DOCSLIB.ORG

Fossil Invertebrates of the Phanerozoic

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

The Origin of Phyla and the Cambrian Explosion of Life Geology 230 Fossils and Evolution Cambrian Life • The first animals evolved about 60 my before the start of the Cambrian. These are the Ediacaran fossils of the latest Proterozoic. • None of these animals had hard parts. • Base of the Cambrian defined by first animals with hard parts. Life at the end of the Proterozoic Life at the end of the Proterozoic Cambrian Life • Early Cambrian fossils consist mostly of small little shells that are later followed by trilobites and brachiopods. Small little shells: sclerites on soft-bodied animals Cambrian trilobites cruising on Saturday night Typical Cambrian trilobites Modern horseshoe crabs look similar to trilobites, but they are not closely related. Example of a “living fossil.” Trilobites are extinct. A living Inarticulate Brachiopod. Very common in the Cambrian. Modern Inarticulate Brachiopods in their burrows Modern Inarticulate Brachiopods for dinner The Cambrian “Explosion” of Life • What is the Cambrian “Explosion”? • Is it a true explosion of phyla, or was there a “slow fuse” back into the Proterozoic? • Why did so many new phyla appear at this time? Hox genes hold the answer. • Why have no new phyla appeared since this time? MicroRNA holds the answer. The Tree of Life www.evogeneao.com/tree.html Cambrian Explosion, radiation of triploblasts (3 tissue layers) Diploblasts (2 tissue layers) Diploblastic Animals: Triploblastic Animals: Two Tissue Layers Three Tissue Layers Mesoderm in blue (jelly) Deuterostomes (mouth is second opening during development) Protostomes (mouth is first opening during development) Ecdysozoa Lophotrochozoa Protostomes (mouth is first opening during development) Deuterostomes (mouth is second opening during development) Prothero, 2007 Prothero, 2007 Hox genes determine the head to tail anatomy of animals. Vertebrates have 4 sets, but their Hox genes are almost identical to those of insects. Mutations in Hox genes create new body plans or phyla. Videos Genetic Tool Kit: Hox genes http://www.pbs.org/wgbh/evolution/library/03/4/l_034_04.html The Cambrian Explosion http://www.pbs.org/wgbh/evolution/library/03/4/l_034_02.html HOX Genes – arranged in order of expression from anterior to posterior Molecular Paleobiology Metazoan Phylogeny Based on the Fossil Record and Molecular Clocks (see Fig. 10.11 in Zimmer) Explosion of Phyla Triploblasts Slow fuse Kevin Peterson, Dartmouth MicroRNA genes: Their evolutionary significance has only been recently understood. They come from “redundant” DNA. They are responsible for developmental precision. MicroRNAs are continually acquired and fixed in animal genomes with the most morphologically complex animals having the greatest number of microRNAs. jellyfish Diploblasts flatworm earthworm Protostomes millipede arthropods Triploblasts Sea urchin Deuterostomes Sea squirt lancelet fish Vertebrates frog Tetrapods dog monkey Time, Ma Kevin Peterson, Dartmouth MicroRNA constrains variability during development so that morphological innovations are constrained as developmental precision increases allowing more complex animals. Note that the microRNA differences between phyla were 95% complete by the end of the Cambrian, and 90% for classes by the Ordovician. of homologous homologous microRNA of Cambrian Ordovician Kevin Peterson, Dartmouth The Burgess Shale of British Columbia: record of the Cambrian Explosion Mt. Stephen in Yoho National Park, Canada Geologists at the Burgess Shale quarry Trilobites! Charles Walcott, Smithsonian Institution Geologist, at the Burgess Shale Quarry, ~ 1910 Paleontologist collecting a slab of fossils Trilobites with preserved legs and antennae The strange animals of the Middle Cambrian Burgess Shale Opabinia and Amwiskia, representatives of two extinct phyla Opabinia Burgess Shale worm Ottoia A spiny “worm,” Wiwaxia Hallucigenia, a spiny lobopod Hallucigenia Specimens of lobopods Living and fossil lobopods Early crustacean from the Burgess Shale, Canadapsis The first sea scorpion on the attack! Marella, extinct class of arthropods Marella as Cambrian road kill (or a squished bug?) Yohoia, an extinct class of arthropods Anomalocaris, the largest predator of the Cambrian. Is it an extinct phylum, or a proto-arthropod? Pikaia Anomalocaris in hot pursuit of Marella Pikaia, an early chordate Pikaia, a chordate from the Burgess Shale Yunnanozoan, a chordate from the early Cambrian of China.
Recommended publications
  • The Secrets of Fossils Lesson by Tucker Hirsch

    The Secrets of Fossils Lesson by Tucker Hirsch

    The Secrets of Fossils Lesson by Tucker Hirsch Video Titles: Introduction: A New view of the Evolution of Animals Cambrian Explosion Jenny Clack, Paleontologist: The First Vertebrate Walks on Land Des Collins, Paleontologist: The Burgess Shale Activity Subject: Assessing evolutionary links NEXT GENERATION SCIENCE STANDARDS and evidence from comparative analysis of the fossil MS-LS4-1 Analyze and interpret data for patterns record and modern day organisms. in the fossil record that document the existence, diversity, extinction, and change of life forms Grade Level: 6 – 8 grades throughout the history of life on Earth under the Introduction assumptions that natural laws operate today as In this lesson students make connections between in the past. [Clarification Statement: Emphasis fossils and modern day organisms. Using the is on finding patterns of changes in the level of information about the Cambrian Explosion, they complexity of anatomical structures in organisms explore theories about how and why organisms diversified. Students hypothesize what evidence and the chronological order of fossil appearance might be helpful to connect fossil organisms to in the rock layers.] [Assessment Boundary: modern organisms to show evolutionary connections. Assessment does not include the names of Students use three videos from shapeoflife.org. individual species or geological eras in the fossil record.] Assessments Written MS-LS4-2 Apply scientific ideas to construct an Time 100-120 minutes (2 class periods) explanation for the anatomical similarities and Group Size Varies; single student, student pairs, differences among modern organisms and between entire class modern and fossil organisms to infer evolutionary relationships. [Clarification Statement: Emphasis Materials and Preparation is on explanations of the evolutionary relationships • Access to the Internet to watch 4 Shape of Life videos among organisms in terms of similarity or • Video Worksheet differences of the gross appearance of anatomical • “Ancient-Modern” Activity.
  • For Peer Review 19 Precise Position Within Total�Group Mollusca Remains Unclear

    For Peer Review 19 Precise Position Within TotalGroup Mollusca Remains Unclear

    View metadata, citation and similar papers at core.ac.uk brought to you by CORE Lethaia provided by Apollo Sclerites and possible mouthparts of Wiwaxia from the temperate palaeolatitudes of Colombia, South America Journal:For Lethaia Peer Review Manuscript ID: LET-OA-02-15-0605.R1 Manuscript Type: Original Article Date Submitted by the Author: n/a Complete List of Authors: Smith, Martin; Royal Ontario Museum, Palaeobiology Hughes, Gareth; Petrostrat Ltd., Vargas, María; Instituto Colombiano del Petróleo-Ecopetrol, Biostratigraphy team de la Parra, Felipe; Instituto Colombiano del Petróleo-Ecopetrol, Biostratigraphy team Small Carbonaceous Fossils, Wiwaxia, Cambrian, South America, Keywords: palynological processing, biogeography Lethaia - manuscript copy Page 1 of 17 Lethaia 1 2 3 4 Sclerites and possible mouthparts of Wiwaxia from the temperate 5 6 palaeolatitudes of Colombia, South America 7 8 9 10 11 12 13 Martin R. Smith* [[email protected]], Department of Earth Sciences, Downing Site, 14 15 University of Cambridge, Cambridge, CB2 3EQ, UK 16 17 18 Gareth M. G. Hughes*For [[email protected]] Peer Review, PetroStrat Ltd., Tan-Y-Graig, 19 20 Parc Caer Seion, Conwy, LL32 8FA, UK 21 22 23 M. Carolina Vargas & Felipe de la Parra, Biostratigraphy team, Instituto Colombiano 24 25 del Petróleo-Ecopetrol, AA 4185, Bucaramanga, Colombia 26 27 28 * These authors contributed equally to the current study 29 30 Abstract 31 32 33 The problematic mollusc Wiwaxia is perhaps the most widely distributed 34 35 non-mineralized Cambrian metazoan, but has only been reported from palaeotropical 36 37 38 latitudes. Here we describe mid-Cambrian (Drumian, c.
  • The Early History of the Metazoa—A Paleontologist's Viewpoint

    The Early History of the Metazoa—A Paleontologist's Viewpoint

    ISSN 20790864, Biology Bulletin Reviews, 2015, Vol. 5, No. 5, pp. 415–461. © Pleiades Publishing, Ltd., 2015. Original Russian Text © A.Yu. Zhuravlev, 2014, published in Zhurnal Obshchei Biologii, 2014, Vol. 75, No. 6, pp. 411–465. The Early History of the Metazoa—a Paleontologist’s Viewpoint A. Yu. Zhuravlev Geological Institute, Russian Academy of Sciences, per. Pyzhevsky 7, Moscow, 7119017 Russia email: [email protected] Received January 21, 2014 Abstract—Successful molecular biology, which led to the revision of fundamental views on the relationships and evolutionary pathways of major groups (“phyla”) of multicellular animals, has been much more appre ciated by paleontologists than by zoologists. This is not surprising, because it is the fossil record that provides evidence for the hypotheses of molecular biology. The fossil record suggests that the different “phyla” now united in the Ecdysozoa, which comprises arthropods, onychophorans, tardigrades, priapulids, and nemato morphs, include a number of transitional forms that became extinct in the early Palaeozoic. The morphology of these organisms agrees entirely with that of the hypothetical ancestral forms reconstructed based on onto genetic studies. No intermediates, even tentative ones, between arthropods and annelids are found in the fos sil record. The study of the earliest Deuterostomia, the only branch of the Bilateria agreed on by all biological disciplines, gives insight into their early evolutionary history, suggesting the existence of motile bilaterally symmetrical forms at the dawn of chordates, hemichordates, and echinoderms. Interpretation of the early history of the Lophotrochozoa is even more difficult because, in contrast to other bilaterians, their oldest fos sils are preserved only as mineralized skeletons.
  • Ontogeny, Morphology and Taxonomy of the Softbodied Cambrian Mollusc

    Ontogeny, Morphology and Taxonomy of the Softbodied Cambrian Mollusc

    [Palaeontology, 2013, pp. 1–15] ONTOGENY, MORPHOLOGY AND TAXONOMY OF THE SOFT-BODIED CAMBRIAN ‘MOLLUSC’ WIWAXIA by MARTIN R. SMITH1,2,3 1Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, M5S 3G5, Canada 2Palaeobiology Section, Department of Natural History, Royal Ontario Museum, Toronto, Ontario, M5S 2C6, Canada 3Current address: Department of Earth Sciences, University of Cambridge, Cambridge, CB2 3EQ, UK; e-mail: [email protected] Typescript received 26 September 2012; accepted in revised form 25 May 2013 Abstract: The soft-bodied Cambrian organism Wiwaxia sclerites. I recognize a digestive tract and creeping foot in poses a taxonomic conundrum. Its imbricated dorsal scleri- Wiwaxia, solidifying its relationship with the contemporary tome suggests a relationship with the polychaete annelid Odontogriphus. Similarities between the scleritomes of worms, whereas its mouthparts and naked ventral surface Wiwaxia, halkieriids, Polyplacophora and Aplacophora hint invite comparison with the molluscan radula and foot. 476 that the taxa are related. A molluscan affinity is robustly new and existing specimens from the 505-Myr-old Burgess established, and Wiwaxia provides a good fossil proxy for Shale cast fresh light on Wiwaxia’s sclerites and scleritome. the ancestral aculiferan – and perhaps molluscan – body My observations illuminate the diversity within the genus plan. and demonstrate that Wiwaxia did not undergo discrete moult stages; rather, its scleritome developed gradually, with Key words: halwaxiids, scleritomorphs, Aculifera, Mollusca, piecewise addition and replacement of individually secreted evolution, Cambrian explosion. T HE slug-like Cambrian organism Wiwaxia perennially Nevertheless, Butterfield (2006, 2008) identified char- resists classification, in part due to its unusual scleritome acters that could place these taxa deeper within of originally chitinous scales and spines.
  • Wiwaxia from the Cambrian Stage 3 Xiaoshiba Lagerst¤Atte.',ScientiC Reports., 4

    Wiwaxia from the Cambrian Stage 3 Xiaoshiba Lagerst¤Atte.',ScientiC Reports., 4

    Durham Research Online Deposited in DRO: 17 November 2015 Version of attached le: Published Version Peer-review status of attached le: Peer-reviewed Citation for published item: Yang, J. and Smith, M.R. and Lan, T. and Hou, J.-B. and Zhang, X.-G. (2014) 'Articulated Wiwaxia from the Cambrian Stage 3 Xiaoshiba Lagerst¤atte.',Scientic reports., 4 . p. 4643. Further information on publisher's website: http://dx.doi.org/10.1038/srep04643 Publisher's copyright statement: This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. The images in this article are included in the article's Creative Commons license, unless indicated otherwise in the image credit; if the image is not included under the Creative Commons license, users will need to obtain permission from the license holder in order to reproduce the image. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-sa/3.0/ Additional information: Use policy The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that: • a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders. Please consult the full DRO policy for further details. Durham University Library, Stockton Road, Durham DH1 3LY, United Kingdom Tel : +44 (0)191 334 3042 | Fax : +44 (0)191 334 2971 https://dro.dur.ac.uk OPEN Articulated Wiwaxia from the Cambrian SUBJECT AREAS: Stage 3 Xiaoshiba Lagersta¨tte PALAEONTOLOGY Jie Yang1, Martin R.
  • Chapter 5. Paleozoic Invertebrate Paleontology of Grand Canyon National Park

    Chapter 5. Paleozoic Invertebrate Paleontology of Grand Canyon National Park

    Chapter 5. Paleozoic Invertebrate Paleontology of Grand Canyon National Park By Linda Sue Lassiter1, Justin S. Tweet2, Frederick A. Sundberg3, John R. Foster4, and P. J. Bergman5 1Northern Arizona University Department of Biological Sciences Flagstaff, Arizona 2National Park Service 9149 79th Street S. Cottage Grove, Minnesota 55016 3Museum of Northern Arizona Research Associate Flagstaff, Arizona 4Utah Field House of Natural History State Park Museum Vernal, Utah 5Northern Arizona University Flagstaff, Arizona Introduction As impressive as the Grand Canyon is to any observer from the rim, the river, or even from space, these cliffs and slopes are much more than an array of colors above the serpentine majesty of the Colorado River. The erosive forces of the Colorado River and feeder streams took millions of years to carve more than 290 million years of Paleozoic Era rocks. These exposures of Paleozoic Era sediments constitute 85% of the almost 5,000 km2 (1,903 mi2) of the Grand Canyon National Park (GRCA) and reveal important chronologic information on marine paleoecologies of the past. This expanse of both spatial and temporal coverage is unrivaled anywhere else on our planet. While many visitors stand on the rim and peer down into the abyss of the carved canyon depths, few realize that they are also staring at the history of life from almost 520 million years ago (Ma) where the Paleozoic rocks cover the great unconformity (Karlstrom et al. 2018) to 270 Ma at the top (Sorauf and Billingsley 1991). The Paleozoic rocks visible from the South Rim Visitors Center, are mostly from marine and some fluvial sediment deposits (Figure 5-1).
  • Proof for Review

    Proof for Review

    Proof For Review First report of Wiwaxia from the Ca mbrian Chengjiang Lagerstätte Journal:Proof Geological For Magazine Review Manuscript ID: GEO-14-1196.R1 Manuscript Type: Rapid Communication Date Submitted by the Author: n/a Complete List of Authors: Zhao, Fangchen; Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Smith, Martin R.; University of Cambridge, Department of Earth Sciences Yin, Zongjun; Nanjing Institute of Geology and Palaeontology, State Key Laboratory of Palaeobiology and Stratigraphy Zeng, Han; Nanjing Institute of Geology and Palaeontology, State Key Laboratory of Palaeobiology and Stratigraphy Hu, Shixue; Chengdu Center of China Geological Survey, Chengdu Institute of Geology and Mineral Resources Li, Guoxiang; Nanjing Institute of Geology and Palaeontology, State Key Laboratory of Palaeobiology and Stratigraphy Zhu, Maoyan; Chinese Academy of Sciences, Nanjing Institute of Geology and Palaeontology Maotianshan shale, Cambrian Series 2, Mollusca, halwaxiids, Cambrian Keywords: explosion, China Page 1 of 17 Proof For Review 1 2 3 4 First report of Wiwaxia from the Cambrian Chengjiang Lagerstätte 5 6 7 8 9 FANG-CHEN ZHAO *†, MARTIN R. SMITH ‡, ZONG-JUN YIN *, HAN ZENG *, 10 11 SHI-XUE HU §, GUO-XIANG LI * & MAO-YAN ZHU * 12 13 14 15 16 * State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of 17 18 Proof For Review 19 Geology and Palaeontology, Chinese Academy of Sciences, 39 East Beijing Road, 20 21 Nanjing 210008, China; 22 23 24 ‡ Department of Earth Sciences, University of Cambridge, Cambridge, CB2 3EQ, 25 26 UK. 27 28 29 § Chengdu Institute of Geology and Mineral Resources, Chengdu Center of China 30 31 Geological Survey, Chengdu 610081, China.
  • Interpreting the Paleoenvironmental Context of Marine Shales

    Interpreting the Paleoenvironmental Context of Marine Shales

    University of Wisconsin Milwaukee UWM Digital Commons Theses and Dissertations December 2012 Interpreting the Paleoenvironmental Context of Marine Shales Deposited During the Cambrian Radiation: Global Insights from Sedimentology, Paleoecology, and Geochemistry Tristan Kloss University of Wisconsin-Milwaukee Follow this and additional works at: https://dc.uwm.edu/etd Part of the Geology Commons Recommended Citation Kloss, Tristan, "Interpreting the Paleoenvironmental Context of Marine Shales Deposited During the Cambrian Radiation: Global Insights from Sedimentology, Paleoecology, and Geochemistry" (2012). Theses and Dissertations. 59. https://dc.uwm.edu/etd/59 This Dissertation is brought to you for free and open access by UWM Digital Commons. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of UWM Digital Commons. For more information, please contact [email protected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
  • The Cambrian Explosion - 550-544 Ma ?

    The Cambrian Explosion - 550-544 Ma ?

    Milestones in the first 3 billion years of life • Origin of life - before 3.8 Ga • Origin of eukaryotes - before 1.4 Ga; before 2.7 Ga ? • Origin of animals (multicellularity) - 600-800 Ma ? • Origin of skeletons - 550 Ma ? • The Cambrian Explosion - 550-544 Ma ? The Cambrian Explosion The relatively sudden appearance and diversification of almost all of the phyla (all but Bryozoa) in the early Cambrian. This event began around 550 million years ago and lasted no more than 20-30 million years. 1 Key Faunas Before/After the Cambrian Explosion: • Burgess Shale (505 Ma) • Chengjiang (520 Ma) • Small Shellies (Manykaian Stage) (544-530 Ma) • Doushantuo embryos (580-570 Ma) • Ediacara (575-545 Ma) The Ediacara Biota 2 The Ediacara Biota Parvancorina Dickensonia Cyclomedusa Tribrachidium Mawsonite s The Ediacara Biota Spriggina Charnia 3 Spaniard's Bay in eastern Newfoundland. 4 The “traditional” interpretation of Ediacara (from Glaessner (1984) Ediacara fronds: Comparison with living Pennatulacean Cnidarians 5 “Traditional” reconstructions of the Ediacara Biota A radical alternative interpretation of the Ediacara Biota: Vendobionta (From Seilacher, 1989) 6 A Chordate in the Ediacara?? (2003) Length ca. 5 cm) The latest on Ediacara… Nov. 2003 • There may be actual bilaterians among the Ediacaran biota • There are at least 3 biostratigraphically recognizeable assemblages: – Avalon 575-565 (e.g., Mistaken Point, Newfoundland) – Nama 565-550 – White Sea 550-545 7 The Ediacara Biota at Mistaken Point, Newfoundland http://geol.queensu.ca/museum/exhibits/ediac/mistaken_point/mistaken_pt.html Key Faunas Before/After the Cambrian Explosion: • Burgess Shale (505 Ma) • Chengjiang (520 Ma) • Small Shellies (Manykaian Stage) (544-530 Ma) • Doushantuo embryos (580-570 Ma) • Ediacara (575-545 Ma) 8 Doushantuo embryos http://more.abcnews.go.com/sections/science/DailyNews/fossils0204.html Bengtson & Zhao 1997, a SEM image depicting a suggested metazoan embryo – possibly Olivooides multisulcatus – at approximately the 256-cell stage.

  • Vinther, J., Parry, L., Briggs, D., & Van Roy, P. (2017). Ancestral

    Vinther, J. , Parry, L., Briggs, D., & Van Roy, P. (2017). Ancestral morphology of crown-group molluscs revealed by a new Ordovician stem aculiferan. Nature, 542(7642), 471–474. https://doi.org/10.1038/nature21055 Peer reviewed version Link to published version (if available): 10.1038/nature21055 Link to publication record in Explore Bristol Research PDF-document This is the accepted author manuscript (AAM). The final published version (version of record) is available online via Nature at http://www.nature.com/nature/journal/vaop/ncurrent/full/nature21055.html. Please refer to any applicable terms of use of the publisher. University of Bristol - Explore Bristol Research General rights This document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/red/research-policy/pure/user-guides/ebr-terms/ 1! Ancestral*morphology*of*crown3group*molluscs*revealed*by*a*new* 2! Ordovician*stem*aculiferan** 3! ! 4! Jakob!Vinther1,2*,!Luke!Parry1,3*,!Derek!E.!G.!Briggs4,5,!Peter!Van!Roy4,6!! 5! ! 6! 1School!of!Biological!Sciences,!University!of!Bristol,!Life!Sciences,!Building,!24! 7! Tyndall!Avenue,!Bristol!BS8!1TQ,!UK.! 8! 2!SChool!of!Earth!SCienCes,!University!of!Bristol,!Wills!Memorial!Building,!Queen’s! 9! Road,!Bristol!BS8!1RJ,!UK.! 10! 3!Department!of!Earth!SCienCes,!The!Natural!History!Museum,!Cromwell!Road,! 11! London,!SW7!5BD.! 12! 4Department!of!Geology!and!GeophysiCs,!Yale!University,!New!Haven,!CT!06511,! 13!
  • Shallow−Water Occurrence of Wiwaxia in the Middle Cambrian of the Barrandian Area, Czech Republic

    Shallow−Water Occurrence of Wiwaxia in the Middle Cambrian of the Barrandian Area, Czech Republic

    Shallow−water occurrence of Wiwaxia in the middle Cambrian of the Barrandian area, Czech Republic OLDŘICH FATKA, PETR KRAFT, and MICHAL SZABAD Isolated sclerites of the genus Wiwaxia are reported from Geologic setting and stratigraphy shale interlayers in lower levels of middle Cambrian (un− named 3rd Series of Cambrian) Buchava Formation in the For the first time the lithostratigraphy of Cambrian in the Skryje− Skryje−Týřovice Basin in the Czech Republic interpreted Týřovice Basin was studied by Barrande (1846). Fatka et al. (in as shallow−water sediments. Geographic distribution of press) summarised the earlier data and distinguished four separate Wiwaxia indicates latitudinal control as all occurrences are members within the Buchava Formation in recent terminology obviously restricted to tropical belt. (Fig. 1). The locality “Orthisový lůmek” near Skryje exposes lower portion of the sequence, from upper levels of the Mileč Member to lower levels of Skryje Member. Detailed description Introduction of the section was published by Kettner (1923: 16). A rich record of specimens with slightly sclerotised skeletal parts or even soft−bodied fossils have been established from several Fauna of the Mileč and Slapnice members well−known lower and middle Cambrian Lagerstätte, e.g., Bur− gess Shale of the Stephen Formation, Kinzers, Marjum, and Sclerites of Wiwaxia were discovered in basal clastic sediments Wheeler formations in North America; Buen Formation in North referred to the Slapnice Member. Slapnice and Mileč members Greenland; Doushantuo, Chengjiang, and Kaili in China; Emu yielded almost identical faunal assemblages, which strongly dif− Bay Shale in Australia and Sinsk FormationinRussia(Conway fers from fauna of the overlaying Skryje Shale.
  • Thomas Dahlgren

    Thomas Dahlgren

    GÖTEBORG UNIVERSITY FACULTY OF NATURAL SCIENCES FROM INDIVIDUALS TO DEEP METAZOAN BRANCHES: RELATIONSHIPS AND DELINEATION OF RECENT AND FOSSIL CHRYSOPETALIDAE (ANNELIDA) Thomas Dahlgren Dissertation Department of Zoology Box 463 405 90 Göteborg SWEDEN Avhandling för filosofie doktorsexamen i zoologi som enligt beslut av tjänsteförslagsnämnden i biologi kommer att offentligen försvaras fredagen den 5:e maj 2000 kl. 10.00 i föreläsningssalen, Zoologiska Institutionen, Medicinaregatan 18, Göteborg. Examinator: Professor Bengt Silverin. Fakultetsopponent: Danny Eibye- Jacobsen Zoologisk Museum, Köpenhamn. FROM INDIVIDUALS TO DEEP METAZOAN BRANCHES: RELATIONSHIPS AND DELINEATION OF RECENT AND FOSSIL CHRYSOPETALIDAE (ANNELIDA) Thomas Dahlgren Department of Zoology, Göteborg University, Box 463, 405 90 Göteborg, Sweden Email: [email protected] Abstract: The chrysopetalid polychaetes are a small group of marine worms that have a global distribution but are most common on tropical coral reefs. Most of the ca. 50 described forms are distinguished by flattened notochaetae which are arranged as roofing tiles on the dorsum. Recent attention to the group has focused on a possible close relationship between chrysopetalids and the Cambrian fossil worms Wiwaxia and Canadia, known mainly from the Burgess Shale, British Columbia. Despite several descriptive studies on the group, one part of the Chrysopetalidae, the “dysponetid” taxa, has been largely neglected. In papers I, II and III, two new (Dysponetus bipapillatus and D. macroculatus) and two poorly known taxa (D. caecus and D. paleophorus) are described from newly collected specimens. Apart from the aim to increase our knowledge on the organismal diversity among the dysponetids, this thesis is the first attempt to resolve problems concerning the phylogeny of chrysopetalids and its allies.