Mid-Cretaceous/Albian (Cretaceous) ostracod assemblages from NW Hungary reflecting deep marine,nearshore and non-marine environments

The Albian sediments of the Transdanubian Range in Hungary were deposited in non-marine to fully-marine environments. The studied sections revealed diverse benthic ostracod faunas with moderately-preserved specimens. Forty-six taxa are identified and Cypridea zalanyii n. sp. is newly described. The detailed palaeoecological study of these ostracod faunas provided an opportunity to distinguish eight assemblages. The assemblages include limnic, brackish lagoon, shallow marine, reef and low oxygenated semi-enclosed basin environments in the Northern Tethys region we investigated. This work contributes to the knowledge about Albian non-marine faunas from Europe and explores ecological requirements of brackish faunas.     

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.     

滴水湖现生介形类与水环境因子间的典范对应关系

滴水湖作为人工新建湖泊,其生态系统形成过程中的跟踪数据对重建其他湖泊生态系统具有重要的参考意义。2013年7月和2014年8月对滴水湖现生介形类分布状况及水环境因子分别进行了调查,结果发现,滴水湖湖水盐度范围介于1.4‰—2.0‰之间,属于微咸水湖。12个采样点共鉴定出现生介形类13种,包括非海相类克氏丽星介Cypria kraepelini(G.W.Müller)和无偶斗星介Cypridopsis vidua(O.F.Müller),海相类中华洁面介Albileberis sinensis Hou、向岛薄丽星介Dolerocypria mukaishimensis Okubo、腹结细花介Leptocythere ventriclivosa Chen、东台新单角介Neomonoceratina dongtaiensis Yang et Chen、长新中华花介Neosinocythere elongata(Hu)、闪光似异口介Paradoxostoma nitida Ho、典型中华美花介Sinocytheridea impressa(Brady)、长中华海花介Sinopontocythere elongata(Gou)、古屋刺花介Spinileberis furuyaensis Ishizaki et Kato、美丽刺面介Spinileberis pulchra Chen和丰满陈氏介Tanella opima Chen。应用典范对应分析(CCA)方法对滴水湖12个样点的8种介形类和9个环境因子进行了相关性研究,结果显示:介形类和环境因子间具有明显的相关性;9个环境因子中叶绿素、总磷和电导率对介形类的分布影响最大,总氮和湖水水温对介形类也有一定影响;从物种分布状况看,相对于低分布频度物种,高分布频度(Y>0.01)物种对环境的耐受性更大,其中Cypria kraepelini和Neomonoceratina dongtaiensis对环境因子的敏感性明显高于其它物种。结合历史资料分析发现,不仅自然环境因子(如电导率、水温等),而且人为干扰因素(如总磷、总氮)都对介形类分布的改变起到重要影响。     

Ostracods had colonized estuaries by the late Silurian

The fossil record of terrestrialization documents notable shifts in the environmental and physiological tolerances of many animal and plant groups. However, for certain significant components of modern freshwater and terrestrial environments, the transition out of marine settings remains largely unconstrained. Ostracod crustaceans occupy an exceptional range of modern aquatic environments and are invaluable palaeoenvironmental indicators in the fossil record. However, pre-Carboniferous records of supposed non-marine and marginal marine ostracods are sparse, and the timing of their marine to non-marine transition has proven elusive. Here, we reassess the early environmental history of ostracods in light of new assemblages from the late Silurian of Vietnam. Two, low diversity but distinct ostracod assemblages are associated with estuarine deposits. This occurrence is consistent with previous incidental reports of ostracods occupying marginal and brackish settings through the late Silurian and Devonian. Therefore, ostracods were pioneering the occupation of marginal marine and estuarine settings 60 Myr before the Carboniferous and they were a component of the early phase of transition from marine to non-marine environments.     

Global diversity of ostracods (Ostracoda,Crustacea) in freshwater

There are close to 2,000 subjective species and about 200 genera of Recent non-marine Ostracoda. Together, Cyprididae (1,000 spp.) and Candonidae (c. 550 spp.) represent more than 75% of the extant specific diversity; the remaining 11 families comprise the other 25% of the species. The Palaearctic region has the highest absolute non-marine ostracod diversity, followed by the Afrotropical. The Australian region has the highest relative endemicity. About 90% of the species and 60% of the genera occur in one zoogeographical region only. This means that all the biological mechanisms which lead up to efficient dispersal and which are present in at least part of the non-marine Ostracoda (e.g. brooding, drought-resistant eggs, parthenogenesis) have not induced common cosmopolitan distributions in ostracods. Several habitats are hotspots for ostracod diversity and endemicity. For example, it appears that the ancient lakes hold up to 25% of the total ostracod diversity. Other speciation-prone habitats are groundwater, temporary pools and Australian salt lakes; in the latter two instances, cladogenesis has often been paralleled by gigantism. The present ostracod diversity results from 9 to 12 separate invasions of the non-marine habitat, starting about 400 Myr ago. Genetic diversity can be very different in different species, mostly, but not always, related to reproductive mode. Guest editors: E. V. Balian, C. Lévêque, H. Segers & K. Martens Freshwater Animal Diversity Assessment     

Pliocene ostracods of Southwestern Europe

This paper analyzes the lithostratigraphic features and ostracod associations of the Pliocene deposits located in the western sector of the Guadalquivir basin (SW Spain). A regressive cycle is defined by the vertical distribution of five main facies (FA-1 to FA-5), which were deposited in upper bathyal to fluvial palaeoenvironments. The broad palaeontological record is utilized to draw a general outline of the food chain in each palaeoenvironment. A comparison with the Pliocene ostracod distribution of southeastern Spain, southwestern France and Portugal permits to define a common ostracod biozonation for southwestern Europe during this period. Four main marine biozones are distinguished: (a): Pontocythere elongata biozone (infralittoral); (b): Costa edwardsii biozone (shallow circalittoral); (c): Bosquetina carinella biozone (deep circalittoral); and (d): Henryhowella asperrima biozone (upper bathyal). Freshwater, brackish and lower bathyal/abyssal species are very scarce in this area during this period.     

Middle Permian Ostracods from Tak Fa Limestone, Phetchabun Province, Central Thailand

This paper presents the first Permian ostracod fauna discovered in Thailand. The ostracods are recovered from the Tak Fa Limestone (Middle Permian) in Phetchabun province, central Thailand. The ostracods belong to eight genera and 15 species. Four species are newly described: Sargentina phetchabunensis nov. sp., Geffenina bungsamphanensis nov. sp., Reviya subsompongensis nov. sp. and Bairdia takfaensis nov. sp. The ostracod assemblages characterize a shallow marine, near shore environment at the time of deposition. Except for one species, which shows palaeobiogeographical links between Central Thailand and South China, all the other species are endemic.     

Danian/Selandian boundary stratigraphy,paleoenvironment and Ostracoda from Sidi Nasseur,Tunisia

Two detailed records (NSF and 05NSC, Sidi Nasseur, Tunisia) across the Danian/Selandian (D/S) boundary were investigated for their micropaleontological content. Calcareous nannofossils and planktic foraminifera provided a biostratigraphic framework. The interval spans part of planktic foraminiferal Zone P2, Subzone P3a and part of Subzone P3b. This corresponds to calcareous nannoplankton Zone NP4. Using a more detailed nannofossil zonation the studied section spans part of Zone NTp6, Zone NTp7a and part of NTp7b. Quantitative ostracod and qualitative benthic foraminiferal data were used to characterize environmental changes across the D/S boundary. The two subsections have yielded a total of 50 ostracod taxa. The ostracod assemblage of the entire section belongs to the Southern Tethyan Type showing subtle but distinct changes up section. Based on statistical analysis of the quantitative ostracod data, faunal changes at a glauconitic maker bed (P3a/P3b boundary) were demonstrated. The local Reticulina proteros assemblage, with the typical species R. proteros, Oertliella vesiculosa and Cytheroptheron lekefense, is gradually replaced by the Protobuntonia nakkadii assemblage, with the typical species Cristaeleberis arabii, Xestoleberis tunisiensis, Cytheropteron sp. and P. nakkadii, across the glauconitic bed. The benthic foraminifera also demonstrated distinct changes at this marker bed. The changes in ostracods and foraminifera are related to changes in paleoproductivity and an overall relative sea-level fall.The lithological and faunal changes at the P3a/P3b zone boundary within the Sidi Nasseur sections seem to correspond to the D/S boundary in the type region in Danmark and are characterized by a significant hiatus, yielding this section not suitable as a GSSP candidate for this boundary.     

Foraminiferal response to Holocene environmental changes of a tidal estuary in Victoria, southeastern Australia

The Holocene strata in the Anderson Inlet area in Victoria can be stratigraphically divided into four units, Unit I, Unit II, Unit III, and Unit IV. Unit I and Unit IV lack fossils and were deposited in non-marine, probably fluvial environments. Unit II and Unit III contain abundant foraminifera with molluscs, ostracods and bryozoans. Foraminiferal analysis suggests that Unit III was formed in a partially sheltered marine environment, while the high plankton content and relatively high diversity of benthic species in Unit II indicate that this unit was deposited in an open bay at water depths possibly less than 5 m. The foraminiferal data are integrated with radiocarbon dates to arrive at the following Holocene palaeoenvironmental history in this area: (1) low alluvial plain stage (10,000–7000 yr B.P.); (2) open bay environment stage (7000–5500 yr B.P.); (3) partially sheltered marine environment stage (5500–4500 yr B.P.); (4) alluvial plain and coastal lagoon environment stage (since about 4500 yr B.P.). The foraminiferal fauna show a clear response to these palaeoenvironmental changes. Globigerina bulloides can be used as an indicator for cold water marine environments. The high concentration of this species in these middle Holocene sediments shows a strong cold water influence on the coastal environments which reduced the effect of regional warm currents during this period. The Holocene palaeoenvironmental changes in the area were controlled by the Holocene sea-level fluctuations associated with the deglaciation history during this period. Similar integrated studies of shallow to marginal marine strata in southern Africa, America and New Zealand will lead to a better understanding of Holocene relative sea-level change and the interplay between Holocene cold and warm water regimes in the Southern Hemisphere.     

Complex controls on ostracod palaeoecology in a shallow coastal brackish‐water lake: implications for palaeosalinity reconstruction

1. The low‐Mg calcite shells of Ostracoda (Crustacea) are often well preserved in the sediments of alkaline lakes. In coastal waters that have undergone large temporal changes in salinity, ostracod assemblages preserved in the sediment record have been used to reconstruct palaeosalinity, often assuming that salinity is the only significant control on the faunas. 2. We evaluate the performance of ostracods as palaeosalinity indicators in Hickling Broad, a shallow brackish coastal lake in Norfolk, U.K., by comparing fossil ostracod assemblages covering two centuries with geochemical inferences and instrumental records of past salinity and water composition along with other palaeolimnological indicators. 3. Despite large changes in the salinity of the lake and the supposed salinity sensitivity of ostracods, the fossil ostracod assemblages do not clearly reflect the salinity trends inferred from the other independent data. Rather, a complex series of changes has occurred in the lake over the past 200 years and factors other than salinity, including eutrophication, toxicity and associated complex alterations in habitat availability have probably influenced ostracod assemblages. In contrast, there is a good broad agreement between inferred or measured salinity and the trace‐element chemistry of ostracod shells. 4. We conclude that ostracod faunas may not always provide unambiguous palaeosalinity records and should therefore not be used to reconstruct salinity changes except as part of a multi‐proxy investigation that includes other palaeoecological and/or geochemical indicators.     

Repeated evolutionary transitions of flavobacteria from marine to non-marine habitats

The taxonomy of marine and non-marine organisms rarely overlap, but the mechanisms underlying this distinction are often unknown. Here, we predicted three major ocean-to-land transitions in the evolutionary history of Flavobacteriaceae, a family known for polysaccharide and peptide degradation. These unidirectional transitions were associated with repeated losses of marine signature genes and repeated gains of non-marine adaptive genes. This included various Na⁺-dependent transporters, osmolyte transporters and glycoside hydrolases (GH) for sulfated polysaccharide utilization in marine descendants, and in non-marine descendants genes for utilizing the land plant material pectin and genes facilitating terrestrial host interactions. The K⁺ scavenging ATPase was repeatedly gained whereas the corresponding low-affinity transporter repeatedly lost upon transitions, reflecting K⁺ ions are less available to non-marine bacteria. Strikingly, the central metabolism Na⁺-translocating NADH: quinone dehydrogenase gene was repeatedly gained in marine descendants, whereas the H⁺-translocating counterpart was repeatedly gained in non-marine lineages. Furthermore, GH genes were depleted in isolates colonizing animal hosts but abundant in bacteria inhabiting other non-marine niches; thus relative abundances of GH versus peptidase genes among Flavobacteriaceae lineages were inconsistent with the marine versus non-marine dichotomy. We suggest that phylogenomic analyses can cast novel light on mechanisms explaining the distribution and ecology of key microbiome components.     

Lowermost occurrence of ostracod Cypridea species in East Asia and implications for the non-marine Jurassic/Cretaceous boundary

Cypridea Bosquet, 1852 is a non-marine ostracod genus of the Superfamily Cypridoidea, and the extinct Family Cyprideidae, which achieved high diversity in the Early Cretaceous. This genus plays an important role in the subdivision and correlation of strata, as well as in paleogeographic and paleoclimatic studies. Cypridea species are remarkably abundant and diverse, and are extensively distributed across East Asia. However, the lowermost occurrence of Cypridea species (LOOC) in East Asia is still being debated, varying from the Upper Jurassic to Lower Cretaceous. Here, we aim to conduct a preliminary investigation of the Cypridea-bearing strata of East Asia (China, Mongolia, Korea and Japan), and attempt to update the strata correlation, based on new progress of the ostracod correlations, as well as the progress of other research methods on the relative Jurassic/Cretaceous (J/K) strata of these areas. Results show that the LOOCs in most basins of East Asia are documented in Lower Cretaceous (～Berriasian) strata. However, Cypridea species are extremely rare near the J/K boundary interval but flourish until Valanginian–Hauterivian in most basins of East Asia. Therefore, we propose that the LOOC in each corresponding basin of East Asia can be used as an auxiliary marker of the non-marine J/K boundary. Cypridea species may have travelled first from Africa (Kimmeridgian) to Europe (J/K period), and then East Asia (Early Cretaceous), which resulted in the LOOC in East Asia later than in the other continents.     

松辽盆地D80井嫩一段介形类化石壳体特征及生物地层

松辽盆地嫩江组一段富含介形类化石,是系统研究Santonian期陆相介形类的理想层位。论文对中央坳陷区D80井嫩一段的介形类化石进行了系统的分类、生物地层和壳体特征分析。鉴定出介形类化石11属30种,划分出6个介形类化石带,并与前人的研究结果进行了对比;描述了该段介形类化石的壳体结构,共识别出4种壳饰类型,8种壳形结构,基于介形类壳体特征和其他证据,初步探讨了该时期湖盆湖平面的变化特征,显示出嫩一段时期松辽湖盆湖平面经历了由深逐渐变浅的过程。     

The effect of environmental change on early Aptian ostracods faunas in the Wessex Basin,southern England

A major phase of transgression in the Wessex Basin (southern England) during the earliest Aptian resulted in the collapse of the generally fresh water Barremian environment and the initiation of the marine milieu.Cypridea-rich faunas in the Shepherd's Chine Member (Vectis Formation), were gradually replaced by faunas dominated by Sternbergella cornigera, Mantelliana mantelli and Theriosynoecum fittoni. This change is interpreted as indicating that salinities had passed from fresh-oligohaline to meso- and pliohaline and that ephemeral water bodies were replaced by more widespread, permanent, lagoonal waters. The ostracods from the highest part of the Vectis Formation appear to be heralding the major transgression that was about to engulf the Wessex Basin.The marine incursion during the obsoletus Ammonite Subzone brought with it newly formed environmental niches that were rapidly occupied by microfaunas. Several ostracod species are interpreted as euryhaline, but others appear to have been restricted to marine or near marine salinities. The earliest marine ostracod faunas were recorded from the Perna Bed Member, Isle of Wight, and include abundant Asciocythere albae and frequent to common Schuleridea derooi, Neocythere gottisi, N. bordeti and Cytherelloidea sp. Other species include rare Cythereis geometrica, C. semiaperta, Eocytheropteron stchepinskyi and Protocythere croutesensis. In addition, elsewhere in southern England, Protocythere mertensi langi, Dolocytheridea intermedia, Paranotacythere (P.) oertlii and P. (P.) atypica occur. The relationship of this earliest Aptian population with that of the Paris Basin cannot be mistaken.     

Distribution and taxonomy of shallow marine Ostracods from Northern Socotra Island (Indian Ocean) - Yemen

Forty-seven species belonging to 30 genera of ostracods have been identified from Recent shallow marine sediments collected along the northern coastline of the island of Socotra (Indian Ocean). The systematics and distribution of these ostracods are discussed. Three genera, Loxoconcha, Bosasella, and Xestoleberis are found to have high species diversity. The species Loxoconcha ghardaqensis, Moosella striata are best documented in the Red Sea and Gulf of Aden while Kotoracythere inconspicua and Triebelina sertata were found to be the most widespread species. The fauna shows a close affinity to other ostracod assemblages of the Indo-Pacific region, East African coast and Red Sea.     

Ostracods and the Holocene palaeolimnology of Lake Qarun, with special reference to past human–environment interactions in the Faiyum (Egypt)

We present an ostracod record covering the past two millennia from an 8.25-m core taken from Lake Qarun, in the Faiyum Depression of Egypt. The occurrence of ostracod species in the lake is controlled primarily by variations in solute composition, which are in turn related to shifts in catchment land use. At times when the Faiyum Depression supported thriving agriculture, lake water contained Na⁺–Cl^? brine, and Cyprideis torosa dominated the ostracod assemblage. When the Faiyum Depression experienced periods of environmental and economic decline, lake water contained Na⁺–HCO₃ ^? brine, and Limnocythere inopinata dominated. The relative abundance of other ostracod species provides additional information about past conditions in Lake Qarun including salinity and lake level changes. Overall, the ostracod assemblages provide evidence for human influences in the Faiyum, which extend back before instrumental or detailed observational records began.     

Pliocene coastal palaeomorphology and ostracod faunas of the Bass Strait hinterland,southeast Australia

Early to late Pliocene sedimentary strata present across the northern Bass Strait hinterland, southeastern Australia yield extensive fossil proxy data relevant to the interpretation of high sea level coastal palaeomorphology. Within the Pliocene Whalers Bluff Formation exposed in coastal cliffs near the township of Portland, Victoria, marine microfossil faunas delineate two broad cycles of deposition. Both these sedimentary cycles are bound below by unconformity surfaces. Within the lower sedimentary cycle, a basal stress-tolerant (low diversity) marginal marine microfossil fauna devoid of ostracods and suggestive of bottom-water hypoxia, is succeeded by a diverse shallow marine ostracod fauna dominated by stenohaline species indicative of a sheltered (but open) oceanic embayment. This lower sedimentary cycle has an early Pliocene (Zanclean) age. Equivalent shallow marine (e.g. coastal embayment) deposits occur broadly across the coastal hinterland of southeastern Australia—reflecting the generally higher global sea levels of this time. The upper cycle in the cliff exposures at Portland is late Pliocene (Piacenzian) in age. Equivalent deposits across the Bass Strait hinterland are restricted to former incised river valley settings. Euryhaline estuarine/coastal lagoon Ostracoda are present throughout the upper cycle in the Portland cliffs. These are associated with a low diversity microfauna at the base of the upper cycle and a high diversity microfauna towards the top of the cycle. Early Pliocene coastal marine deposits can be distinguished from late Pliocene coastal marine deposits across the northern Bass Strait hinterland on the basis of the presence or absence of certain open marine (‘stenohaline’) ostracod species.     

Distribution of living polycystine radiolarians in the Gulf of Mexico and Caribbean Sea,and comparison with the sedimentary record

Plankton tows and bottom samples from the Gulf of Mexico and Caribbean Sea were examined to study the distribution, ecology, and preservation of modern radiolarians. Abundances of radiolarians from this region, an area of low primary productivity, are low. Diversities are variable in the surface waters; diversity indices decrease with increasing water depth, indicating that fewer niches are occupied by radiolarians in deep water. Living radiolarians are confined to specific water masses, some species ranging between two masses, and can be used as indicators of these water masses in ecologic or paleo-oceanographic studies.The record of radiolarian tests present in the sediment is dissimilar to the record of living radiolarians in the water column, but is similar to the record of empty tests falling through the water column. This indicates that a considerable length of time is involved in the settling of radiolarian tests. It also confirms the validity of ecologic interpretations based on a study of sediments only.     

Oldest known non-marine diatoms (Aulacoseira) from the uppermost Cretaceous Deccan Intertrappean beds and Lameta Formation of India

Non-marine diatoms occur in the Deccan Intertrappean beds (Upper Cretaceous) of Mohgaon-Kalan, Chhindwara District, Madhya Pradesh and Pisdura, Lameta Formation (Upper Cretaceous), Maharashtra, India. This represents the oldest record of non-marine diatoms yet reported and the oldest from the Indian subcontinent. The diatoms were recovered from thin sections of chert and dinosaur coprolites by random fracturing. Solitary forms are the most common but colonial filaments up to five cells were also observed. Based on the morphological characters, the diatoms are identified as Aulacoseira Thwaites. The Lower Cretaceous marine diatom genus Archepyrgus Gersonde and Harwood also resembles Aulacoseira in general morphological characters and it seems that Aulacoseira evolved from Archepyrgus and migrated to the non-marine realm.     

Polymorphism in recent ostracods of southwestern Spain: an environmental approach

The analysis of the surface ornamentation permits us to differentiate two morphotypes in the recent populations of the ostracod Urocythereis oblonga collected in shallow marine sediments of the Huelva littoral (SW Spain). An environmental analysis was made and its abundances were compared with different environmental parameters. Morph 1 (reticulated or “normal”) is almost always dominant, characterizing microenvironments with low salinity water changes, low to moderate energy levels, poorly sorted bottom sediments with high percentages of fine grain sizes (very fine sands, silts and clays) and moderate to high ostracod diversity. Morph 2 (punctuated or “degraded”) is significantly represented (> 10%) in stressing conditions, i.e., moderate salinity fluctuations, moderate to high hydrodynamic levels, low organic matter contents, moderate to well-sorted sediments with high percentages of medium sands and low to very low ostracod diversity. These differences make clear the potential of these microcrustaceans as environmental tracers in these transitional areas.