DOCSLIB.ORG

Two Episodes of Environmental Change at the Permian–Triassic Boundary of the GSSP Section Meishan

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Two Episodes of Environmental Change at the Permian–Triassic Boundary of the GSSP Section Meishan Earth-Science Reviews 115 (2012) 163–172 Contents lists available at SciVerse ScienceDirect Earth-Science Reviews journal homepage: www.elsevier.com/locate/earscirev Two episodes of environmental change at the Permian–Triassic boundary of the GSSP section Meishan Hongfu Yin a,⁎, Shucheng Xie a, Genming Luo a, Thomas J. Algeo b, Kexin Zhang a a State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China b Department of Geology, University of Cincinnati, Cincinnati, OH 45221, USA article info abstract Article history: High-resolution stratigraphic records through the Permian–Triassic boundary (PTB) interval of the global Received 4 May 2012 stratotype section and point (GSSP) at Meishan, Zhejiang Province, China reveal that the PTB crisis was not a sin- Accepted 10 August 2012 gle, abrupt catastrophe. A bed-by-bed analysis of environmental and biotic changes makes clear that the crisis Available online 29 August 2012 can be resolved into two discrete episodes, each consisting of three stages: A) unstably oscillating conditions, B) peak crisis conditions, and C) ameliorating conditions. The first crisis episode commenced in Bed 23, peaked Keywords: in Beds 24e–26, and ameliorated in Beds 27 and 28, while the second crisis episode commenced in Bed 29, Mass extinction – Conodont biostratigraphy peaked in Beds 34 38, and ameliorated in Beds 39 and higher. The macroscopic mass extinctions happened Carbon isotopes not at the beginning, nor the end of each cycle, but at times when the crisis or perturbation of environments Volcanic event beds began. These extinction events do not show detectable feedbacks to concurrent environmental changes. In Biomarkers each episode, cyanobacteria proliferation postdated the macroscopic extinction while proliferation of green sul- Geomicrobial functional groups fur bacteria predated the environmental crisis. Causational analysis between environmental and microbial changes show that geomicrobial functional groups exercised pronounced effects on the marine C–N–Scycles and ocean redox conditions during the PTB crisis. It is possible thus that the microbial crises played an important role in strengthening or evening triggering the environmental crisis. © 2012 Elsevier B.V. All rights reserved. Contents 1. Introduction .............................................................. 164 2. Methods ............................................................... 164 3. Event sequence at Meishan ....................................................... 165 3.1. Pre-crisis: relatively normal conditions (Beds 22 and lower) .................................... 165 3.2. Episode 1, Stage A: oscillating conditions (Beds 23 and 24d) .................................... 166 3.3. Episode 1, Stage B: crisis peak (Beds 24e–26)........................................... 166 3.3.1. Bed 24e ........................................................ 166 3.3.2. Bed 25 ......................................................... 166 3.3.3. Bed 26 ......................................................... 167 3.3.4. Environments of Beds 24e–26.............................................. 167 3.4. Episode 1, Stage C: ameliorating conditions (Beds 27 and 28) ................................... 168 3.5. Episode 2, Stage A: oscillating conditions (Beds 29–33)...................................... 168 3.6. Episode 2, Stage B: crisis peak (Beds 34–38)........................................... 169 3.7. Episode 2, Stage C: ameliorating conditions (Beds 39 and higher) ................................. 169 4. Discussion and conclusion ....................................................... 169 Acknowledgments ............................................................. 170 ⁎ Corresponding author at: Office of President, China University of Geosciences, Wuhan, Hubei, 430074, China. Tel.: +86 27 67884812(h.), +86 27 87481030(secr.); fax: +86 27 87481392. E-mail addresses: [email protected], [email protected] (H. Yin), [email protected] (S. Xie), [email protected] (G. Luo), [email protected] (T.J. Algeo), [email protected] (K. Zhang). URL: http://www.cug.edu.cn (H. Yin). 0012-8252/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.earscirev.2012.08.006 164 H. Yin et al. / Earth-Science Reviews 115 (2012) 163–172 Appendix A. Supplementary data ..................................................... 170 References ................................................................. 170 1. Introduction the lower part of the Isarcicella isarcica Zone (the full range of which is Beds 29b–51). The duration of the I. isarcica Zone (~390 Kyr) was The mass extinction at the Permian–Triassic boundary (PTB) has been constrained by cyclostratigraphic analyses of PTB sections at Chaohu recognized as the largest mass extinction in geological history (Erwin, (Anhui Province) and Daxiakou (Hubei Province), on the basis of 1993). Biotic, climatic, and environmental events accompanying this which we estimated the duration of Beds 29b–38 as ~100 ka. The extinction have been extensively investigated at Meishan, the GSSP of Bed 29b–38 interval consists of ca. 20 high-frequency sedimentary the PTB, based on many types of paleobiologic and chemostratigraphic cycles (Zhang et al., 1997, 2009; Wu et al., 2012), which thus repre- records (Yin et al., 2001). To date, these events have been reported in sent a sub-Milankovitch periodicity (~5 Kyr) (Guo et al., 2008; Wu et separate publications, and many of them are regarded as isolated (i.e., al., 2012). These considerations yield an estimated age of 252.00 Ma mono-episodic) phenomena. Recent advances in isotopic dating (S.Z. for Bed 38, and the total duration of the interval from Bed 24e to Bed Shen et al., 2011) and biostratigraphic zonation (Zhang et al., 2009)of 38 (the focus of this study) is thus about 0.3 Ma. The nearest overlying the PTB interval have laid the groundwork for our development of a eventwithaδ13C excursion, interpreted as coincident with a microbial high-resolution temporal framework for the Meishan succession. This boost, is located at the Griesbachian–Dienerian transition, within the framework includes 8 conodont zones, yielding a temporal resolution Neospathodus kummeri Zone, a few hundred of thousand years younger of ~0.01 Myr, thus making feasible a detailed synthesis of the event than the interval considered here (Payne et al., 2004; Zuo et al., 2006). sequence at Meishan. In this paper, we compile the various events that This makes the Beds 23–39 interval a critical PTB interval of ancient have been documented in the Meishan GSSP into a single record, in global change readily separated from under- and overlying strata. order to understand better the patterns and processes of global change The stratigraphic framework of the Meishan succession is based on during the PTB crisis. the following references: system boundary and formation names (Yin et al., 2001), bed numbers and their descriptions (Yin et al., 1996), age 2. Methods (Shen et al., 2011a, plus a 252.00 age of Bed 38); conodont zonation (Zhang et al., 2009, which is a synthesis of most published conodont stud- According to earlier publications, the PTB extinction at Meishan began ies of the Meishan GSSP, see Supporting material). Changes of the proxy inBed24eandendedinBed28(Xie et al., 2007; Yin et al., 2007a; S.Z. datasets in the columns of Figs. 1 and 2 are interpreted within narrowly Shen et al., 2011). As documented herein, however, the environmental defined stratigraphic intervals and subdivided into peaks, ebbs, and crisis actually continued to Bed 38 (Figs. 1 and 2). Beds 29b–38 cover other relevant trends as shown in Fig. 3. Abscissa values of the proxies Fig. 1. The PTB event sequence at Meishan. Beds within the mass extinction interval (Beds 24–28; 27a/b and 27c/d each regarded as a single bed) are given larger and roughly averaged thicknesses than the other beds; all data are re-dotted to the rescaled columns. The original references are as follows: system boundary and formation names (Yin et al., 2001), bed numbers and their descriptions (Yin et al., 1996), age (Shen et al., 2011a,b,c, and others, see text); conodont zonation: Zhang et al. (2009); diversity (species): Jin 13 13 et al. (2000, SOM); cyanobacteria (C31 2MHP index): Xie et al. (2005); δ Ccarb: Cao et al. (2002); Xie et al. (2007); δ Corg: Cao et al. (2009); redox (isorenieratane, black; aryl isoprenoids, lg (C14–C27), (ppm/TOC) light blue): Grice et al. (2005), (pyrite framboids, red): Shen et al. (2007);δ15N: Cao et al. (2009). H. Yin et al. / Earth-Science Reviews 115 (2012) 163–172 165 Fig. 2. The PTB event sequence at Meishan (continued). All data are re-dotted to the rescaled columns. The original references are as follows: terrestrial input (C29-M/C30-HP, red; C30-M/C30-HP, black): Xie et al. (2007); (light blue square): Wang (2007); DBF: Xie et al. (2007, 2009); volcanic ash: Yin et al. (1996); wildfire (black carbon, red): Xie et al. (2007), W.J. Shen et al. (2011); (PAHs, black): W.J. Shen et al. (2011); TOC: Cao et al. (2002) (light blue); Grice et al. (2005) (red); W.J. Shen et al. (2011) (black); δ18O: Joachimski et al. (2012); sea level: Cao and Zheng (2009) (red); Zhang et al. (1997) (black). are arranged such that correlation of their fluctuations can be visually but, rather, consisted of multiple fluctuations defining two main perceived, so the values may either increase or decrease toward the episodes. right side. Generally but not always, excursions toward
Load more

Recommended publications
  • DOGAMI Open-File Report O-86-06, the State of Scientific
    "ABLE OF CONTENTS Page INTRODUCTION ..~**********..~...~*~~.~...~~~~1 GORDA RIDGE LEASE AREA ....................... 2 RELATED STUDIES IN THE NORTH PACIFIC .+,...,. 5 BYDROTHERMAL TEXTS ........................... 9 34T.4 GAPS ................................... r6 ACKNOWLEDGEMENT ............................. I8 APPENDIX 1. Species found on the Gorda Ridge or within the lease area . .. .. .. .. .. 36 RPPENDiX 2. Species found outside the lease area that may occur in the Gorda Ridge Lease area, including hydrothermal vent organisms .................................55 BENTHOS THE STATE OF SCIENTIFIC INFORMATION RELATING TO THE BIOLOGY AND ECOLOGY 3F THE GOUDA RIDGE STUDY AREA, NORTZEAST PACIFIC OCEAN: INTRODUCTION Presently, only two published studies discuss the ecology of benthic animals on the Gorda Sidge. Fowler and Kulm (19701, in a predominantly geolgg isal study, used the presence of sublittor31 and planktsnic foraminiferans as an indication of uplift of tfie deep-sea fioor. Their resuits showed tiac sedinenta ana foraminiferans are depositea in the Zscanaba Trough, in the southern part of the Corda Ridge, by turbidity currents with a continental origin. They list 22 species of fararniniferans from the Gorda Rise (See Appendix 13. A more recent study collected geophysical, geological, and biological data from the Gorda Ridge, with particular emphasis on the northern part of the Ridge (Clague et al. 19843. Geological data suggest the presence of widespread low-temperature hydrothermal activity along the axf s of the northern two-thirds of the Corda 3idge. However, the relative age of these vents, their present activity and presence of sulfide deposits are currently unknown. The biological data, again with an emphasis on foraminiferans, indicate relatively high species diversity and high density , perhaps assoc iated with widespread hydrotheraal activity.
    [Show full text]
  • Mechanics Unlocks the Morphogenetic Puzzle of Interlocking Bivalved Shells
    Mechanics unlocks the morphogenetic puzzle of interlocking bivalved shells Derek E. Moultona,1 , Alain Gorielya , and Regis´ Chiratb aMathematical Institute, University of Oxford, Oxford, OX2 6GG, United Kingdom; and bCNRS 5276, LGL-TPE (Le Laboratoire de Geologie´ de Lyon: Terre, Planetes,` Environnement), Universite´ Lyon 1, 69622 Villeurbanne Cedex, France Edited by Sean H. Rice, Texas Tech University, Lubbock, TX, and accepted by Editorial Board Member David Jablonski November 11, 2019 (received for review September 24, 2019) Brachiopods and mollusks are 2 shell-bearing phyla that diverged tal events causing shell injuries. Yet, in all cases the interlocking from a common shell-less ancestor more than 540 million years ago. of the 2 shell edges is tightly maintained. These observations Brachiopods and bivalve mollusks have also convergently evolved imply that the interlocking pattern emerges as the result of epi- a bivalved shell that displays an apparently mundane, yet strik- genetic interactions modulating the behavior of the secreting ing feature from a developmental point of view: When the shell mantle during shell development. is closed, the 2 valve edges meet each other in a commissure that Here, we provide a geometric and mechanical explanation forms a continuum with no gaps or overlaps despite the fact that for this morphological trait based on a detailed analysis of the each valve, secreted by 2 mantle lobes, may present antisymmet- shell geometry during growth and the physical interaction of the ric ornamental patterns of varying regularity and size. Interlock- shell-secreting soft mantle with both the rigid shell edge and ing is maintained throughout the entirety of development, even the opposing mantle lobe.
    [Show full text]
  • Analysis of the Complete Mitochondrial DNA Sequence of the Brachiopod Terebratulina Retusa Places Brachiopoda Within the Protostomes
    See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/12415870 Analysis of the complete mitochondrial DNA sequence of the brachiopod Terebratulina retusa places Brachiopoda within the protostomes Article in Proceedings of the Royal Society B: Biological Sciences · November 1999 DOI: 10.1098/rspb.1999.0885 · Source: PubMed CITATIONS READS 83 50 2 authors, including: Martin Schlegel University of Leipzig 151 PUBLICATIONS 2,931 CITATIONS SEE PROFILE Some of the authors of this publication are also working on these related projects: Rare for a reason? Scale-dependence of factors influencing rarity and diversity of xylobiont beetles View project Bat diversity and vertical niche activity in the fluvial flood forest Leipzig View project All content following this page was uploaded by Martin Schlegel on 22 May 2014. The user has requested enhancement of the downloaded file. Analysis of the complete mitochondrial DNA sequence of the brachiopod Terebratulina retusa places Brachiopoda within the protostomes Alexandra Stechmann* and Martin Schlegel UniversitÌt Leipzig, Institut fÏr Zoologie/Spezielle Zoologie,Talstr. 33, 04103 Leipzig, Germany Brachiopod phylogeny is still a controversial subject. Analyses using nuclear 18SrRNA and mitochondrial 12SrDNA sequences place them within the protostomes but some recent interpretations of morphological data support a relationship with deuterostomes. In order to investigate brachiopod a¤nities within the metazoa further,we compared the gene arrangement on the brachiopod mitochondrial genome with several metazoan taxa. The complete (15 451bp) mitochondrial DNA (mtDNA) sequence of the articulate brachiopod Terebratulina retusa was determined from two overlapping long polymerase chain reaction products. All the genes are encoded on the same strand and gene order comparisons showed that only one major rearrangement is required to interconvert the T.retusa and Katharina tunicata (Mollusca: Polyplaco- phora) mitochondrial genomes.
    [Show full text]
  • Coincidence of Photic Zone Euxinia and Impoverishment of Arthropods
    www.nature.com/scientificreports OPEN Coincidence of photic zone euxinia and impoverishment of arthropods in the aftermath of the Frasnian- Famennian biotic crisis Krzysztof Broda1*, Leszek Marynowski2, Michał Rakociński1 & Michał Zatoń1 The lowermost Famennian deposits of the Kowala quarry (Holy Cross Mountains, Poland) are becoming famous for their rich fossil content such as their abundant phosphatized arthropod remains (mostly thylacocephalans). Here, for the frst time, palaeontological and geochemical data were integrated to document abundance and diversity patterns in the context of palaeoenvironmental changes. During deposition, the generally oxic to suboxic conditions were interrupted at least twice by the onset of photic zone euxinia (PZE). Previously, PZE was considered as essential in preserving phosphatised fossils from, e.g., the famous Gogo Formation, Australia. Here, we show, however, that during PZE, the abundance of arthropods drastically dropped. The phosphorous content during PZE was also very low in comparison to that from oxic-suboxic intervals where arthropods are the most abundant. As phosphorous is essential for phosphatisation but also tends to fux of the sediment during bottom water anoxia, we propose that the PZE in such a case does not promote the fossilisation of the arthropods but instead leads to their impoverishment and non-preservation. Thus, the PZE conditions with anoxic bottom waters cannot be presumed as universal for exceptional fossil preservation by phosphatisation, and caution must be paid when interpreting the fossil abundance on the background of redox conditions. 1 Euxinic conditions in aquatic environments are defned as the presence of H2S and absence of oxygen . If such conditions occur at the chemocline in the water column, where light is available, they are defned as photic zone euxinia (PZE).
    [Show full text]
  • Clustered Brachiopod Hox Genes Are Not Expressed Collinearly and Are
    Clustered brachiopod Hox genes are not expressed PNAS PLUS collinearly and are associated with lophotrochozoan novelties Sabrina M. Schiemanna,1, José M. Martín-Durána,1, Aina Børvea, Bruno C. Vellutinia, Yale J. Passamaneckb, and Andreas Hejnol1,a,2 aSars International Centre for Marine Molecular Biology, University of Bergen, Bergen 5006, Norway and bKewalo Marine Laboratory, Pacific Biosciences Research Center, University of Hawaii, Honolulu, HI 96822 Edited by Sean B. Carroll, Howard Hughes Medical Institute and University of Wisconsin–Madison, Madison, WI, and approved January 19, 2017 (received for review August 30, 2016) Temporal collinearity is often considered the main force preserving viding spatial information (29). They also are involved in Hox gene clusters in animal genomes. Studies that combine patterning different tissues (30), and often have been recruited genomic and gene expression data are scarce, however, particularly for the evolution and development of novel morphological traits, in invertebrates like the Lophotrochozoa. As a result, the temporal such as vertebrate limbs (31, 32), cephalopod funnels and arms collinearity hypothesis is currently built on poorly supported foun- (28), and beetle horns (33). dations. Here we characterize the complement, cluster, and expres- Thus, it is not surprising that Hox genes show diverse ar- sion of Hox genes in two brachiopod species, Terebratalia transversa rangements regarding their genomic organization and expression and Novocrania anomala. T. transversa has a split cluster with 10 profiles in the Spiralia (34), a major animal clade that includes lab pb Hox3 Dfd Scr Lox5 Antp Lox4 Post2 Post1 genes ( , , , , , , , , ,and ), highly disparate developmental strategies and body organizations N. anomala Post1 whereas has 9 genes (apparently missing ).
    [Show full text]
  • GY 112L: Earth History Lab
    UNIVERSITY OF SOUTH ALABAMA GY 112L: Earth History Lab Week 9: Paleozoic Part 3 Instructor: Dr. Douglas W. Haywick Today’s Agenda The Paleozoic Part 3 (Week 9 exercises) 1) Brachiopods 2) Molluscs 3) Alabama Stratigraphy Brachiopoda Brachiopod Facts: Taxonomy: (under review) Phylum: Brachiopoda Class: Inarticulata Class: Articulata Brachiopoda Brachiopod Facts: Taxonomy: Phylum: Brachiopoda Class: Inarticulata Class: Articulata Range: Cambrian-Recent (Inarticulates were first) Brachiopoda Brachiopod Facts: Taxonomy: Phylum: Brachiopoda Class: Inarticulata Class: Articulata Range: Cambrian-Recent Mode of Life: Marine, benthic, filter feeder Brachiopoda Brachiopod Facts: Taxonomy: Phylum: Brachiopoda Class: Inarticulata Class: Articulata Range: Cambrian-Recent Mode of Life: Marine, benthic, filter feeder Mineral composition: calcite, phosphate Brachiopoda Brachiopod Facts: Taxonomy: Phylum: Brachiopoda Class: Inarticulata Class: Articulata Range: Cambrian-Recent Mode of Life: Marine, benthic, filter feeder Mineral composition: calcite, phosphate Fossil Pres.: pristine (sometimes external molds) The Brachiopod Animal Inarticulates The Brachiopod Animal Inarticulates Brachiopod Symmetry Symmetrical across the valves (down the medial line) Brachiopod Symmetry Symmetrical across the valves (down the medial line) Brachiopod Symmetry Symmetrical across the valves (down the medial line) Articulate Brachiopods Brachiopod Symmetry Symmetrical across the valves (down the medial line) Articulate Brachiopods Brachiopod Symmetry Not symmetrical between
    [Show full text]
  • Fossils of Indiana of Indiana of Indiana
    Fossils of Indiana Lesson Plan Grades 4 ––– 666 INFORMATION FOR EDUCATORS TABLE OF CONTENTS Background Text for Educators……pps. 3 – 9 Vocabulary…………………………pps. 10 – 12 Discussion Questions…………........pps. 13 – 17 Activities…………………………...pps. 18 – 32 Additional Activities……………….pps. 33 – 37 Activity Handouts………………….pps. 38 – 45 Activity Answers..…………………pps. 46 – 49 Resources……………………………p. 50 Evaluation……………………………p. 51 INTRODUCTION The study of fossils is a key element to understanding our past. Fossils give us clues about how humans and different animals lived and evolved. This lesson plan incorporates oral and written language, reading, vocabulary development, science, social studies and critical thinking. The lessons contained in this packet are intended for grades 4 to 6. The activities are designed to be innovative and meet Indiana Academic Standards. The text and worksheets are reproducible. SETTING THE STAGE To begin the lesson plan, you might want the environment of your entire classroom to reflect the ideas of science, geology and discovery. This can be achieved by incorporating this theme into bulletin boards, learning centers, art projects and whatever else you are doing in your classroom. Educators looking for good picture resources for their classroom can contact the Indiana State Museum Store and ask about our The Carr Poster Series, which depicts animals throughout Indiana’s geologic history and includes a geologic timeline. When you set the tone of your classroom in this manner, learning becomes an all- encompassing experience for your students. We encourage you to use this lesson plan as a springboard to further knowledge about fossils and their importance in understanding history. This lesson plan is comprised of four general areas: Geologic Time, Fossil Formation, Discovering Fossils and Paleozoic Fossils.
    [Show full text]
  • Discovery and Evolution of Novel Hemerythrin Genes in Annelid Worms Elisa M
    Costa-Paiva et al. BMC Evolutionary Biology (2017) 17:85 DOI 10.1186/s12862-017-0933-z RESEARCHARTICLE Open Access Discovery and evolution of novel hemerythrin genes in annelid worms Elisa M. Costa-Paiva1,2, Nathan V. Whelan2,3, Damien S. Waits2, Scott R. Santos2, Carlos G. Schrago1 and Kenneth M. Halanych2* Abstract Background: Despite extensive study on hemoglobins and hemocyanins, little is known about hemerythrin (Hr) evolutionary history. Four subgroups of Hrs have been documented, including: circulating Hr (cHr), myohemerythrin (myoHr), ovohemerythrin (ovoHr), and neurohemerythrin (nHr). Annelids have the greatest diversity of oxygen carrying proteins among animals and are the only phylum in which all Hr subgroups have been documented. To examine Hr diversity in annelids and to further understand evolution of Hrs, we employed approaches to survey annelid transcriptomes in silico. Results: Sequences of 214 putative Hr genes were identified from 44 annelid species in 40 different families and Bayesian inference revealed two major clades with strong statistical support. Notably, the topology of the Hr gene tree did not mirror the phylogeny of Annelida as presently understood, and we found evidence of extensive Hr gene duplication and loss in annelids. Gene tree topology supported monophyly of cHrs and a myoHr clade that included nHrs sequences, indicating these designations are functional rather than evolutionary. Conclusions: The presence of several cHrs in early branching taxa suggests that a variety of Hrs were present in the common ancestor of extant annelids. Although our analysis was limited to expressed-coding regions, our findings demonstrate a greater diversity of Hrs among annelids than previously reported.
    [Show full text]
  • Nemertean and Phoronid Genomes Reveal Lophotrochozoan Evolution and the Origin of Bilaterian Heads
    Nemertean and phoronid genomes reveal lophotrochozoan evolution and the origin of bilaterian heads Author Yi-Jyun Luo, Miyuki Kanda, Ryo Koyanagi, Kanako Hisata, Tadashi Akiyama, Hirotaka Sakamoto, Tatsuya Sakamoto, Noriyuki Satoh journal or Nature Ecology & Evolution publication title volume 2 page range 141-151 year 2017-12-04 Publisher Springer Nature Macmillan Publishers Limited Rights (C) 2017 Macmillan Publishers Limited, part of Springer Nature. Author's flag publisher URL http://id.nii.ac.jp/1394/00000281/ doi: info:doi/10.1038/s41559-017-0389-y Creative Commons Attribution 4.0 International (http://creativecommons.org/licenses/by/4.0/) ARTICLES https://doi.org/10.1038/s41559-017-0389-y Nemertean and phoronid genomes reveal lophotrochozoan evolution and the origin of bilaterian heads Yi-Jyun Luo 1,4*, Miyuki Kanda2, Ryo Koyanagi2, Kanako Hisata1, Tadashi Akiyama3, Hirotaka Sakamoto3, Tatsuya Sakamoto3 and Noriyuki Satoh 1* Nemerteans (ribbon worms) and phoronids (horseshoe worms) are closely related lophotrochozoans—a group of animals including leeches, snails and other invertebrates. Lophotrochozoans represent a superphylum that is crucial to our understand- ing of bilaterian evolution. However, given the inconsistency of molecular and morphological data for these groups, their ori- gins have been unclear. Here, we present draft genomes of the nemertean Notospermus geniculatus and the phoronid Phoronis australis, together with transcriptomes along the adult bodies. Our genome-based phylogenetic analyses place Nemertea sis- ter to the group containing Phoronida and Brachiopoda. We show that lophotrochozoans share many gene families with deu- terostomes, suggesting that these two groups retain a core bilaterian gene repertoire that ecdysozoans (for example, flies and nematodes) and platyzoans (for example, flatworms and rotifers) do not.
    [Show full text]
  • Changing Depositional Environments in an Upper Ordovician Stratigraphic Sequence, Ashlock Formation, Madison County, Kentucky
    Eastern Kentucky University Encompass Geosciences Undergraduate Theses Geosciences Fall 2010 Changing Depositional Environments in an Upper Ordovician Stratigraphic Sequence, Ashlock Formation, Madison County, Kentucky Kevin Greff Follow this and additional works at: https://encompass.eku.edu/geo_undergradtheses CHANGING DEPOSITIONAL ENVIRONMENTS IN AN UPPER ORDOVICIAN STRATIGRAPHIC SEQUENCE, ASHLOCK FORMATION, MADISON COUNTY, KENTUCKY By KEVIN GRANT GREFF Bachelor of Science Eastern Kentucky University Richmond, Kentucky 2010 Submitted to Dr. Walter S. Borowski Department of Geography and Geology Eastern Kentucky University Senior Thesis, BACHELOR OF SCIENCE in GEOLOGY August, 2010 ABSTRACT We investigate the sedimentology, stratigraphy, and depositional environments of a 7-meter, Upper Ordovician limestone sequence cropping out in Richmond, Kentucky. The stratigraphic section lies within the Ashlock Formation with good lateral exposure stretching along 200 meters of a highway roadcut. We took approximately 20 samples from the measured section, focusing on representative samples and lithologic transitions. We use standard laboratory procedures in slabbing rock samples and making thin sections. The Ashlock Formation at this locality consists of alternating layers of limey mudstone and limestone. Megafossils - brachiopods, bryozoans, trilobites, gastropods, ostracodes, coralline algae, and bivalves - are abundant in various limestone units. The observed transitions from limestones and limy muds to lithologies with more terrigenous mud suggests any combination of: (1) migration of depositional environment with a slight increase in water depth; (2) climatic change resulting in more runoff; or (3) tectonic activity delivering more mud to the basin. These shallow water environments change to glauconitic mudstone and laminated shales, which we interpret as deeper shelf deposits. The measured section is capped by shaley limestones and mudstones that signal a return to shallow subtidal environments.
    [Show full text]
  • Mitochondrial Genomes of Clymenella Torquata (Maldanidae) and Riftia Pachyptila (Siboglinidae): Evidence for Conserved Gene Order In
    p. 1 Submitted to MBE as Research Article Mitochondrial Genomes of Clymenella torquata (Maldanidae) and Riftia pachyptila (Siboglinidae): Evidence for Conserved Gene Order in Annelida Robert M. Jennings* and Kenneth M. Halanych*,† * Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543 USA email: [email protected] † Department of Biological Sciences, Auburn University, Auburn, Alabama 36849 USA email: [email protected] Running Title: Annelid mtDNA Key Words: Phylogeny, gene order, mitochondria, genome, Annelida Contact information: Ken Halanych Department of Biological Sciences 101 Life Science Building Auburn University, AL 36849 Phone: (334) 844-3222 Fax: (334) 844-2333 Email: [email protected] p. 2 Abstract Mitochondrial genomes are useful tools for inferring evolutionary history. However, many taxa are poorly represented by available data. Thus, to further understand the phylogenetic potential of complete mitochondrial genome sequence data in Annelida (segmented worms), we examined the complete mitochondrial sequence for Clymenella torquata (Maldanidae) and an estimated 80% of the sequence of Riftia pachyptila (Siboglinidae). These genomes have remarkably similar gene orders to previously published annelid genomes, suggesting that gene order is conserved across annelids. This result is interesting given the high variation seen in the closely related Mollusca and Brachiopoda. Phylogenetic analyses of DNA sequence, amino acid sequence and gene order all support the recent hypothesis that Sipuncula and Annelida are closely related. Our findings suggest that gene order data is of limited utility in annelids but that sequence data holds promise. Additionally, these genomes show AT bias (~66%) and codon usage biases, but have a typical gene complement for bilaterian mitochondrial genomes. p.
    [Show full text]
  • The Macro-Structure of Modern and Fossil Brachiopod Archives Abstract Shells of Brachiopods Chemistry Proxy for Paleo-Environmen
    The macro-structure of modern and fossil brachiopod archives Abstract Brachiopods, are not the dominant element in modern oceans, but were very common in the past. Over 12,000 species and 5,000 genera fossils have found and recognized. As high variation and longtime distribution in the Paleozoic ocean, brachiopods are very important tools for paleontology research. Moreover, owing to the unique features of shells, which may very hard withstanding post-depositional alteration, and be considered the very credible indicators of climate changes in the ancient oceans. Shells of brachiopods Brachiopods have two hard "valves" (or shells: ventral valve and dorsal valve) on the upper and lower surfaces, also be called “lamp shells” due to the curved shells of the class Terebratulida look rather like pottery oil-lamps. Based on the hinged tooth and socket arrangement between two valves, there are two major groups of brachiopods are recognized, articulate and inarticulate. From outside to inside, articulate brachiopod shells are generally composed of following representative shell layers: 1)a thin organic periostracum (rarely preserved in fossils); 2)a thin outer primary layer(rare except in extremely well-preserved fossil shells); 3)a thicker inner secondary layer(always present in fossils); 4)a tertiary layer(always absent except in specific order). (e.g., Armstrong, 1968; Williams, 1968, 1997; Grossman et al., 1993; Azmy et al., 1998, 2006) Different kinds of brachiopods will have very different fabrics and structure of the layers, especially in the secondary layer. (Williams, 1997) Detailed different kinds secondary layer have described in (Williams, 1997): 1) organophosphatic lamination; 2) calcitic fabrics; 3) calcitic fibers; 4) calcitic tabular lamination; 5) calcitic cross-bladed lamination.
    [Show full text]