Bohemian Cretaceous Basin Research Articles

Reindeer prey mobility and seasonal hunting strategies in the late Gravettian mammoth steppe

Reindeer are part of the faunal suite that dominated central Europe during the last glacial cycle. Their importance to Late Gravettian hunters as prey and a source of raw materials (hide, bone, antler) is well attested, however the context of Late Gravettian reindeer predation is lesser understood. This paper presents an investigation of human and reindeer predator-prey interactions at the Late Gravettian kill-butchery site of Lubná VI, Czech Republic. We reconstruct seasonal mobility (87Sr/86Sr, δ18O), diet (δ13C, δ15N) and season of death (dental cementum) of up to nine reindeer prey, to inform on the strategic choices made by Late Gravettian hunters. Results indicate that most hunted reindeer lived year-round in the foothills of the Bohemian-Moravian highlands near where Lubná is located, at altitudes between ~ 200–450 m above present sea level, while a smaller number showed evidence of seasonal migration between this area and the open plains of the Elbe river corridor (Bohemian Cretaceous basin). No evidence for long distance migration of reindeer was detected, indicating that productive local environments were supporting reindeer herds within a single annual territory. Meanwhile, areas higher than ~ 450 m above present sea level were avoided entirely by all analysed individuals, consistent with these areas being topographic barriers to movement due to climate severity. We conclude that hunters visited Lubná as part of a logistically-organised subsistence strategy, deliberately targeting reindeer in late autumn when fat supplies, hides and antler are in prime condition knowing that they would reliably encounter their prey at this location.

Cenomanian terrestrial paleoenvironments from the Bohemian Cretaceous Basin in Central Europe and their implications for angiosperm paleoecology

In this paper, we reconstruct the vegetation communities of five terrestrial paleoenvironments from the Cretaceous (Cenomanian) Peruc-Korycany Formation of the Bohemian Cretaceous Basin in Czechia. Reconstructions are based on a synthesis of numerous studies of paleobotany, palynology, paleoecology, sedimentology and geochemistry analyses. Ordered in a transect from coastal marine settings to elevated hinterland regions, paleoenvironments and plant assemblages are reconstructed as follows: (1) Saltmarsh vegetation comprising a Frenelopsis-Classopollis assemblage; (2) Coastal freshwater swamp vegetation comprising a Cunninghamites-Taxodiaceaepollenites assemblage; (3) Meandering river floodplain vegetation comprising a Myrtophyllum-Perucipollis assemblage; (4) Braided river floodplain vegetation comprising a Eucalyptolaurus-Mauldinia assemblage; and (5) Vegetation of drier upland areas comprising fern prairies with angiosperms and Bennettitales - a Zamites-Ephedripites assemblage. Our study shows that in Cenomanian times, angiosperms were diversified, particularly in alluvial plains, where lauroid and platanoid angiosperms prevailed. Comparison of these Cenomanian paleoenvironments in Czechia with other Cenomanian paleoenvironments across Europe show a widespread dominance of angiosperms in the vegetation of alluvial plains across much of the continent. This contrasts with Barremian-Albian times when angiosperms occupied only disturbed habitats, and our findings suggest that angiosperm exchanged a ruderal (disturbed) strategy for a competitive strategy during the Albian-Cenomanian transition. Conversely, conifers dominated alluvial plains in Early Cretaceous times, while they rose to dominate saltmarshes and swamps in the Bohemian Cenomanian, exchanging a competitive strategy for a stress-tolerant strategy.

The serpulid tube worm Laqueoserpula reussi (Weinzettl, 1910) from the Upper Cretaceousof the Bohemian Cretaceous Basin – an alleged gastropodwhich has turned out to be a characteristic faunal elementof marine nearshore high-energy environments

The serpulid tube worm Laqueoserpula reussi (Weinzettl, 1910), originally introduced as a gastropod named Burtinella(?) reussi, is described from the Upper Cenomanian and Lower Turonian of the Bohemian Cretaceous Basin. It had usually been confused with other species and genera before 2008. Comparison with specimens from the type locality of the type species of the genus Laqueoserpula Lommerzheim, 1979 confirms the affiliation of the Bohemian species to this genus. The simple prismatic (SP) ultrastructure of the tube wall of L. reussi agrees with an assignment to the tribe Serpulini Rafinesque, 1815. In the Upper Cretaceous, representatives of Laqueoserpula are exclusively found in nearshore deposits, where they are accompanied by a high diverse marine invertebrate fauna. By its compact, large and robust tube forming a spiral and extremely thick tube wall, L. reussi was well-adapted to live in nearshore high energy environments, where its tube could be encrusted by bryozoans, brachiopods and oysters, and infested by hydroids and borers.

Morphostructural evolution of the Labe and Jizera rivers confluence area (the Bohemian massif, Czechia)

This article investigates the morphostructural evolution of the Labe and Jizera rivers confluence area in the Bohemian Massif of Czechia. The main stages of morphostructural evolution are identified and related landform patterns are described. The lithological and tectonic character of this contact area between the Barrandian and the Bohemian Cretaceous Basin has been gradually evolving since the Early Palaeozoic. Tectonic subsidence of the northeastern part of the Bohemian Massif and the Cretaceous transgression of the sea caused extensive marine sedimentation, which covered the pre-Cenomanian relief. The uplift of the Bohemian Massif during the Santonian initiated a widespread erosion and denudation in the Tertiary. The Labe River valley constitutes a remarkable boundary between the morphostructural plateaus in the south and the system of river accumulation terraces of the Labe and Jizera in the north. The originally extensive and currently considerably eroded III. river terrace of the Labe was formed in the Elsterian glacial period (Cromerian complex c). The conspicuous Jizera alluvial fan developed during the aggradation phase of the VII. river terrace in the Upper Pleistocene. Subsidence along the NW-SE-trending Labe Fault zone, deciphered from the vertical throw of the VII. terrace rock bases of Labe as well as related paleochannels of its local tributaries, which caused the current asymmetry of the Labe valley, reached up to 14 meters prior to the Holocene. The different rock resistance to weathering, arrangement of fault structures and neotectonic movements that took place even during the late Quaternary significantly influenced the intensity of varied climate-morphogenetic processes.

Origin of Fracture-Controlled Conduits in Calcite-Rich Highly Productive Aquifers Impregnated with Diagenetic Silica

The origin of highly permeable flow paths in carbonate-siliciclastic rocks, such as large-aperture fractures in aquifers in the Eastern Bohemian Cretaceous Basin (EBCB), is poorly understood. The karst potential was assessed from the rock carbonate content and the degree of disintegration after leaching in HCl. Surprisingly, dissolution of calcite in EBCB usually did not lead to rock disintegration until calcite > 78%. Instead, porosity increased significantly. High-porosity rock is held together by microns-thick secondary silica cement with a foam-like structure and considerable tensile strength. Three types of conduits occur in the EBCB: (i) bedding-parallel conduits associated with calcite-rich layers, (ii) subvertical fracture swarm conduits that develop on damaged zones of fracture swarms, and (iii) conduits formed by dissolution of calcite veins by groundwater flow. These are ghost-rock karst features where calcite is leached from the rock in the first phase and the residue is washed out by conduits under steep hydraulic gradients in the second phase. Very similar features have been described in Minnesota and Wisconsin, USA. Research has shown that fractures with sharp-edged walls that give the impression of an extensional tectonics origin may actually be ghost-rock karst features in which dissolution and piping have played an important role in their enlargement.

The relationship of plant leaf δ13Cn-alkanes and salinity in coastal ecosystems applied to palaeobotany: Case study from the Cenomanian of the Bohemian Cretaceous Basin, Czechia

Stable carbon isotopes in fossil leaf cuticles (n-alkanes, δ13Cn−alkanes) extracted from the sediment are widely used for palaeoenvironmental reconstructions. This approach relies on a series of assumptions (such as the plant-group-specific isotopic range, or the atmospheric CO2 being the major factor for the isotopic values) and leaves out the complexity of the carbon isotope fractionation within the plant through time, space, and different environments. The leaf cuticle is a unique archive of local environmental conditions, which has the potential to constrain individual plant habitat. To explore the applicability of the information gained from the δ13Cn−alkanes from fossil plants, a fossil coastal environment was studied.During the Cenomanian (100.5–93.9 Ma), the basal part of the Bohemian Cretaceous Basin, including locality Pecínov (Czechia), was formed as a result of sea transgression to the Palaeozoic Bohemian Massif triggered by the Alpine orogenesis. Coastal halophytic vegetation growing in this zone of prograding sea has no extant equivalent, and there are uncertainties associated with vegetation distribution or individual taxa habitat.Therefore, we examine the relationship between δ13Cn−alkanes extracted from individual leaves of coastal C3 plants (fossil and modern) and osmotic stress (salinity and drought) to reconstruct the individual plant habitat, thus, vegetation distribution in the coastal zone. We investigated modern mangrove and salt marsh vegetation in New Zealand and the United Kingdom, respectively, as well as transition zones (mangrove invading original salt marshes) for δ13C, soil moisture and salinity to build a calibration of the relationship, which is then applied to the Cenomanian fossil leaves from the locality of Pecínov.We found a positive correlation between water stress (caused by salinity or drought) and the δ13C values of n‐C25, n‐C27, n‐C29 and n‐C31 alkanes when combining all species from all modern localities. However, the absence of a strong correlation within individual species suggests a combination of several factors controlling the carbon isotopic composition. Nevertheless, the general response of δ13C to osmotic stress can be applied to compare the habitat of modern and fossil coastal plants. Thus, by using this relationship, we reconstructed the relative salinity and water stress of individual species of the Cenomanian plants by relating them to modern species-specific ranges of n‐C29 isotopic signatures.We showed that the δ13Cn−alkanes of fossil plant cuticles/leaves can be a valuable tool in the reconstruction of plant habitat and help us understand evolution of fossil environments in time and space. Additionally, our data further confirm that the δ13C acquired from plants should be used with caution when reconstructing global atmospheric CO2 because the osmotic stress can shift the δ13C in plants growing in terrestrial environments, particularly in coastal sea-influenced ecosystems.

Activity of flow-like landslides on the escarpment cuesta (tree-ring–based study on the eastern margin of the Bohemian Cretaceous Basin)

Activity of flow-like landslides on the escarpment cuesta (tree-ring–based study on the eastern margin of the Bohemian Cretaceous Basin)

Contrasting response of sea-level change to orbital eccentricity in greenhouse and icehouse climates

Climate-controlled changes in eustatic sea level (ESL) are linked to transfers of water between ocean and land, thus offering a rare insight into the past hydrological cycle. In this study, we examine the timing and phase of Milankovitch-scale ESL cycles in the peak Cretaceous greenhouse, the early Turonian (∼93–94 million years, Myr, ago). A high-resolution astronomical framework established for the Bohemian Cretaceous Basin (central Europe) suggests a ∼400-kyr pace and a distinct asymmetry of interpreted ESL cycles. The rising limbs of ESL change constitute only 20–30 % of the cycle, and are encased entirely within the falling phase of the 405-kyr eccentricity; the intervening ESL falls (≤6 m in magnitude) are more protracted, starting within 70 kyr prior to the eccentricity minima and culminating ∼60 kyr after the 405-kyr eccentricity maxima. Despite similarities to the sawtooth shape of ∼100-kyr glacioeustatic oscillations of the Late Pleistocene, the time scales and phasing are unparalleled in the Pleistocene icehouse. A similar, 405-kyr pace is found in ice-volume variations of the early Miocene, but the timing of glacioeustatic change relative to eccentricity forcing is incompatible with the phase of greenhouse sea-level oscillations. The phasing points to major differences in the geographic location and insolation sensitivity of the key hydrological reservoirs under icehouse and greenhouse regimes. The inferred structure of greenhouse eustasy points to low- or middle-latitude water storage, likely aquifers, that charge (expand) with rising seasonality variations and discharge (contract) with declining seasonality amplitudes on the 405-kyr scale. The net volume of water transferred on these time scales is within 2.2 × 106 km3, equivalent to ≤10 % of the present-day storage in the uppermost 2 km of continental crust; potential additive interference with steric eustasy, proportionally relevant during greenhouse regimes, could reduce the volumes required for continental storage.

Bite traces of a large, mosasaur-type(?) vertebrate predator in the lower Turonian ammonite Mammites nodosoides (Schlüter, 1871) from the Czech Republic

A specimen of the acanthoceratid ammonite Mammites nodosoides from the lower Turonian of the Bohemian Cretaceous Basin shows signs of having been preyed upon by a reptile, probably with a mosasaur-like dentition. Based on these traces, a new ichnotaxon, Nihilichnus quadripertitus Mikuláš, isp. nov., is erected. Several bite traces are arranged into two convergent, straight rows, which would rule out sauropterygian reptiles or fishes as agents. Jaw margins appear to contour the ammonite aperture, suggesting an attack directed at the apertural part with the head and arm crown. The lethal nature of the bite(s) inflicted is supported by the crushed anterior, albeit not anteriormost, portion of the body chamber. Spacing, size and angle of these traces, as well as the angle of convergence between both rows would suggest that the agent was a medium-sized (up to 6 m) member of the marine lizard family Mosasauridae, and more specifically, of the subfamily Tethysaurinae. However, a representative of another closely related subfamily, the Yaguarasaurinae (which includes the genus Romeosaurus), cannot be ruled out. The bite marks on the present ammonite shell contribute to a palaeoecological evaluation of tethysaurines (in particular with regard to food adaptations) and to a better picture of the palaeogeographical distribution of early Turonian mosasauroids across central European shelves.

Changes in bivalve assemblages at the onset of the OAE2 event in the Peri-Tethyan area (Bohemian Cretaceous Basin)

The Ocean Anoxic Event (OAE2) at the Cenomanian-Turonian boundary presents a unique record of gradual global warming and its effects on benthic organisms. The present research considers a palaeoecological, systematical and statistical evaluation of bivalve assemblages from the Pecínov Member in the Bohemian Cretaceous Basin. The well-exposed succession of Cenomanian through lower Turonian strata contains one of the most complex records of the OAE2 in central Europe. In total, 392 specimens have been studied and assigned to 24 genera within 21 families and 9 orders. The bivalve association prior to the positive shift of the δ13Corg (peak “a” sensu global carbon curve; lower part of the Metoicoceras geslinianum Zone) is strongly dominated by infaunal suspension feeders, followed by semi-infaunal suspension feeders. The near-absence of free-living epifaunal bivalves may be linked to a very fine, muddy substrate and water turbidity, a limiting factor for many epifaunal species. Infaunal deposit feeders are also present but comparatively rare, indicating a nutrient-rich environment with energy levels sufficiently high to keep organic matter in suspension. The Cucullaea glabra – Pseudoptera anomala assemblage of this level is considered to have formed during normal, shallow (15–20 m, supported by abundant material of Pinna) marine conditions. The association inhabiting the area above this level (upper part of the M. geslinianum Zone, S. gracile/E. septemseriatum Subzone) is characterized by the Panopea gurgitis – Rhynchostreon suborbiculatum assemblage suggesting considerably shallower depths and higher energy. Clusters of Modiolus and small oysters characterize the upper parts directly prior to the prominent positive δ13Corg peak “b” (the major peak of OAE2 CIE; ? base/lower part of the N. juddii Zone). No benthic fauna occurs above this level.

Papillaephyllum, a new genus of angiosperm foliage from the Cenomanian of the Czech Republic

Angiosperm foliage Papillaephyllum labutae Čepičková et J. Kvaček, gen. et sp. nov. is described from the Cenomanian, Late Cretaceous of the Peruc-Korycany Formation in the Bohemian Cretaceous Basin, Czech Republic. Papillaephyllum labutae has been erected for rarely-found fossils with basal-angiosperm signs, characterized by serrate, sometimes double-serrate margins with rounded chloranthoid teeth, each bearing a papilla. Venation is semicraspedodromous to festooned-semicraspedodromous with reticulate tertiary venation. Its micromorphology is distinctive in having the entire abaxial cuticle covered by papillae. Papillae of the subsidiary cells often form as visible wreaths around the stomata. Stomata are latero-cyclocytic and stephanocytic-bicyclic.Well-pronounced and numerous papillae of the external epidermal surface are an indicator of possible fresh-water stress, identifying the taxon as possibly meso- to xerophytic. Based on macro- and micromorphological comparison with fossil and recent material, affinity of Papillaephyllum labutae with the family Chloranthaceae is highly probable.

In situ-preservation of jaws in the upper Turonian acanthoceratid ammonite Prionocyclus germari (Reuss, 1845): Palaeobiological and taphonomic aspects

Cephalopod mandibles are rare in the Bohemian Cretaceous Basin (BCB) of Central Europe, occurring only as isolated jaw elements, the sole exception being a specimen of Yezoites bladenensis found with a lower jaw in situ in the second half of the 19th century. Here, we present a second record, a specimen of the acanthoceratoid ammonite Prionocyclus germari (Upper Cretaceous, upper Turonian). The ammonite preservation shows similarities to ammonoids from Solnhofen-type Lagerstätten, including phosphatised siphuncles, while the flattened ammonite conch is poorly preserved or fully dissolved. The lower jaw of P. germari is referred to the genus Praestriaptychus. Linking the jaw apparatus with an index ammonite taxon of the uppermost Turonian fills a gap in our knowledge of Upper Cretaceous acanthoceratoid ammonite jaw anatomy. The preservation of altered (secondarily carbonised) organic matter has been revealed by Raman spectroscopy analysis at the tip of the aptychus.The associated fauna and flora, consisting of complete crustaceans, fish, chondrichthyans and gymnosperm plant remains, reflect an unusual and unique preservational/taphonomic window within the BCB.

In situ estimation of effective rock elastic moduli by seismic ambient vibrations

In this study, we performed a non-invasive ambient noise investigation of unsaturated rock structures in the Bohemian Paradise (Bohemian Cretaceous Basin, Czech Republic). Our study focused on two key topics: 1) An in situ elastic moduli estimate of competent, horizontally deposited sandstone layers using ambient noise array measurements. Recordings were processed using an f-k array analysis, from which frequency-dependent Love and Rayleigh wave dispersion curves, as well as Rayleigh wave ellipticity, were retrieved. Data were inverted for the P- and S-wave velocity profiles, from which Young's and shear moduli were successfully estimated. 2) A study of the local response of the Kapelník rock tower. We analysed a dataset of ambient noise recordings obtained from the top of the tower and its foot. Information regarding tower oscillation frequencies and directions, together with amplification ratios, were retrieved from a particle motion polarisation analysis and from site-to-reference spectral ratios. Euler-Bernoulli beam theory was also employed for interpreting measured data using elastic moduli estimated from noise array measurements.

Fossil leaves of Cenomanian basal angiosperms from the Peruc-Korycany Formation, Czechia, central Europe

Two leaf forms are described from the Cenomanian, Late Cretaceous of the Peruc-Korycany Formation in the Bohemian Cretaceous Basin in Central Europe. A new foliage genus and species Ascarinophyllum pecinovense Čepičková et J. Kvaček, gen. et sp. nov. is characterised by serrate margins with rounded chloranthoid teeth bearing a papilla. The leaf is hypostomatic, coriaceous, with resin bodies in the mesophyll. Its venation is festooned semicraspedodromous, with a robust midvein. On the abaxial cuticle, it shows laterocytic/laterocyclocytic, stephanocytic-bicyclic, amphibrachyparacytic, and less frequently brachyparacytic and holoparacytic stomata, showing sometimes T-shaped thickenings of the internal cuticle at the poles. The abaxial cuticle bears external striations; stomata are surrounded by stomatal rims. The leaf is compared to similar Early and Late Cretaceous angiosperm foliage, and to foliage of extant basal angiosperms. Cuticle analysis shows similarities in stomatal construction and external striations of the abaxial cuticle with fossil leaves of Mesodescolea plicata and extant Chloranthaceae.Todziaphyllum saportanum (Velen.) Čepičková et J.Kvaček comb.nov. is revised and its diagnosis is emended. T. saportanum leaf is characterised by serrate margins and semicraspedodromous venation. It is compared to morphologically similar Cretaceous angiosperm foliage, including Ascarinophyllum pecinovense. It is particularly similar to the recently defined fossil leaf Todziaphyllum elongatum, interpreted as having chloranthaceous affinity.

Geological interpretation of a seismic reflection profile in the eastern part of the Bohemian Cretaceous Basin

Geological interpretation of a seismic reflection profile in the eastern part of the Bohemian Cretaceous Basin

Domichnial Borings in Serpulid Tube Walls: Prosperous Benthic Assemblages in the Cretaceous of France and the Czech Republic

The calcareous tubes inhabited by some polychaetes (some Serpulidae and the sabellid Glomerula) which are adapted to live sticking in soft ground, starting from the Permian, represent widespread but widely neglected and understudied substrates for domichnial bioerosion. Serpulids can be considered small macrofauna. However, due to the thinness of serpulid tubes, borings in them are sized in the order of 0.01–0.9 mm in diameter and thus rather considered micropaleontological objects. Extensive and methodologically broad search (vacuum castings studied at SEM; micro-computed tomography) for and study of borings in these specific substrates was performed on material from the Cenomanian of Le Mans area (France) and the Cenomanian and Turonian of the Bohemian Cretaceous Basin (Czechia). It shows that the bioerosive traces can be assigned to the existing ichnogenera Rogerella, Trypanites, Entobia, Maeandropolydora, and Iramena. Somewhat surprising is the frequency and disparity of dwelling borings. Several clues, especially in the more abundant ichnogenera Rogerella, Trypanites, and Entobia, support the hypothesis that the tracemakers of these borings adapted to the small size of their substrates by necessarily staying very small by themselves but nevertheless living to adulthood.

Nový výskyt příbojové facie u Ronova nad Doubravou (kolínský litofaciální vývoj, česká křídová pánev)

A rocky-coast facies in the Bohemian Cretaceous Basin (BCB) are developed mainly in the Kolín lithofacial area at its southern margin. Ronov – the newly described locality – is situated south of Ronov nad Doubravou, on the right bank of the Doubrava river near the St. Kříž church. The outcrop located in a ditch was partially excavated in order to study the character and extent of Cretaceous sediments (Beds No. 1–3; see Figs. 1–3). Bed 1 is composed of red clay with yellow streaks, representing lateritically weathered crystalline bedrock – likely amphibolites and garnet migmatites (Fig. 2). Overlying bed 2 consists of yellow to gray-green clay; in the lower part, the layer contains fragments of fossils that occur in the overlying layer, and sandy “intraclasts” interpreted as bioturbations. The most conspicuous bed 3 (25 cm in thickness) is represented by calcareous, coarse-grained sandstone to conglomerate with glauconite and abundant fauna (mainly fragmentary; Figs. 4 and 5). This type of rock in the wider area (between Ronov nad Doubravou and Žleby) was reported by Sejček (1982) who described three occurrences as scree or fragments on the surface but has not found any rock outcrops in situ despite excavation work. The individual layers were sampled for the study of foraminifers, calcareous nannoplankton and macrofauna. Shells of Rhynchostreon suborbiculatum, which are always disarticulated, often fragmented and bioturbated (Entobia exogyrarum), represent the most prominent element of macrofauna. In addition, Rastellum diluvianum and Amphidonte halitoidea, unspecified large colonies of bryozoans, spines of the echinoids Cidaris vesiculosa, complete shells of brachiopods Cyclothyris aff. difformis and tiny teeth of sharks Otodus rarely occur. Calcareous nannofossils were found only in bed 3. Isolated small, mostly difficult to identify fragments belong to long-range stratigraphic taxa (Fig. 6) and may indicate an interval from the uppermost Cenomanian to the lowermost Turonian. Similar poor nannofossil assemblages are known also in other rocky-coast facies of the BCB. The refining indicator of stratigraphic classification is thus macrofauna. Similar communities with Rhynchostreon suborbiculatum and echinoderms are known from Upper Cenomanian and Lower Turonian in the area of Heřmanův Městec, Čáslav and especially Kutná Hora. However, brachiopods Cyclothyris aff. difformis and oyster Amphidonte halitoidea recorded from Ronov are typical representatives of Upper Cenomanian “rocky-coast” faunas, whereas typically Lower Turonian elements such as the oyster Exogyra reticulata, Exogyra sigmoidea, or the spines of the Cidaris sorigneti are missing in the studied community. The study of macrofossil and nannofossil communities shows that the Upper Cretaceous rocks, represented by the calcareous glauconitic sandstones to conglomerates in Ronov locality, are most likely of the Upper Cenomanian age and represent the Korycany Member of the Peruc-Korycany Formation.

Plagioptychus (Hippuritida) dominated assemblage from northern Peri-Tethys margin (Bohemian Cretaceous Basin, Cenomanian–Turonian transition)

Rudist bivalves are frequently used as an important tool for stratigraphy and palaeoecological reconstructions in Cretaceous ecosystems. In this study, we partly refine stratigraphic ranges of rudist genera and species reported from the Bohemian Cretaceous Basin (BCB). The first occurrences of Plagioptychus haueri (Teller) and consequently, the entire genus Plagioptychus might be dated to the upper Cenomanian. The research focused on two sites exposing near-shore/shallow-water deposits, located in the north-western part of BCB. This area represents palaeobiogeographical boundary between Tethyan and Boreal Realms. Here, the Tethyan rudist fauna reaches its northern limits within the Peri-Tethyan shelfs in Central Europe. Revision resulted in detection of the following rudist species: Plagioptychus haueri, Radiolites bohemicus (both already recognised), Petalodontia aculeodentata, Radiolites sanctaebarbarae and Radiolites saxoniae. Furthermore, large numbers of rudist fragments assignable to Hippuritidina suborder, corals and other macrofauna have been detected. Localities described herein are possibly of upper Cenomanian age, even though lower Turonian origin of some of the material deposited in studied localities cannot be excluded. We assign this taphocenosis with co-occurrence of rudist and coral fauna to ‘Coral-Rudist Lithosomes’ with two distinctive rudist eco-morphotypes typical of different substrate types and/or environments. Additionally, we discuss stratigraphical position of several taxa within the context of the entire Bohemian Cretaceous Basin.

New species of Zamites from the Cenomanian of the Bohemian Cretaceous Basin

Zamites pateri J.Kvaček is described as a new member of the Bennettitales from the Cenomanian of the Peruc-Korycany Formation, Bohemian Cretaceous Basin in the Czech Republic. It comes from fluvial sediments exposed in the Pecínov quarry. It is compared to Zamites bayeri J.Kvaček from the Peruc-Korycany Formation, from which it differs in having pinnae attached to the dorsal part of the rachis and in cuticular details, particularly in having costal zones narrower than intercostal zones, stomata orientated always perpendicularly to the leaf margins and a thinner adaxial cuticle. Epidermal characters, particularly sunken stomata and numerous papillae underpin the mesophytic/xerophytic nature of the plant fossil.

Trans-Atlantic correlation of Late Cretaceous high-frequency sea-level cycles

Previous studies of Cretaceous sedimentary rocks have used multi-proxy correlation methods to suggest eustatic change, modulated by the c. 400 kyr long eccentricity rhythm. Although numerous authors have inferred eustatic changes on shorter timescales, none have demonstrated synchronous sea-level changes in separate basins on different plates, thousands of kilometres apart. Our study integrates basin-scale, three-dimensional sequence architecture, molluscan biostratigraphy, and carbon-isotope chemostratigraphy to demonstrate synchronous sea-level changes in upper Turonian to lower Coniacian shallow-marine clastic successions in the Western Canada Foreland Basin, and the Bohemian Cretaceous Basin. Depositional sequences in both basins are plotted in a common time domain using an astronomically calibrated age model, allowing direct comparison. In both basins, at least seven major transgressive events can be shown to be synchronous within the limits of combined biostratigraphic and chemostratigraphic resolution. ‘Major’ and ‘minor’ sequences of late Turonian age appear to have been paced, respectively, by the long (c. 400 kyr) and short (c. 100 kyr) eccentricity cycles. In contrast, early Coniacian sequences evidence pacing by the c. 38 kyr obliquity rhythm. Stratal architecture suggests that sequences developed in response to eustatic changes of c. 14–20 m at average rates ranging 0.08 to >1.3 m/kyr. At a time of ‘warm greenhouse’ climate, sea-level change of this magnitude and timescale may not be explicable entirely as a result of thermal- and aquifer-eustasy, and hence glacio-eustasy may also have been a contributing factor.