“Modern-Type Plate Tectonics”?
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Protozoan Fauna of Freshwater Habitats in South Dum Dum Municipality, North 24 Parganas, West Bengal
Journal of Academia and Industrial Research (JAIR) Volume 3, Issue 3 August 2014 139 ISSN: 2278-5213 RESEARCH ARTICLE Protozoan Fauna of Freshwater Habitats in South Dum Dum Municipality, North 24 Parganas, West Bengal J. Chitra Protozoology Section, Lower Invertebrate Division, M Block, New Alipore, Kolkata-700053, India [email protected]; +91 98315 47265 ______________________________________________________________________________________________ Abstract Wetlands of South Dum Dum Municipality were focused to reveal the status of the planktonic protozoan fauna in detail. A total of 37 different sites were selected and plankton samples from these sites were collected. About 16 sp. of protozoa were identified from few localities from the present investigation. Eight species of rhizopoda belonged to 4 genera, 4 family (Pelomyxidae, Arcellidae, Centropyxidae and Difflugiidae) and 2 order (Pelobintida and Arcellinida), Four species of flagellate belongs to 2 genera, 1 family (Euglinidae) and 1 order (Euglenida), 4 species of ciliate belongs to 4 genera, 4 family (Colepidae, Vorticellidae, Euplotidae and Paramaeciidae), 2 order (Prorodontida and Peritrichida) and 2 suborder (Sporadotrichinia and Peniculina). Among 37 localities, protozoans were observed only in L2, L3, L8, L9, L12, L13, L15, L17, L18, L19, L21, L24, L26, L32, L33, L34 and L36 localities. Protozoan diversity and their abundance were noticed higher in L12, L18, L21, L26, L33 and L34 localities. Euglena viridis, E. acus, E. oxyuris and Phacus acumininata, Pelomyxa palustris, Vorticella companula were found to be higher in abundance and distribution. Keywords: South Dum Dum municipality, planktonic protozoan, Euglena viridis, abundance, distribution. Introduction Dumdum Park, Amarpalli, Telipukur, Nager Bazar, Protozoa are highly abundant in all aquatic habitats and Patipukur and Dum Dum were selected and the plankton greatly involved in food chain (Finlay, 1997). -
Ctenophore Relationships and Their Placement As the Sister Group to All Other Animals
ARTICLES DOI: 10.1038/s41559-017-0331-3 Ctenophore relationships and their placement as the sister group to all other animals Nathan V. Whelan 1,2*, Kevin M. Kocot3, Tatiana P. Moroz4, Krishanu Mukherjee4, Peter Williams4, Gustav Paulay5, Leonid L. Moroz 4,6* and Kenneth M. Halanych 1* Ctenophora, comprising approximately 200 described species, is an important lineage for understanding metazoan evolution and is of great ecological and economic importance. Ctenophore diversity includes species with unique colloblasts used for prey capture, smooth and striated muscles, benthic and pelagic lifestyles, and locomotion with ciliated paddles or muscular propul- sion. However, the ancestral states of traits are debated and relationships among many lineages are unresolved. Here, using 27 newly sequenced ctenophore transcriptomes, publicly available data and methods to control systematic error, we establish the placement of Ctenophora as the sister group to all other animals and refine the phylogenetic relationships within ctenophores. Molecular clock analyses suggest modern ctenophore diversity originated approximately 350 million years ago ± 88 million years, conflicting with previous hypotheses, which suggest it originated approximately 65 million years ago. We recover Euplokamis dunlapae—a species with striated muscles—as the sister lineage to other sampled ctenophores. Ancestral state reconstruction shows that the most recent common ancestor of extant ctenophores was pelagic, possessed tentacles, was bio- luminescent and did not have separate sexes. Our results imply at least two transitions from a pelagic to benthic lifestyle within Ctenophora, suggesting that such transitions were more common in animal diversification than previously thought. tenophores, or comb jellies, have successfully colonized from species across most of the known phylogenetic diversity of nearly every marine environment and can be key species in Ctenophora. -
A Revised Classification of Naked Lobose Amoebae (Amoebozoa
Protist, Vol. 162, 545–570, October 2011 http://www.elsevier.de/protis Published online date 28 July 2011 PROTIST NEWS A Revised Classification of Naked Lobose Amoebae (Amoebozoa: Lobosa) Introduction together constitute the amoebozoan subphy- lum Lobosa, which never have cilia or flagella, Molecular evidence and an associated reevaluation whereas Variosea (as here revised) together with of morphology have recently considerably revised Mycetozoa and Archamoebea are now grouped our views on relationships among the higher-level as the subphylum Conosa, whose constituent groups of amoebae. First of all, establishing the lineages either have cilia or flagella or have lost phylum Amoebozoa grouped all lobose amoe- them secondarily (Cavalier-Smith 1998, 2009). boid protists, whether naked or testate, aerobic Figure 1 is a schematic tree showing amoebozoan or anaerobic, with the Mycetozoa and Archamoe- relationships deduced from both morphology and bea (Cavalier-Smith 1998), and separated them DNA sequences. from both the heterolobosean amoebae (Page and The first attempt to construct a congruent molec- Blanton 1985), now belonging in the phylum Per- ular and morphological system of Amoebozoa by colozoa - Cavalier-Smith and Nikolaev (2008), and Cavalier-Smith et al. (2004) was limited by the the filose amoebae that belong in other phyla lack of molecular data for many amoeboid taxa, (notably Cercozoa: Bass et al. 2009a; Howe et al. which were therefore classified solely on morpho- 2011). logical evidence. Smirnov et al. (2005) suggested The phylum Amoebozoa consists of naked and another system for naked lobose amoebae only; testate lobose amoebae (e.g. Amoeba, Vannella, this left taxa with no molecular data incertae sedis, Hartmannella, Acanthamoeba, Arcella, Difflugia), which limited its utility. -
Geobiological Events in the Ediacaran Period
Geobiological Events in the Ediacaran Period Shuhai Xiao Department of Geosciences, Virginia Tech, Blacksburg, VA 24061, USA NSF; NASA; PRF; NSFC; Virginia Tech Geobiology Group; CAS; UNLV; UCR; ASU; UMD; Amherst; Subcommission of Neoproterozoic Stratigraphy; 1 Goals To review biological (e.g., acanthomorphic acritarchs; animals; rangeomorphs; biomineralizing animals), chemical (e.g., carbon and sulfur isotopes, oxygenation of deep oceans), and climatic (e.g., glaciations) events in the Ediacaran Period; To discuss integration and future directions in Ediacaran geobiology; 2 Knoll and Walter, 1992 • Acanthomorphic acritarchs in early and Ediacara fauna in late Ediacaran Period; • Strong carbon isotope variations; • Varanger-Laplandian glaciation; • What has happened since 1992? 3 Age Constraints: South China (538.2±1.5 Ma) 541 Ma Cambrian Dengying Ediacaran Sinian 551.1±0.7 Ma Doushantuo 632.5±0.5 Ma 635 Ma 635.2±0.6 Ma Nantuo (Tillite) 636 ± 5Ma Cryogenian Nanhuan 654 ± 4Ma Datangpo 663±4 Ma Neoproterozoic Neoproterozoic Jiangkou Group Banxi Group 725±10 Ma Tonian Qingbaikouan 1000 Ma • South China radiometric ages: Condon et al., 2005; Hoffmann et al., 2004; Zhou et al., 2004; Bowring et al., 2007; S. Zhang et al., 2008; Q. Zhang et al., 2008; • Additional ages from Nama Group (Namibia), Conception Group (Newfoundland), and Vendian (White Sea); 4 The Ediacaran Period Ediacara fossils Cambrian 545 Ma Nama assemblage 555 Ma White Sea assemblage 565 Ma Avalon assemblage 575 Ma 585 Ma Doushantuo biota 595 Ma 605 Ma Ediacaran Period 615 Ma -
Testate Lobose Amoebae)
Palaeontologia Electronica palaeo-electronica.org Mediolus, a new genus of Arcellacea (Testate Lobose Amoebae) R. Timothy Patterson ABSTRACT Mediolus, a new arcellacean genus of the Difflugidae (informally known as the- camoebia, testate rhizopods, or testate lobose amoebae) differs from other genera of the family in having distinctive tooth-like inward oriented apertural crenulations and tests generally characterized by a variable number of hollow basal spines. R. Timothy Patterson. Ottawa-Carleton Geoscience Centre and Department of Earth Sciences, Carleton University, Ottawa, Ontario, K1S 5B6, Canada. [email protected] Keywords: Arcellacea; thecamoebian; testate lobose amoebae; Quaternary, new genus INTRODUCTION of the simple unilocular test (e.g., Bonnet, 1975; Medioli et al., 1987, 1990; Beyens and Meisterfeld, Arcellacea (also informally known as the- 2001), although some researchers have placed camoebians, testate amoebae, testate rhizopods, more emphasis on test composition (e.g., Ander- or testate lobose amoebae; Patterson et al., 2012) son, 1988). The proliferation of species descrip- are a diverse group of unicellular testate rhizopods tions within the Difflugia, often based on subtle test that occur in a wide array of aquatic and terrestrial differences, has resulted in considerable taxo- environments (Patterson and Kumar, 2002) from nomic confusion (Patterson and Kumar, 2002). the tropics to poles (Dalby et al., 2000). Although Researchers have often described new species most common in Quaternary sediments fossil based on regional interest, often with little consid- arcellaceans have been found preserved in sedi- eration of the previous literature or the systematic ments deposited under freshwater and brackish value of distinguishing characters (see discussions conditions spanning the Phanerozoic and into the in Medioli and Scott, 1983; Medioli et al., 1987; Neoproterozoic (Porter and Knoll, 2000; Van Ogden and Hedley, 1980; Tolonen, 1986; Bobrov Hengstum, 2007). -
Conicocassis, a New Genus of Arcellinina (Testate Lobose Amoebae)
Palaeontologia Electronica palaeo-electronica.org Conicocassis, a new genus of Arcellinina (testate lobose amoebae) Nawaf A. Nasser and R. Timothy Patterson ABSTRACT Superfamily Arcellinina (informally known as thecamoebians or testate lobose amoebae) are a group of shelled benthic protists common in most Quaternary lacus- trine sediments. They are found worldwide, from the equator to the poles, living in a variety of fresh to brackish aquatic and terrestrial habitats. More than 130 arcellininid species and strains are ascribed to the genus Centropyxis Stein, 1857 within the family Centropyxidae Jung, 1942, which includes species that are distinguished by having a dorsoventral-oriented and flattened beret-like test (shell). Conicocassis, a new arcel- lininid genus of Centropyxidae differs from other genera of the family, specifically genus Centropyxis and its type species C. aculeata (Ehrenberg, 1932), by having a unique test comprised of two distinct components; a generally ovoid to subspherical, dorsoventral-oriented test body, with a pronounced asymmetrically positioned, funnel- like flange extending from a small circular aperture. The type species of the new genus, Conicocassis pontigulasiformis (Beyens et al., 1986) has previously been reported from peatlands in Germany, the Netherlands and Austria, as well as very wet mosses and aquatic environments in High Arctic regions of Europe and North America. The occurrence of the species in lacustrine environments in the central Northwest Ter- ritories extends the known geographic distribution of the genus in North America con- siderably southward. Nawaf A. Nasser. Department of Earth Sciences, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, K1S 5B6, Canada. [email protected] R. Timothy Patterson. -
The Phanerozoic Thermo-Tectonic Evolution of Northern Mozambique Constrained by Ar, Fission Track and (U-Th)/He Analyses
THE PHANEROZOIC THERMO-TECTONIC EVOLUTION OF NORTHERN MOZAMBIQUE 40 39 CONSTRAINED BY AR/ AR, FISSION TRACK AND (U-TH)/HE ANALYSES Dissertation zur Erlangung des Doktorgrades der Naturwissenschaften am Fachbereich Geowissenschaften der Universität Bremen Vorgelegt von Matthias Ch. Daßinnies Bremen, 2006 Tag des Kolloquiums: 22.12.2006 Gutachter: Prof. Dr. J. Jacobs Prof. Dr. W. Bach Prüfer: Prof. Dr. T. Mörz Prof. A. Kopf Contents CONTENTS ACKNOWLEDGEMENTS ...................................................................................................... v SUMMARY........................................................................................................................ vii ZUSAMMENFASSUNG ......................................................................................................... x CHAPTER 1 INTRODUCTION .................................................................................................................. 1 1.1 Scope of thesis.................................................................................................. 1 1.2 Research objectives and methods..................................................................... 3 1.3 Outline of thesis ............................................................................................... 4 CHAPTER 2 THERMOCHRONOLOGICAL METHODS AND ANALYTICS ...................................................... 6 2.1 40Ar/39Ar dating method................................................................................... 6 2.1.1 Argon isotope measurements -
Tectonics and Crustal Evolution
Tectonics and crustal evolution Chris J. Hawkesworth, Department of Earth Sciences, University peaks and troughs of ages. Much of it has focused discussion on of Bristol, Wills Memorial Building, Queens Road, Bristol BS8 1RJ, the extent to which the generation and evolution of Earth’s crust is UK; and Department of Earth Sciences, University of St. Andrews, driven by deep-seated processes, such as mantle plumes, or is North Street, St. Andrews KY16 9AL, UK, c.j.hawkesworth@bristol primarily in response to plate tectonic processes that dominate at .ac.uk; Peter A. Cawood, Department of Earth Sciences, University relatively shallow levels. of St. Andrews, North Street, St. Andrews KY16 9AL, UK; and Bruno The cyclical nature of the geological record has been recog- Dhuime, Department of Earth Sciences, University of Bristol, Wills nized since James Hutton noted in the eighteenth century that Memorial Building, Queens Road, Bristol BS8 1RJ, UK even the oldest rocks are made up of “materials furnished from the ruins of former continents” (Hutton, 1785). The history of ABSTRACT the continental crust, at least since the end of the Archean, is marked by geological cycles that on different scales include those The continental crust is the archive of Earth’s history. Its rock shaped by individual mountain building events, and by the units record events that are heterogeneous in time with distinctive cyclic development and dispersal of supercontinents in response peaks and troughs of ages for igneous crystallization, metamor- to plate tectonics (Nance et al., 2014, and references therein). phism, continental margins, and mineralization. This temporal Successive cycles may have different features, reflecting in part distribution is argued largely to reflect the different preservation the cooling of the earth and the changing nature of the litho- potential of rocks generated in different tectonic settings, rather sphere. -
Lifestyle of the Octoradiate Eoandromeda in the Ediacaran
Lifestyle of the Octoradiate Eoandromeda in the Ediacaran Authors: Wang, Ye, Wang, Yue, Tang, Feng, Zhao, Mingsheng, and Liu, Pei Source: Paleontological Research, 24(1) : 1-13 Published By: The Palaeontological Society of Japan URL: https://doi.org/10.2517/2019PR001 BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access titles in the biological, ecological, and environmental sciences published by nonprofit societies, associations, museums, institutions, and presses. Your use of this PDF, the BioOne Complete website, and all posted and associated content indicates your acceptance of BioOne’s Terms of Use, available at www.bioone.org/terms-of-use. Usage of BioOne Complete content is strictly limited to personal, educational, and non - commercial use. Commercial inquiries or rights and permissions requests should be directed to the individual publisher as copyright holder. BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research. Downloaded From: https://bioone.org/journals/Paleontological-Research on 15 Feb 2020 Terms of Use: https://bioone.org/terms-of-use Access provided by Bing Search Engine Paleontological Research, vol. 24, no. 1, pp. 1–13, JanuaryEoandromeda 1, 2020 ’s Lifestyle 1 © by the Palaeontological Society of Japan doi:10.2517/2019PR001 Lifestyle of the Octoradiate Eoandromeda in the Ediacaran YE WANG1, YUE WANG1, FENG TANG2, MINGSHENG ZHAO3 and PEI LIU1 1Resource and Environmental Engineering College, Guizhou University, Huanx 550025, Guiyang, Guizhou, China (e-mail: [email protected]) 2Institute of Geology, Chinese Academy of Geological Sciences, 26 Baiwanzhuang Street 100037, Beijing, China 3College of Paleontology, Shenyang Normal Univeristy, 253 Huanhe N Street 110034, Shengyang, Liaoning, China Received May 14, 2018; Revised manuscript accepted January 26, 2019 Abstract. -
A Review of the Neoproterozoic to Cambrian Tectonic Evolution
Accepted Manuscript Orogen styles in the East African Orogen: A review of the Neoproterozoic to Cambrian tectonic evolution H. Fritz, M. Abdelsalam, K.A. Ali, B. Bingen, A.S. Collins, A.R. Fowler, W. Ghebreab, C.A. Hauzenberger, P.R. Johnson, T.M. Kusky, P. Macey, S. Muhongo, R.J. Stern, G. Viola PII: S1464-343X(13)00104-0 DOI: http://dx.doi.org/10.1016/j.jafrearsci.2013.06.004 Reference: AES 1867 To appear in: African Earth Sciences Received Date: 8 May 2012 Revised Date: 16 June 2013 Accepted Date: 21 June 2013 Please cite this article as: Fritz, H., Abdelsalam, M., Ali, K.A., Bingen, B., Collins, A.S., Fowler, A.R., Ghebreab, W., Hauzenberger, C.A., Johnson, P.R., Kusky, T.M., Macey, P., Muhongo, S., Stern, R.J., Viola, G., Orogen styles in the East African Orogen: A review of the Neoproterozoic to Cambrian tectonic evolution, African Earth Sciences (2013), doi: http://dx.doi.org/10.1016/j.jafrearsci.2013.06.004 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. 1 Orogen styles in the East African Orogen: A review of the Neoproterozoic to Cambrian 2 tectonic evolution 3 H. -
Rethinking the Paleoproterozoic Great Oxidation Event: a Biological Perspective
RETHINKING THE PALEOPROTEROZOIC GREAT OXIDATION EVENT: A BIOLOGICAL PERSPECTIVE John W. Grula Observatories of the Carnegie Institution for Science 813 Santa Barbara Street Pasadena, CA 91101 USA [email protected] ABSTRACT Competing geophysical/geochemical hypotheses for how Earth’s surface became oxygenated – organic carbon burial, hydrogen escape to space, and changes in the redox state of volcanic gases – are examined and a more biologically-based hypothesis is offered in response. It is argued that compared to the modern oxygenated world, organic carbon burial is of minor importance to the accumulation of oxygen in a mainly anoxic world where aerobic respiration is not globally significant. Thus, for the Paleoproterozoic Great Oxidation Event (GOE) ~ 2.4 Gyr ago, an increasing flux of O2 due to its production by an expanding population of cyanobacteria is parameterized as the primary source of O2. Various factors would have constrained cyanobacterial proliferation and O2 production during most of the Archean and therefore a long delay between the appearance of cyanobacteria and oxygenation of the atmosphere is to be expected. Destruction of O2 via CH4 oxidation in the atmosphere was a major O2 sink during the Archean, and the GOE is explained to a significant extent by a large decline in the methanogen population and corresponding CH4 flux which, in turn, was caused primarily by partial oxygenation of the surface ocean. The partially oxygenated state of these waters also made it possible for an aerobic methanotroph population to become established. This further contributed to the large reduction in the CH4 flux to the atmosphere by increasing the consumption of CH4 diffusing upwards from the deeper anoxic depths of the water column as well as any CH4 still being produced in the upper layer. -
The Origin of Tetraradial Symmetry in Cnidarians
The origin of tetraradial symmetry in cnidarians JERZY DZIK, ANDRZEJ BALINSKI AND YUANLIN SUN Dzik, J., Balinski, A. & Sun, Y. 2017: The origin of tetraradial symmetry in cnidarians. Lethaia, DOI: 10.1111/let.12199. Serially arranged sets of eight septa-like structures occur in the basal part of phosphatic tubes of Sphenothallus from the early Ordovician (early Floian) Fenxi- ang Formation in Hubei Province of China. They are similar in shape, location and number, to cusps in chitinous tubes of extant coronate scyphozoan polyps, which supports the widely accepted cnidarian affinity of this problematic fossil. However, unlike the recent Medusozoa, the tubes of Sphenothallus are flattened at later stages of development, showing biradial symmetry. Moreover, the septa (cusps) in Sphenothallus are obliquely arranged, which introduces a bilateral component to the tube symmetry. This makes Sphenothallus similar to the Early Cambrian Paiutitubulites, having similar septa but with even more apparent bilat- eral disposition. Biradial symmetry also characterizes the Early Cambrian tubular fossil Hexaconularia, showing a similarity to the conulariids. However, instead of being strictly tetraradial like conulariids, Hexaconularia shows hexaradial symme- try superimposed on the biradial one. A conulariid with a smooth test showing signs of the ‘origami’ plicated closure of the aperture found in the Fenxiang For- mation supports the idea that tetraradial symmetry of conulariids resulted from geometrical constrains connected with this kind of closure. Its minute basal attachment surface makes it likely that the holdfasts characterizing Sphenothallus and advanced conulariids are secondary features. This concurs with the lack of any such holdfast in the earliest Cambrian Torellella, as well as in the possibly related Olivooides and Quadrapyrgites.