DOCSLIB.ORG

The Continuing Classificatory Conundrum of Chaetognaths

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Continuing Classificatory Conundrum of Chaetognaths View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Elsevier - Publisher Connector Dispatch R593 action-specific reward values in the 13. Rabin, M. (1993). Incorporating Department of Psychological and Brain striatum. Science 310, 1337–1340. Fairness into Game Theory and Sciences and Krieger Mind/Brain 11. Matsumoto, K., Suzuki, W., and Economics. Am. Econ. Rev. 83, Institute, Johns Hopkins University, Tanaka, K. (2003). Neuronal correlates of 1281–1302. goal-based motor selection in the 14. de Quervain, D.J., Fischbacher, U., 3400 North Charles Street, Baltimore, prefrontal cortex. Science 301, Treyer, V., Schellhammer, M., Maryland 21218, USA. 229–232. Schnyder, U., Buck, A., and Fehr, E. E-mail: [email protected] 12. Camerer, C.F. (2003). Behavioral Game (2004). The neural basis of altruistic Theory (Princeton: Princeton University punishment. Science 305, Press). 1254–1258. DOI: 10.1016/j.cub.2006.07.005 Phylogeny: The Continuing chaetognaths, although it bears some resemblance to the nervous Classificatory Conundrum of systems of nematodes, kinorhynchs and priapulids [1]. The Chaetognaths age of the phylum is borne out by fossils from the Cambrian Burgess Shale which show a remarkable The phylogenetic conundrum posed by the Chaetognatha, a cryptic resemblance to modern phylum consisting largely of planktonic predators, is the subject of two chaetognaths [3] (Figure 2), short papers in this issue of Current Biology. These analyses go some suggesting chaetognaths have way towards defining the phylogenetic position of the chaetognaths, existed without major which possess features apparently spanning the protostome/ morphological change for at least deuterostome divide. 500 million years. Chaetognaths are unusual among marine Eldon E. Ball1,* and David J. Miller2 of the chaetognaths (Figure 1A,B) invertebrates in that they are direct is relatively constant across the developers, hatching from the egg It would be difficult to invent a more phylum, although details may vary essentially as small adults rather bizarre group of creatures than the considerably. The structure of the than as a distinct larval stage. chaetognaths or arrow worms, nervous system reveals little about Chaetognaths appear to rely (literally ‘bristle jaws’). The the evolutionary affinities of mainly on vibrations for information chaetognaths are an ancient lineage of invertebrates that shares Figure 1. Chaetognath mor- A BC phology. some characteristics with just Grasping (A) The deep water chaetog- spines about every other major Ciliate corona invertebrate phylum and has nath Eukrohnia sp. from the Sargasso Sea (Photo Collarette consequently puzzled taxonomists courtesy Russ Hopcroft/ Intestine ever since its original description in UAF/NOAA/CoML). In con- 1769. Darwin described trast to most shallow water forms, this species is chaetognaths as ‘‘remarkable for Hair fans pigmented, making the in- the obscurity of their affinities’’ and Muscles they have puzzled a succession of ternal organs easily visible. (B) This labelled drawing of Lateral eminent zoologists ever since [1]. the pelagic chaetognath, fin Though unfamiliar to most Heterokrohnia, provides a good introduction to the biologists, chaetognaths are Ovary typically the most abundant basic features of chaetog- Anus planktonic predators, sometimes nath anatomy. Some au- Posterior septum accounting for more than 10% of thors divide the body into head and trunk, while others Testis zooplankton biomass and being add a tail, dividing the trunk outnumbered only by their major at the posterior septum. Muscles prey, the copepods. Approximately There are three body cavi- Median 20 genera have been described, ties, which, together with mesentery containing more than 100 the cuticle and the longitudi- Caudal species ([2], see also: http:// nal muscles, form a hydro- static skeleton. One or two fin academic.evergreen.edu/t/ pairs of longitudinal fins pro- Current Biology thuesene/chaetognaths/ vide stabilisation, while the chaetognaths.htm). flattened caudal fin provides locomotory power. There is no circulatory system and no Although most chaetognaths specialised excretory system. The anterior grasping spines used in prey capture are are only a few mm in size and shown spread, although they are normally folded under a hood, which presumably planktonic, there are some inshore serves the dual purpose of protecting them and streamlining the head during swimming. Eggs are released into the thoracic coelomic space and sperm into the coelomic space of benthic and deep-water species the tail. Modified from [20], with permission. (C) Drawing of Sagitta hispida showing the that may be much larger, up to 12 closely spaced hair fans which presumably provide the sensory input required for such cm in length. The basic body plan complex behaviours as mating and prey capture. Modified with permission from [4]. Current Biology Vol 16 No 15 R594 Grasping Figure 2. Fossil chaetog- months in the upper 100 m, spines naths. descending to the 100–250 m The assumption that mod- zone during the winter. Transverse ern chaetognaths epitomize muscles All chaetognath species that an ancient and successful Intestine anatomical design, which have been studied are has remained unchanged hermaphrodites with testes in the Ventral ganglion since the Cambrian, is con- tail and ovaries in the posterior firmed by beautiful fossils trunk, the latter maturing only after Ovaries from the Burgess Shale, the tail coeloms are filled with Anus such as this Oesia disjuncta, sperm. Self-fertilization has been in which many modern Lateral described in Sagitta, but it is fins anatomical features have been tentatively identified unclear whether this occurs in B Seminal (A–C). Modified with permis- nature. Mating specimens of vesicle sion from [3]. Spadella cephaloptera become Caudal A fin aligned head to tail in parallel and C simultaneously exchange sperm Current Biology packets [9], although one-way transfer has also been reported. about their environment and they or glass probe vibrating at an The most amazing mating can hunt in darkness. Their appropriate frequency and behaviour, starting with a dance vibration sense is mediated amplitude with the same ferocity as and ending with a leap to through fans of mechanoreceptive it will attack a copepod [6]. deposit the sperm bundle or hairs [4] (Figure 1C) which Chaetognaths swallow their prey spermatophore, has been apparently play critical roles in all whole and will apparently eat described for Paraspadella gotoi behaviours. In addition to these anything that can be [10] (pictured at http:// hairs, chaetognaths have two eyes. accommodated in their mouth. As www.uibk.ac.at/zoology/ultra/ In some genera the eyes are the chaetognath strikes its prey, evol_ecol/former_research/ inverted, with the photoreceptor the hood over the grasping spines paraspadella/mating/ cells pointing inward and is withdrawn, allowing them to fly mating_behaviour.html). This embedded in a single large outward and form a net that complex behaviour is pigment cell while in others the surrounds the prey and brings it probably mediated by the eyes are everted with the into contact with the formidable mechanoreceptive hair fans [4]. photoreceptors pointing outward. teeth around the mouth. As if these Probably the strangest The eyes have relatively few impressive weapons weren’t chaetognath of all is a deep-sea receptor units and lack lenses, so enough, at least some form, Bathybelos typhlops, they apparently are not chaetognaths appear to use the described originally from a single image-forming. However, two potent neurotoxin tetrodotoxin to specimen from a depth of 2,500 m features that appear to be unique stun potential prey [7]. The exact in the Gulf of Mexico. This to chaetognath eyes are the source of the venom was not specimen showed many unusual conical body, for which some identified but it is most likely features including rayless lateral have suggested an optical role, produced by symbiotic bacteria fins, an elongated head and and the unusual lamellar and injected from one of the a dorsal nervous system, in organization of the distal segment structures surrounding the contrast to the usual ventral one. of at least some species [5].In mouth. Bathybelos is apparently addition, their photoreceptor cell is Chaetognaths seem to spend a bottom-living form, living with clearly ciliary, in contrast to the most of their time gliding on their the ventral side pressed into rhabdomeric photoreceptors fins, until eventually they begin to bottom sediments containing very found in many invertebrates. sink. Sinking is counteracted by low oxygen [11]. Chaetognaths Based on this eye structure, swimming with a series of short, lack a circulatory system, so their chaetognaths should have an rapid darts, followed by another tissues are dependent on opsin characteristic of ciliary type glide. Some species show diurnal diffusion for oxygen. Under such eyes, thus adding to the other vertical migrations, tending to conditions, there would molecular evidence against maintain themselves in a constant presumably be selective pressure ecdysozoan affinities. twilight zone. There is also a for the normally ventral nervous tendency for larger chaetognaths system to move dorsally. Behaviour – Feeding, Sexual to occur at greater depths. More specimens of benthic and Other Weirdness According to Marshall [8], Sagitta deep-water chaetognaths are Chaetognaths are remarkable gazellae in the Southern Ocean eagerly awaited. killers that appear to hunt primarily sink deeper in the water column by sensing vibration using the as they mature, releasing their Where Do Chaetognaths Fit in hair fans (http://www.cc.mie-u.ac. eggs at about 1000 m. The eggs the Scheme of Living Things? jp/wsagitta/lab.html). The are buoyant and float upward, Ever since their discovery, the chaetognath Spadella hatching at about 250 m. The phylogenetic position of cephaloptera will attack a metal hatchlings spend the summer chaetognaths has posed Dispatch R595 a conundrum. In particular, it has gene set. The fact that ‘blind’ particularly of benthic deep-water never been clear to which of the analyses based on many other species, are eagerly awaited.
Load more

Recommended publications
  • Contributions in BIOLOGY and GEOLOGY
    MILWAUKEE PUBLIC MUSEUM Contributions In BIOLOGY and GEOLOGY Number 51 November 29, 1982 A Compendium of Fossil Marine Families J. John Sepkoski, Jr. MILWAUKEE PUBLIC MUSEUM Contributions in BIOLOGY and GEOLOGY Number 51 November 29, 1982 A COMPENDIUM OF FOSSIL MARINE FAMILIES J. JOHN SEPKOSKI, JR. Department of the Geophysical Sciences University of Chicago REVIEWERS FOR THIS PUBLICATION: Robert Gernant, University of Wisconsin-Milwaukee David M. Raup, Field Museum of Natural History Frederick R. Schram, San Diego Natural History Museum Peter M. Sheehan, Milwaukee Public Museum ISBN 0-893260-081-9 Milwaukee Public Museum Press Published by the Order of the Board of Trustees CONTENTS Abstract ---- ---------- -- - ----------------------- 2 Introduction -- --- -- ------ - - - ------- - ----------- - - - 2 Compendium ----------------------------- -- ------ 6 Protozoa ----- - ------- - - - -- -- - -------- - ------ - 6 Porifera------------- --- ---------------------- 9 Archaeocyatha -- - ------ - ------ - - -- ---------- - - - - 14 Coelenterata -- - -- --- -- - - -- - - - - -- - -- - -- - - -- -- - -- 17 Platyhelminthes - - -- - - - -- - - -- - -- - -- - -- -- --- - - - - - - 24 Rhynchocoela - ---- - - - - ---- --- ---- - - ----------- - 24 Priapulida ------ ---- - - - - -- - - -- - ------ - -- ------ 24 Nematoda - -- - --- --- -- - -- --- - -- --- ---- -- - - -- -- 24 Mollusca ------------- --- --------------- ------ 24 Sipunculida ---------- --- ------------ ---- -- --- - 46 Echiurida ------ - --- - - - - - --- --- - -- --- - -- - - ---
    [Show full text]
  • A Stem Group Echinoderm from the Basal Cambrian of China and the Origins of Ambulacraria
    ARTICLE https://doi.org/10.1038/s41467-019-09059-3 OPEN A stem group echinoderm from the basal Cambrian of China and the origins of Ambulacraria Timothy P. Topper 1,2,3, Junfeng Guo4, Sébastien Clausen 5, Christian B. Skovsted2 & Zhifei Zhang1 Deuterostomes are a morphologically disparate clade, encompassing the chordates (including vertebrates), the hemichordates (the vermiform enteropneusts and the colonial tube-dwelling pterobranchs) and the echinoderms (including starfish). Although deuter- 1234567890():,; ostomes are considered monophyletic, the inter-relationships between the three clades remain highly contentious. Here we report, Yanjiahella biscarpa, a bilaterally symmetrical, solitary metazoan from the early Cambrian (Fortunian) of China with a characteristic echinoderm-like plated theca, a muscular stalk reminiscent of the hemichordates and a pair of feeding appendages. Our phylogenetic analysis indicates that Y. biscarpa is a stem- echinoderm and not only is this species the oldest and most basal echinoderm, but it also predates all known hemichordates, and is among the earliest deuterostomes. This taxon confirms that echinoderms acquired plating before pentaradial symmetry and that their history is rooted in bilateral forms. Yanjiahella biscarpa shares morphological similarities with both enteropneusts and echinoderms, indicating that the enteropneust body plan is ancestral within hemichordates. 1 Shaanxi Key Laboratory of Early Life and Environments, State Key Laboratory of Continental Dynamics and Department of Geology, Northwest University, 710069 Xi’an, China. 2 Department of Palaeobiology, Swedish Museum of Natural History, Box 50007104 05, Stockholm, Sweden. 3 Department of Earth Sciences, Durham University, Durham DH1 3LE, UK. 4 School of Earth Science and Resources, Key Laboratory for the study of Focused Magmatism and Giant Ore Deposits, MLR, Chang’an University, 710054 Xi’an, China.
    [Show full text]
  • 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.
    [Show full text]
  • Cambrian Suspension-Feeding Tubicolous Hemichordates Karma Nanglu1* , Jean-Bernard Caron1,2, Simon Conway Morris3 and Christopher B
    Nanglu et al. BMC Biology (2016) 14:56 DOI 10.1186/s12915-016-0271-4 RESEARCH ARTICLE Open Access Cambrian suspension-feeding tubicolous hemichordates Karma Nanglu1* , Jean-Bernard Caron1,2, Simon Conway Morris3 and Christopher B. Cameron4 Abstract Background: The combination of a meager fossil record of vermiform enteropneusts and their disparity with the tubicolous pterobranchs renders early hemichordate evolution conjectural. The middle Cambrian Oesia disjuncta from the Burgess Shale has been compared to annelids, tunicates and chaetognaths, but on the basis of abundant new material is now identified as a primitive hemichordate. Results: Notable features include a facultative tubicolous habit, a posterior grasping structure and an extensive pharynx. These characters, along with the spirally arranged openings in the associated organic tube (previously assigned to the green alga Margaretia), confirm Oesia as a tiered suspension feeder. Conclusions: Increasing predation pressure was probably one of the main causes of a transition to the infauna. In crown group enteropneusts this was accompanied by a loss of the tube and reduction in gill bars, with a corresponding shift to deposit feeding. The posterior grasping structure may represent an ancestral precursor to the pterobranch stolon, so facilitating their colonial lifestyle. The focus on suspension feeding as a primary mode of life amongst the basal hemichordates adds further evidence to the hypothesis that suspension feeding is the ancestral state for the major clade Deuterostomia. Keywords: Enteropneusta, Hemichordata, Cambrian, Burgess Shale Background no modern counterpart [11]. The coeval Oesia disjuncta Hemichordates are central to our understanding of Walcott [12] has been compared to groups as diverse as deuterostome evolution.
    [Show full text]
  • Sepkoski, J.J. 1992. Compendium of Fossil Marine Animal Families
    MILWAUKEE PUBLIC MUSEUM Contributions . In BIOLOGY and GEOLOGY Number 83 March 1,1992 A Compendium of Fossil Marine Animal Families 2nd edition J. John Sepkoski, Jr. MILWAUKEE PUBLIC MUSEUM Contributions . In BIOLOGY and GEOLOGY Number 83 March 1,1992 A Compendium of Fossil Marine Animal Families 2nd edition J. John Sepkoski, Jr. Department of the Geophysical Sciences University of Chicago Chicago, Illinois 60637 Milwaukee Public Museum Contributions in Biology and Geology Rodney Watkins, Editor (Reviewer for this paper was P.M. Sheehan) This publication is priced at $25.00 and may be obtained by writing to the Museum Gift Shop, Milwaukee Public Museum, 800 West Wells Street, Milwaukee, WI 53233. Orders must also include $3.00 for shipping and handling ($4.00 for foreign destinations) and must be accompanied by money order or check drawn on U.S. bank. Money orders or checks should be made payable to the Milwaukee Public Museum. Wisconsin residents please add 5% sales tax. In addition, a diskette in ASCII format (DOS) containing the data in this publication is priced at $25.00. Diskettes should be ordered from the Geology Section, Milwaukee Public Museum, 800 West Wells Street, Milwaukee, WI 53233. Specify 3Y. inch or 5Y. inch diskette size when ordering. Checks or money orders for diskettes should be made payable to "GeologySection, Milwaukee Public Museum," and fees for shipping and handling included as stated above. Profits support the research effort of the GeologySection. ISBN 0-89326-168-8 ©1992Milwaukee Public Museum Sponsored by Milwaukee County Contents Abstract ....... 1 Introduction.. ... 2 Stratigraphic codes. 8 The Compendium 14 Actinopoda.
    [Show full text]
  • A New Phyllopod Bed-Like Assemblage from the Burgess Shale of the Canadian Rockies
    ARTICLE Received 30 Dec 2013 | Accepted 7 Jan 2014 | Published 11 Feb 2014 DOI: 10.1038/ncomms4210 A new phyllopod bed-like assemblage from the Burgess Shale of the Canadian Rockies Jean-Bernard Caron1,2,3, Robert R. Gaines4,Ce´dric Aria1,2, M. Gabriela Ma´ngano5 & Michael Streng6 Burgess Shale-type fossil assemblages provide the best evidence of the ‘Cambrian explosion’. Here we report the discovery of an extraordinary new soft-bodied fauna from the Burgess Shale. Despite its proximity (ca. 40 km) to Walcott’s original locality, the Marble Canyon fossil assemblage is distinct, and offers new insights into the initial diversification of metazoans, their early morphological disparity, and the geographic ranges and longevity of many Cambrian taxa. The arthropod-dominated assemblage is remarkable for its high density and diversity of soft-bodied fossils, as well as for its large proportion of new species (22% of total diversity) and for the preservation of hitherto unreported anatomical features, including in the chordate Metaspriggina and the arthropod Mollisonia. The presence of the stem arthropods Misszhouia and Primicaris, previously known only from the early Cambrian of China, suggests that the palaeogeographic ranges and longevity of Burgess Shale taxa may be underestimated. 1 Department of Natural History-Palaeobiology, Royal Ontario Museum, 100 Queen’s Park, Toronto, Ontario, Canada M5S 2C6. 2 Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, Canada M5S 3B2. 3 Department of Earth Sciences, University of Toronto, 25 Russell Street, Toronto, Ontario, Canada M5S 3B1. 4 Geology Department, Pomona College, 185 E. Sixth Street, Claremont, California 91711, USA.
    [Show full text]
  • Paleoecology of the Greater Phyllopod Bed Community, Burgess Shale ⁎ Jean-Bernard Caron , Donald A
    Available online at www.sciencedirect.com Palaeogeography, Palaeoclimatology, Palaeoecology 258 (2008) 222–256 www.elsevier.com/locate/palaeo Paleoecology of the Greater Phyllopod Bed community, Burgess Shale ⁎ Jean-Bernard Caron , Donald A. Jackson Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada M5S 3G5 Accepted 3 May 2007 Abstract To better understand temporal variations in species diversity and composition, ecological attributes, and environmental influences for the Middle Cambrian Burgess Shale community, we studied 50,900 fossil specimens belonging to 158 genera (mostly monospecific and non-biomineralized) representing 17 major taxonomic groups and 17 ecological categories. Fossils were collected in situ from within 26 massive siliciclastic mudstone beds of the Greater Phyllopod Bed (Walcott Quarry — Fossil Ridge). Previous taphonomic studies have demonstrated that each bed represents a single obrution event capturing a predominantly benthic community represented by census- and time-averaged assemblages, preserved within habitat. The Greater Phyllopod Bed (GPB) corresponds to an estimated depositional interval of 10 to 100 KA and thus potentially preserves community patterns in ecological and short-term evolutionary time. The community is dominated by epibenthic vagile deposit feeders and sessile suspension feeders, represented primarily by arthropods and sponges. Most species are characterized by low abundance and short stratigraphic range and usually do not recur through the section. It is likely that these are stenotopic forms (i.e., tolerant of a narrow range of habitats, or having a narrow geographical distribution). The few recurrent species tend to be numerically abundant and may represent eurytopic organisms (i.e., tolerant of a wide range of habitats, or having a wide geographical distribution).
    [Show full text]
  • TREATISE ONLINE Number 109
    TREATISE ONLINE Number 109 Part V, Second Revision, Chapter 2: Class Enteropneusta: Introduction, Morphology, Life Habits, Systematic Descriptions, and Future Research Christopher B. Cameron 2018 Lawrence, Kansas, USA ISSN 2153-4012 paleo.ku.edu/treatiseonline Enteropneusta 1 PART V, SECOND REVISION, CHAPTER 2: CLASS ENTEROPNEUSTA: INTRODUCTION, MORPHOLOGY, LIFE HABITS, SYSTEMATIC DESCRIPTIONS, AND FUTURE RESEARCH CHRISTOPHER B. CAMERON [Département de sciences biologiques, Université de Montréal, Montréal QC, H2V 2S9, Canada, [email protected]] Class ENTEROPNEUSTA MORPHOLOGY Gegenbaur, 1870 The acorn worm body is arranged [nom. correct. HAECKEL, 1879, p. 469 pro Enteropneusti GEGENBAUR, into an anterior proboscis, a collar, and a 1870, p. 158] posterior trunk (Fig. 1). Body length can Free living, solitary, worms ranging from vary from less than a millimeter (WORSAAE lengths of less than a millimeter to 1.5 & others, 2012) to 1.5 meters (SPENGEL, meters; entirely marine; body tripartite, 1893). The proboscis is muscular and its with proboscis, collar, and trunk; proboscis epidermis replete with sensory, ciliated, coelom contains heart-kidney-stomochord and glandular cells (BENITO & PARDOS, complex; preoral ciliary organ posterior- 1997). Acorn worms deposit-feed by trap- ventral; collagenous Y-shaped nuchal skel- ping sediment in mucus and transporting eton extends from proboscis through neck it to the mouth with cilia. A pre-oral ciliary before bifurcating into paired horns in organ on the posterior proboscis (BRAMBEL & collar; paired dorsal perihaemal coeloms COLE, 1939) (Fig. 2.1) directs the food-laden associated with collar dorsal blood vessel; mucous thread into the mouth (GONZALEZ anterior trunk pharynx perforated with & CAMERON, 2009). The proboscis coelom paired gill slits that connect via atria to contains a turgid stomochord (Fig.
    [Show full text]
  • PROGRAMME, ABSTRACTS and AGM Papers
    The Palaeontological Association 60th Annual Meeting 14th–17th December 2016 Université Claude Bernard Lyon 1 Lyon, France PROGRAMME, ABSTRACTS and AGM papers ANNUAL MEETING Palaeontological Association 1 The Palaeontological Association 60th Annual Meeting 14th–17th December 2016 Université Claude Bernard Lyon 1 Lyon, France The programme and abstracts for the 60th Annual Meeting of the Palaeontological Association are provided after the following information and summary of the meeting. Venue The Conference takes place at the Laënnec Campus, Domaine de la Buire, Université Claude Bernard Lyon 1 (Metro line D, station ‘Laënnec’; tram T2 or T5, stop ‘Ambroise Paré’) in the eastern part of Lyon. Oral Presentations All speakers (apart from the symposium speakers) have been allocated 15 minutes. You should therefore present for only 12 minutes to allow time for questions and switching between speakers. We have a number of parallel sessions in adjacent theatres so timing is especially important. All of the lecture theatres have an A/V projector linked to a large screen. All presentations should be submitted on a memory stick and checked the day before they are scheduled. This is particularly relevant for Mac-based presentations as UCBL is PC-based. Poster presentations Poster boards will accommodate an A0-sized poster presented in portrait format only. Materials to affix your poster to the boards are available at the meeting. Travel grants to student members Students who have been awarded a PalAss travel grant should see the Executive Officer, Dr Jo Hellawell (e-mail <[email protected]>) to receive their reimbursement. Lyon Lyon (<www.onlylyon.com/en/visit-lyon.html>), capital of Gaul, is an ancient Roman city and a UNESCO World Heritage Site.
    [Show full text]
  • Canada Archives Canada Published Heritage Direction Du Branch Patrimoine De I'edition
    THE BURGESS SHALE: A CAMBRIAN MIRROR FOR MODERN EVOLUTIONARY BIOLOGY by Keynyn Alexandra Ripley Brysse A thesis submitted in conformity with the requirements for the degree of Doctor of Philosophy Institute for the History and Philosophy of Science and Technology University of Toronto © Copyright by Keynyn Alexandra Ripley Brysse (2008) Library and Bibliotheque et 1*1 Archives Canada Archives Canada Published Heritage Direction du Branch Patrimoine de I'edition 395 Wellington Street 395, rue Wellington Ottawa ON K1A0N4 Ottawa ON K1A0N4 Canada Canada Your file Votre reference ISBN: 978-0-494-44745-1 Our file Notre reference ISBN: 978-0-494-44745-1 NOTICE: AVIS: The author has granted a non­ L'auteur a accorde une licence non exclusive exclusive license allowing Library permettant a la Bibliotheque et Archives and Archives Canada to reproduce, Canada de reproduire, publier, archiver, publish, archive, preserve, conserve, sauvegarder, conserver, transmettre au public communicate to the public by par telecommunication ou par Plntemet, prefer, telecommunication or on the Internet, distribuer et vendre des theses partout dans loan, distribute and sell theses le monde, a des fins commerciales ou autres, worldwide, for commercial or non­ sur support microforme, papier, electronique commercial purposes, in microform, et/ou autres formats. paper, electronic and/or any other formats. The author retains copyright L'auteur conserve la propriete du droit d'auteur ownership and moral rights in et des droits moraux qui protege cette these. this thesis. Neither the thesis Ni la these ni des extraits substantiels de nor substantial extracts from it celle-ci ne doivent etre imprimes ou autrement may be printed or otherwise reproduits sans son autorisation.
    [Show full text]
  • Oesia – a New Tube Worm from Deep Cambrian Times
    Oesia – a new tube worm from deep Cambrian times The discovery of new fossils of an ancient seabed dwelling hemichordate called Oesia, reveals clues about their deep ancestry which is shared with humans. Oesia was found in 500 million year old, Mid Cambrian age, Burgess Shale strata of British Columbia in Canada. The fossil has been described by Professor Simon Conway Morris of the University of Cambridge and colleagues from the universities of Toronto and Montreal and the Royal Ontario Museum in Toronto in the latest issue of the journal BMC Biology. Image shows artist's impression of Oesia inside its tubular home. Credit: Marianne Collins Over the last 100 years the ancient strata of the Burgess Shale, exposed in the mountains and canyons of the Canadian Rockies, have been explored by generations of palaeontologists. In the 1960s the late Professor Harry Whittington (1916-2010), then Woodwardian Professor in the University of Cambridge, initiated a research programme on the extraordinarily well preserved fossils of the Burgess Shale, their biological relationships, ecology and evolution. Simon Conway Morris was part of Harry Whittington’s team from the 1970s and continues the research with colleagues in Cambridge and Canada. Despite the recovery of some 200,000 fossil specimens belonging to some 200 different species, the Burgess Shale biota continues to provide surprising new insights into seabed life in Mid Cambrian times, such as the surprising life habits of this new hemichordate Oesia. The new fossils were found in the Marble Canyon outcrop of the Burgess Shale in Kootenay National Park. Although Oesia fossils were first found over 100 years ago, their rarity held back reliable identification.
    [Show full text]
  • Vinther, J., & Parry, L
    Vinther, J. , & Parry, L. (2019). Bilateral Jaw Elements in Amiskwia sagittiformis Bridge the Morphological Gap between Gnathiferans and Chaetognaths. Current Biology, 29(5), 881-888.e1. https://doi.org/10.1016/j.cub.2019.01.052 Peer reviewed version License (if available): CC BY-NC-ND Link to published version (if available): 10.1016/j.cub.2019.01.052 Link to publication record in Explore Bristol Research PDF-document This is the author accepted manuscript (AAM). The final published version (version of record) is available online via Cell Press at https://www.sciencedirect.com/science/article/pii/S0960982219300818 . 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/ Bilateral jaw elements in Amiskwia sagittiformis bridge the morphological gap between gnathiferans and chaetognaths Jakob Vinther1,2,4* and Luke A. Parry1,3 1School of Earth Sciences, University of Bristol, Life Sciences Building, 24 Tyndall Avenue, BS8 1TQ, Bristol, UK. 2School of Biological Sciences, University of Bristol, Life Sciences Building, 24 Tyndall Avenue, BS8 1TQ, Bristol, UK. 3Department of Geology and Geophysics, Yale University, 210 Whitney Av., New Haven, Connecticut, 06511, USA. 4 Lead Contact *Corresponding author Summary Amiskwia sagittiformis Walcott 1911 is an iconic soft bodied taxon from the Burgess Shale [1-3]. Originally interpreted as a chaetognath [1], but later interpreted as a pelagic nemertean [2], or considered of uncertain affinity [3].
    [Show full text]