Late neogene biostratigraphy and paleoceanography of DSDP site 310 Central North Pacific and correlation with the Southwest Pacific

Late Neogene planktonic foraminifera have been examined at Site 310 in the Central North Pacific and their stratigraphic ranges and frequencies are presented here. Blow's (1969) zonation developed for tropical regions has been applied where applicable. Where tropical index taxa are rare or absent in this temperate region, Globorotalia crassaformis, and the evolutionary bioseries G. conoidea — G. conomiozea and G. puncticula — G. inflata have been found useful for zonal subdivisions. A correlation between stratigraphic ranges and frequency distributions of these species at Site 310 in the Central North Pacific, and Site 284 in the Southwest Pacific indicates that these species are relatively consistent biostratigraphic markers in temperate regions of both the North and South Pacific Oceans. An informal zonation for temperate latitudes of the Southwest Pacific has been established by Kennett (1973) and a similar zonal subdivision can be made at Site 310.Paleoclimatic/paleoceanographic interpretations based on coiling ratios, percent abundance, and phenotypic variations of Neogloboquadrina pachyderma indicate four major cold events during early, middle, and late Pliocene, and early Pleistocene. Faunal correlations of these events with similar events elsewhere in the Northeast and Southwest Pacific which have been paleomagnetically dated indicate the following approximate ages for these cold events: 4.7 Ma, 3.0 Ma, 2.6–1.8 Ma. and 1.2 Ma. Faunal assemblages have been divided into three groups representing cool, intermediate, and warmer water assemblages. Cool water assemblages are dominated by >60% N. pachyderma; intermediate temperature faunas are dominated by species of Globigerina and Globigerinita and contain between 20% and 30% N. pachyderma. Warmer water assemblages are dominated by species of Globorotalia and contain <10% N. pachyderma. Frequency oscillations within these groups, in addition to paleotemperature parameters evident in N. pachyderma, afford refined paleoclimatic/paleoceanographic interpretations.     

Paedomorphosis in the Turonian (Late Cretaceous) collignoniceratine ammonite lineage from the north Pacific region

Ontogenetic development and variation of shell ornament of the four Turonian collignoniceratine ammonites, Collignoniceras woollgari (Mantell 1822), Subprionocyclus neptuni (Geinitz 1850), S. normalis (Anderson 1958) and S. minimus (Hayasaka & Fukada 1951) have been compared on the basis of large population samples from Hokkaido (Japan), California and the US Western Interior Province. Our study revealed that the ornament types observed in the early-middle stage of C. woollgari occur in the middle-late stage of the three other species, and that those in the early-middle stage of S. neptuni appear in the middle-late stage of S. normalis and S. minimus. These species are generally regarded as closely related phylogenetically, because they share several common morphological features such as the presence of double ventrolateral tubercles and a serrated keel. If a postulated phylogeny starting from C. woollgari to S. normalis and S. minimus via S. neptuni is accepted, the mode of morphological evolution in the lineages can be explained by paedomorphosis. Available palaeobiogeographical data suggest that this paedomorphic evolution occurred independently on the northwestern and northeastern sides of the northern Pacific, where the C. woollgari – S. neptuni – S. minimus, and C. woollgari – S. neptuni – S. normalis sublineages evolved.     

Late Miocene brackish Loxoconchidae (Crustacea, Ostracoda) from Italy

The Late Miocene Italian brackish Loxoconchidae are herein discussed and illustrated. Three genera and two subgenera have been recognized in the brackish Italian basins: Loxoconcha, Loxocorniculina, Loxoconchissa (Loxoconchissa) and Loxoconchissa (Loxocaspia). Taking into account the diagnostic characters of several Loxoconchidae genera, in this paper Loxocorniculina is raised at a generic rank, Loxocaspia is confirmed as a subgenus within genus Loxoconchissa and several new species are established: Loxoconchissa (Loxoconchissa) kinoi nov. sp., Loxoconchissa (Loxocaspia) cosentinoi nov. sp., Loxoconchissa (Loxocaspia) nuda nov. sp., Loxoconchissa (Loxocaspia) punctata nov. sp., Loxoconchissa (Loxocaspia) reticulata nov. sp., Loxoconchissa (Loxocaspia) tuberosa nov. sp. and Loxoconchissa (Loxocaspia) velonae nov. sp. Loxocorniculina is a typical Paratethyan genus which widespread into the Palaeo-Mediterranean during the late Messinian Lago-Mare event. Loxoconchissa was known to be widespread only in the Paratethyan realm and in this paper it is signalled for the first time in the Late Tortonian-early Messinian of Italy. The palaeobiogeography of these genera is discussed and the observed continuous distribution of Loxocorniculina against the disjunct distribution of Loxoconchissa leads to suggest that this latter genus underwent a passive dispersal via aquatic birds.     

Late Pliocene dinoflagellate cyst and diatom analysis from a high resolution sequence in DSDP Site 594, Chatham Rise, south west Pacific

A high resolution mixed carbonate and siliciclastic sequence from DSDP Site 594 contains a detailed record of climate change in the late Pliocene. The sequence can be accurately dated by the LAD of Nitzschia weaveri, the LAD of Thalassiosira insigna, the LAD of T. vulnifica and the LAD of T. kolbei diatom datums. Carbonate content and δ¹⁸O signatures provide added resolution and place the sequence between isotope stages 100 and 92.The sequence contains well-preserved and diverse dinoflagellate cyst floras. Use of principal component (PCA) and canonical correspondence analyses (CCA) identifies changes in the assemblages that principally reflect warming and cooling trends. Species associated with warmer climates included Impagidinium patulum, I. paradoxum and I. sp. cf. paradoxum while those from cooler climates include Invertecysta tabulata and I. velorum. CCA is shown to be a valuable method of determining the past environmental preferences of extinct species such as I. tabulata.     

Gilianelles: Late Cretaceous microproblematica from Europe and Central America

Abstract: During the last two decades, a range of microfossils have been collected from strata of Late Cretaceous (Coniacian–Maastrichtian) age. The name gilianelles has been coined to accommodate these microproblematica. On the basis of many thousands of specimens, typical features of this group have now been assessed. Distinctive traits are calcareous unilocular, basically axially symmetrical test, in the size range 80–200 μm, with a single‐layered wall of radially arranged crystals, 15 μm thick, the outer surface with a crochet‐like nanostructure, a small‐sized aperture (one tenth of test diameter), situated on the upper surface in vivo. Secondary criteria include modification of axial test symmetry into radial or bilateral symmetry, development of expansions, either spiny or laminar and presence of longitudinal and latitudinal ornament. To date, 60 taxa have been described from northern Spain to northern Germany and from Central America. Evolutionary patterns of gilianelles are diverse, with both short‐ and long‐ranging forms, some of which comprise lineages that were affected by a marked crisis dated at about 73 Ma. This event is here illustrated by the tribe Coraliellini, of which a key taxon, Coraliella cognatio, is described as new. Previous interpretations of Gilianelles as dinoflagellate cysts are discussed and rejected.     

Lower Cretaceous benthic foraminifera from DSDP Site 263: micropalaeontological constraints for the early evolution of the Indian Ocean

Analysis of 66 samples from DSDP Site 263 (Cores 263-4R-4 to 263-29R-4) reveals a unique faunal composition with a predominance of agglutinated taxa, many of them previously unrecorded from any other DSDP and ODP Indian Ocean sites. A total of 66 agglutinated and 31 calcareous taxa are documented and five new species are described: Hippocrepina gracilis n.sp., “Textulariopsis” elegans n.sp., Aaptotoichus challengeri n.sp., “Gaudryinopsis” pseudobettenstaedti n.sp. and “Gaudryina” cuvierensis n.sp. Three assemblages are recognized based on changes in the composition of dominant taxa and occurrences of stratigraphically important species: (1) a high-diversity Valanginian to Barremian Bulbobaculites-Recurvoides Assemblage (Cores 263-29R to -18R), comprised of numerous elongate agglutinated forms, rare nodosariids, and variable numbers of tubes and ammodiscids; (2) a moderately diverse Aptian to Albian Rhizammina-Ammodiscus-Glomospira Assemblage (Cores 26318R to -7R) with highly fluctuating numbers of the nominate taxa and Haplophragmoides, Trochammina, Verneuilinoides spp., and Vemeuilina howchini; (3) a very low diversity Albian or younger Assemblage (Cores 263-6R to -4R) containing sparse agglutinated foraminifera, rare nodosariids and rotaliids. We interpret the assemblages as shelf to lower slope and consider them to reflect a deepening palaeobathymetry as the Cuvier margin subsided after the initial breakup of East Gondwana during the Valanginian. Our interpretation is in sharp contrast with initial palaeodepth estimates of less than 100 m, as well as with original chronostratigraphic interpretations based on foraminifera and nannofossils which correlated the base of the recovered interval with the Aptian. The absence of many cosmoplitan forms, despite high diversity, suggests strong faunal differentiation in the Austral realm or endemisn within the Cuvier Basin during the Early Cretaceous.     

Late Cretaceous (Cenomanian–Maastrichtian) calcareous nannofossils from Goban Spur (DSDP Sites 549, 551): Implications for the palaeoceanography of the proto North Atlantic

The early late Cretaceous (Cenomanian–early Turonian) is thought to have been one of the warmest periods of the Phanerozoic. This period was characterised by tropical sea surface temperatures of up to 36 °C and a pole-to-equator-gradient of less than 10 °C. The subsequent Turonian–Maastrichtian was characterised by a continuous climatic cooling, peaking in the Maastrichtian. This climatic cooling and the resulting palaeoceanographic changes had an impact on planktic primary producer communities including calcareous nannofossils. In order to gain a better understanding of these Cenomanian–Maastrichtian palaeoceanographic changes, calcareous nannofossils have been studied from the proto North Atlantic (Goban Spur, DSDP Sites 549, 551). In order to see potential differences between open oceanic and shelf dwelling nannofossils, the data from Goban Spur have been compared to findings from the European shelf (northern Germany).A total of 77 samples from Goban Spur were studied for calcareous nannofossils revealing abundant (mean 6.2 billion specimens/g sediment) and highly diverse (mean 63 species/sample) nannofossil assemblages. The dominant taxa are Watznaueria spp. (mean 30.7%), Prediscosphaera spp. (mean 18.3%), Zeugrhabdotus spp. (mean 8.3%), Retecapsa spp. (mean 7.2%) and Biscutum spp. (mean 6.6%). The Cenomanian assemblages of both Goban Spur (open ocean) and Wunstorf (shelf) are characterised by elevated abundances of high fertility taxa like Biscutum spp., Zeugrhabdotus spp. and Tranolithus orionatus. Early Turonian to Maastrichtian calcareous nannofossil assemblages of Goban Spur are, however, quite different to those described from European sections. Oceanic taxa like Watznaueria spp., Retecapsa spp. and Cribrosphearella ehrenbergii dominate in Goban Spur whereas the fertility indicators Biscutum spp. and T. orionatus are more abundant in the European shelf assemblages. This shift from a homogeneous distribution of calcareous nannofossils in the Cenomanian towards a heterogeneous one in the Turonian–Maastrichtian implies a change of the ocean circulation. The “eddy ocean” system of the Cenomanian was replaced by an oceanic circulation similar to the modern one in the Turonian–Maastrichtian, caused by the cooling. The increased pole-to-equator-gradients resulted in an oceanic circulation similar to the modern one.     

A new mosasauroid (Squamata) from the Late Cretaceous (Turonian) of Morocco

Tethysaurus nopcsai gen. et sp. nov. is described on the basis of both cranial and postcranial material from the Late Cretaceous (Early Turonian) of the Goulmima region, southern Morocco. This new mosasauroid is mainly characterized by a parietal table ending posteriorly in two pointed pegs; jugal with a large ascending ramus; splenial with a large and notched dorsomedial process; surangular exposed medially ventral to the coronoid; large paracotylar and parazygosphenal foramina on vertebrae. A phylogenetic analysis shows that Tethysaurus is the sister-group of Mosasauridae. It fills the gap between the aigialosaurids (mainly Cenomanian) and the mosasaurids (known from the Middle-Late Turonian to the Latest Maastrichtian). To cite this article: N. Bardet et al., C. R. Palevol 2 (2003).     

Ostracoda of the subfamilies Protocytherinae and Trachyleberidinae from the British Lower Cretaceous

The distribution and range of the members of these two subfamilies are given for material of Hauterivian, Barremian, Aptian and Albian age from the Speeton Clay in Yorkshire, England. Eleven species are described and figured of whichProtocythere gaultina, Protocythere intermedia, Protocythere mertensi, Protocythere speetonensis, Homocythere reticulata, Cythereis blanda andCythereis lamplughi are new. The genusHomocythere is described for the first time. An ontogenetic study ofProtocythere triplicata (F. A. Roemer) is undertaken.     

Track analysis of the marine palaeofauna from the Turonian (Late Cretaceous)

Aim  To analyse the worldwide distribution patterns of Turonian marine biotas using a panbiogeographical approach.
Location  Turonian localities of southern and north-eastern Brazil, Mexico, Canada, central Europe, England and Morocco.
Method  Panbiogeographical track analysis.
Results  Nine generalized tracks and six nodes were found. The generalized tracks comprise two vicariant track patterns (one northern and one mid-southern) across the Atlantic.
Main conclusions  The generalized tracks show clearly two separate marine biotas, which were associated with the proto-South Atlantic and the proto-North Atlantic oceans. These generalized tracks, as well as the two vicariant track clusters between the north and south Atlantic, are identified by vicariant relationships shared by most of the taxa analysed, and illustrate the final break up of the Gondwana and Laurasia supercontinents and the consequences of vicariant events for the biogeography of the Atlantic Ocean.     

Late Cretaceous (Maastrichtian) Sporo-Pollen Assemblages from Northern Nei Monggol

Sporo-pollen assemblages, with proteaceous pollen and Normapolles, are obtained from the boring cores and some black clay deposits in the vicinity of Er-Lian-Hao-Te city of northern Nei Monggol (Inner-Mongolia). Seventy species are reported, in which Proteacidites microverrucatus, Beaupreaidites striatus, Triatriapollenites echina- tus and Echitriporites magnus, are described as new. These assemblages are conspicuously poor in pteridophytes and rich in gymnosperms of the families and genera: Pinaceae, Podocarpaceae and Ephedraceae, especially Cedripites, Podocarpidites and Ephedripites. Angiosperms are quite diverse in types, besides the proteaceous pollen and Normapolles (Altantopollis, Pseudoatlantopollis cf. simulatus, Choanopollenites), Momipites coryloides, Momipites tenuipolus, Paraal- nipollenites confusus, Platycarga, Ulmoideipites tricostatus, U. krempii, Cranwellia cf rumseyensis, Disyllabipollis labeosus, Rhoipites, Lonicerapollis gallwitzi, L. scabratus etc. These pollen assemblages are assigned to the families Myricaceae, Juglandaceae, Betulaceae, Fagaceae, Ulmaceae, Proteaceae, Lorathaceae, Anacordiaceae, Symplocaceae, Aquifoliaceae and others. Most of them are tropical and subtropical. This indicates; that a warm-temperate and dry climate was prevailing at that time. Based upon the nature of sporo-pollen assemblages, the age of the black clay deposits is assigned to Maastrichtian. Maastrichtian pollen flora of northern Nei Monggol is associated with Siberian- Pacific Province by the abundanee of proteaceous pollen on one side and with the Euro-American Province by the presence of Normapolles on the other.     

Reconstruction of Late Cretaceous coastal paleotemperature from halite deposits of the Late Cretaceous Nongbok Formation (Khorat Plateau,Laos)

Cretaceous evaporites of the Maha Sarakhan Formation in Thailand (e.g., the Nongbok Formation, Laos) have been studied for almost a century as the huge potash deposits in the world. The consistently high local paleotemperatures should lead to huge salt deposits during the evaporation process. Primary fluid inclusions in halite can provide surface brine water temperatures directly and quantitatively. Until now, there have been no data published from paleotemperature of primary fluid inclusions of Cretaceous halite. The non-marine halite from the Cretaceous Nongbok Formation (Laos) precipitated from shallow brine waters with temperatures of 17.7–42.3 °C.     

New Late Cretaceous dinosaur findings from northwestern Transylvania (Romania)

In 1905, Nopcsa tentatively identified a fragmentary rib from the Jibou Formation at Someş Odorhei as belonging to an ornithopod dinosaur. Therefore, he concluded that the base of this formation is Late Cretaceous, but this hypothesis was subsequently ignored or rejected by other authors. New dinosaur bones discovered in this locality by new excavations are here interpreted as belonging to the euornithopod Zalmoxes shqiperorum Weishampel, Jianu, Csiki and Norman, 2003. The base of the Jibou Formation can therefore be regarded as Maastrichtian, correlative to the Sânpetru Formation and to the middle member of the Densuş Ciula Formation from the Haţeg Basin, as well as the base of the Şard Formation in the southwestern Basin of Transylvania, in the Alba Iulia area. The presence of Zalmoxes at Someş Odorhei also confirms the northeastern extension for the ‘Haţeg Island’ in Transylvania.     

Myliobatid and pycnodont fish from the Late Cretaceous of Central India and their paleobiogeographic implications

Bulk sampling from Upper Cretaceous (Maastrichtian) Deccan volcano-sedimentary sequences at Kisalpuri (District Dindori, Madhya Pradesh) and Pisdura–Dongargaon (Chandrapur District, Maharashtra) in Peninsular India has yielded the dental remains of myliobatid and pycnodont fish. This fish fauna comprises Igdabatis indicus, Pycnodontoidea indet. and Pycnodontidae indet., and resembles assemblages known from Upper Cretaceous deposits in Africa and Europe. While paleobiogeographically speaking, the presence of Igdabatis suggests a series of shallow marine dispersals that may have occurred between Africa and India, possibly along the margins of the Kohistan–Ladakh island arc during the latest Cretaceous; the record of pycnodont fish favours instead a Gondwanan dispersal event.     

A new baurusuchid crocodyliform (Archosauria) from the Late Cretaceous of Patagonia (Argentina)

A new baurusuchid, Wargosuchus australis gen. et sp. nov., coming from the Bajo de La Carpa Formation, Neuquén Province (Argentina), is described. This new taxon is based on a fragment of snout and a portion of the cranial roof. Wargosuchus differs from other crocodyliforms by possessing a deep median groove on the frontals, a contact between nasals and frontals extremely reduced, a large depression for the olfactory bulbs, three large foramina surrounding the large, smooth perinarial depression, and a hypertrophied, conical last premaxillary tooth followed by a large paracanine fossa. The finding of Wargosuchus in Patagonia (Argentina), a taxon with a strong resemblance to Brazilian baurusuchids, reinforces the hypothesis of a similar biota between both regions by the Late Cretaceous. Wargosuchus and Cynodontosuchus represent the only Argentinian mesoeucrocodylians to be included within Baurusuchidae. This finding extends the number of crocodyliforms from the Bajo de la Carpa Formation, which, in turn, corresponds to the most taxonomically diverse one in Argentina.     

A new polycotylid plesiosaur from the Late Cretaceous (Turonian) of Morocco

A new Polycotylidae (Plesiosauria) from the Late Cretaceous (Turonian) of southern Morocco is described. Thililua longicollis gen. et sp. nov. is based on a complete cranium and 37 associated vertebrae. It differs from other polycotylids in several cranial and especially vertebral characters, such as the occurrence of 30 cervical vertebrae, whose centra are nearly as long as high and bear laterally longitudinal ridges. Thililua is the first polycotylid hitherto found in Africa and under subtropical palaeolatitudes. To cite this article: N. Bardet et al., C. R. Palevol 2 (2003).     

The evolutionary history of Late Permian Darwinulocopina Sohn, 1988 (Ostracoda) from the Russian Plate

Evolutionary trends in Late Permian Darwinulocopina are summarised with reference to extensive collections from eastern European Russia, from the White Sea in the North to the Cis-Caspian in the South. They inhabited large, shallow lakes in which the variety of habitats was favourable for high ostracod diversity. Three superfamilies are represented: the Darwinuloidea preferred lakes with terrigenous sedimentation and insignificant bicarbonate, the Suchonelloidea inhabited lakes with increased bicarbonate and could also live in low-sulphate waters, and the Darwinuloidoidea inhabited high-bicarbonate water bodies and could also survive in low-magnesium waters. Different evolutionary trends account for the different ages of the crucial stages of development of each superfamily: the beginning of the mid-Tatarian for the Darwinuloidea, the late Tatarian for the Suchonelloidea and Darwinuloidoidea.     

Encrustation patterns on Late Cretaceous (Turonian) echinoids from southern Poland

This study focuses on sclerobionts from a large collection of epibenthic echinoids (>2,000 specimens) of the genera Conulus and Camerogalerus. Samples were collected from five localities in southern Poland (Polish Jura and Miechów Trough), where Turonian carbonates with terrigenous input are exposed. Low intensity (mean ca. 5 %, maximum ca. 10 %) and slight encrustation (“loosening effect”) exclusively by episkeletozoans probably resulted from low productivity of encrusters while the importance of other factors cannot be excluded unambiguously. Echinoids served as a main substratum and after death formed shellgrounds (‘echinoid carpet’) offering abundant benthic islands for encrusters in an otherwise soft-bottom environment. The moderate abundance but low-diversity assemblage is represented by bivalves, sedentary polychaetes, foraminifera, bryozoans, corals, and sponges. This assemblage is similar to a nearly contemporaneous assemblage from the Bohemian Basin. The presence of numerous spirorbins offers insights into their early evolution and may indicate that their first peak in abundance after origination was not prior to the earliest Turonian. This is regarded as one of the important ecological steps towards the rise of modern sclerobiont communities. Encruster diversities are independent of their abundance and, as shown in our novel planar projections, lateral parts of tests were preferentially encrusted. This pattern is explained by the combination of largest flat area and stable orientation. Encrusting bivalves and serpulids dominated hard substrate environments in the Turonian of Poland.     

Late miocene ostracodes (Ostracoda,Crustacea) from the Enikal Strait (Eastern Paratethys) as indicators of salinity changes

The species composition of ostracodes from the upper Maeotian and lower Pontian deposits of the Kerch-Taman Depression (Enikal Strait, Eastern Paratethys) is reported. The sedimentological and paleoenvironmental study shows that mass ostracode occurrences were controlled by hydrological changes in the Late Miocene brackish-water basins under consideration.