Ostracod Associations Research Articles

Late Turonian ostracod assemblages record a shift from mesotrophic to oligtrophic hemipelagic deposits in the Bohemian Cretaceous Basin (Czech Republic)

The late Turonian marine benthic ostracods have been identified in the hemipelagic marlstones and limestones of the Bohemian Cretaceous Basin situated between the Boreal and Tethyan Realms. Cytherella cf. concava, C. cf. ovata, Cytherelloidea hindei and C. stricta (all Platycopida and survivors of the upper Cenomanian OAE2 low-oxygen level) were dominant in the monotonous poorly fossiliferous marlstone of the Jizera Formation. The cooling associated with cool water shift to the south and marked by the Hyphantoceras Event enabled the spread of the diverse Boreal faunae and the ostracod fauna of the Teplice Formation, which highly resembles the British Islands ostracod associations. Their biodiversity increased in mesotrophic conditions and the maximum was attained in an oligotrophic system depleted in nutrition. The ratio of Platycopida/Podocopida changed from 9:1 in hypoxic dark marlstone to 1:2 in times of supposed oligotrophic, well aerated conditions in the grayish and dark marlstones deposited in the period of maximum flooding surface. Although the dinoflagellates and coccolithophorids of appropriate size were very common to abundant for filter feeder platycopids, they were replaced upwards by deposit feeder podocopids.

Lectostratotype of maikopian group – Belaya River section upstream of Maikop town (Western Ciscaucasia) in the Oligocene part

Belaya River Section of Maikop deposits is the closest to the Maikop town, typical for Western and Central Ciscaucasus, well outcropped and studied and should be considered as a type section for the Maikop Group. Here it is possible to observe a continuous transition from the underlying light marls of Belaya Glina Formation to the dark clays of Pshekha Formation at the base of the Maikop succession. Pshekha Fm is characterized by nannoplankton NP21 and NP22 zones, dinocysts Phthanoperidinium amoenum (D13) and Wetzeliella symmetrica zones, mollusk association with Pterolucina batalpashinica at the bottom and rich fish fauna. The succession shows a normal polarity chron C13n for the base of the Pshekha and revers polarity C12r above.
 Marl of Polbian Bed with brackish Lower Solenovian mollusks, ostracod association with Disopontocipris oligocaenica, nannoplankton of NP23 Zone and dinocysts of Wetzeliella gohtii Zone lies above with erosion contact. Overlying Lower Morozkina Balka Subformation contains from non-calcareous clays and concludes the remains of fish and dinocysts of Wetzeliella gohtii Zone. The Upper Morozkina Balka Subformation contains calcareous sublayers with nannoplankton NP23 Zone in lower part and NP24 one above, dinocysts Chiropteridium partispinatum Zone, Rhombodinium draco Subzone. Polarity pattern we interpret to correspond to C10n, C9r and C9n.
 Batalpashinsk Formation corresponds to the time of maximum hydrogen sulfide contamination of the Late Oligocene basin and is dated by nannoplankton NP25 Zone, and dinocysts Chiropteridium patrispinatum Zone with Rhombodinium draco Subzone in lower part and Deflandrea spinulosa (non typica) Subzone in the middle and upper parts. Septarian+Zelenchuk Fm is composed of clays with septarian concretions, and interbedded sands with the same dinocysts and foraminifera with Spiroplectammina aff. terekensis. Calcareous interlayers in the top of the formation conclude nannoplankton of NP25-NN1 Zone. Karadzhalga Formation is composed mainly “fish lithofacies” and includes dinocysts zone Labyrinthodinium truncatum (Lower Miocene) in basal part.

Holocene marginal marine ostracod successions from the Kızılırmak River delta; Implications for depositional environments and sea-level changes at the Southern Black Sea coast

Holocene delta formations are unique records of regional sea-climate interactions. The Kızılırmak Delta is the biggest and richest wetland ecosystem in the Black Sea region of Turkey. The Black Sea was uniquely affected by rising sea levels due to its disconnection from the world oceans during the last glacial period. To understand the palaeoenvironmental impact on the delta plain we analysed a 14.5-m-long sediment core using palaeoecological ostracod analyses accompanied by a palaeo-salinity reconstruction based on sieve pore analysis on the ostracod Cyprideis torosa. This study depicts the interplay of terrestrial and marine settings forming mesohaline, shallow lagoons and deltaic lakes since ca. 7.9 ka cal BP. Lagoons with α-mesohaline to polyhaline salinities and β-mesohaline to oligohaline lake environments were identified. Reconstructed palaeo-sea level estimations depict a remarkable environmental variability. The lagoon habitats at 7.9 to 7.0 and 5.3 to 4 ka cal BP were dominated by Cyprideis torosa. Marine influence led to ostracod associations with Loxoconcha spp. and Tyrrhenocythere amnicola especially between 7.9 and 7.0 ka cal BP. Riverine influence in the same period, but especially at about 7.7 ka cal BP, caused dominating Amnicythere spp. Cyprideis torosa and Candona neglecta that characterise short phases of a mesohaline deltaic lake environment at about 7.7 and 7.0 ka cal BP as well as after 4 ka cal BP. With a subsequent salinity decrease, C. neglecta and (later on) Pseudocandona marchica became dominant with an interruption by another short-term lagoonal phase that might be associated with a ‘megadrought’ between 3.7 and 3.0 ka cal BP.

Some Reports of Paratethyan Ostracods from the Central Mediterranean Area

Uppermost Miocene stratigraphic sections have been sampled in Sicily and eastern Tunisia. Some of the stratigraphic levels contained in them are related to the continentalization phase (“Lago Mare”) of the Mediterranean Basin, which occurred at the end of the Messinian Salinity Crisis. Within these levels, ostracod associations reflecting fresh or brackish water environments are reported here for the first time. Species considered to be Paratethyan in affinity lived in these environments. The discovery, both in Sicily and Tunisia, of species such as C agrigentina, A propinqua, and M. punctate, suggests that the Sicilian Channel did not prevent the migration of the non-marine fauna from NW to SE in the Paleomediterranean area during the Post Evaporitic Phase

Late Carnian (Tuvalian, Tropites dilleri zone) ostracods (Crustacea) from the Mufara Formation (Monte Scalpello, Central-Eastern Sicily, Italy)

Ostracod association from the Upper Triassic (Tropites dilleri zone of the Carnian stage) of the sedimentary succession (Mufara Formation) exposed along the east side of Monte Scalpello (Catenanuova, central eastern Sicily) has been studied for the first time. The specimens, silicified, are rare but well preserved and often consist of complete carapaces. They belong to eight families: Healdiidae, Cavellinidae, Bairdiidae, Acratiidae, Bythocyprididae, Pontocyprididae, Judahellidae, Glorianellidae. Twenty-three taxa have been listed; the family Bairdiidae is the most represented among all the others with fifteen species. Four species are new: Bairdia scaliae n. sp., Acratia maugerii n. sp., “Anchistrocheles” gemmellaroi n. sp. and Judahella? montanarii n. sp. Other species are left in open nomenclature because of the lack of specimens.

Ostracods across the Frasnian/Famennian boundary (Devonian) in the Hony railway section (southern border of the Dinant Synclinorium, Belgium)—geochemical consequences

Ostracods are extremely rare in the upper part of the Frasnian but sometimes very abundant in the base of the Famennian exposed in the Hony railway section. The associations of ostracods in the base of the Famennian belong to the Eifelian Mega-Assemblage and are indicative of shallow and sometimes semi-restricted marine environments, but this fauna has been mobilised periodically most likely by seismic activity. The abnormally high abundance of particularly well-preserved dissociated valves of adults and instars indicates a depositional environment very close to the shore at Hony, as is the case in some other localities in the southern border of the Dinant Synclinorium. In the fine dark shales straddling the Frasnian/Famennian boundary, ostracods are silicified and are evidence of an intense circulation of ground water during diagenesis. That may explain the increase of chalcophile elements and the absence of a significant iridium anomaly reported in this bed. A new zone based on metacopid ostracods, the Ovatoquassilites avesnellensis Zone, is established in the base of the Famennian.

Late Holocene wet/dry intervals from Fuegian steppe at Laguna Carmen, southern Argentina, based on a multiproxy record

Late Holocene environmental conditions are reconstructed from a sedimentary core (LCTF2) retrieved from Laguna Carmen (53° 40′ 60″S, 68° 18′ 0″W, 29 m a.s.l.) in the Fuegian steppe, northern Tierra del Fuego, southern Argentina. The multiproxy study utilizes pollen/spores, algae, ostracods, palynofacies, Total Organic Carbon (TOC), carbonate content, and lithology. Findings show that grass communities developed over the landscape from 4200 to 1400 cal yr BP. After that, the plant communities fluctuated between grasses to scrubland vegetation. Changes in the lake level as indicated by the halophytes, algal content and ostracod associations, revealed alternation of wet and dry intervals. The palynofacies indicate environments close to the terrestrial source with a great input of terrigenous organic matter into the lake in agreement with the sedimentary environment. By comparison with other sites from Tierra del Fuego and southwestern Patagonia, the record of wind-carried Nothofagus pollen is consistent with variations in the Andean forest communities as a consequence of shifts in the latitudinal position and/or strength of the westerlies. The short-term wet/dry intervals seem to be associated with climate events of local occurrence. On the other hand, some wet intervals have been reported in lacustrine records from southern Patagonia. The last millennium showed high environmental variability. Humid conditions characterized the Medieval Climate Anomaly (MCA) event, while dryness conditions were related to the Little Ice Age (LIA) event. In particular this latter interval has been related to a northward migration of the westerlies from their present day focus.

First data on ostracods and foraminifera living in Cystoseira associations in western Ionian Sea

For the first time ostracod and foraminifera populations living on infralittoral algae were analysed from three different localities near the Ciclopi Islands Marine Protected Area along the Etnean Ionian coast of Sicily, few km N of the city of Catania. Six series of samples, each of three samples, were collected at 5, 10 and 26 m water depth in sea bottom areas where the Biocoenosis of the Infralittoral Algae is developed. Some samples were collected inside the Ciclopi Islands Marine Protected Area (CIMPA) and some outside it.In all the samples the ostracod association is characteristically constituted by a mixture of true shallow water phytal taxa and and infralittoral sediment-dwelling taxa. The family Xestoleberididae is markedly dominant, mainly in the shallowest samples. Xestoleberis dispar represents more than 60% of all the specimens, followed by X. communis and X. dispar. The families Paradoxostomatidae (with Paradoxostoma rarum, P. simile, P. parallelum, P. intermedium, P. atrum and P. caecum), Hemicytheridae (with Aurila prasina and A. convexa), Bairdidae (with Neonesidea mediterranea, N. corpulenta, and N. Longevaginata) follow. Loxoconchidae (with Loxoconcha rhomboidea), Pontocyprididae (with Pontocypris mediterranea and Pontocypris pirifera) and Cytheruridae (with very few specimens of Semicytherura spp.) are subordinate.Foraminifera are represented almost exclusively by phytal benthic taxa. Between them the the family Miliolidae is markedly prevalent, mostly represented by Quinqueloculina species, followed by the family Rotaliidae with Elphidium crispum, E. depressum, E. aculeatum, and Elphidium spp. Discorbidae, with Rosalina spp.; Cibidididae, largely represented by Cibicides refulgens and C. advenum; Planorbulinidae with Planorbulina mediterranensis, are also present.

Les ostracodes plio-pléistocènes de la côte orientale de la Péninsule du Cap Bon (Tunisie)

This article concerns the study of the ostracods of the Upper Pliocene-Lower Pleistocene sedimentary deposits cropping out along the south-eastern coast of the Cape Bon Peninsula (Tunisia, Hammamet region, Sidi Khelas section). Fourteen samples were taken along a thirty-two-meters thick sedimentary silico-clastic series. Seventy species of ostracods belonging to twenty-four genera were found. The autochthonous association, which originally lived in an environment located in the infralittoral and upper circalittoral stages of the benthic marine domain, is cyclically affected by inputs from the more superficial environments due to the presence of relatively well-developed lagoon and/or estuary environments in the surrounding coastal areas. Within the ostracod association, the presence of Bythocythere turgida – a true “northern guest” – is particularly significant. This species indicates that these sediments were deposited during the cold phases of the Early Pleistocene. Among the ostracods found, those belonging to the families Trachyleberididae, Hemicytheridae and Bythocytheridae, which are dominant and include particularly significant species from the environmental and paleoclimatic point of view, are systematically recorded and commented on. Some species that are probably new have been described and photographed, but are currently left in open nomenclature because of how few specimens have been found.

Arid and humid phases in central Italy during the Late Pleistocene revealed by the Lake Trasimeno ostracod record

A multiproxy approach in a sediment core from Lake Trasimeno has been used to reconstruct the climate history of central Italy during the Late Pleistocene to Early Holocene period (ca. 47,000–9,000calyr B.P.). Ostracod assemblages and sedimentological data (lithology and carbonate content) have been used to infer past hydrological changes in the area. Ostracods were analyzed throughout the core using diversity indexes and multivariate statistic analyses (Cluster and PCA). Three main associations linked to lake level and salinity variations were recognized: 1) the C. torosa association, indicating permanent lacustrine conditions with high lake levels and low salinities; 2) the S. aculeata association, linked to very shallow/temporary waters with higher salinity conditions; and 3) the S. aculeata-E. mareotica association pointing to temporary water conditions and the highest salinities. Furthermore, the presence of C. fuscata and L. blankenbergensis during wide parts of the Late Pleistocene indicates temperatures lower than present days. Alternations of these three ostracod associations compares well with the oxygen isotope curve from Greenland (NGRIP) and are thus interpreted as climatically driven. At the Holocene transition (Termination 1), the ostracod associations indicate a delay in the increasing warming and humidity with respect to the NGRIP temperature record.

Остракоди крайових частин Борисфенської затоки Східного Паратетису в середньому сарматі

This work continues the analysis of assemblages of ostracoda from the Middle Sarmatian deposits of the Borisphen Gulf of the Eastern Paratethys. Ivanova at al. (2007), Bondar (2015) present data on the history of the study of Sarmatian ostracods, on the factual data, methods of study, and lithological and palaeontological description of the composite Sarmatian sections of the marginal parts of the Borisphen Gulf. This publication presents a palaeoecological analysis of the ostracod assemblages, which contributes to the description of the shallow-marine environment which existed in the Middle Sarmatian basin. The material studied consists mainly of benthic ostracods, closely associated with the near-bottom environment of the basin. This makes them a reliable indicator of the palaeoecological environment. Any changes of the living environment is leaded to restructuring of the entire ostracod assemblage. The main environmental factors, influencing the systematic and quantitative composition, and the domination of one taxa over others, include water depth, salinity, hydrodynamic conditions in the basin, temperature conditions, substrate type, and organic carbonate and oxygen content of the water. The reconstruction of the palaeoenvironment is based primarily on the actualistic approach, where the environmental parameters of modem communities are extrapolated to the ancient fauna with certain assumptions. A total of 16 species of ostracod, belonging to 6 genera of 6 families, were identified in the Middle Sarmatian deposits. Investigation of these ostracod assemblages included taxonomic, quantitative, taphonomic and palaeoecological analyses. The palaeoecological analysis of ostracods from the deposits of the marginal parts Middle Sarmatian sea demonstrates that the assemblages developed in the more or less favorable environments of a warm shallow basin (deep up to 20 m, temperature about 20 oC). Limited diversity of the species, abundance of certain specimens, large and heavy shells of ostracods are typical of the shallowest parts of a basin with active hydrodynamic environments (Aurila). The highest taxonomic diversity of the ostracod associations was encountered in the fairly shallow and calm environments with low sorting of substrate and weak near-bottom hydrodynamics (Loxoconcha, Leptocythere). The salinity of the basin was unstable. So there are Cyprideis torosa, Cyprinotus luminosus in the assemblages.

Wetland evolution in the Qinghai Lake area, China, in response to hydrodynamic and eolian processes during the past 1100 years

The Daotanghe riverine wetland in close proximity to the Qinghai Lake was investigated to demonstrate the interrelationships between Qinghai Lake hydrodynamic processes, eolian mobility and ecological conditions during the past 1100 years in response to climate change. We used ostracod assemblages from various sites east of Qinghai Lake and from the sediment core QW15 of Daotanghe Pond and combined them with grain size and geochemical data from the same core. The statistical extraction of grain size endmembers (EM) revealed three different transportation processes responsible for pond-related fluvio-lacustrine, pure fluvial and eolian deposits. Identified seasonal effects (eolian mobility phase) and timing of ice cover are possible tracers for the competing influence between the Asian summer monsoon and the Westerlies in the Daotanghe Wetland and surrounding area.Our results show that ostracod associations and sediment properties are evidence of a fluvio-lacustrine fresh water environment without ingression of Qinghai Lake into the wetland. Hydrodynamic variations coupled with phases of eolian input indicate highly variable water budgets in response to climate-induced effective moisture supply. The Medieval Warm Period (MWP) until about 1270 CE displays generally moist and warm climate conditions with minor fluctuations, likely in response to variations in summer monsoon intensity. The three-partite period of the Little Ice Age (LIA), shows hydrologically unstable conditions between 1350 and 1530 CE with remarkably colder periods, assigned to a prolonged seasonal ice cover. Pond desiccation and replacement by fluvial deposits occurred between 1530 and 1750 CE, superimposed by eolian deposits. The phase 1730–1900 CE is recorded by the re-occurrence of a pond environment with reduced eolian input. Principal Component Analysis (PCA) on ostracod abundances shows similar trends. All three phases of the LIA developed during a weak summer monsoon influence, favoring westerly-derived climate conditions until ca. 1850 CE, in accordance with records from the adjacent regions.Seasonal freezing periods in excess of the average time of frozen water bodies also occurred in periods of the well-known grand solar minima and indicate stronger seasonality, possibly independent from variations in summer monsoon strength but with links to global northern hemispheric climate.

Asociaciones de ostrácodos bentónicos actuales y del Holoceno del estuario de Bahía Blanca (Buenos Aires, Argentina): interpretaciones paleoambientales

The study of ostracod fauna in sediment samples from present environments at the Bahia Blanca estuary led to the identification of different ostracod associations, through which it was possible to identify Holocene depositional environments. Based on the systematic analysis of the ostracods present in different core levels, a total of 11 genera represented by 13 species of benthic ostracods were identified, out of which Neocytherideis ruidis, Loxocythere variasculpta and Callistocythere litoralensis were dominant along the core. The quantitative and qualitative analysis of ostracods from the Holocene allowed us to determine the following palaeoenvironments: at the base of the core the sediments were deposited in an intertidal environment with developed mudflats; the middle sector evidenced an increase in environmental energy; and the upper portion of the core contained deposits of marshes environment with greater freshwater input. The detailed study of the benthic Ostracoda allowed to identify palaeoenvironments and to provide new evidence of negative fluctuations of the mean sea level for the Holocene.

New Insights on Earliest Devonian (Lochkovian) Ostracods from the Argentine Precordillera

Abstract. Ostracods from the Lower Devonian (Lochkovian) of the Argentine Precordillera Basin (upper levels of the Los Espejos Formation and lowermost ones of the Talacasto Formation) were studied. These units represent one of the best Lochkovian stratigraphic records in the Malvinokaffric basins. According to this revision, records of Devonian ostracod faunas in southwestern Gondwana can be extended to older stratigraphic levels. One new genus Suinella and ten species, including five new records (Suinella huarpesi gen. and sp. nov., Amphizona? argentinensis sp. nov., Bollia talacastensis sp. nov., Petrisigmoopsis? rotundum sp. nov. and Pircawayra antiqua sp. nov.) and one reassignment (Thilpsurella aff. T. putea Coryell and Cuskley) were hereby defined. The studied taxonomic assemblage differs from younger Devonian Malvinokaffric ostracod associations by being relatively diverse and composed mainly of drepanelloideans together with metacopids. The association is characterised by species with thin and spi...

Ostracod response to habitat change in an early Aptian shelf sea

Changes in ostracod assemblage composition from the Lower Aptian of the Lower Saxony Basin (Germany) are investigated to estimate their potential as proxies for palaeoenvironmental habitat changes in an epicontinental setting. The studied palaeoenvironmental factors include oxygen depletion, increasing temperatures during OAE 1a and an increasing water depth caused by the supra-regionally recorded early Aptian transgression. In the late early Aptian, a distinct short-term decrease of water depth is inferred. Five ostracod associations are recognized: two are characterized by a unique composition of species and three are unique by dominance of certain species. The stratigraphic record is unique for one association, all other associations are exclusively occurring in short intervals of the section, but are co-occurring with the sub- and superjacent ostracod association. We observe a change from Veeniacythereis–Acrocythere–Dolocythere-dominated to Cytherella-dominated associations, initiating well before OAE 1a and ending slightly before the upper limit of OAE 1a, most likely triggered by increasing temperatures and affected by increasing water depth. Changing water depth proved to be the most important factor affecting the successive appearance of ostracod associations. Moreover, ostracod associations change in dominance from Cytherella- to Pontocyprella–Schuleridea-and finally to Neocythere-dominated faunas parallel to an increasing water depth. A re-establishment of palaeoenvironmental conditions typical for the Veeniacythereis–Dolocythere-dominated association gave rise to a Saxocythere–Batavocythere-dominated replacement association. Although ostracods are very sensitive organisms with respect to oxygen deficiency, the oxygen depletion during OAE 1a was not a major factor for changing ostracod associations. During black-shale deposition ostracods vanished completely, a recognized change in associations started before the anoxic period and ended afterwards. High resolution ostracod studies appeared to be a very powerful proxy for changing water depth, temperature and oxygenation in early Cretaceous epicontinental settings like the Lower Saxony Basin.

Évolution des microfaunes pléistocènes le long de la bordure sud du lac de Bizerte (coupe de Sidi Mansour, Nord-est de la Tunisie) : interprétation paléoenvironnementale

We studied ostracod associations and benthic foraminifera of an Early Pleistocene sedimentary succession cropping out at Sidi Mansour along the southern side of the Bizerte Lake (Tunisia). The microfaunistic analysis allowed us to reconstruct the evolution of the palaeoenvironment during the Pleistocene in this region of northern Tunisia. Thus, the palaeoenvironment evolved from a shallow water lagoon open to the sea, represented in the basal levels of the section, towards progressively shallower environments, from transitional and brackish in the intermediate levels, to hypersaline and monotypic environments (sebkha) in the upper levels. Towards the top of the series the palaeoenvironmental conditions become again coastal and shallow marine.

Spatial distribution and ecology of the Recent Ostracoda from Tangra Yumco and adjacent waters on the southern Tibetan Plateau: A key to palaeoenvironmental reconstruction

• Distribution and ecology of modern freshwater ostracods from a remote region, Tibetan Plateau. • Ecology of living ostracods from extremely high altitudes freshwater ecosystems. • Contribution to biodiversity and taxonomy of Tibetan Recent ostracods. • Baseline data for palaeolimnological investigations using Tibetan ostracods. We elucidate the ecology of Recent Ostracoda from a deep brackish lake, Tangra Yumco (30°45′—31°22′N and 86°23′—86°49′E, 4595 m a.s.l.) and adjacent waters on the southern Tibetan Plateau. Ostracod associations (living and empty valves) in sixty-six sediment samples collected from diverse aquatic habitats (lakes, estuary-like water and lagoon-like water waters, rivers, ponds and springs) were quantitatively assessed. Eleven Recent Ostracoda were found (nine living and two as empty valves only). Cluster analysis established two significant (p < 0.05) habitat specific associations; (i) Leucocytherella sinensis , Limnocythere inopinata , Leucocythere ? dorsotuberosa , Fabaeformiscandona gyirongensis and Candona xizangensis are lacustrine fauna . (ii) Tonnacypris gyirongensis , Candona candida , Ilyocypris sp., Heterocypris incongruens and Heterocypris salina are temporary water species . Ostracod distribution and abundance are significantly (p < 0.05) correlated to physico-chemical variables. The first two axes of a canonical correspondence analysis (CCA) explain 30.9% of the variation in the species abundance data. Conductivity and habitat types are the most influential ecological factors explaining the presence and abundance of ostracods. Spearman correlation analysis reveals that: (i) Two species, L .? dorsotuberosa (r = 0.25) and L. inopinata (r = 0.36) have a significant positive correlation with conductivity while one species, T. gyirongensis (r = −0.68) displays a significant negative correlation with conductivity. Limnocythere inopinata correlates significantly positive (r = 0.37) with alkalinity. Fabaeformiscandona gyirongensis correlates significantly positive (r = 0.28) with water depth. Key indicator living assemblages are: (i) L . sinensis dominates Ca-depleted brackish waters although ubiquitously distributed; (ii) L. ? dorsotuberosa dwells in fresh to brackish waters; (iii) L . inopinata predominates in mesohaline to polyhaline waters; (iv) F. gyirongensis inhabits exclusively brackish-lacustrine deeper waters; (v) C . candida populates freshwaters; (vi) T . gyirongensis and Ilyocypris sp. are restricted to shallow temporary waters; (vii) H . incongruens occurs in ponds. Water depth indicators are F . gyirongensis and L.? dorsotuberosa , useful in ostracod assemblages for palaeo-water depth reconstruction. Our results expand the knowledge of the ecological significance of Recent Tibetan Ostracoda ecology. This is a new insight on habitat chacteristics of both living assemblages and sub-Recent associations of ostracods in mountain aquatic ecosystems. The new modern ostracod dataset can be used for the quantitative reconstruction of past environmental variables (e.g., conductivity) and types of water environment. The key indicator ostracods are relevant in palaeolimnological and climate research on the Tibetan Plateau.

Palaeoenviromental and palaeogeographical traits on deep-water ostracod assemblages from the Lower Pleistocene sediments along the Ionian side of Mount Etna (Sicily, Italy)

The ostracod associations of the Lower Pleistocene sedimentary succession cropping out at Serra San Biagio (Catania, Sicily NE) have been investigated. The ostracod fauna from nine samples is poorly diversified but well-preserved: A total of forty taxa of ostracods have been identified, thirty-three at specific level and seven at genus level or doubtful species. Thirty species are considered as constituents of the in situ original assemblages. The associations consist almost exclusively of bathyal taxa such as Bythocypris obtusata (Sars), Anchistrocheles antemacella Maddocks, Henryhowella ex H. hirta (Costa) group, Quasibuntonia radiatopora (Seguenza), Retibythere (Bathybythere) scaberrima (Brady) and Bathycythere vansraateni Sissingh. Also the Krithe group is well-represented with Krithe compressa (Seguenza) and K. pernoides (Bornemann). Almost all species, some, particularly interesting from the palaeoecological and palaeogeographical point of view, have been here described, illustrated and commented on, including a species belonging to the genus Cytherella Jones, 1849, found in all samples of the section, which is here proposed as new.

Ostracods from the marginal coastal Lower Cretaceous (Aptian) of the Central Tunisian Atlas (North Africa): Paleoenvironment, biostratigraphy and paleobiogeography

This work provides the first detailed taxonomic study of ostracod species from the Lower Cretaceous (Aptian) marginal coastal deposits of the Central Tunisian Atlas, the Kebar Formation, as well as biostratigraphic, paleoecological and paleobiogeographic implications. The ostracod fauna provides new insights into the depositional environment and biostratigraphic framework of the Kebar Formation, and is represented mainly by freshwater and brackish-water species among them, Perissocytheridea tunisiatlasica nov. sp., is newly described. The environmental setting of this formation comprises marginal-littoral conditions in its lower part, thus not exclusively non-marine/continental as assumed previously. The ostracod associations from the studied locality, Jebel Ksaïra, indicate a minimum age of Early Aptian as recently attributed to the lower member of the Kebar Formation based on charophytes (presence of Late Barremian to Early Aptian Globator maillardii var. biutricularis Vicente and Martín-Closas, 2012), whereas an Early Albian age had been previously assigned to the Jebel Kebar site. The relative sea-level fall documented in the lower member of the Kebar formation at Jebel Ksaïra might correspond to the 3rd order cycle major eustatic sea-level fall event starting at the base of the Aptian. Paleobiogeographically, the non-marine ostracod fauna newly discovered in the Kebar Formation shows some affinities to contemporaneous faunas of southern and western Europe, e.g. that of the uppermost Weald Clay Group of southern England (Cypridea fasciata subzone of Horne, 1995), West Africa, and possibly to eastern South America (Brazil). Hence, the studied ostracods further support the hypothesis of supraregional faunal exchange by passive ostracod dispersal during the Early Cretaceous – between Europe and Northern Africa on the one hand, and eastern South America/western Africa and North Africa on the other hand. This leads to the hypothesis that the Peri-Tethyan islands could have worked as effective bridges for non-marine ostracods to become widely dispersed passively by “island-hopping” of larger animals and thus, ultimately, facilitated intercontinental faunal exchanges between South America and Europe – potentially even Asia – via North Africa during the Early Cretaceous.

PALEOBIOGEOGRAPHY AND PALEOECOLOGY OF THE OSTRACOD HELIOCYTHERE BONADUCE, RUGGIERI & RUSSO, 1988 WITH RE-DESCRIPTION OF MIDDLE MIOCENE HELIOCYTHERE MORAVICA (PROCHÁZKA, 1893) FROM THE CARPATHIAN FOREDEEP (CZECH REPUBLIC)

Twelve species attributed to the genus Heliocythere have been recorded from the epineritic/neritic and circalittoral/epibathyal deposits of Cenozoic subtropical seas. The oldest species is from the Lower Oligocene deposits of the northwest Indian Ocean. The youngest species are confirmed from the Late Miocene (Messinian) of the Mediterranean area and one stratigraphically uncertain record from the Early Pliocene of Vejer de la Frontera (southern Spain). Heliocythere profited of a marine connection between the Mediterranean and the Paratethys through the Slovenian corridor during the latest Burdigalian (Karpatian) and settled in Central Europe and Balkan Peninsula marine biotopes, but a paleogeographic and paleoecologic change during the late Serravallian caused an extinction of Paratethyan Heliocythere . In Late Miocene times, Heliocythere spread through the entire Mediterranean area and extended its biogeographic range to the eastern Atlantic Ocean. This was a period of maximum species diversity of Heliocythere. No Heliocythere species has been described from present-day marine ostracod associations and we suppose that this fully marine genus is extinct. Due to the loss of the type material and the necessary correction of genus attribution, we designate herewith a neotype for theearly Badenian (early Langhian) Cythere moravica Proch√°zka, 1893 from the Carpathian Foredeep, referred to in this work as Heliocythere moravica (Proch√°zka, 1893). We discuss its paleoecology and position within the genus Heliocythere .