratigraphical distribution of Porosphaera globularis, a common calcareous sponge in the Upper Cretaceous (mostly Campanian and Maastrichtian) of Poland was studied. The presented material, both new and from museum collections, comes from the Campanian of the Miechów Synclinorium, in southern Poland, and from the Lower Campanian of Mielnik in the south-eastern part of the Mazury-Podlasie Homocline, in eastern Poland. The significance of the species in extra-regional correlation, its palaeobiogeography and stratigraphical potential is critically reviewed.

6

Upper Campanian calciclastic turbidite sequences from the Hacımehmet area (eastern Pontides, NE Turkey): integrated biostratigraphy and microfacies analysis

Sari B., Kandemır R., Özer S., Walaszczyk I., Görmüş M., Demırcan H., Yilmaz C.

Acta Geologica Polonica

|

2014

|

Vol. 64, no. 4

393--418

EN

The upper Campanian (Cretaceous) of the Hacımehmet area (south of the city of Trabzon; Eastern Pontides) is mainly composed of calciclastic turbidites. The basinal unit of the 119 m thick succession includes thin red pelagic limestone interlayers and conglomerates dominated by volcanic clasts. The overlying upper slope and lower slope units of the sequence consist of an alternation of allochthonous calcarenite/calcirudite beds and pelagic marls and mudstones. Calcarenite/calcirudite beds dominate the upper slope unit of the succession and are composed of transported material, including benthic foraminifers, red algae, bryozoan, crinoid and rudist fragments, inoceramid bivalve prisms and neritic and pelagic carbonate lithoclasts. The occurrence of Helicorbitoides boluensis (Sirel) extracted from the calcarenite/calcirudite beds indicates a Campanian age. Identifiable rudists such as Joufia reticulata Boehm, Bournonia cf. anatolica Özer, Biradiolites cf. bulgaricus Pamouktchiev and ?Biradiolites sp. from the upper slope unit of the succession indicate a late Campanian–Maastrichtian age. The planktonic foraminifers within the red pelagic limestone beds, marls and mudstones throughout the succession consist mainly of Campanian–Maastrichtian forms and suggest mainly basinal depositional conditions. The presence of Radotruncana cf. calcarata (Cushman) accompanied by Globotruncanita elevata (Brotzen) in the basinal unit of the succession indicates an early late Campanian age for the lower part of the succession. Inoceramid bivalves have been collected from the upper part of the succession. The fauna is dominated by ‘Inoceramus’ tenuilineatus Hall and Meek, 1854 and Cataceramus haldemensis (Giers, 1964); other taxa recognised are: ‘Inoceramus’ algeriensis Heinz, 1932, Platyceramus vanuxemi (Meek and Hayden, 1860), ‘Inoceramus’ cf. nebrascensis Owen, 1852, Cataceramus aff. barabini (Morton, 1834), Cataceramus gandjaensis (Aliev, 1956), and ‘Inoceramus’ sp.; the assemblage indicates the ‘Inoceramus’ tenuilineatus Zone; corresponding to the middle–late Campanian boundary interval. The uppermost part of the succession is characterized by the presence of the trace fossils Scolicia strozzii and Scolicia isp., indicating a mixed Skolithos-Cruziana ichnofacies. This ichnofacies suggests a well-oxygenated environment.

7

The Belemnella stratigraphy of the Campanian-Maastrichtian boundary; a new methodological and taxonomic approach

Remin Z.

Acta Geologica Polonica

|

2012

|

Vol. 62, no. 4

495-533

EN

The taxonomy and stratigraphy of the Upper Campanian and Lower Maastrichtian belemnites from the Vistula (central Poland) and Kronsmoor (northern Germany) sections are revised on the basis of new collections from the Vistula section as well as a reinvestigation of the classic collection of Schulz from the Kronsmoor section. For the taxonomic description a new biometric procedure is proposed, which can be applied to both the genera Belemnella and Belemnitella. For the species-level taxa recognition the Artificial Neural Networks method, the self-organizing Kohonen algorithm, was implemented. This new taxonomic and methodological approach enabled the recognition of nine species of the genus Belemnella. Five of them can be assigned to the existing species B. lanceolata, B. longissima, B. inflata, B. obtusa and B. vistulensis. However, the species concept differs from that applied by Schulz (1979). As a consequence, the stratigraphic ranges of these species are modified. Four species are left in open nomenclature and represent possibly new species. Future studies may reveal that they might be assigned to East European forms from Ukraine or Russia. The species of Belemnella recognized are placed into the stratigraphic framework based on the standard ammonite and inoceramid bivalve zonations, especially those recognized in the Vistula section. The newly proposed belemnite zonation for the Vistula and Kronsmoor sections is correlated via inoceramids with the standard GSSP at Tercis, France, in order to identify the base of the Maastrichtian Stage. The Campanian/Maastrichtian boundary as defined in Tercis is placed here at the base of the newly defined B. obtusa and B. vistulensis Zones ["obtusa/vistulensis"] - thus it is markedly higher than the traditional boundary based on the FAD of representatives of the genus Belemnella - This new boundary coincides well with a distinct turnover of belemnite guard morphology and represents one of the most important points in the early evolutionary history of Belemnella. Three belemnite zones defined by their lower boundaries are recognized in the Campanian/Maastrichtian interval, in addition to three subzones recognized within the B. obtusa Superzone. The B. lanceolata and B. inflata zones as understood here are referred to the Upper Campanian [Tercis definition]. The B. obtusa Zone is subdivided into three subzones, viz.: Belemenlla vistulensis, Belemnella sp. G and Belemnella sp. F, which are referred to the Lower Maastrichtian [Tercis definition]. The fast evolving species of Belemnella enable the proposal of a biostratigraphic scheme with a resolution that is higher than those based on inoceramid bivalves and ammonites - the longevity of a belemnite zone could be as low as 200Ky.

8

Stratigraphically important ammonites from the Campanian-Maastrichtian boundary interval of the Middle Vistula River section, central Poland

Machalski M.

Acta Geologica Polonica

|

2012

|

Vol. 62, no. 1

91-116

EN

The formal definition of the Global Stratotype Section and Point (GSSP) for the base of the Maastrichtian Stage at Tercis, southwest France, is based on the first or last occurrences of twelve taxa, including three species of ammonites, Pachydiscus (Pachydiscus) neubergicus, Diplomoceras cylindraceum, and Nostoceras (Nostoceras) hyatti. The taxonomy and stratigraphical distribution of these, and allied forms, are studied, on the basis of material from the opoka succession across the upper Campanian.lowermost Maastrichtian boundary in the Middle Vistula River section, central Poland. in view of the imprecise location of two ammonite GSSP markers in that section, a direct ammonite-based correlation with the GSSP at Tercis is impossible. however, data available indicate that in the Middle Vistula River section the first occurrence of Pachydiscus (P.) neubergicus and the last occurrence of Nostoceras (N.) hyatti are situated significantly higher than the first occurrence of Belemnella lanceolata, the traditional belemnite marker for the base of the Maastrichtian Stage in the Boreal Realm, and that Diplomoceras cylindraceum appears significantly below this level. There are no unequivocal records of Pachydiscus (P.) neubergicus from the Belemnella lanceolata Zone s.l. in the Middle Vistula River section.

9

Integrated stratigraphy of the Campanian-Maastrichtian boundary succession of the Middle Vistula River (central Poland) section; introduction

Walaszczyk I.

Acta Geologica Polonica

|

2012

|

Vol. 62, no. 4

485-493

EN

The Campanian-Maastrichtian boundary interval of the Middle Vistula River valley section (central Poland) represents a continuous, lithologically monotonous, fossiliferous succession, with a good stable isotope and palaeomagnetic signal. It yields all the biostratigraphically critical macro- and microfossil groups: ammonites, belemnites, inoceramid bivalves, foraminifera, nannofossils and dinoflagellates. Additionally, it is located in the transitional zone between the Boreal and Tethyan biogeographic provinces, as well as between the western and eastern biogeographic areas of Europe. The section supplements the data on the interval acquired recently from the basal Maastrichtian stratotypic section in Tercis, south-west France, and from the interval reference section in Kronsmoor, northern Germany.

10

Hexactinellid sponge assemblages across the Campanian.Maastrichtian boundary in the Middle Vistula River section, central Poland

Świerczewska-Gładysz E.

Acta Geologica Polonica

|

2012

|

Vol. 62, no. 4

561-580

EN

The sponge fauna from the Upper Campanian.lowermost Maastrichtian succession of the Middle Vistula River valley (central Poland) is represented mainly by dictyid hexactinellid sponges (Hexactinosida and Lychniscosida). Their greatest abundance and taxonomic variability is noted in the "Inoceramus" inkermanensis Zone (Upper Campanian), and they are less diverse in the overlying (Upper Campanian) Trochoceramus costaecus Zone and lower "Inoceramus" redbirdensis Zone. In the upper "Inoceramus" redbirdensis Zone (basal Maastrichtian in the sense of the Tercis rather than the Boreal definition) they are extremely rare. With the beginning of the Maastrichtian the number of dictyid sponges gradually increases. The observed changes in the abundance and taxonomic variability of the dictyid sponges indicate environmental changes in the latest Campanian.earliest Maastrichtian sea in the area. It seems that changes in basin bathymetry, confined to eustatic sea-level changes in the latest Campanian and early Maastrichtian, were the most important factor. Progressive shallowing of the basin in the latest Campanian drastically restricted the development of dictyids. In the peak regression, the sea level could have fallen to only several tens of metres. The gradual recovery of the sponge assemblages correlates with subsequent deepening of the basin with the start of the Maastrichtian.

11

Early representatives of the belemnite genus Belemnella (Cephalopoda) from the uppermost Campanian-Lower Maastrichtian of the Middle Vistula River section, central Poland

Keutgen N., Remin Z., Walaszczyk I.

Acta Geologica Polonica

|

2012

|

Vol. 62, no. 4

535-559

EN

Representatives of the belemnite genus Belemnella from the uppermost Campanian and lowermost Maastrichtian of the Middle Vistula River Valley section (central Poland) have been studied, using the species concept proposed by Schulz in 1979. Results have been compared to a recently proposed new interpretation of the genus Belemnella based on artificial neural networks, as put forward by Remin in 2007 and 2012. In the interval studied, four taxa have been recognised: Bln. longissima, Bln. inflata, Bln. obtusa and Bln. vistulensis, the last-named being a senior synonym of Bln. pseudobtusa. Three additional forms have been left in open nomenclature: Bln. cf. lanceolata, Bln. ex gr. lanceolata/inflata and Belemnella sp. Based on their documented vertical ranges, three Belemnella standard zones, as originally distinguished in the Kronsmoor section by Schulz (1979), northern Germany, have been defined, in ascending order: the Bln. lanceolata, Bln. vistulensis and Bln. obtusa zones. The bases of the lanceolata and obtusa zones in the Middle Vistula River Valley section can be directly correlated with the same zones at Kronsmoor, and appear to be isochronous within limits of stratigraphic resolution. The base of the vistulensis Zone (Bln. vistulensis according to the species concept of Schulz in 1979), however, is probably diachronous, being older in the Middle Vistula section. Although Schulz's and Remin's species concepts differ quite considerably, they do result in similar stratigraphic subdivisions of the Kronsmoor and Middle Vistula River sections.

12

Integrated stratigraphy of the Kronsmoor section (northern Germany), a reference point for the base of the Maastrichtian in the Boreal Realm

Niebuhr B., Hampton M., Gallagher L., Remin Z.

Acta Geologica Polonica

|

2011

|

Vol. 61, no. 2

193-214

EN

Results of detailed multistratigraphic analyses of the Campanian.Maastrichtian boundary section at Kronsmoor in northern Germany are summarised and calibrated with the GSSP at Tercis les Bains, southwest France. Additional markers for the definition of the boundary in the Boreal Realm are proposed, and a detailed carbon isotope curve around the Campanian.Maastrichtian boundary in the chalk facies of the Boreal epicontinental sea is presented. The C isotopic GSSP marker for global correlation is the markedly abrupt decrease of c. 0.7 [per mil] [delta^13]C directly at the Campanian.Maastrichtian boundary as dated by ammonites. In electronic borehole measurements the Kronsmoor section covers the SP peaks 53 to 64 and the base of the Maastrichtian being situated just below SP peak 60. The first occurrence (FO) of the ammonite Pachydiscus neubergicus, which corresponds to biohorizon 1 at Tercis, falls in the upper part of nannofossil Zone UC15, at both localities. Biohorizon 3 is the FO of the ammonite Diplomoceras cylindraceum, which first appears in the Upper Campanian of Tercis and at Kronsmoor enters significantly above the FO of Belemnella lanceolata, the conventional Boreal belemnite marker for the base of the Maastrichtian Stage. Based on ammonite evidence, the internationally accepted base of the Maastrichtian at Kronsmoor is located between the FOs of Diplomoceras cylindraceum (Upper Campanian) and Pachydiscus neubergicus (Lower Maastrichtian) c. 11 m above flint layer F 600, at which the first representatives of the belemnite genus Belemnella, in particular Bn. lanceolata occur. The latter thus is a Late Campanian species, appearing c. 450 ky prior to the ammonite-based boundary. The FOs of Belemnella pseudobtusa (sensu Schulz) resp. Belemnella obtusa (sensu Remin) directly at the boundary can be use as the coleoid proxy for the definition of the base of the Maastrichtian in the Boreal Realm. To define the boundary by benthic foraminifera the last occurrence (LO) of Neoflabellina praereticulata is suitable. Biohorizon 12, as defined at Tercis, involves the nannofossil Uniplanarius trifidus, however, at Kronsmoor this species is rare, occurs only sporadically and also significantly lower in comparison to Tercis. It is possible though to compare and correlate nannofossil events between Kronsmoor and Tercis using cosmopolitan taxa such as Broinsonia parca constricta and Eiffellithus eximius. The LO of the latter appears to be situated just above the boundary in both sections; it follows from this that the top of nannofossil Zone UC15 is of Early Maastrichtian age.

13

Nanoplankton wapienny górnokredowych facji pelagicznych jednostki podśląskiej polskich Karpat fliszowych

Jugowiec-Nazarkiewicz M.

Biuletyn Państwowego Instytutu Geologicznego

|

2007

|

nr 426

53-70

PL

W pelagicznych osadach jednostki podśląskiej (marglach węglowieckich, marglach typu frydeckiego, marglach żegocińskich, piaskowcach z Rybia) oraz w marglach bakulitowych jednostki skolskiej i marglach z Bonarki występujących na monoklinie śląsko-krakowskiej (odsłonięcie Bonarka w Krakowie) stwierdzono liczne formy nanoplanktonu wapiennego wieku kampan-mastrycht. Wyznaczono poziomy nanoplanktonowe, określając wiek badanych osadów. W marglach bakulitowych, nazywanych też marglami z Węgierki, występujących w jednostce skolskiej, odnotowano podobny skład i charakter nanoplanktonu wapiennego jak w szarych marglach typu frydeckiego występujących w jednostce podśląskiej w zachodniej części Karpat. W badanych osadach jednostki podśląskiej nie stwierdzono ciągłego przejścia sedymentacyjnego między osadami mastrychtu i danu. Badania nanoplanktonu potwierdziły istnienie połączenia między strefą borealną i tetydzką na obszarze polskich Karpat zewnętrznych w kampanie i mastrychcie, o czym świadczy obecność w próbkach form nanoplanktonu uważanych za typowo borealne.

EN

In pelagic sediments of the Subsilesian Unit (Węglówka marls, Frydek-type marls, Żegocina marls and Rybie sandstones) and in the bakulit marls from the Skole Unit, and in marls from Bonarka in Silesian-Cracow Monocline many forms of calcareous nannoplankton of Campanian-Maastrichtian age were noted. Distinguishing of several nannoplankton assemblage zones allowed for more detailed time resolution of the studied sediments. Existing of the connection between the boreal and Tethyan realms in Polish Outher Carpathians during Campanian/Maastrichtian has been confirmed. Calcareous nannoplankton of the bakulit marls (Skole Unit) appeared similar to that from the Frydek-type marls (Subsilesian Unit). No continuous transition between sediments of the Maastrichtian and Danian within the studied Subsilesian Unit has been stated. Transition between Boreal and Tethyan realms on the Polish Outher Carpathians area, during Campanian and Maastrichtian age are confirmed.

14

First record of the late Campanian heteromorph ammonite Nostoceras hyatti from the Alpine Cretaceous (Grunbach, Gosau Group, Lower Austria)

Summesberger H., Machalski M., Wagreich M.

Acta Geologica Polonica

|

2007

|

Vol. 57, no. 4

443-451

EN

The heteromorph ammonite Nostoceras (Nostoceras) hyatti is described for the first time from the Piesting Formation (Gosau Group; Upper retaceous) at Grunbach along the eastern margin of the Northern Calcareous Alps, Lower Austria. This record significantly extends the geographic range of this late Campanian marker species; it was not previously known from the Alpine Cretaceous. Moreover, it corroborates earlier age assignments as late Campanian of the (lower) part of the Piesting Formation. A matrix sample taken from the specimen studied has yielded taxa whose range covers zones CC20 to CC23, or UC 15[^tp] to UC18, of the standard nannofossil zonation.

15

Paleoekologia i paleośrodowisko późnego kampanu na podstawie wybranych profili z doliny środkowej Wisły

Zatoń M.

Przegląd Geologiczny

|

2003

|

Vol. 51, nr 8

678-684

PL

Trzy odsłonięcia górnego kampanu, należące do trzech kolejnych poziomów amonitowych (Neancyloceras phaleratum, Bostrychoceras polyplocum i Didymoceras donezianum) w dolinie środkowej Wisły, zostały zbadane pod kątem paleośrodowiskowym. Bogata makrofauna ze wszystkich szczebli troficznych, świadczy o spokojnym środowisku, odpowiadającemu dzisiejszej strefie pogranicza wewnętrznego i zewnętrznego szelfu, o normalnym zasoleniu, dobrze natlenionych wodach przydennych i podłożu o zróżnicowanej konsystencji, stwarzającego różnorodnej faunie odmienne nisze ekologiczne.

EN

The paleoecology of macrofauna from three Upper Campanian outcrops in the Middle Vistula valley, belonging to three successive ammonite zones (Neancyloceras phaleratum, Bostrychoceras polyplocum and Didymoceras donezianum), have been investigated on paleoenvironmental ground. The rich macrofauna of all trophic levels indicates the calm epicratonic basin, corresponding to the inner to outer shelf environment, of normal salinity waters, good bottom-water oxygenation and with substrate of varied consistency, providing different niches for diverse fauna.