DOCSLIB.ORG

Torney, Clare (2011) Mineral Eyes : Lessons from the Natural World. Phd Thesis

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Torney, Clare (2011) Mineral Eyes : Lessons from the Natural World. Phd Thesis Torney, Clare (2011) Mineral eyes : lessons from the natural world. PhD thesis. http://theses.gla.ac.uk/2331/ Copyright and moral rights for this thesis are retained by the author A copy can be downloaded for personal non-commercial research or study, without prior permission or charge This thesis cannot be reproduced or quoted extensively from without first obtaining permission in writing from the Author The content must not be changed in any way or sold commercially in any format or medium without the formal permission of the Author When referring to this work, full bibliographic details including the author, title, awarding institution and date of the thesis must be given Glasgow Theses Service http://theses.gla.ac.uk/ [email protected] Mineral Eyes – Lessons from the Natural World Clare Torney BSc. (Hons) University of Glasgow Submitted in fulfilment of the requirements for the Degree of Doctor of Philosophy School of Geographical and Earth Sciences College of Science and Engineering University of Glasgow September 2010 ii Abstract The compound eyes of trilobites, which appeared in the Early Cambrian, represent one of the first preserved visual systems. Application of state-of-the- art microscopy techniques in the present study has revealed fine details of the microstructure and chemistry of these unusual calcite eyes that, until now, have been inaccessible and this has facilitated new insights into their growth and function. Six species from three families of trilobite with holochroal eyes, ranging from Early Ordovician to Middle Carboniferous, and 21 species from three families of trilobite with schizochroal eyes, ranging from Early Ordovician to Middle Devonian, were investigated. High-resolution microscopy techniques, including Electron Backscatter Diffraction, Transmission Electron Microscopy and Electron Probe Micro-analysis have made it possible to ‘see’ through the diagenesis of trilobite lenses to reveal the likely original lens microstructure and chemistry. Computer-based optical modelling has further shown how original lens microstructure and chemistry enhanced lens function. The discovery of sub-micron sized crystals that display a gradual and precise change in orientation shows that in many lenses much of the original microstructure has remained intact despite exposure to pore fluids and elevated temperatures and pressures during diagenesis. Although microstructure varies slightly with lens shape, there is often exceptionally precise crystal orientation. In holochroal eyes there is a direct relationship between lens shape and microstructure; where lens surfaces are planar, crystals are of uniform orientation, but where lens surfaces are convex, c axis orientation fans out, away from the lens axis. Several microstructural patterns have been identified in iii schizochroal lenses. However, a single original microstructural pattern, in which c axis orientation fans out at lens surfaces but remains parallel to the lens axis in the centre of the lens, may be applicable to all schizochroal lenses. The original chemical composition of the lenses, in particular those of schizochroal type, is less commonly preserved. However, the unravelling of a diagenetic pathway of change, through understanding the intricacies of relationships between different minerals in the lenses, has made possible a better understanding of how these lenses were altered during diagenesis. Lenses in holochroal eyes are invariably low-magnesium calcite, like the rest of the exoskeleton, as has been established for some time. The present study clarifies the original structures of schizochroal lenses and in doing so, ends the controversy over lens function; lenses were originally constructed as doublets, as suggested by Clarkson and Levi-Setti, and were not gradient index lenses, as was suggested by Campbell and Bruton and Haas. Lenses in schizochroal eyes, were constructed of high-magnesium calcite, with highest concentrations of magnesium in the lower ‘intralensar bowl’ and central ‘core’ regions of the lens. The degree of partitioning of high levels of magnesium, of up to 8 mole % MgCO3, in the schizochroal eyes is remarkable given the magnesium-poor ‘calcite seas’ in which they were formed. This is perhaps the first example of element partitioning within biominerals for a specific function. Based on the growth sequence of modern arthropod exoskeletons lenses in trilobite eyes are likely to have grown from the outer surface in, one lamella at a time, with microstructure and chemical composition controlled by an organic matrix. Assessment of the trilobite optical structures, using Code V optical modelling software, leads to the conclusions that the trilobite eyes functioned in a similar manner to the apposition eyes of modern animals. Code V modelling of holochroal and schizochroal eyes, and the subsequent determination of their resolution and sensitivity, shows that both eye types probably had a single optically isolated photoreceptor beneath each lens. Using a combination of specific lens size, shape, spacing, microstructure and composition, the schizochroal eye was adapted to low light intensities, similar to the eye of the iv modern isopod Cirolana. These adaptations would have provided the trilobite with light and dark detection of a resolution sufficient to identify movement, allowing it to detect prey and defend itself against predators. The birefringent properties of the calcite from which these lenses were made could be a hindrance, resulting in double refraction of light rays and the formation of ‘ghost’ images. Fascinatingly however this property provides the lenses with the refractive power required to make full use of the light available to them, vital for an organism with a crystalline lens with a fixed focal length. Study of the calcified lenses of ostracods and brittlestars and comparison to lenses in schizochroal trilobite eyes confirms that these modern organisms do not provide accurate analogues for trilobite eyes. No other organism that shares all characteristics of schizochroal trilobite eyes has yet been found; the eyes of the phacopine trilobites remain unique in the natural world. v Table of Contents Abstract ....................................................................................... ii List of Tables ................................................................................. x List of Figures .............................................................................. xiii List of Equations ..........................................................................xviii Acknowledgements ........................................................................ xix Declaration ................................................................................ xxii Abbreviations ..............................................................................xxiii Chapter 1 Introduction ...................................................................25 1.1 Aims ................................................................................25 1.2 The Significance of Visual System Studies ...................................26 1.3 Types of Eye ......................................................................27 1.3.1 Simple Eyes..................................................................27 1.3.2 Compound Eyes .............................................................28 1.3.2.1 Apposition Eyes........................................................28 1.3.2.1.1 Neural Superposition Eyes ........................................30 1.3.2.2 Superposition Eyes....................................................31 1.3.2.2.1 Refracting superposition..........................................32 1.3.2.2.2 Reflecting Superposition..........................................33 1.3.2.2.3 Parabolic Superposition...........................................33 1.4 Eye function: Requirement, Adaptation, Compromise ....................34 1.4.1 The Field of View of Daphnia.............................................35 1.5 Trilobite Eyes.....................................................................35 1.5.1 Holochroal Eyes.............................................................36 1.5.1.1 Lens Arrangement ....................................................37 1.5.1.2 Lens Structure .........................................................38 1.5.1.3 Lens Function..........................................................39 1.5.2 Schizochroal Eyes...........................................................39 1.5.2.1 Lens Arrangement ....................................................41 1.5.2.2 Lens Structure .........................................................43 1.5.2.3 Lens Function..........................................................49 1.5.3 Abathochroal Eyes..........................................................52 1.5.3.1 Eye Structure ..........................................................52 1.5.3.2 Eye Function ...........................................................52 1.5.4 Biomineralisation and the Construction of the Trilobite Eye .......53 1.6 Calcite in Modern Optical Systems ............................................55 1.6.1 Ostracods ....................................................................55 1.6.2 Brittlestars ..................................................................57 1.7 Detailed Aims of the Present Study...........................................60 vi Chapter 2 Techniques ....................................................................61 2.1 Optical
Load more

Recommended publications
  • Exoskeletal Structures and Ultrastructures in Lower Devonian Dalmanitid Trilobites of the Prague Basin (Czech Republic)
    Exoskeletal structures and ultrastructures in Lower Devonian dalmanitid trilobites of the Prague Basin (Czech Republic) PETR BUDIL & FRANTIEK HÖRBINGER Our current studies of the exoskeletal structures and ultrastructures in Lower Devonian dalmanitid trilobites of the Prague Basin are briefly described and discussed. The interior of the exoskeleton in most specimens from the Prague Ba- sin is recrystallised and largely filled with very fine homogeneous sparitic cement. The ultrastructures sensu stricto, e.g., the lamination, layers forming the exoskeleton, and the fine pores or “Osmólska” cavities, are mostly imperceptible even at higher magnifications. However, ultrastructural relics were observed in some polished thin sections and exoskeletal fragments using electron microscopy. Larger structures, especially the eyes, the megapores penetrating the exoskeleton, and the surface sculptures (prosopon sensu Gill 1949), are relatively well preserved and show very fine details. The bio- logical significance of megapores is briefly discussed. Modification of the inner parts of the exoskeletons by diagenetic processes, obscuring most of the fine internal structures, is evident. • Key words: Trilobita, Dalmanitidae, exoskeleton microstructure. BUDIL,P.&HÖRBINGER, F. 2007. Exoskeletal structures and ultrastructures in Lower Devonian dalmanitid trilobites of the Prague Basin (Czech Republic). Bulletin of Geosciences 82(1), 27–36 (4 figures, 1 table). Czech Geological Survey, Prague. ISSN 1214-1119. Manuscript received January 17, 2007; accepted
    [Show full text]
  • Message from the New Chairman
    Subcommission on Devonian Stratigraphy Newsletter No. 21 April, 2005 MESSAGE FROM THE NEW CHAIRMAN Dear SDS Members: This new Newsletter gives me the pleasant opportunity to thank you for your confidence which should allow me to lead our Devonian Subcommission successfully through the next four years until the next International Geological Congress in Norway. Ahmed El Hassani, as Vice-Chairman, and John Marshall, as our new Secretary, will assist and help me. As it has been our habit in the past, our outgoing chairman, Pierre Bultynck, has continued his duties until the end of the calendar year, and in the name of all the Subcommission, I like to express our warmest thanks to him for all his efforts, his enthusi- asm for our tasks, his patience with the often too slow progress of research, and for the humorous, well organized and skil- ful handling of our affairs, including our annual meetings. At the same time I like to thank all our outgoing Titular Members for their partly long-time service and I express my hope that they will continue their SDS work with the same interest and energy as Corresponding Members. The new ICS rules require a rather constant change of voting members and the change from TM to CM status should not necessarily be taken as an excuse to adopt the lifestyle of a “Devonian pensioner”. I see no reason why constantly active SDS members shouldn´t become TM again, at a later stage. On the other side, the rather strong exchange of voting members should bring in some fresh ideas and some shift towards modern stratigraphical tech- niques.
    [Show full text]
  • Trilobites of the Hagastrand Member (Tøyen Formation, Lowermost Arenig) from the Oslo Region, Norway. Part Il: Remaining Non-Asaphid Groups
    Trilobites of the Hagastrand Member (Tøyen Formation, lowermost Arenig) from the Oslo Region, Norway. Part Il: Remaining non-asaphid groups OLE A. HOEL Hoel, O. A.: Trilobites of the Hagastrand Member (Tøyen Formation, lowermost Arenig) from the Oslo Region, Norway. Part Il: remaining non-asaphid groups. Norsk Geologisk Tidsskrift, Vol. 79, pp. 259-280. Oslo 1999. ISSN 0029-196X. This is Part Il of a two-part description of the trilobite fauna of the Hagastrand Member (Tøyen Formation) in the Oslo, Eiker­ Sandsvær, Modum and Mjøsa areas. In this part, the non-asaphid trilobites are described, while the asaphid species have been described previously. The history and status of the Tremadoc-Arenig Boundary problem is also reviewed, and I have found no reason to insert a Hunnebergian Series between the Tremadoc and the Arenig series, as has been suggested by some workers. Descriptions of the localities yielding this special trilobite fauna are provided. Most of the 22 trilobite species found in the Hagastrand Member also occur in Sweden. The 12 non-asaphid trilobites described herein belong to the families Metagnostidae, Shumardiidae, Remopleurididae, Nileidae, Cyclopygidae, Raphiophoridae, Alsataspididae and Pliomeridae. One new species is described; Robergiella tjemviki n. sp. Ole A. Hoel, Paleontologisk Museum, Sars gate l, N-0562 Oslo, Norway. Introduction contemporaneous platform deposits in Sweden are domi­ nated by a condensed limestone succession. In Norway, the The Tremadoc-Arenig Boundary interval is a crucial point Tøyen Formation is divided into two members: the lower in the evolution of several invertebrate groups, especially among the graptolites and the trilobites. In the graptolites, this change consisted most significantly in the loss of bithekae and a strong increase in diversity.
    [Show full text]
  • Available Generic Names for Trilobites
    AVAILABLE GENERIC NAMES FOR TRILOBITES P.A. JELL AND J.M. ADRAIN Jell, P.A. & Adrain, J.M. 30 8 2002: Available generic names for trilobites. Memoirs of the Queensland Museum 48(2): 331-553. Brisbane. ISSN0079-8835. Aconsolidated list of available generic names introduced since the beginning of the binomial nomenclature system for trilobites is presented for the first time. Each entry is accompanied by the author and date of availability, by the name of the type species, by a lithostratigraphic or biostratigraphic and geographic reference for the type species, by a family assignment and by an age indication of the type species at the Period level (e.g. MCAM, LDEV). A second listing of these names is taxonomically arranged in families with the families listed alphabetically, higher level classification being outside the scope of this work. We also provide a list of names that have apparently been applied to trilobites but which remain nomina nuda within the ICZN definition. Peter A. Jell, Queensland Museum, PO Box 3300, South Brisbane, Queensland 4101, Australia; Jonathan M. Adrain, Department of Geoscience, 121 Trowbridge Hall, Univ- ersity of Iowa, Iowa City, Iowa 52242, USA; 1 August 2002. p Trilobites, generic names, checklist. Trilobite fossils attracted the attention of could find. This list was copied on an early spirit humans in different parts of the world from the stencil machine to some 20 or more trilobite very beginning, probably even prehistoric times. workers around the world, principally those who In the 1700s various European natural historians would author the 1959 Treatise edition. Weller began systematic study of living and fossil also drew on this compilation for his Presidential organisms including trilobites.
    [Show full text]
  • Copertina Guida Ai TRILOBITI V3 Esterno
    Enrico Bonino nato in provincia di Bergamo nel 1966, Enrico si è laureato in Geologia presso il Dipartimento di Scienze della Terra dell'Università di Genova. Attualmente risiede in Belgio dove svolge attività come specialista nel settore dei Sistemi di Informazione Geografica e analisi di immagini digitali. Curatore scientifico del Museo Back to the Past, ha pubblicato numerosi volumi di paleontologia in lingua italiana e inglese, collaborando inoltre all’elaborazione di testi e pubblicazioni scientifiche a livello nazonale e internazionale. Oltre alla passione per questa classe di artropodi, i suoi interessi sono orientati alle forme di vita vissute nel Precambriano, stromatoliti, e fossilizzazioni tipo konservat-lagerstätte. Carlo Kier nato a Milano nel 1961, Carlo si è laureato in Legge, ed è attualmente presidente della catena di alberghi Azul Hotel. Risiede a Cancun, Messico, dove si dedica ad attività legate all'ambiente marino. All'età di 16 anni, ha iniziato una lunga collaborazione con il Museo di Storia Naturale di Milano, ed è a partire dal 1970 che prese inizio la vera passione per i trilobiti, dando avvio a quella che oggi è diventata una delle collezioni paleontologiche più importanti al mondo. La sua instancabile attività di ricerca sul terreno in varie parti del globo e la collaborazione con professionisti del settore, ha permesso la descrizione di nuove specie di trilobiti ed artropodi. Una forte determinazione e la costruzione di un nuovo complesso alberghiero (AZUL Sensatori) hanno infine concretizzzato la realizzazione
    [Show full text]
  • Enrollment and Coaptations in Some Species of the Ordovician Trilobite Genus Placoparia
    Enrollment and coaptations in some sp eeies of the Ordovician trilobite genus Placoparia JEAN-LOUIS HENRY AND EUAN N.K. CLARKSON Henry, J.-L. & Clarkson, E.N.K. 1974 12 15: Enrollment and coaptations in some species of the Ordovician trilobite genus Placoparia. Fossils and Strata, No. 4, pp. 87-95. PIs. 1-3. Oslo ISSN 0300-949l. ISBN 82-00-04963-9. The species Pl. (Placoparia) cambriensis, Pl. (Coplacoparia ) tournemini and Pl. (Coplacoparia ) borni, described by Hammann (1971) from the Spanish Ordovician, are found in Brittany in formations attributed to the Llanvirn and the LIandeilo. The lateral borders of the librigenae of Pl. (Coplacoparia) tournemini and Pl. (Coplacoparia ) borni bear depressions into which the distal ends of the thoracic pleurae and the tips of the first pair of pygidial ribs come and fit during enrollment. These depressions, or coaptative structures sensu Cuenot (1919), are also to be observed in Pl. (Placoparia) zippei and Pl. (Hawleia) grandis, from the Ordovician of Bohemia. However, in the species tournemini and borni, additional depressions appear on the anterior cephalic border, and the coaptations evolve towards an increasing complexity. From Pl. (Placoparia) cambriensis, an ancestrai form with a wide geographic distribution, two distinct populations se em to have individu· alised by a process of allopatric speciation; one of these, probably neotenous, is represented by Pl. (Coplacoparia ) tournemini (Massif Armoricain and Iberian Peninsula), the other by Pl. (Placoparia ) zippei (Bohemia). Geo­ graphic isolation may be indirectly responsible for the appearance of new coaptative devices. jean-Louis Henry, Laboratoire de Paleontologie et de Stratigraphie, Institut de Geologie de l'Universite, B.P.
    [Show full text]
  • 'Placoderm' (Arthrodira)
    Jobbins et al. Swiss J Palaeontol (2021) 140:2 https://doi.org/10.1186/s13358-020-00212-w Swiss Journal of Palaeontology RESEARCH ARTICLE Open Access A large Middle Devonian eubrachythoracid ‘placoderm’ (Arthrodira) jaw from northern Gondwana Melina Jobbins1* , Martin Rücklin2, Thodoris Argyriou3 and Christian Klug1 Abstract For the understanding of the evolution of jawed vertebrates and jaws and teeth, ‘placoderms’ are crucial as they exhibit an impressive morphological disparity associated with the early stages of this process. The Devonian of Morocco is famous for its rich occurrences of arthrodire ‘placoderms’. While Late Devonian strata are rich in arthrodire remains, they are less common in older strata. Here, we describe a large tooth-bearing jaw element of Leptodontich- thys ziregensis gen. et sp. nov., an eubrachythoracid arthrodire from the Middle Devonian of Morocco. This species is based on a large posterior superognathal with a strong dentition. The jawbone displays features considered syna- pomorphies of Late Devonian eubrachythoracid arthrodires, with one posterior and one lateral row of conical teeth oriented postero-lingually. μCT-images reveal internal structures including pulp cavities and dentinous tissues. The posterior orientation of the teeth and the traces of a putative occlusal contact on the lingual side of the bone imply that these teeth were hardly used for feeding. Similar to Compagopiscis and Plourdosteus, functional teeth were pos- sibly present during an earlier developmental stage and have been worn entirely. The morphological features of the jaw element suggest a close relationship with plourdosteids. Its size implies that the animal was rather large. Keywords: Arthrodira, Dentition, Food web, Givetian, Maïder basin, Palaeoecology Introduction important to reconstruct character evolution in early ‘Placoderms’ are considered as a paraphyletic grade vertebrates.
    [Show full text]
  • 001-012 Primeras Páginas
    PUBLICACIONES DEL INSTITUTO GEOLÓGICO Y MINERO DE ESPAÑA Serie: CUADERNOS DEL MUSEO GEOMINERO. Nº 9 ADVANCES IN TRILOBITE RESEARCH ADVANCES IN TRILOBITE RESEARCH IN ADVANCES ADVANCES IN TRILOBITE RESEARCH IN ADVANCES planeta tierra Editors: I. Rábano, R. Gozalo and Ciencias de la Tierra para la Sociedad D. García-Bellido 9 788478 407590 MINISTERIO MINISTERIO DE CIENCIA DE CIENCIA E INNOVACIÓN E INNOVACIÓN ADVANCES IN TRILOBITE RESEARCH Editors: I. Rábano, R. Gozalo and D. García-Bellido Instituto Geológico y Minero de España Madrid, 2008 Serie: CUADERNOS DEL MUSEO GEOMINERO, Nº 9 INTERNATIONAL TRILOBITE CONFERENCE (4. 2008. Toledo) Advances in trilobite research: Fourth International Trilobite Conference, Toledo, June,16-24, 2008 / I. Rábano, R. Gozalo and D. García-Bellido, eds.- Madrid: Instituto Geológico y Minero de España, 2008. 448 pgs; ils; 24 cm .- (Cuadernos del Museo Geominero; 9) ISBN 978-84-7840-759-0 1. Fauna trilobites. 2. Congreso. I. Instituto Geológico y Minero de España, ed. II. Rábano,I., ed. III Gozalo, R., ed. IV. García-Bellido, D., ed. 562 All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system now known or to be invented, without permission in writing from the publisher. References to this volume: It is suggested that either of the following alternatives should be used for future bibliographic references to the whole or part of this volume: Rábano, I., Gozalo, R. and García-Bellido, D. (eds.) 2008. Advances in trilobite research. Cuadernos del Museo Geominero, 9.
    [Show full text]
  • The Bulletin of Zoological Nomenclature. Vol 12, Part 3
    VOLUME 12. Part 3 26if/i June, 1956 pp. 65—96 ; 1 pi. THE BULLETIN OF ZOOLOGICAL NOMENCLATURE The Official Organ of THE INTERNATIONAL COMMISSION ON ZOOLOGICAL NOMENCLATURE Edited by FRANCIS HEMMING, C.M.G., C.B.E. Secretary to the International Commission on Zoological Nomenclature Contents: Notices prescribed by the International Congress of Zoology : Page Date of commencement by the International Commission on Zoo¬ logical Nomenclature of voting on applications published in the Bulletin of Zoological Nomenclature .. .. .. .. .. 65 Notice of the possible use by the International Commission on Zoo¬ logical Nomenclature of its Plenary Powers in certain cases .. 65 (continued outside back wrapper) LONDON: Printed by Order of the International Trust for Zoological Nomenclature and Sold on behalf of the International Commission on Zoological Nomenclature by the International Trust at its Publication Office, 41, Queen's Gate, London, S.W.7 1956 Price Nineteen Shillings IAll rights reserved) Original from and digitized by National University of Singapore Libraries INTERNATIONAL COMMISSION ON ZOOLOGICAL NOMENCLATURE A. The Officers of the Commission Honorary Life President: Dr. Karl Jordan (British Museum (Natural History), Zoological Museum, Tring, Herts, England) President: Professor James Chester Bradley (Cornell University, Ithaca, N.Y., U.S.A.) (12th August 1953) Vice-President: Senhor Dr. Afranio do Amaral (Sao Paulo, Brazil) (12th August 1953) Secretary : Mr. Francis Hemming (London, England) (27th July 1948) B. The Members of the Commission (Arranged in order of precedence by reference to date of election or of most recent re-election, as prescribed by the International Congress of Zoology) Professor H. Boschma (Rijksmuseum van Natuurlijke Historie, Leiden, The Netherlands) (1st January 1947) Senor Dr.
    [Show full text]
  • 9 Paleontological Conference Th
    Polish Academy of Sciences Institute of Paleobiology 9th Paleontological Conference Warszawa, 10–11 October 2008 Abstracts Warszawa Praha Bratislava Edited by Andrzej Pisera, Maria Aleksandra Bitner and Adam T. Halamski Honorary Committee Prof. Oldrich Fatka, Charles University of Prague, Prague Prof. Josef Michalík, Slovak Academy of Sciences, Bratislava Assoc. Prof. Jerzy Nawrocki, Polish Geological Institute, Warszawa Prof. Tadeusz Peryt, Polish Geological Institute, Warszawa Prof. Grzegorz Racki, Institute of Paleobiology, Warszawa Prof. Jerzy Trammer, University of Warsaw, Warszawa Prof. Alfred Uchman, Jagiellonian University, Kraków Martyna Wojciechowska, National Geographic Polska, Warszawa Organizing Committee Dr Maria Aleksandra Bitner (Secretary), Błażej Błażejewski, MSc, Prof. Andrzej Gaździcki, Dr Adam T. Halamski, Assoc. Prof. Anna Kozłowska, Assoc. Prof. Andrzej Pisera Sponsors Institute of Paleobiology, Warszawa Polish Geological Institute, Warszawa National Geographic Polska, Warszawa Precoptic Co., Warszawa Cover picture: Quenstedtoceras henrici Douvillé, 1912 Cover designed by Aleksandra Hołda−Michalska Copyright © Instytut Paleobiologii PAN Nakład 150 egz. Typesetting and Layout: Aleksandra Szmielew Warszawska Drukarnia Naukowa PAN ABSTRACTS Paleotemperature and paleodiet reconstruction on the base of oxygen and carbon isotopes from mammoth tusk dentine and horse teeth enamel during Late Paleolith and Mesolith MARTINA ÁBELOVÁ State Geological Institute of Dionýz Štúr, Mlynská dolina 1, SK−817 04 Bratislava 11, Slovak Republic; [email protected] The use of stable isotopes has proven to be one of the most effective methods in re− constructing paleoenvironments and paleodiet through the upper Pleistocene period (e.g. Fricke et al. 1998; Genoni et al. 1998; Bocherens 2003). This study demonstrates how isotopic data can be employed alongside other forms of evidence to inform on past at great time depths, making it especially relevant to the Palaeolithic where there is a wealth of material potentially available for study.
    [Show full text]
  • The Evolution of Trilobite Body Patterning
    ANRV309-EA35-14 ARI 20 March 2007 15:54 The Evolution of Trilobite Body Patterning Nigel C. Hughes Department of Earth Sciences, University of California, Riverside, California 92521; email: [email protected] Annu. Rev. Earth Planet. Sci. 2007. 35:401–34 Key Words First published online as a Review in Advance on Trilobita, trilobitomorph, segmentation, Cambrian, Ordovician, January 29, 2007 diversification, body plan The Annual Review of Earth and Planetary Sciences is online at earth.annualreviews.org Abstract This article’s doi: The good fossil record of trilobite exoskeletal anatomy and on- 10.1146/annurev.earth.35.031306.140258 togeny, coupled with information on their nonbiomineralized tis- Copyright c 2007 by Annual Reviews. sues, permits analysis of how the trilobite body was organized and All rights reserved developed, and the various evolutionary modifications of such pat- 0084-6597/07/0530-0401$20.00 terning within the group. In several respects trilobite development and form appears comparable with that which may have charac- terized the ancestor of most or all euarthropods, giving studies of trilobite body organization special relevance in the light of recent advances in the understanding of arthropod evolution and devel- opment. The Cambrian diversification of trilobites displayed mod- Annu. Rev. Earth Planet. Sci. 2007.35:401-434. Downloaded from arjournals.annualreviews.org ifications in the patterning of the trunk region comparable with by UNIVERSITY OF CALIFORNIA - RIVERSIDE LIBRARY on 05/02/07. For personal use only. those seen among the closest relatives of Trilobita. In contrast, the Ordovician diversification of trilobites, although contributing greatly to the overall diversity within the clade, did so within a nar- rower range of trunk conditions.
    [Show full text]
  • Key to the Common Shallow-Water Brittle Stars (Echinodermata: Ophiuroidea) of the Gulf of Mexico and Caribbean Sea
    See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/228496999 Key to the common shallow-water brittle stars (Echinodermata: Ophiuroidea) of the Gulf of Mexico and Caribbean Sea Article · January 2007 CITATIONS READS 10 702 1 author: Christopher Pomory University of West Florida 34 PUBLICATIONS 303 CITATIONS SEE PROFILE All content following this page was uploaded by Christopher Pomory on 21 May 2014. The user has requested enhancement of the downloaded file. All in-text references underlined in blue are added to the original document and are linked to publications on ResearchGate, letting you access and read them immediately. 1 Key to the common shallow-water brittle stars (Echinodermata: Ophiuroidea) of the Gulf of Mexico and Caribbean Sea CHRISTOPHER M. POMORY 2007 Department of Biology, University of West Florida, 11000 University Parkway, Pensacola, FL 32514, USA. [email protected] ABSTRACT A key is given for 85 species of ophiuroids from the Gulf of Mexico and Caribbean Sea covering a depth range from the intertidal down to 30 m. Figures highlighting important anatomical features associated with couplets in the key are provided. 2 INTRODUCTION The Caribbean region is one of the major coral reef zoogeographic provinces and a region of intensive human use of marine resources for tourism and fisheries (Aide and Grau, 2004). With the world-wide decline of coral reefs, and deterioration of shallow-water marine habitats in general, ecological and biodiversity studies have become more important than ever before (Bellwood et al., 2004). Ecological and biodiversity studies require identification of collected specimens, often by biologists not specializing in taxonomy, and therefore identification guides easily accessible to a diversity of biologists are necessary.
    [Show full text]