To see the other types of publications on this topic, follow the link: Fossile Foraminiferen.
Journal articles on the topic 'Fossile Foraminiferen'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Fossile Foraminiferen.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Lesen, Amy E., and Jere H. Lipps. "What have natural and human changes wrought on the foraminifera of San Francisco Bay late Quaternary estuaries?" Quaternary Research 76, no. 2 (September 2011): 211–19. http://dx.doi.org/10.1016/j.yqres.2011.06.005.
Full textAbstract:
AbstractIn this study we compare the foraminifera of modern South San Francisco Bay with fossils from sediments of a previous estuary at 125 ka to provide a basis for interpreting the impact of natural and human change on the benthic ecosystem. All the species found in the Pleistocene sediments of this study are estuarine and/or shallow-water species occurring commonly in San Francisco Bay today, except for the introduced foraminifer Trochammina hadai, a native of Japan that was not found in samples taken in San Francisco Bay before 1983. The biodiversity and species composition of the fossil and modern assemblages before the introduction of T. hadai are nearly identical, suggesting that the environmental and physical changes in the 125,000-year-old and modern estuaries have not had a significant effect on the meiofauna of the Bay. In contrast, modern anthropogenic change in the form of species introductions has impacted the modern foraminiferal assemblage: T. hadai began to dominate the modern assemblage a decade after its introduction. Similar to the recorded impacts of introductions of marine metazoan invertebrate species, the dominance of T. hadai changed species proportions in the post-1980s foraminiferal assemblage, however no known extinctions in the native foraminiferal fauna occurred.
2
Burke, Janet E., Willem Renema, Michael J. Henehan, Leanne E. Elder, Catherine V. Davis, Amy E. Maas, Gavin L. Foster, Ralf Schiebel, and Pincelli M. Hull. "Factors influencing test porosity in planktonic foraminifera." Biogeosciences 15, no. 21 (November 7, 2018): 6607–19. http://dx.doi.org/10.5194/bg-15-6607-2018.
Full textAbstract:
Abstract. The clustering of mitochondria near pores in the test walls of foraminifera suggests that these perforations play a critical role in metabolic gas exchange. As such, pore measurements could provide a novel means of tracking changes in metabolic rate in the fossil record. However, in planktonic foraminifera, variation in average pore area, density, and porosity (the total percentage of a test wall that is open pore space) have been variously attributed to environmental, biological, and taxonomic drivers, complicating such an interpretation. Here we examine the environmental, biological, and evolutionary determinants of pore characteristics in 718 individuals, representing 17 morphospecies of planktonic foraminifera from 6 core tops in the North Atlantic. Using random forest models, we find that porosity is primarily correlated to test surface area, test volume, and habitat temperature, key factors in determining metabolic rates. In order to test if this correlation arose spuriously through the association of cryptic species with distinct biomes, we cultured Globigerinoides ruber in three different temperature conditions, and found that porosity increased with temperature. Crucially, these results show that porosity can be plastic: changing in response to environmental drivers within the lifetime of an individual foraminifer. This demonstrates the potential of porosity as a proxy for foraminiferal metabolic rates, with significance for interpreting geochemical data and the physiology of foraminifera in non-analog environments. It also highlights the importance of phenotypic plasticity (i.e., ecophenotypy) in accounting for some aspects of morphological variation in the modern and fossil record.
3
Gooday, Andrew J. "Some recent advances in the study of deep-sea foraminiferal biology and their palaeoecological significance." Paleontological Society Special Publications 6 (1992): 111. http://dx.doi.org/10.1017/s2475262200006717.
Full textAbstract:
During the past two decades, biologists have become increasingly aware of the diversity and abundance of foraminifera in marine benthic ecosystems. These protists are probably the most important eukaryotes present in ocean floor communities. In some areas, particularly central oceanic regions, foraminiferal assemblages are dominated by newly discovered, soft-bodied forms with morphologies quite unlike those of “conventional” foraminifers and with little fossilisation potential. However, despite the presumed loss of these delicate forms from the fossil record, foraminiferal tests are still the only microfossils to occur commonly in ancient deep-sea sediments. Thus, they are a focus of attention for both geologists and biologists. This presentation will concentrate on two main areas of biological research which have palaeontological significance.Foraminiferal microhabitats. Recent research indicates that particular species tend to live infaunally (deep or shallow), epifaunally or suprabenthically. Growth above or below the sediment-water interface has major implications for the stable isotope chemistry of calcareous tests, an important tool in palaeooceanography. Other species inhabit organic detritus composed of phytoplankton material rapidly sedimented from the euphotic zone. This “phytodetritus” arrives suddenly on the ocean floor following the spring bloom and is quickly colonized by foraminiferal species which feed on it, reproduce and rapidly develop large populations. These populations collapse when the food source is exhausted. The direct consumption of phytodetritus (and other organic matter inputs) by benthic foraminifers may be a widespread phenomenon which influences their population dynamics, regional distribution patterns and isotope chemistry.Recolonization. The defaunation of large tracts of ocean floor by turbidity currents or anoxic events must have happened on countless occasions over geological time, particularly along ocean margins and in basinal areas. Evidence from sediment tray experiments suggests that it may take several years for a stable community (including foraminifers) to become reestablished in small areas of defaunated sediment. Large devastated areas may require substantially longer to recover. However, on the Madeira Abyssal Plain, a normal foraminiferal assemblage occurs on the surface of a turbidite deposited several hundred years ago, suggesting that large-scale recolonization may occupy decades rather than centuries. The fossil foraminiferal assemblages present in deep-water flysch sequences are presumably the product of similar recolonization (?successional) events.These and other biological processes often operate on time scales (days, months, years) which usually can not be resolved in the stratigraphic record. This inevitably complicates the application of biological research to palaeontology.
4
Pint, Anna, Max Engel, Sandra Melzer, Peter Frenzel, Birgit Plessen, and Helmut Brückner. "How To Discriminate Athalassic and Marginal Marine Microfaunas: Foraminifera and Other Fossils from an Early Holocene Continental Lake in Northern Saudi Arabia." Journal of Foraminiferal Research 47, no. 2 (April 1, 2017): 175–87. http://dx.doi.org/10.2113/gsjfr.47.2.175.
Full textAbstract:
Abstract The occurrence of athalassic foraminiferal species, along with the brackish-water ostracod Cyprideis torosa, the barnacle Amphibalanus amphitrite, and brackish-water gastropods, prove the existence of a saline lake at Tayma, northern Saudi Arabia, during the early to mid-Holocene. Outcrops at the former shoreline, as well as a single sediment core, allow a reconstruction of the history of the main lake phase. Whereas these outcrops contain masses of calcareous micro- and macrofossils, the core from the modern sabkha does not. Four foraminiferal species were identified: Ammonia tepida is dominant, Quinqueloculina seminula is common, Flintinoides labiosa and Discorinopsis aguayoi are rare. Sieve-pore analysis and shell chemistry of C. torosa, as well as varying but generally high proportions of test anomalies (up to 50%) in foraminifers, indicate fluctuating, mostly hypersaline lacustrine conditions. We suggest, based on these results and on a literature overview on the worldwide distribution of Quaternary athalassic foraminifer taxa, that a combination of low diversity, exclusively marginal marine taxa, combined with occurrences of test anomalies >10% can be used to recognize athalassic saline waters in the fossil record.
5
Langer, Martin R., and Harmeet Bagi. "Tubicolous polychaetes as substrates for epizoic foraminifera." Journal of Micropalaeontology 13, no. 2 (December 1, 1994): 132. http://dx.doi.org/10.1144/jm.13.2.132.
Full textAbstract:
Abstract. Associations of epizoic foraminifera and invertebrates are widespread and have been reported from polar to tropical and shallow to bathyal environments (Zumwalt & DeLaca, 1980). Their fossil record stretches far back into Palaeozoic times as documented by agglutinated foraminifera attached to crinoids in Silurian and Devonian reef deposits of Morocco and Gotland (Franzen, 1974). Strong preferences for filter-feeding hosts suggest that epizoic foraminifera benefit from increased nutritional resources accumulated in the immediate flow microhabitat (Langer & Long, 1994).In the course of a broader study on foraminifera/invertebrate associations, several hundred foraminifera attached to the outer wall of agglutinated tubes of various polychaetes (e.g. Sabella sp., Potamilla sp.) were collected from sediment samples dredged at 61 m depth off the University of California, Moss Landing Marine Laboratory (NW Pacific). Attached foraminifera display a remarkable mode to obtain and differentially cement grains from the host tube that previously has not been reported. Agglutinated polychaete tubes and fragments thereof may reach 2 cm or more in length and are composed of fine sand, silt and micas cemented together by secreted organic material (Fig. 1). Tubes are typically orientated vertically in the mud and project above the sediment surface into the water column.NEW OBSERVATIONSExamination of agglutinated polychaete tubes revealed that their outer walls were commonly colonized by one to three foraminiferans (Figs 1–3, tube diameter 1.5–2.0 mm). The epizoic foraminiferal fauna comprised exclusively agglutinated taxa and included the following species: Alveophragmium advenum (Cushman), Textularia abbreviata Lalicker & McCulloch, Textularia schencki . . .
6
Hayward, Bruce W., François Le Coze, Leen Vandepitte, and Bart Vanhoorne. "Foraminifera in the World Register of Marine Species (Worms) Taxonomic Database." Journal of Foraminiferal Research 50, no. 3 (July 1, 2020): 291–300. http://dx.doi.org/10.2113/gsjfr.50.3.291.
Full textAbstract:
ABSTRACT Most foraminiferal research is founded on sound taxonomy. To clearly communicate such research, similar species concepts and consistent use of names is desirable. As a contribution to this larger goal, the World Foraminifera Database (http://www.marinespecies.org/foraminifera) was set up in 2010 as a subset within the World Register of Marine Species (WoRMS). The purpose is to provide an authoritative, open-access inventory of all foraminiferal taxonomic names. The inventory is almost complete for both fossil and Recent foraminiferal taxa, containing 4932 generic and 55,884 species (including infraspecies) names. There are ∼61,000 genus-species combinations of which ∼54,600 are currently “accepted” species and infraspecies (with 9600 extant). Associated data includes 14,700 linked foraminiferal literature sources, ∼6600 images, and species-level links to many other databases and images, such as the Cushman Collection (Smithsonian Institution), American Museum of Natural History, Mikrotax (planktic foraminifera), GenBank, and Zootaxon. The WoRMS database is owned by the global taxonomic community and hosted and serviced by the Flanders Marine Institute (VLIZ), Belgium. We recommend that all researchers working with foraminifera both use and contribute to the World Foraminifera Database, as that will improve the accuracy of the database's content and save investigators many hours of searching elsewhere.
7
Lowenstein, Tim K., and Bärbel Hönisch. "The Use of Mg/Ca as a Seawater Temperature Proxy." Paleontological Society Papers 18 (November 2012): 85–100. http://dx.doi.org/10.1017/s1089332600002564.
Full textAbstract:
The underlying basis for Mg/Ca paleothermometry is that the amount of magnesium in calcite precipitated from seawater is dependent on temperature. Here we review the state of the art of the Mg/Ca seawater paleotemperature proxy, summarized by the following: 1) Calcite, whether formed abiotically or biologically as foraminifera and ostracode shells, incorporates variable amounts of magnesium into the crystal structure. 2) Uptake of Mg varies positively with temperature. 3) The relationship between temperature and the amount of Mg in calcite has been quantified by experiments on synthetic calcite growth and by culture, core top, and sediment trap experiments using living organisms. 4) The most careful calibrations of the Mg/Ca paleothermometer have been done for planktic foraminifera, then benthic foraminifera; there are species-specific variations in the amount of Mg incorporated into foraminifera shells. 5) The Mg/Ca ratio of calcite from planktic foraminifera in deep-sea cores has been widely used to interpret sea surface temperatures. 6) Measurement of both Mg/Ca and δ18O in planktic foraminifera have been used to calculate δ18O in seawater, and after correction for global ice volume, salinity could be inferred. 7) Mg/Ca from benthic foraminifera have been used to reconstruct deep-sea temperatures and cooling of ~12° over the last 50 million years. 8) One problem with the Mg/Ca seawater temperature proxy is partial dissolution of foraminifer shells, which lowers the Mg/Ca, and leads to an underestimation of ocean temperature. Benthic foraminifers appear to be more resistant to partial dissolution. 9) Past changes in the Mg/Ca ratio of seawater are an important factor in determining the amount of Mg in fossil skeletal calcite, and thus add another variable to the Mg/Ca temperature proxy. All Mg/Ca paleotemperature studies on fossil calcite older than Pleistocene should take into account the Mg/Ca of the seawater from which it precipitated.
8
Aurahs, Ralf, Markus GÖker, Guido W. Grimm, Vera Hemleben, Christoph Hemleben, Ralf Schiebel, and Michal Kučera. "Using the Multiple Analysis Approach to Reconstruct Phylogenetic Relationships among Planktonic Foraminifera from Highly Divergent and Length-polymorphic SSU rDNA Sequences." Bioinformatics and Biology Insights 3 (January 2009): BBI.S3334. http://dx.doi.org/10.4137/bbi.s3334.
Full textAbstract:
The high sequence divergence within the small subunit ribosomal RNA gene (SSU rDNA) of foraminifera makes it difficult to establish the homology of individual nucleotides across taxa. Alignment-based approaches so far relied on time-consuming manual alignments and discarded up to 50% of the sequenced nucleotides prior to phylogenetic inference. Here, we investigate the potential of the multiple analysis approach to infer a molecular phylogeny of all modern planktonic foraminiferal taxa by using a matrix of 146 new and 153 previously published SSU rDNA sequences. Our multiple analysis approach is based on eleven different automated alignments, analysed separately under the maximum likelihood criterion. The high degree of congruence between the phylogenies derived from our novel approach, traditional manually homologized culled alignments and the fossil record indicates that poorly resolved nucleotide homology does not represent the most significant obstacle when exploring the phylogenetic structure of the SSU rDNA in planktonic foraminifera. We show that approaches designed to extract phylogenetically valuable signals from complete sequences show more promise to resolve the backbone of the planktonic foraminifer tree than attempts to establish strictly homologous base calls in a manual alignment.
9
Washington, Kirstin E., A. Joshua West, Boriana Kalderon-Asael, Joachim A. R. Katchinoff, Emily I. Stevenson, and Noah J. Planavsky. "Lithium isotope composition of modern and fossilized Cenozoic brachiopods." Geology 48, no. 11 (July 13, 2020): 1058–61. http://dx.doi.org/10.1130/g47558.1.
Full textAbstract:
Abstract Seawater lithium stable isotope ratios, represented by δ 7 Li sw (‰), hold key information about the evolution of global climate and the carbon cycle over geologic time. Reconstructions based on foraminifera suggest an ∼9‰ increase in δ 7 Li sw over the past 60 m.y., interpreted as reflecting changes in the silicate weathering regime that may have contributed to global cooling over this time. However, culture experiments suggest that vital effects in foraminifers might cause varied δ 7 Li fractionation that could have affected past records. Thus, other archives are needed to determine whether the observed rise in foraminifer δ 7 Li values over the Cenozoic indeed reflects secular changes in δ 7 Li sw . Such archives would also open possibilities for robust determination of δ 7 Li sw deeper in geologic time. We analyzed δ 7 Li compositions in modern brachiopods ( n = 34) and found a relatively narrow range of +24.2 ‰ to +28.8‰ (mean = +26.8‰; 1σ = 0.5‰), similar to the range reported for inorganic calcite precipitated from seawater. These results confirm that brachiopods are good candidates for providing a representative record of δ 7 Li sw . We present data from fossil specimens dating from 65 Ma to ca. 700 ka, finding that fossilized brachiopods record a similar magnitude of change in δ 7 Li sw as foraminifers. These results are the first to corroborate the ∼9‰ increase in Cenozoic δ 7 Li sw and open possibilities for generating robust records of δ 7 Li sw in deep time, prior to foraminifer evolution.
10
Norris, Richard D. "Symbiosis as an evolutionary innovation in the radiation of Paleocene planktic foraminifera." Paleobiology 22, no. 4 (1996): 461–80. http://dx.doi.org/10.1017/s0094837300016468.
Full textAbstract:
Symbioses are often regarded as an important means for the creation of evolutionary novelty as well as a trigger for the abrupt appearance of higher taxa. The fossil record of foraminifer-algal symbiosis suggests that the appearance of this ecological association contributed to the radiation of Paleogene planktic foraminifera. Isotopic evidence shows that photosymbiosis evolved in synchrony with a major diversification of trochospiral planktic foraminifera about 3.5 m.y. after the end-Cretaceous extinction. In modern planktic foraminifera, photosymbiotic species tend to have more cosmopolitan distributions than asymbiotic foraminifera and a greater ability to withstand periods of nutrient stress. The simultaneous taxonomic radiation and acquisition of photosymbiosis are evidence that the ecological strategy permitted Paleocene foraminifera to expand their niche in pelagic environments by diversifying into low-nutrient surface waters.A comparison of the species longevities of Neogene and Paleogene symbiotic clades suggests that photosymbiosis does not regulate the characteristic rate of taxonomic turnover in clades after they appear. Species longevities are much shorter in Paleocene and Eocene photosymbiotic morphospecies than they are among photosymbiotic Neogene clades; apparently photosymbiosis does not exert a significant control over long-term evolutionary rates. In addition, the absence of a characteristic morphology associated with photosymbiosis in Cenozoic planktic foraminifera suggests that morphology, as with rate of evolutionary turnover, is linked to symbiosis only because of common inheritance instead of a functional relationship. Although the coincidence between the acquisition of photosymbiosis and generic diversification does suggest a linkage between this ecology and the appearance of foraminiferal higher taxa, there is little indication at the present that symbioses control long-term morphological or ecological patterns within these groups after their appearance. Photosymbiosis, and other evolutionary innovations, may be more a catalyst for the differentiation of major groups than a predictable governor on evolutionary rates.
11
Dubicka, Zofia, Maria Gajewska, Wojciech Kozłowski, and Valeria Mikhalevich. "Test structure in some pioneer multichambered Paleozoic foraminifera." Proceedings of the National Academy of Sciences 118, no. 26 (June 21, 2021): e2100656118. http://dx.doi.org/10.1073/pnas.2100656118.
Full textAbstract:
Foraminiferal wall microstructures, consistent with the molecular-based high-rank classification, are critical to understanding foraminiferal evolution and advanced taxonomic relationships. Although test structures are well documented for recent, Cenozoic, and some Mesozoic foraminifera, the diagnostic characteristics of Paleozoic taxa are largely unexplored. The majority of calcareous Paleozoic foraminifera have been assigned to the Fusulinata based on questionable homogeneously “microgranular” test wall microstructures, which have never been sufficiently documented for most taxa. We investigated the test structures of exceptionally well-preserved Devonian (Eifelian) Semitextularia thomasi, representing the first calcareous true multichambered (serial) foraminifera, and compared this species with a large fusiform Permian representative of “true” fusulinids (Neoschwagerinidae). The tests of Semitextularia thomasi display lamellar structures that are not observed in any other fossil or recent foraminiferal group. The Paleozoic foraminifera, traditionally referred to one taxon (the class Fusulinata), possess at least three contrasting test wall microstructures, representing separate high-rank taxonomic groups. Fusulinata is most likely a highly polyphyletic group that is in need of taxonomic revision. The term Fusulinata, defined as including all Paleozoic calcareous forms except Miliolida and Lagenata, is not phylogenetically meaningful and should no longer be used or should be restricted to true complex fusulinids with microgranular test structures, which appeared in the Carboniferous.
12
Ando, Atsushi, Brian T. Huber, and Kenneth G. MacLeod. "Depth-habitat reorganization of planktonic foraminifera across the Albian/Cenomanian boundary." Paleobiology 36, no. 3 (2010): 357–73. http://dx.doi.org/10.1666/09027.1.
Full textAbstract:
New mid-Cretaceous stable isotope (δ18O and δ13C) records of multiple planktonic foraminiferal species and coexisting coccoliths from Blake Nose (western North Atlantic) document a major depth-ecology reorganization of planktonic foraminifera. Across the Albian/Cenomanian boundary, deep-dwellingPraeglobotruncana stephaniandRotalipora globotruncanoidesadapted to living at a shallower depth, while, at the same time, the population of surface-dwellingParacostellagerina libycadeclined. Subsequently, the opportunistic speciesHedbergella delrioensisshifted to a deep environment, and the deep-dwelling formsRotalipora montsalvensisandRotalipora reichelifirst appeared. The primary paleoenvironmental cause of the observed changes in planktonic adaptive strategies is uncertain, yet their coincidence with an earliest Cenomanian cooling trend reported elsewhere implicates the importance of reduced upper-ocean stratification. Although there has been an implicit assumption that the species-specific depth habitats of fossil planktonic foraminifera were invariant through time, planktonic paleoecology is a potential variable. Accordingly, the possibility of evolutionary changes in planktonic foraminiferal depth ecology should be a primary consideration (along with other environmental parameters) in paleoceanographic interpretations of foraminiferal stable isotope data.
13
Takagi, Haruka, Kazuyoshi Moriya, Toyoho Ishimura, Atsushi Suzuki, Hodaka Kawahata, and Hiromichi Hirano. "Exploring photosymbiotic ecology of planktic foraminifers from chamber-by-chamber isotopic history of individual foraminifers." Paleobiology 41, no. 1 (January 2015): 108–21. http://dx.doi.org/10.1017/pab.2014.7.
Full textAbstract:
AbstractEvolution of photosymbiotic ecology is an important adaptation for planktic foraminifers that enhances the ecological advantage of living in oligotrophic oceans. Therefore, detecting photosymbiotic ecology in fossil species is one of the keys to understanding the paleobiodiversity dynamics of planktic foraminifers. Because foraminiferal tests record the ontogenetic history of ecological information in geochemical signatures, analyzing individual geochemical profiles with growth can reveal a species’ ecology. This study examined chamber-by-chamber stable isotopes (δ13C and δ18O) of foraminiferal individuals to identify photosymbiotic signals. We observed an ontogenetic δ13C increase of up to 2.4‰, accompanied by relatively stable, negative δ18O, in the symbiotic species Globigerinoides conglobatus and Globigerinoides sacculifer. In contrast, δ13C and δ18O showed significant positive correlation during ontogeny in the asymbiotic species Globorotalia truncatulinoides. These two ecological groups produce contrasting isotopic profiles, thereby allowing us to use our ontogenetic isotopic analyses of individual specimens to identify algal photosymbiosis in fossil foraminifers. The chamber-by-chamber isotope analyses with individual ontogeny have great advantages in analyzing rare species because only one individual is required to describe ontogenetic isotopic history. In addition to photosymbiotic identification, our methods hold great potential to provide new insight into species paleoecological studies such as the ontogenetic history of calcification depth.
14
Roche, Didier M., Claire Waelbroeck, Brett Metcalfe, and Thibaut Caley. "FAME (v1.0): a simple module to simulate the effect of planktonic foraminifer species-specific habitat on their oxygen isotopic content." Geoscientific Model Development 11, no. 9 (September 3, 2018): 3587–603. http://dx.doi.org/10.5194/gmd-11-3587-2018.
Full textAbstract:
Abstract. The oxygen-18 to oxygen-16 ratio recorded in fossil planktonic foraminifer shells has been used for over 50 years in many geoscience applications. However, different planktonic foraminifer species generally yield distinct signals, as a consequence of their specific living habitats in the water column and along the year. This complexity is usually not taken into account in model–data integration studies. To overcome this shortcoming, we developed the Foraminifers As Modeled Entities (FAME) module. The module predicts the presence or absence of commonly used planktonic foraminifers and their oxygen-18 values. It is only forced by hydrographic data and uses a very limited number of parameters, almost all derived from culture experiments. FAME performance is evaluated using the Multiproxy Approach for the Reconstruction of the Glacial Ocean surface (MARGO) Late Holocene planktonic foraminifer calcite oxygen-18 and abundance datasets. The application of FAME to a simple cooling scenario demonstrates its utility to predict changes in planktonic foraminifer oxygen-18 to oxygen-16 ratio in response to changing climatic conditions.
15
Morard, Raphaël, Franck Lejzerowicz, Kate F. Darling, Béatrice Lecroq-Bennet, Mikkel Winther Pedersen, Ludovic Orlando, Jan Pawlowski, Stefan Mulitza, Colomban de Vargas, and Michal Kucera. "Planktonic foraminifera-derived environmental DNA extracted from abyssal sediments preserves patterns of plankton macroecology." Biogeosciences 14, no. 11 (June 6, 2017): 2741–54. http://dx.doi.org/10.5194/bg-14-2741-2017.
Full textAbstract:
Abstract. Deep-sea sediments constitute a unique archive of ocean change, fueled by a permanent rain of mineral and organic remains from the surface ocean. Until now, paleo-ecological analyses of this archive have been mostly based on information from taxa leaving fossils. In theory, environmental DNA (eDNA) in the sediment has the potential to provide information on non-fossilized taxa, allowing more comprehensive interpretations of the fossil record. Yet, the process controlling the transport and deposition of eDNA onto the sediment and the extent to which it preserves the features of past oceanic biota remains unknown. Planktonic foraminifera are the ideal taxa to allow an assessment of the eDNA signal modification during deposition because their fossils are well preserved in the sediment and their morphological taxonomy is documented by DNA barcodes. Specifically, we re-analyze foraminiferal-specific metabarcodes from 31 deep-sea sediment samples, which were shown to contain a small fraction of sequences from planktonic foraminifera. We confirm that the largest portion of the metabarcode originates from benthic bottom-dwelling foraminifera, representing the in situ community, but a small portion (< 10 %) of the metabarcodes can be unambiguously assigned to planktonic taxa. These organisms live exclusively in the surface ocean and the recovered barcodes thus represent an allochthonous component deposited with the rain of organic remains from the surface ocean. We take advantage of the planktonic foraminifera portion of the metabarcodes to establish to what extent the structure of the surface ocean biota is preserved in sedimentary eDNA. We show that planktonic foraminifera DNA is preserved in a range of marine sediment types, the composition of the recovered eDNA metabarcode is replicable and that both the similarity structure and the diversity pattern are preserved. Our results suggest that sedimentary eDNA could preserve the ecological structure of the entire pelagic community, including non-fossilized taxa, thus opening new avenues for paleoceanographic and paleoecological studies.
16
Davis, Catherine V., Tessa M. Hill, Ann D. Russell, Brian Gaylord, and Jaime Jahncke. "Seasonality in planktic foraminifera of the central California coastal upwelling region." Biogeosciences 13, no. 18 (September 16, 2016): 5139–50. http://dx.doi.org/10.5194/bg-13-5139-2016.
Full textAbstract:
Abstract. The close association between planktic foraminiferal assemblages and local hydrography make foraminifera invaluable proxies for environmental conditions. Modern foraminiferal seasonality is important for interpreting fossil distributions and shell geochemistry as paleoclimate proxies. Understanding this seasonality in an active upwelling area is also critical for anticipating which species may be vulnerable to future changes in upwelling intensity and ocean acidification. Two years (2012–2014) of plankton tows, along with conductivity–temperature–depth profiles and carbonate chemistry measurements taken along the north-central California shelf, offer new insights into the seasonal dynamics of planktic foraminifera in a seasonal coastal upwelling regime. This study finds an upwelling affinity for Neogloboquadrina pachyderma as well as a seasonal and upwelling associated alternation between dominance of N. pachyderma and Neogloboquadrina incompta, consistent with previous observations. Globigerina bulloides, however, shows a strong affinity for non-upwelled waters, in contrast to findings in Southern California where the species is often associated with upwelling. We also find an apparent lunar periodicity in the abundances of all species and document the presence of foraminifera even at very low saturation states of calcite.
17
Jentzen, Anna, Dirk Nürnberg, Ed C. Hathorne, and Joachim Schönfeld. "Mg ∕ Ca and <i xmlns="">δ</i><sup>18</sup>O in living planktic foraminifers from the Caribbean, Gulf of Mexico and Florida Straits." Biogeosciences 15, no. 23 (November 29, 2018): 7077–95. http://dx.doi.org/10.5194/bg-15-7077-2018.
Full textAbstract:
Abstract. Past ocean temperatures and salinities can be approximated from combined stable oxygen isotopes (δ18O) and Mg ∕ Ca measurements in fossil foraminiferal tests with varying success. To further refine this approach, we collected living planktic foraminifers by net sampling and pumping of sea surface water from the Caribbean Sea, the eastern Gulf of Mexico and the Florida Straits. Analyses of δ18O and Mg ∕ Ca in eight living planktic species (Globigerinoides sacculifer, Orbulina universa, Neogloboquadrina dutertrei, Pulleniatina obliquiloculata, Globorotalia menardii, Globorotalia ungulata, Globorotalia truncatulinoides and Globorotalia tumida) were compared to measured in situ properties of the ambient seawater (temperature, salinity and δ18Oseawater) and fossil tests of underlying surface sediments. “Vital effects” such as symbiont activity and test growth cause δ18O disequilibria with respect to the ambient seawater and a large scatter in foraminiferal Mg ∕ Ca. Overall, ocean temperature is the most prominent environmental influence on δ18Ocalcite and Mg ∕ Ca. Enrichment of the heavier 18O isotope in living specimens below the mixed layer and in fossil tests is clearly related to lowered in situ temperatures and gametogenic calcification. Mg ∕ Ca-based temperature estimates of G. sacculifer indicate seasonal maximum accumulation rates on the seafloor in early spring (March) at Caribbean stations and later in the year (May) in the Florida Straits, related to the respective mixed layer temperatures of ∼26 ∘C. Notably, G. sacculifer reveals a weak positive linear relationship between foraminiferal derived δ18Oseawater estimates and both measured in situ δ18Oseawater and salinity. Our results affirm the applicability of existing δ18O and Mg ∕ Ca calibrations for the reconstruction of past ocean temperatures and δ18Oseawater reflecting salinity due to the convincing accordance of proxy data in both living and fossil foraminifers, and in situ environmental parameters. Large vital effects and seasonally varying proxy signals, however, need to be taken into account.
18
LANDING, ED, SANDRA PATRUCCO REYES, AMANDA L. ANDREAS, and SAMUEL S. BOWSER. "First discovery of Early Palaeozoic Bathysiphon (Foraminifera) – test structure and habitat of a ‘living fossil’." Geological Magazine 149, no. 6 (April 12, 2012): 1013–22. http://dx.doi.org/10.1017/s0016756812000155.
Full textAbstract:
AbstractThe giant, agglutinated foraminiferan Bathysiphon Sars, previously Triassic–Recent, occurs in much older sedimentary rock (Early Ordovician, late early Tremadocian) of Avalonia. The genus extends back to c. 485 Ma based on its discovery in platform mudstone of the Chesley Drive Group in Cape Breton Island, Nova Scotia. Elongate (up to 60 mm), epibenthic Bathysiphon tubes occur in wave-rippled, green-grey mudstone with a low diversity, probably dysoxic fauna. The mudstone is coeval with and lithologically similar to the Shineton Formation in Shropshire and the Welsh Borderlands. Scanning microscopy of the Bathysiphon walls shows imbricated mica grains that parallel the long axis of the tests. The lumen has a mélange of packed sediment grains, some of which are spherical structures of siliciclastic mud studded with tetrahedral pyrite crystals. A felt-like, agglutinated test, a lumen packed with spherical structures (probable stercomata) and the domal ends of some specimens are consistent with modern Bathysiphon. This report is the first time that cytoplasmic activity and stercomata formation have been used to refer fossil protists to a modern group. Bathysiphon differs from the Cambrian foraminiferan Platysolenites Pander, which has an open lumen without stercomata, but support a comparable, sediment deposit-feeding niche. Bathysiphon is truly a ‘living fossil’, with a mode of test construction, cytoplasmic activity that formed stercomata and a niche unchanged for almost 500 million years. Foraminiferans have not been found prior to the Cambrian Period, and the Early Cambrian appearance of agglutinated foraminiferans is part of the radiation of Phanerozoic communities.
19
Stelck, C. R., and Dale A. Leckie. "Biostratigraphy of the Albian Paddy Member (Lower Cretaceous Peace River Formation), Goodfare, Alberta." Canadian Journal of Earth Sciences 27, no. 9 (September 1, 1990): 1159–69. http://dx.doi.org/10.1139/e90-123.
Full textAbstract:
Thirty-seven taxa of arenaceous foraminifera, recovered from cores of the upper part of the Paddy Member (Peace River Formation) and the superjacent lower Shaftesbury Formation in the Goodfare area of northwestern Alberta, are assigned to the lower part of the Verneuilina canadensis Subzone of the Miliammina manitobensis Zone of the Lower Cretaceous (upper Albian). A stratigraphic hiatus of eight foraminiferal subzones is implied between the Paddy Member and subjacent Cadotte Member. Progressive transgression of the M. manitobensis sea is reflected by a succession of four faunules of foraminifera and trace fossils. Shallow-water facies and reduced salinity are indicated for the Paddy environment, and a return to normal salinity during deposition of the overlying Shaftesbury Formation. A distinctive Miliammina–Ammotium faunule is figured from the upper part of the Paddy Member.
20
Meric, Engin, Niyazi Avsar, Mehmet Baki Yokes, and Feyza Dincer. "Atlas of Recent Benthic foraminifera from Turkey." Micropaleontology 60, no. 3-4 (2014): 211–398. http://dx.doi.org/10.47894/mpal.60.3.01.
Full textAbstract:
Benthic foraminifera are single-celled organisms abundantly found in all kind of marine environments from brackish estuaries to the deep ocean basins at all latitudes. Foraminifera are covered with an organic test which accumulate in the sediment and make up a significant amount of sedimentary rock. Many species have well defined salinity and temperature preferences making them particularly useful for reconstructing ecological changes occured in the past. The fossil tests not only used for paleoenvironmental interpretition, but also for biostratigraphy and age-dating. Anthropogenic pollution or environmental factors may cuase abnormal development of the test, such as aberrant chamber shape and size, twisted or distorted chamber arrangement, multiple apertures, twin, triplet and even quadruplet forms. These abnormalities are commonly used as indicators of pollution. Many researchers have studied the recent benthic and planktic foraminifera of the Mediterranean fauna. The studies have investigated the distribution and abundance of the species, composition of the foraminiferal assemblages, ecological factors and interractions of tests with the substrate. Recent studies, mainly focused on the alien species and their ecological impact. Despite the numerous researches, there is a lack of a comprehensive illustrated guide to the Mediterranean foraminifeal fauna, except the “Mediterranean Foraminifera” (Cimerman and Langer 1991), which included samples from Adriatic and Tyrrhenian Seas, representing mostly the western Mediterranean fauna. With the presented SEM photos of 299 species in 84 plates, the aim of the present Atlas is to fill the gap and provide an updated checklist of foraminiferal fauna of the Turkish coastline, representing the majority of the Levantine Basin.
21
Laursen, Gitte Vestergaard, and Søren Blegvad Andersen. "A Late Palaeocene–Early Eocene benthic foraminiferal record from Bovlstrup, Denmark, showing a remarkable agglutinated fauna." Journal of Micropalaeontology 16, no. 1 (May 1, 1997): 19–29. http://dx.doi.org/10.1144/jm.16.1.19.
Full textAbstract:
Abstract. The Bovlstrup well, Denmark, provides a detailed record of benthic foraminifera from the Upper Palaeocene and Lower Eocene deposits. The investigated interval spans four litho-units: an informal Grey Clay unit, the Holmehus Formation, the Ølst Formation and the Røsnæs Clay Formation (Danian?–Ypresian). Five interval zones based on benthic foraminifera have been established. Three of these zones (Zones 2, 3, and 4) contain exclusively agglutinated faunas. No foraminifera have previously been found in the Ølst Formation (Late Thanetian–Early Ypresian), but at Bovlstrup the formation contains a remarkable low-diversity agglutinated fauna (Zone 4). A programme of relatively dense sampling yielded information that may be lost in commercial oil well analysis. The five foraminiferal zones at Bovlstrup are correlated to established North Sea zonations, and the recognition of the faunas of Zones 3 and 4 leads to the conclusion that the zonation of King (In: Jenkins, D. G. & Murray, J. W. (Eds), Stratigraphical Atlas of Fossil Foraminifera, Ellis Horwood, 1989) can be refined.The benthic faunas indicate changes in the bottom environment both at the sea floor and within the overlying water mass. A transition from a calcareous fauna to an agglutinated fauna is interpreted as the result of a change from a neutral to a slightly acidic environment at the sea floor. There is a fluctuation in water depth through the studied section with a minimum water depth during the Thanetian and Early Ypresian. Volcanic ash layers in the Ølst Formation presumably resulted in low pH values, thereby causing the extreme low diversity of the benthic foraminiferal faunas.
22
Ngo, Chi Kim Thi, and Bat Van Dang. "Characterization of foraminifera in the southern East Sea during the late Holocene." Journal of Mining and Earth Sciences 62, no. 6 (December 31, 2021): 8–13. http://dx.doi.org/10.46326/jmes.2021.62(6).02.
Full textAbstract:
Twenty marine sediment samples have been collected in the Quaternary sediments in the southwest deep-depression East Sea region to study the foraminifera’s characterization. By analyzing foraminifer components under a microscope and taking photos under SEM, the authors determined that foraminifera fossils in the research area belonged to 01 sub-ordo as per the classification system proposed by Loeblich A.R. and Tappan H., which is Globigerinina Delage and Hérouard, 1896 sub-ordo, including four families, ten genera and 24 species. 04 families are Globigerinidae (06 genera and 13 species), Globorotaliidae (with two genera and nine species), Pulleniatidae (one genus and one species), and Catapsydracidae (one genus and one species). They all belong to the planktonic foraminifer group, living in the deep sea. Their indicator ages range from Miocene to Recent.
23
Kopaevich, L. F., P. A. Proshina, I. P. Ryabov, M. N. Ovechkina, and N. O. Grechikhina. "New microfossils data about the Santonian-Campanian boundary in the Alan-Kyr section (Central Crimea)." Moscow University Bulletin. Series 4. Geology, no. 2 (April 28, 2020): 43–50. http://dx.doi.org/10.33623/0579-9406-2020-2-43-50.
Full textAbstract:
The article presents the results of the determinations of foraminifera and nannoplankton from the section of Upper Cretaceous deposits Alan-Kyr (Central part of Crimea Mountains). Interpretation of these data to gether with the palinological ans paleomagnethic materials obtained earlier in this section allows to justify the age of deposits. In the lower part of the section planktonic foraminifera assemblages are correlated with the Satonian part of the Dicarinella asymetrica Zone. The benthic foraminiferal assemblages also show on the Santonian interval and allow it to be divided in more detail. On the nannoplankton data it was possible to identify fossils of the transition Zone CC17, corresponding to Upper Santonian–Lower Campanian. Within these deposits is the base of a probable magnetic chron analogue C 33r, which is proposed to be used as a primary feature to define the lower boundary of the Campanian.
24
El Kateb, Akram, Valentina Beccari, Stephanie Stainbank, Silvia Spezzaferri, and Giovanni Coletti. "Living (stained) foraminifera in the Lesser Syrtis (Tunisia): influence of pollution and substratum." PeerJ 8 (April 6, 2020): e8839. http://dx.doi.org/10.7717/peerj.8839.
Full textAbstract:
Foraminifera are protozoans with biomineralized tests that can be successfully used as a low cost monitoring tool to assess the health status of marine environments. Living benthic foraminiferal assemblages can provide essential information on natural and/or anthropogenic stresses and provide baseline conditions for studies on fossil material. Several studies have highlighted the negative impact of phosphate treatment industries along the Gulf of Gabes (Lesser Syrtis, Tunisia) on the marine environment. However, only a few studies, based on living (stained) benthic foraminifera, are presently available to assess environmental and/or ecological conditions in this Gulf. Thirty-eight surface sediment samples were quantitatively investigated to identify the dominant living benthic foraminiferal species and potential pollution-sensitive and stress-tolerant species. One-hundred and sixty-one species were identified, and grouped into seven clusters representing different environments within the Gulf. These groups represent polluted settings (Cluster A and B), polluted environments characterized by physicochemical variability (Cluster C), seagrass meadows and “pristine” sites (Cluster D and E) and the region subjected to major industrial impact (Cluster F). The final outlier Cluster, identified the foraminifera barren and all shallow coastal stations. A SIMPER analysis helped identify species with clear and fast responses to environmental perturbations (Ammonia tepida, Amphistegina lessonii, Brizalina striatula, Bulimina marginata, Buliminella elegantissima, Eggereloides scaber, Peneroplis perutusus, Rosalina macropora, Rosalina villardeboana, Trochammina inflata). A comparison with the measured geochemical parameters (TOC, phosphorus in the sediments and heavy metal concentrations in the seawater) has shown that the benthic foraminiferal assemblages are mainly linked to phosphorus, TOC, As and Cd pollution. We also provide here the first compilation of the identified living species in the Lesser Syrtis, their synonyms and digital images of important species.
25
Kaminski, Michael A., Alfred Uchman, Theodor Neagu, and Claudia G. Cetean. "A larger agglutinated foraminifer originally described as a marine plant: the case of <i>Arthrodendron</i> Ulrich, 1904 (Foraminifera), its synonyms and homonyms." Journal of Micropalaeontology 27, no. 2 (November 1, 2008): 103–10. http://dx.doi.org/10.1144/jm.27.2.103.
Full textAbstract:
Abstract. The large, agglutinated foraminiferal genus Aschemocella Vialov, 1966 (type species Aschemonella carpathica Neagu, 1964) and the body fossil Halysium Świdziński, 1934 (type species Halysium problematicum Świdziński, 1934) are herein synonymized with the genus Arthrodendron Ulrich, 1904 (type species A. diffusum Ulrich, 1904), a form originally described as a marine alga from Upper Cretaceous (Maastrichtian) flysch sediments of the Kodiak Formation of the Yakutat Group (formerly Yakutat Formation) on Pogibshi Island, Alaska. The species Aschemonella carpathica Neagu is regarded as a subjective junior synonym of Arthrodendron diffusum Ulrich, which is herein lectotypified and transferred to the Foraminifera.
26
Drinia, H., Koskeridou E. Koskeridou E., Antonarakou A. Antonarakou A., and E. Tzortzaki. "BENTHIC FORAMINIFERA ASSOCIATED WITH THE ZOOXANTHELLATE CORAL CLADOCORA IN THE PLEISTOCENE OF THE KOS ISLAND (AEGEAN SEA, GREECE): SEA LEVEL CHANGES AND PALAEOENVIRONMENTAL CONDITIONS." Bulletin of the Geological Society of Greece 43, no. 2 (January 23, 2017): 613. http://dx.doi.org/10.12681/bgsg.11223.
Full textAbstract:
A Pleistocene section, cropping out in the northern Kos Island has been selected for study. The main lithology (clayey sands, sandy marls) of the section is interrupted by a prominent Cladocora bank which allows a proper extraction of its faunal contents and identification at species level. The evaluation of benthic foraminiferal assemblages from this bank helps to determine the range of the environmental controls in sedimentation. The foraminiferal assemblage is related to a relatively high supply of organic material and rather strong current intensities in water depth of the coral growth. We suggest that the fossil reef of Cladocora grew in coastal waters characterised by a marked seasonality, with periodical inputs of terrigenous sediments, moderate turbidity and higher temperature than today. Such results, although preliminary, suggest that Cladocora together with benthic foraminifera could be reference species for future work on changing Mediterranean climate and sea level.
27
Kaminski, Michael A., Alfred Uchman, and Andrew K. Rindsberg. "Arthrodendron maguricum n. sp., a new larger agglutinated foraminifer from the Eocene Magura flysch of the Polish Carpathians and its relationship to komokiaceans and trace fossils." Journal of Paleontology 84, no. 6 (November 2010): 1015–21. http://dx.doi.org/10.1666/09-029.1.
Full textAbstract:
Arthrodendron maguricum n. sp. is described from deep-sea flysch of the lower Eocene Życzanów Conglomerate Member of the Szczawnica Formation (Magura Unit) in the Polish Carpathians. Arthrodendron maguricum is a larger agglutinated foraminifer showing regular, tubular chambers that may branch dichotomously. Its wall is tripartite and composed of an outer organic-rich layer, a main agglutinated layer, and an internal organic-rich layer. The organism evidently lived as epibenthos on the muddy sea floor. Because of their branching morphology and comparatively large dimensions, larger agglutinated foraminifera of the genus Arthrodendron have previously been confused with algae and trace fossils. Care should be taken in such cases to resolve the agglutinated wall and chambers of this deep-water agglutinated foraminifer. Arthrodendron maguricum displays superficial similarities to some modern komokiaceans, especially to Septuma. Further investigations are needed for clarification of their affinities and possible taxonomic consequences.
28
Majewski, Wojciech, Jarosław Stolarski, and Philip J. Bart. "Two Rare Pustulose/spinose Morphotypes of Benthic Foraminifera from Eastern Ross Sea, Antarctica." Journal of Foraminiferal Research 49, no. 4 (October 23, 2019): 405–22. http://dx.doi.org/10.2113/gsjfr.49.4.405.
Full textAbstract:
Abstract Habitats proximal to grounded ice and below ice shelves are rarely studied for microfossils. A recently described, well-resolved deglaciation record from the Whales Deep Basin of the eastern Ross Sea provided an opportunity to study sub-fossil foraminifera in such settings. Among other foraminiferal taxa, two forms with pustulose/spinose ornamentation were especially important as they were restricted to habitats associated with proximity to the calving front or presence of an ice-shelf. Based on gradation from strongly pustulose/spinose to typical morphologies and existing molecular data, these rarely reported forms are considered to be morphotypes of Globocassidulina biora (Crespin, 1960) and Trifarina earlandi (Parr, 1950). They seemed to flourish in polynya areas near grounding-line and in sub-ice-shelf environments with bottom currents. Their unusual morphologies may be a response to limited food resources. These foraminifera deserve special attention because they appear to be restricted to extreme Antarctic environments and hence are potentially very important for paleoenvironmental reconstructions.
29
Meilijson, Aaron, Sarit Ashckenazi-Polivoda, Peter Illner, Heiko Alsenz, Robert P. Speijer, Ahuva Almogi-Labin, Shimon Feinstein, Wilhelm Püttmann, and Sigal Abramovich. "Evidence for specific adaptations of fossil benthic foraminifera to anoxic–dysoxic environments." Paleobiology 42, no. 1 (October 26, 2015): 77–97. http://dx.doi.org/10.1017/pab.2015.31.
Full textAbstract:
AbstractIt has generally been argued that the majority of fossil benthic foraminifera, the most common proxy for paleo bottom oceanic conditions, could not tolerate anoxia. Here we present evidence that fossil foraminifera were able to successfully colonize anoxic–dysoxic bottom waters, by using adaptations similar to those found in living species. Our study is based on a multi proxy micropaleontological and geochemical investigation of the Upper Cretaceous sediments from the Levant upwelling regime. A shift from buliminid to diverse trochospiral dominated assemblages was recorded in an interval with a distinct anoxic geochemical signature coinciding with a regional change in lithology. This change was triggered by an alteration in the type of primary producers from diatoms to calcareous nannoplankton, possibly causing modifications in benthic foraminiferal morphological and physiological adaptations to life in the absence of oxygen.Our data show that massive blooms of triserial (buliminid) benthic foraminifera with distinct apertural and test morphologies during the Campanian were enabled by their ability to sequester diatom chloroplasts and associate with bacteria, in a similar manner as their modern analogs. Diverse trochospiral forms existed during the Maastrichtian by using nitrate instead of oxygen for their respiratory pathways in a denitrifying environment. Species belonging to the Stilostomellidae and Nodosariidae families might have been affected by the change in food type arriving to the seafloor after the phytoplankton turnover at the Campanian/Maastrichtian boundary, in a similar manner as their mid Pleistocene descendants prior to their extinction. This study promotes the need for a re-evaluation of the current models used for interpreting paleoceanographic data and demonstrates that the identification of adaptations and mechanisms involved in promoting sustained life under anoxic to dysoxic conditions should become a standard in faunal paleoceanographic studies.
30
Etienne, Rampal S., Bart Haegeman, Tanja Stadler, Tracy Aze, Paul N. Pearson, Andy Purvis, and Albert B. Phillimore. "Diversity-dependence brings molecular phylogenies closer to agreement with the fossil record." Proceedings of the Royal Society B: Biological Sciences 279, no. 1732 (October 12, 2011): 1300–1309. http://dx.doi.org/10.1098/rspb.2011.1439.
Full textAbstract:
The branching times of molecular phylogenies allow us to infer speciation and extinction dynamics even when fossils are absent. Troublingly, phylogenetic approaches usually return estimates of zero extinction, conflicting with fossil evidence. Phylogenies and fossils do agree, however, that there are often limits to diversity. Here, we present a general approach to evaluate the likelihood of a phylogeny under a model that accommodates diversity-dependence and extinction. We find, by likelihood maximization, that extinction is estimated most precisely if the rate of increase in the number of lineages in the phylogeny saturates towards the present or first decreases and then increases. We demonstrate the utility and limits of our approach by applying it to the phylogenies for two cases where a fossil record exists (Cetacea and Cenozoic macroperforate planktonic foraminifera) and to three radiations lacking fossil evidence ( Dendroica , Plethodon and Heliconius ). We propose that the diversity-dependence model with extinction be used as the standard model for macro-evolutionary dynamics because of its biological realism and flexibility.
31
Abdulsamad, Esam O., and Roberto Barbieri. "Foraminiferal distribution and palaeoecological interpretation of the Eocene–Miocene carbonates at Al Jabal al Akhdar (northeast Libya)." Journal of Micropalaeontology 18, no. 1 (June 1, 1999): 45–65. http://dx.doi.org/10.1144/jm.18.1.45.
Full textAbstract:
Abstract. In the coastal area of northeastern Cyrenaica (Libya), the excellent exposures of Cenozoic limestone sequences of Al Jabal al Akhdar average around 1000 m in thickness and allow detailed stratigraphic investigations to be undertaken. This study of the biostratigraphy and depositional environments has been augmented by an analysis of the microfacies and of matrix-free foraminiferal assemblages. The biotic contents of the microfacies provide a good tool for correlation with the Letter classification developed from the Indo-Pacific region. The palaeoecological significance of the biota has been evaluated by comparison with the ecological requirements of their present day counterparts. Limitations for the palaeoecological interpretations are mainly due to the inadequate relationships with existing ecological data sets and to some local bias in fossil recovery because of some unfavourable lithologies. In the investigated Eocene to Miocene shallow marine carbonate succession nine different microfacies and sub-microfacies were distinguished through depositional texture and biotic components. Wilson’s standard carbonate facies belts, integrated with present day foraminiferal distribution models, have been used for reference in microfacies analysis and description. Most of the microfossils present are foraminifera and a total of 150 taxa, including larger, small and planktonic foraminifera, have been recognized and their stratigraphic and palaeaeocological distribution reported. Physiographically, the rock sequences investigated are referred to a shelf–carbonate platform complex, in which the depositional environments range from open shelf to restricted platform conditions. The nature and distribution of the foraminiferal assemblages and related biota, in association with sedimentological evidence, indicate a generalized shallowing upward trend in which several bathymetric oscillations, especially in the Oligocene, are reported. These reflect the interplay between local tectonics and large-scale eustatic changes.
32
Honarmand, Atusa, Mohamad Vahidinia, Mohamad Hosein Mahmudy Gharaie, and Meysam Shafiee Ardestani. "Biostratigraphy of Upper Cretaceous planktonic foraminifera of the Abtalkh Formation in an east-west transect, Kopet-Dagh Basin, northeastern Iran." Micropaleontology 66, no. 4 (2020): 285–300. http://dx.doi.org/10.47894/mpal.66.4.02.
Full textAbstract:
The Upper Cretaceous Abtalkh Formation of the Kopet-Dagh Basin (northeastern Iran) was studied in four stratigraphic sections (Bahadorkhan, Hammam Galeh, Type section and Shorab). All sections display limestones, shales and calcareous shales. The Bahadorkhan section is approximately 480 m thick. We identified 32 planktonic foraminifera species belonging to 13 genera in 6 biozones: 1. Dicarinella asymetrica Total Range Zone, 2. Globotruncanita elevata Partial Range Zone, 3. Contusotruncana plummerae Interval Zone, 4. Radotruncana calcarata Total Range Zone, 5. Globotruncanella havanensis Partial Range Zone and Globotruncana aegyptiaca Interval Zone. Based on foraminiferal biostratigraphy, the Bahadorkhan section was dated to the latest Santonian to late Campanian. This study identifies 11 genera and 25 species of planktonic foraminifera in the 1500m thick Hammam Galeh section, spanning 7 biozones: 1. Dicarinella asymetrica Total Range Zone, 2. Globotruncanita elevata Partial Range Zone, 3. Contusotruncana plummerae Interval Zone, 4. Radotruncana calcarata Total Range Zone, 5. Globotruncanella havanensis Partial Range Zone, 6. Globotruncana aegyptiaca Interval Zone, 7. Gansserina gansseri Interval Zone. Latest Santonian to late Campanian ages have been established for the Abtalkh Formation. The type locality of the Abtalkh Formation is 750mthick and contains 31 planktonic foraminiferal species belonging to 12 genera. Based on this fossil content, we identified 6 biozones. The age of the formation is estimated to be the latest Santonian to late Campanian, as for the Bahadorkhan type section. The Shorab section of the Abtalkh Formation is 990m thick. In this section, 19 species belonging to 10 genera were identified, as were 5 biozones: 1. Globotruncanita elevata Partial Range Zone, 2. Contusotruncana plummerae Interval Zone, 3. Radotruncana calcarata Total Range Zone, 4. Globotruncanella havanensis Partial Range Zone, 5. Globotruncana aegyptiaca Interval Zone. Based on this fossil assemblage, the Shorab section dates to the early to late Campanian.
33
WILLIAMS, MARK, ALAN M. HAYWOOD, CLAUS-DIETER HILLENBRAND, and IAN P. WILKINSON. "Efficacy of δ18O data from Pliocene planktonic foraminifer calcite for spatial sea surface temperature reconstruction: comparison with a fully coupled ocean–atmosphere GCM and fossil assemblage data for the mid-Pliocene." Geological Magazine 142, no. 4 (July 2005): 399–417. http://dx.doi.org/10.1017/s0016756805000828.
Full textAbstract:
Sea surface temperature (SST) estimates using the δ18O composition of fossil planktonic foraminifer calcite, within the time slice 3.12 to 3.05 Ma (Pliocene, Kaena Subchron – C2An1r) are assessed for nine Atlantic Ocean sites. These are compared with SST estimates from fossil assemblages for the ‘Time Slab’ 3.29–2.97 Ma and with estimates from a fully coupled ocean–atmosphere General Circulation Model (GCM) for the same time interval. Most SST estimates derived from the δ18O data indicate a cooler ocean surface than at present, through the latitudinal range 69.25° N to 46.88° S. At some sites the temperature difference is greater than 5 °C (cooler than at present). This contrasts with SST estimates from fossil assemblages that give warmer than present temperatures at mid- to high latitudes, and similar temperatures in the tropics, and with the GCM, which predicts SSTs warmer than at present across all latitudes for this time interval. Difficulties interpreting the ecology of fossil foraminifer assemblages and inaccurate estimates of mid-Pliocene seawater δ18O composition (δ18Osw) at some sites may partly produce the temperature discrepancy between isotope-based and fossil-based SST estimates, but do not adequately explain the cool signal of the former. We interpret the cool SST estimates from the δ18O data to be the product of: (a) calcite formed at a level deep within or below the ocean mixed-layer during the life-cycle of the foraminifera; (b) secondary calcite with higher δ18O formed in the planktonic foraminifer tests in sea bottom pore waters. Although these effects differ between sites, secular and temporal oceanographic trends are preserved in the primary calcite formed in the mixed-layer near the ocean surface, witnessed by the latitudinal variation in estimated SSTs. Reconstructing accurate mid-Pliocene SSTs with much of the existing published oxygen isotope data probably requires a detailed re-assessment of taphonomy, particularly at tropical sites. This study also indicates that methods for estimating Atlantic Pliocene δ18Osw need to be refined.
34
Scott, D. B., and J. O. R. Hermelin. "A device for precision splitting of micropaleontological samples in liquid suspension." Journal of Paleontology 67, no. 1 (January 1993): 151–54. http://dx.doi.org/10.1017/s0022336000021302.
Full textAbstract:
The impetus for writing this paper has come from many people who have shown an interest in the device we describe; prior to this paper, we had no reference to provide for interested parties. The original device was described in Elmgren (1973) and illustrated in Thomas (1986). These papers are not readily available to many micropaleontologists; hence, we felt the need to redescribe it here with a few modifications. Traditionally, foraminiferal researchers, especially those working in fossil deposits, work on samples that are first processed and then dried. To split these dry samples to aliquots of manageable numbers of foraminifera, they use the well-known “Otto” microsplitter, which provides accurate splits plus or minus 10–20 percent.
35
Babazadeh, Seyed Ahmad. "New agglutinated Foraminifera from Early Eocene deposits of Mahallat region, Central Iran: implication on biostratigraphy and paleoecology." Revista Brasileira de Paleontologia 25, no. 4 (December 31, 2022): 274–91. http://dx.doi.org/10.4072/rbp.2022.4.03.
Full textAbstract:
This paper describes the foraminiferal associations along with the presentation of three new agglutinated conical foraminiferal species to the construction of the biozonation framework in the Mahallat region of central Iran. The stratigraphic distribution of benthic foraminifers is used to characterize three assemblage zones that are in ascending order: rotaliids-valvulinids Assemblage Zone, alveolinids-coskinolinids Assemblage Zone, and nummulitids-discocyclinids Assemblage Zone. These associations are characterized by marker fossils and localized from the inner ramp to the proximal outer ramp depositional environments. Their biostratigraphic range is assigned to the middle Cuisian to early Lutetian. In addition, three new agglutinated conical foraminiferal species: Daviesiconus mahallatensis sp. nov., Barattolites arghadehensis sp. nov., and Coleiconus minimus sp. nov. are described and figured for the first time from the lower Eocene shallow-water limestone in the studied area. These new species have common characteristics such as eccentric conical test with a low number of comparably coiled chambers in the early stage and uniserial chambers in the adult stage, but they differ in size, the form of test, and radial subepidermal partitions (beams, intercalary beams, and rafters). They are associated with the index Alveolina fauna and their biostratigraphic range is assigned to middle–late Cuisian (Ypresian, Early Eocene). Keywords: biostratigraphy, Early Eocene, new taxa, Mahallat, Iran.
36
Velić, Ivo. "Stratigraphy and Palaeobiogeography of Mesozoic Benthic Foraminifera - Part 1." Geologia Croatica 60, no. 1 (2007): 1–113. http://dx.doi.org/10.4154/gc.2007.01a.
Full textAbstract:
The Adriatic Carbonate Platform (AdCP), was a separate shallowmarine depositional system characterized by a lack of terrigenous input and was connected to Gondwana towards the South via Gavrovo–Tripolitza or Apulia. It existed for approximately 120 MY, from the Early Jurassic Pliensbachian/Toarcian) to the end of the Cretaceous, resulting in a 4000–6500 m thick succession of almost pure carbonates. However, this is part of a thicker (>8000 m) sequence of predominantly carbonate rocks which forms the Karst Dinarides, and was deposited during more than 270 MY – at least from the Carboniferous (Moscovian) to the Late Eocene. Among many different groups of fossil organisms, benthic foraminifera are especially abundant and well preserved, so they, along with calcareous algae (Dasycladales), are the most important fossils used for age determination and stratigraphic subdivision of shallow-marine carbonate deposits. Within the 257 determined taxa belonging to different foraminiferal families which lived through the Mesozoic, numerous different index fossils occur in assemblages indicating various ages: Early Triassic, Anisian, Carnian, Norian–Rhaetian, Late Sinemurian, Early and Late Pliensbachian (Carixian and Domerian), Early and Late Aalenian, Early and Late Bajocian, Early and Late Bathonian, Callovian, Early and Late Oxfordian, Kimmeridgian, Tithonian, Berriasian, Valanginian, Late Hauterivian, Late Barremian, Early and Late Aptian (Bedulian and Gargasian), Early and Late Albian, Early, Middle and Late Cenomanian, Turonian, Coniacian, Santonian, Early and Late Campanian and Early and Late Maastrichtian. A total of 64 biostratigraphic units – biozones of different categories, from subzone to superzone, were defined within the stratigraphic interval from the Carnian to the Late Maastrichtian. This enabled very detailed biostratigraphic subdivision of the carbonate deposits within the Karst Dinarides. This is one of the most precise sequences, not only in this area, but also among former shallow marine deposits of the entire Neotethyan realm in the present Mediterranean region. The palaeobiogeographic characteristics of biotopes and the composition of foraminiferal assemblages during the Mesozoic were controlled by the position of the study area within the Neotethyan bioprovinces. Until the Albian, this area represented part of the Southern Neotethyan bioprovince, while from the Cenomanian to its final disintegration at the end of the Cretaceous it belonged to a separate, Central Mediterranean Neotethyan bioprovince.
37
Aba Alkhayl, Saleh Suliman. "Oxfordian Benthic Foraminifera and Ostracods from the Hanifa Formation (Hawtah Member), Central Saudi Arabia." Micropaleontology 67, no. 6 (2021): 573–86. http://dx.doi.org/10.47894/mpal.67.6.04.
Full textAbstract:
The Hanifa Formation in Saudi Arabia consists of mostly carbonate units of Late Jurassic age and is well exposed along the Tuwaiq Mountain escarpment. Micropaleontological analyses of samples from three outcrops have revealed the presence of benthic foraminifera and ostracods. The study of fossil faunas from the Hawtah Member, has led to the identification of six foraminiferal species: Alveosepta (Redmondellina) powersi, Oolina globosa, Nautiloculina oolithica, Kurnubia palastiniensis, Pseudomarssonella cf. maxima, Lenticulina sp. and two ostracod species: Hutsonia asiatica and Cytherella cf. umbilica. The survey of species covered in this research suggests that they indicate a predominantly euryhaline to polyhaline marine setting, possibly with a slightly brackish influence and deposited in a supratidal environment, suggesting a progressively shallowing environment on the inner shelf with intermittent shoal complexes.
38
Ćosović, Vlasta, Katica Drobne, Bojan Ogorelec, Alan Moro, Mladen Koić, Ivan Šoštarko, Alceo Tarlao, and Giorgio Tunis. "Decastronema barattoloi (DE CASTRO), characteristic fossil of the Palaeocene and the Eocene peritidal sediments from the Adriatic carbonate platform." Geologia Croatica 61, no. 2-3 (December 25, 2008): 321–32. http://dx.doi.org/10.4154/gc.2008.24.
Full textAbstract:
The renewed deposition in the Palaeogene and the oldest part of the non-interrupted Palaeocene succession is characterized by the presence of Decastronema barattoloi (DE CASTRO), cyanobacterial tubes originally described in the Apennines. The reinterpretation of limestones from several sections located in the Kras region (NW part of the AdCP: Basovizza, Dolenja vas, Sopada, ?ebulovica) confi rmed the presence of these microfossils in peritidal sediments of Danian age (SBZ 1). The Cuisian (Late Lower Eocene) sediments, from eastern Istria (Brnjci section), Cres Island (Koroma?na Cove section) and Ravni kotari (Benkovac–Korlat section) contain individuals of this species in great numbers. The cyanobacterial tubes are scattered in laminated, fi ne grained mudstones and wackestones, immediately above the Cretaceous sediments (occasionally above bauxites or breccias). The Decastronema-bearing sediments pass upward into the Foraminiferal limestones of Cuisian age (SBZ 11, based on conical agglutinated foraminifera and alveolinids), allowing the age determination of the cyanobacterial remnants. The Palaeocene specimens are minute (up to about 180 ?m long), thick walled tubes that occur with the index fossil Bangiana hanseni DROBNE. The Eocene forms accompanied by ostracods, pelecypods, and miliolid and rotaliid foraminifera are segmented tubes, up to 400 mm long and usually thin walled.
39
Gutschick, Raymond C. "Middle Ordovician agglutinated foraminifera including Reophax from the Mifflin Formation, Platteville Group of Illinois." Journal of Paleontology 60, no. 2 (March 1986): 233–48. http://dx.doi.org/10.1017/s0022336000021776.
Full textAbstract:
Agglutinated siliceous foraminifera occur in the Middle Ordovician (Blackriveran) Mifflin Formation of the Platteville Group in northern Illinois. The fauna consists of globular saccamminids and a new form Reophax blackriveranus n. sp. which records the oldest validated representative of this genus. This marks the earliest known occurrence of agglutinated foraminifera with multichambered uniserial tests of progressively expanding chambers from the proloculus to the aperture. This early innovation of test morphology was probably developed to control unfavorable changes in the water chemistry of the environment.Mifflin lithofacies consist of light gray, thin, wavy-bedded, lithographic limestone and fine-grained dolomite with green shale interbeds, thin calcarenite layers with graded bedding, a K-bentonite ash layer and hardground corrosion bedding surfaces. Mifflin biofacies include the foraminiferan fauna, brachiopods and molluscan shelly faunas, bryozoans, trilobites, ostracodes, echinoderms, solitary corals, conodonts, chitinozoans, scolecodonts, sponges and trace fossils particularly Chondrites.The Mifflin strata were deposited on an exceedingly gentle slope off the Pecatonica carbonate platform which flanked the Wisconsin Arch. Thin Mifflin clinothem limestone beds wedge out into shales in the moderately deep (<200 m) aerobic starved basin in eastern Iowa. This occurred in south tropical seas during a eustatic rise in sealevel and major marine transgression. Reophax is associated with saccamminids in the benthos of the marine upper foreslope. Apparently slope-dwelling Reophax foraminifera of the Ordovician were displaced downslope into the basin by the rapid development and expansion of hyperamminids which occupy the lower and middle foreslope in the Mississippian.
40
Mitchell, Simon F. "Biostratigraphy of Late Maastrichtian larger foraminifers in Jamaica and the importance of <i>Chubbina</i> as a Late Maastrichtian index fossil." Journal of Micropalaeontology 24, no. 2 (October 1, 2005): 123–30. http://dx.doi.org/10.1144/jm.24.2.123.
Full textAbstract:
Abstract. The succession of larger foraminifers from the White Rock River Bridge section of the Guinea Corn Formation (Late Maastrichtian) in Jamaica, West Indies, contains: Sulcoperculina dickersoni (Palmer), Ayalaina rutteni (Palmer), Orbitoides cf. megaloformis Papp & Küpper, Vaughania cubensis Palmer and Chubbina cardenasensis (Barker & Grimsdale). A. rutteni occurs in the lower beds and C. cardenasensis occurs in the upper beds. The orbitoid foraminifer Or. cf. megaloformis is restricted to the middle beds. The White Rock River Bridge Section can be correlated to the standard Guinea Corn successions using lithological/biostratigraphic markers and rudist marker beds, and linked ages derived from Sr-isotope values. This indicates that Or. cf. megaloformis occurs in the last 1.3 Ma of the Cretaceous in the Caribbean and that its evolution was retrograde compared to coeval populations in Europe. The first appearance of Chubbina represents a valuable datum since the genus occurs in various different biofacies (both with and without orbitoid foraminifers) and allows correlation in the Caribbean, Central America and Florida.
41
Padgett, Jason S., Simon E. Engelhart, Harvey M. Kelsey, Robert C. Witter, Niamh Cahill, and Eileen Hemphill-Haley. "Timing and amount of southern Cascadia earthquake subsidence over the past 1700 years at northern Humboldt Bay, California, USA." GSA Bulletin 133, no. 9-10 (February 12, 2021): 2137–56. http://dx.doi.org/10.1130/b35701.1.
Full textAbstract:
Abstract Stratigraphic, lithologic, foraminiferal, and radiocarbon analyses indicate that at least four abrupt mud-over-peat contacts are recorded across three sites (Jacoby Creek, McDaniel Creek, and Mad River Slough) in northern Humboldt Bay, California, USA (∼44.8°N, −124.2°W). The stratigraphy records subsidence during past megathrust earthquakes at the southern Cascadia subduction zone ∼40 km north of the Mendocino Triple Junction. Maximum and minimum radiocarbon ages on plant macrofossils from above and below laterally extensive (>6 km) contacts suggest regional synchroneity of subsidence. The shallowest contact has radiocarbon ages that are consistent with the most recent great earthquake at Cascadia, which occurred at 250 cal yr B.P. (1700 CE). Using Bchron and OxCal software, we model ages for the three older contacts of ca. 875 cal yr B.P., ca. 1120 cal yr B.P., and ca. 1620 cal yr B.P. For each of the four earthquakes, we analyze foraminifera across representative mud-over-peat contacts selected from McDaniel Creek. Changes in fossil foraminiferal assemblages across all four contacts reveal sudden relative sea-level (RSL) rise (land subsidence) with submergence lasting from decades to centuries. To estimate subsidence during each earthquake, we reconstructed RSL rise across the contacts using the fossil foraminiferal assemblages in a Bayesian transfer function. The coseismic subsidence estimates are 0.85 ± 0.46 m for the 1700 CE earthquake, 0.42 ± 0.37 m for the ca. 875 cal yr B.P. earthquake, 0.79 ± 0.47 m for the ca. 1120 cal yr B.P. earthquake, and ≥0.93 m for the ca. 1620 cal yr B.P. earthquake. The subsidence estimate for the ca. 1620 cal yr B.P. earthquake is a minimum because the pre-subsidence paleoenvironment likely was above the upper limit of foraminiferal habitation. The subsidence estimate for the ca. 875 cal yr B.P. earthquake is less than (<50%) the subsidence estimates for other contacts and suggests that subsidence magnitude varied over the past four earthquake cycles in southern Cascadia.
42
Miller, William. "Examples of Mesozoic and Cenozoic Bathysiphon (Foraminiferida) from the Pacific Rim and the taxonomic status of Terebellina Ulrich, 1904." Journal of Paleontology 69, no. 4 (July 1995): 624–34. http://dx.doi.org/10.1017/s0022336000035162.
Full textAbstract:
The generic name Terebellina was proposed by E. O. Ulrich for large (> 100 mm long, several millimeters wide), siliceous, tubular fossils from Cretaceous rocks of southern Alaska. Originally interpreted as annelid tubes, these unusual agglutinated fossils are locally abundant in Triassic to Neogene flysch and other basinal deposits of the Pacific borderlands. Other generic names employed for the same fossils include Torlessia (used in New Zealand) and Yokoia (in Japan). Although most authors have regarded the tubes as body fossils of worms, some workers have speculated recently that Pacific Terebellina are really large bathysiphonid foraminiferids. At the same time, the name has been co-opted by trace fossil workers for thick-walled, grain-lined burrows usually occurring in outer-shelf to slope facies.Based on comparisons with modern and fossil bathysiphonids, including a new species (Bathysiphon harperi) from the Cretaceous of southwestern Oregon, the body fossils called Terebellina are here reinterpreted as large species of Bathysiphon, and the name Terebellina is therefore a junior synonym of this foraminiferid genus. Except for the compression and recrystallization of tubes, Pacific Terebellina resemble very closely the tests of larger species of modern Bathysiphon. Terebellina should not be salvaged for use as an ichnogenus. Most of the trace fossils identified with this name in the recent literature could be accommodated in other established ichnogenera, primarily Palaeophycus (where grain-lined burrows occur individually and are dominantly horizontal) and Schaubcylindrichnus (where they occur in curved bundles).
43
Lipps, Jere H. "Microfossils." Paleontological Society Papers 2 (October 1996): 217–26. http://dx.doi.org/10.1017/s1089332600003284.
Full textAbstract:
Microfossils are the tiny remains of bacteria, protists, fungi, animals, and plants. Microfossils are a heterogeneous bunch of fossil remains studied as a single discipline because rock samples must be processed in certain ways to remove them and microscopes must be used to study them. Thus, microfossils, unlike other kinds of fossils, are not grouped according to their relationships to one another, but only because of their generally small size and methods of study. For example, fossils of bacteria, foraminifera, diatoms, very small invertebrate shells or skeletons, pollen, and tiny bones and teeth of large vertebrates, among others, can be called microfossils. But it is an unnatural grouping. Nevertheless, this utilitarian subdivision of paleontology, first recognized in 1883, is very significant in geology, paleontology, and biology.
44
Barbieri, Giulia, and Stefano Claudio Vaiani. "Benthic foraminifera or Ostracoda? Comparing the accuracy of palaeoenvironmental indicators from a Pleistocene lagoon of the Romagna coastal plain (Italy)." Journal of Micropalaeontology 37, no. 1 (January 29, 2018): 203–30. http://dx.doi.org/10.5194/jm-37-203-2018.
Full textAbstract:
Abstract. Integrated analyses of multiple groups of microfossils are frequently performed to unravel the palaeoenvironmental evolution of subsurface coastal successions, where the complex interaction among several palaeoecological factors can be detected with benthic assemblages. This work investigates the palaeoenvironmental resolution potential provided by benthic foraminifera and ostracoda within a Pleistocene lagoonal succession of the Romagna coastal plain (northern Italy). Quantitative approaches and statistical techniques have been applied to both groups in order to understand the main factors that controlled the composition of assemblages and compare the palaeoecological record provided by single fossil groups. The two faunal groups are characterized by the high dominance of opportunistic species (Ammonia tepida–Ammonia parkinsoniana and Cyprideis torosa); however, detailed palaeoecological information is inferred from less common taxa. Benthic foraminiferal assemblages are mainly determined by the frequencies of abnormal individuals and species related to high concentrations of organic matter, showing two assemblages: a stressed assemblage, consistent with a brackish-water environment subject to salinity and oxygen fluctuations, and an unstressed assemblage, which indicates more stable conditions. Despite the lower number of species, ostracoda show more significant differences in terms of species composition and ecological structure between their three assemblages, formed in response to a salinity gradient and indicative of inner, central, and outer lagoon conditions. The stratigraphic distribution of ostracod assemblages shows a general transgressive–regressive trend with minor fluctuations, whereas benthic foraminifera highlight the presence of a significant palaeoenvironmental stress. In this case, the higher abundance along the stratigraphic succession, the higher differentiation of the assemblages, and the well-defined relationship between taxa and ecological parameters determine Ostracoda as the most reliable fossil group for precise palaeoenvironmental reconstructions. Nevertheless, benthic foraminifera indicate palaeoenvironmental stress and can be used to refine the environmental interpretation in the presence of monospecific ostracod assemblages.
45
Pearson, Paul N. "Survivorship Analysis of Fossil Taxa When Real-Time Extinction Rates Vary: The Paleogene Planktonic Foraminifera." Paleobiology 18, no. 2 (March 1992): 115–31. http://dx.doi.org/10.1017/s0094837300013920.
Full textAbstract:
For a survivorship curve to show a meaningful pattern, it is essential that a suitably homogeneous group is selected for analysis. If taxa have originated at different times in the geological record and have consequently experienced different extinction probabilities during the times that they existed, they do not constitute such a homogeneous group. A correction factor for variations in real-time extinction rates must be employed, as is described here. By application of the “corrected survivorship score,” it is shown that the Paleogene planktonic foraminifera exhibit a very strong survivorship pattern, namely an extinction probability that progressively increases with taxonomic longevity. That is to say, when extinction occurred, it was preferentially selective of older taxa. This is manifested as convexity in the survivorship curves. However, the pattern is degraded by variations in the real-time extinction rate, which causes straightening of the survivorship curves if they are calculated in the usual uncorrected way. If the law of constant extinction is to be tested for a given group, it is necessary either that stochastically constant real-time extinction rates are demonstrated or that variations in the extinction rate are corrected for in the manner described. As a separate issue, it is also essential that biologically meaningful taxa are analyzed. The convexity of planktonic foraminiferal survivorship curves is probably an artifact of the way evolving lineages have been subdivided in the application of typological taxonomy. Consequently, we are still a long way from being able to use survivorship analysis of planktonic foraminiferal data for adequately testing evolutionary models such as the Red Queen's hypothesis.
46
Franco-Fraguas, Paula, Karen Badaraco Costa, and Felipe Antonio de Lima Toledo. "Relationship between isotopic composition (Δ18O and Δ13C) and plaktonic foraminifera test size in core tops from the Brazilian Continental Margin." Brazilian Journal of Oceanography 59, no. 4 (December 2011): 327–38. http://dx.doi.org/10.1590/s1679-87592011000400003.
Full textAbstract:
Stable oxygen (δ18O) and carbon (δ13C) isotopic signature registered in fossil planktonic foraminifera tests are widely used to reconstruct ancient oceanographic conditions. Test size is a major source of stable isotope variability in planktonic foraminifera found in sediment samples and thus can compromise paleoceanographic interpretations. Test size/stable isotope (δ18O and δ13C) relationships were evaluated in two planktonic foraminifer species (Globigerinoides ruber (white) and Globorotalia truncatulinoides (right)) in two core tops from the Brazilian Continental Margin. δ18 Omeasurements were used to predict the depth of calcification of each test size fraction. δ13C offsets for each test size fraction were then estimated. No systematic δ18O changes with size were observed in G. ruber (white) suggesting a similar calcification depth range (c.a. 100 m) during ontogeny. For G. truncatulinoides (right) δ18O values increased with size indicating ontogenetic migration along thermocline waters (250-400 m). δ13C measurements and δ13C offsets increased with size for both species reflecting well known physiological induced ontogenetic-related variability. In G. ruber (white) the largest test size fractions (300µm and >355µm) more closely reflect δ13C DIC indicating they are best suited for paleoceanographic studies.
47
Concheyro, Andrea, Andrea Caramés, Cecilia R. Amenábar, and Marina Lescano. "Nannofossils, foraminifera and microforaminiferal linings in the Cenozoic diamictites of Cape Lamb, Vega Island, Antarctica." Polish Polar Research 35, no. 1 (March 1, 2014): 1–26. http://dx.doi.org/10.2478/popore-2014-0003.
Full textAbstract:
AbstractMicropaleontological and palynological samples from three Cenozoic diamictites at Cape Lamb, Vega Island, James Ross Basin were analysed. Fossiliferous samples yielded reworked and autochthonous assemblages of Mesozoic calcareous nanno− fossils, impoverished Cretaceous foraminifera together with Neogene species, as well as Late Cretaceous dinoflagellate cysts, pollen, spores and abundant Cenozoic micro− foraminiferal linings. The recovered nannoflora indicates Early Cretaceous (Hauteri− vian-Albian) and Late Cretaceous (Santonian-Early Campanian) ages, suggesting an in− tensive reworking of marine sediments. The presence of the Early Cretaceous species Nannoconus circularis Deres et Acheriteguy in the diamictite represents its first record for the James Ross Basin. The scarce foraminiferal fauna includes Pullenia jarvisi Cushman, which indicates reworking from lower Maastrichtian-lower Paleocene sediments, and also the Neogene autochthonous Trochammina sp. aff. T. intermedia. The in− ner−organic layer observed inside this specimen appears to be identical to microfora− miniferal linings recovered from the same sample. Palynomorphs found in the studied samples suggest erosion from the underlying Snow Hill Island and the Lopez de Bertodano Formation beds (upper Campanian-upper Maastrichtian). These recovered assemblages indicate either different periods of deposition or reworking from diverse sources during Cenozoic glaciation, originating in James Ross Island and the Antarctic Peninsula with the influence of local sediment sources.
48
Kiessling, W., R. Scasso, M. Aberhan, L. Ruiz, and S. Weidemeyer. "A Maastrichtian microbial reef and associated limestones in the Roca Formation of Patagonia (Neuquén Province, Argentina)." Fossil Record 9, no. 2 (August 1, 2006): 183–97. http://dx.doi.org/10.1002/mmng.200600007.
Full textAbstract:
Abstract. We describe a small microbial reef and associated limestones occurring in a Maastrichtian transgressive succession of mixed carbonate-siliciclastic lithologies at Sierra Huantraico near Chos Malal (Neuquén, Argentina). Strontium isotope data suggest that the reef is of earliest Maastrichtian age. The small reef (0.8 m thick, 2 m wide) is mostly composed of peloidal bindstone, dense stromatolite-cement crusts and thrombolite. Except for some ostracods, no metazoan fossils were found in the reef structure, although the majority of peloids are fecal pellets, probably of larger crustaceans. Small foraminifers with calcite tests and probable green algae have also been noted. Sedimentological data and fossils within and immediately above the reef suggest that the reef was formed in a transgressive systems tract under freshwater to brackish-water conditions. Limestones above the reef are serpulid-bryozoan packstones and intraclast-ooid grainstones. These limestones yield a mixture of typical non-tropical (common serpulids and bryozoans) and typical tropical aspects (common dasycladaceans and ooids). This mosaic is explained by salinity fluctuations, which in our case dominate over temperature in determining the grain associations. Wir beschreiben ein kleines mikrobielles Riff, das in der Sierra Hunatraico (Neuquén, Argentinien) in einer transgressiven, gemischt siliziklastisch-kalkigen Abfolge gefunden wurde. Nach Strontiumisotopen-Datierung ist das Riff in das unterste Maastrichtium zu stellen. Das kleine Riff (0,8 m Mächtigkeit, 2 m Breite) besteht überwiegend aus peloidalem Bindstone, dichten Stromatolith-Zement-Krusten und Thrombolith. Mit Ausnahme von Ostrakoden konnten keine Metazoen in der Riffstruktur nachgewiesen werden, obwohl die Mehrzahl der Peloide als Kotpillen zu interpretieren sind, die vermutlich auf größere Krebse zurückgehen. Kleine Foraminiferen und mögliche Grünalgen sind die einzigen zusätzlich nachweisbaren Eukaryoten. Die Fossilien im Riff und in den überlagernden Kalken sprechen für ein Riffwachstum unter transgressiven aber hyposalinen Bedingungen. Die Kalke über dem Riff tragen ein gemischtes paläoklimatisches Signal, das sowohl typisch nicht-tropische als auch typisch tropische Komponenten beinhaltet. Dieses Mosaik ist möglicherweise durch die starken Salinitätsschwankungen erklärbar und erfordert ein Überdenken der bisherigen Modelle zur klimatischen Steuerung der Karbonatsedimentation. doi:10.1002/mmng.200600007
49
Gasiński, M. Adam, Alexandra Olshtynska, and Alfred Uchman. "Late Maastrichtian foraminiferids and diatoms from the Polish Carpathians (Ropianka Formation, Skole Nappe): a case study from the Chmielnik-Grabówka composite section." Acta Geologica Polonica 63, no. 4 (December 1, 2013): 515–25. http://dx.doi.org/10.2478/agp-2013-0022.
Full textAbstract:
ABSTRACT Gasiński, M.A., Olshtynska, A. and Uchman, A. 2013. Late Maastrichtian foraminiferids and diatoms from the Polish Carpathians (Ropianka Formation, Skole Nappe): a case study from the Chmielnik-Grabowka composite section. Acta Geologica Polonica, 63(4), 515-525. Warszawa. Well-preserved foraminiferids have been found in the Chmielnik-Grabowka section (Skole Nappe, Polish Carpathians). The Abathomphalus mayaroensis (late Maastrichtian) and Racemiguembelina fructicosa (earlylate Maastrichtian) standard planktonic foraminiferal biozones have been recognized, based on the occurrence of their respective index species. Sediments of the R. fructicosa Zone contain diatoms, which are a rare component of Cretaceous flysch microfossil assemblages in the Carpathians. The diatom frustules and some foraminiferid tests are pyritized, probably after burial in the sediment, below the redox boundary or in the oxygen- deficient microenvironment inside the frustules or tests of microfossils; the presence of trace fossils and bioturbational structures in the same bed indicate an oxygenated sea floor.
50
R. Nimnu, J., G. O Aigbadon, and F. Ogbikaya. "Foraminiferal biostratigrpahy of oshi-13 field, coastal and central swamp depobelt, Niger delta basin, Nigeria." International Journal of Advanced Geosciences 6, no. 1 (May 30, 2018): 127. http://dx.doi.org/10.14419/ijag.v6i1.10907.
Full textAbstract:
A high resolution Foraminiferal biostratigrpahic study has been carried out using data from three wells located in the Coastal and Central Swamp depobelts of Niger Delta.The study defined six (N6-N15) Foraminiferal zones for the early to middle Miocene Niger Delta on the basis of index Foraminiferal and this was correlated to Blow, 1969 and Bergreen et al., 1995. Foraminiferal analysis shows that Oshi-13Field is very rich in calcareous and araneceous benthics, calcareous and planktic foraminiferal. The abudance of fossils and index fossils are responsible for constructing the biostratigraphic chart and hydrocarbon saturation in the field. The biostratigraphy chart constructed act as a basis in establishing the ages of sediments/ sequence in the studied field.