Fossil Focus: Chelicerata
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Functional Morphology and Evolu Tion of Xiphosurids
Func tional morphol ogy and evolu tion of xiphosurids JAN BERGSTROM Bergstrom, J. 1 975 07 15: Functional morphology and evolution of xiphosurids. Fossils and Strata, No. 4, pp. 291-305, Pl. 1. Oslo. ISSN 0300-9491. ISBN 82-00-04963-9. Aspects of the morphology, evolution and systematics of the Xiphosurida are treated. The ancestrai forms lacked specialization for ploughing, and their chilaria were evidently developed as prosomal walking legs. The cor responding tergite (of the pregenital segment) was probably separate from the main prosomal shield in the early xiphosurids as well as in the eurypter ids. From this stem two main groups seem to have evolved. One consists of the synziphosurids, large-eyed eurypterid-like hunters with stri king opistho somal tagmosis. The other consists of the burrowing and ploughing xipho surids, in which the opisthosomal tergites were subject to progressive fusion ending with a single opisthothoracic tergal shield in the Late Palaeo zoic. The last prosomal appendages evolved into the chilaria, if this did not happen earlier, and the corresponding free tergite disappeared. Probably in Carboniferous time the limulines came into existence through a sudden displacement of the prosomal/opisthosomal boundary. Jan Bergstram, Department of His torical Geology and Palaeontology, Un iversity of Lund, Solvegatan 13, S-223 62 Lund, 1st August 1973. The Xiphosura may be considered to constitute a subdass or dass of chelicerate arthropods. The delimitation has been diseussed in the past, but no general agreement seems to exist. Generally, the xiphosurids are induded with the aglaspidids and eurypterids in the Merostorna ta. However, as generally understood, this taxon probably represents an evolutionary grade rather than a phylogenetic unit. -
Morphology and Function in the Cambrian Burgess Shale
Haug et al. BMC Evolutionary Biology 2012, 12:162 http://www.biomedcentral.com/1471-2148/12/162 RESEARCH ARTICLE Open Access Morphology and function in the Cambrian Burgess Shale megacheiran arthropod Leanchoilia superlata and the application of a descriptive matrix Joachim T Haug1*, Derek EG Briggs2,3 and Carolin Haug1 Abstract Background: Leanchoilia superlata is one of the best known arthropods from the middle Cambrian Burgess Shale of British Columbia. Here we re-describe the morphology of L. superlata and discuss its possible autecology. The re-description follows a standardized scheme, the descriptive matrix approach, designed to provide a template for descriptions of other megacheiran species. Results: Our findings differ in several respects from previous interpretations. Examples include a more slender body; a possible hypostome; a small specialised second appendage, bringing the number of pairs of head appendages to four; a further sub-division of the great appendage, making it more similar to that of other megacheirans; and a complex joint of the exopod reflecting the arthropod’s swimming capabilities. Conclusions: Different aspects of the morphology, for example, the morphology of the great appendage and the presence of a basipod with strong median armature on the biramous appendages indicate that L. superlata was an active and agile necto-benthic predator (not a scavenger or deposit feeder as previously interpreted). Keywords: Megacheira, Great-appendage arthropods, Chelicerata sensu lato, Descriptive matrix, Active predator Background shared with other species. As a consequence, morpho- The description of species is fundamental to the science logical details in many phylogenetic matrices have to be of zoology, including taxonomy, phylogenetic systema- (re-)interpreted, often without the benefit of a compre- tics, functional morphology and ultimately evolutionary hensive description. -
The Origin and Evolution of Arthropods Graham E
INSIGHT REVIEW NATURE|Vol 457|12 February 2009|doi:10.1038/nature07890 The origin and evolution of arthropods Graham E. Budd1 & Maximilian J. Telford2 The past two decades have witnessed profound changes in our understanding of the evolution of arthropods. Many of these insights derive from the adoption of molecular methods by systematists and developmental biologists, prompting a radical reordering of the relationships among extant arthropod classes and their closest non-arthropod relatives, and shedding light on the developmental basis for the origins of key characteristics. A complementary source of data is the discovery of fossils from several spectacular Cambrian faunas. These fossils form well-characterized groupings, making the broad pattern of Cambrian arthropod systematics increasingly consensual. The arthropods are one of the most familiar and ubiquitous of all ani- Arthropods are monophyletic mal groups. They have far more species than any other phylum, yet Arthropods encompass a great diversity of animal taxa known from the living species are merely the surviving branches of a much greater the Cambrian to the present day. The four living groups — myriapods, diversity of extinct forms. One group of crustacean arthropods, the chelicerates, insects and crustaceans — are known collectively as the barnacles, was studied extensively by Charles Darwin. But the origins Euarthropoda. They are united by a set of distinctive features, most and the evolution of arthropods in general, embedded in what is now notably the clear segmentation of their bodies, a sclerotized cuticle and known as the Cambrian explosion, were a source of considerable con- jointed appendages. Even so, their great diversity has led to consider- cern to him, and he devoted a substantial and anxious section of On able debate over whether they had single (monophyletic) or multiple the Origin of Species1 to discussing this subject: “For instance, I cannot (polyphyletic) origins from a soft-bodied, legless ancestor. -
Segmentation and Tagmosis in Chelicerata
Arthropod Structure & Development 46 (2017) 395e418 Contents lists available at ScienceDirect Arthropod Structure & Development journal homepage: www.elsevier.com/locate/asd Segmentation and tagmosis in Chelicerata * Jason A. Dunlop a, , James C. Lamsdell b a Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Invalidenstrasse 43, D-10115 Berlin, Germany b American Museum of Natural History, Division of Paleontology, Central Park West at 79th St, New York, NY 10024, USA article info abstract Article history: Patterns of segmentation and tagmosis are reviewed for Chelicerata. Depending on the outgroup, che- Received 4 April 2016 licerate origins are either among taxa with an anterior tagma of six somites, or taxa in which the ap- Accepted 18 May 2016 pendages of somite I became increasingly raptorial. All Chelicerata have appendage I as a chelate or Available online 21 June 2016 clasp-knife chelicera. The basic trend has obviously been to consolidate food-gathering and walking limbs as a prosoma and respiratory appendages on the opisthosoma. However, the boundary of the Keywords: prosoma is debatable in that some taxa have functionally incorporated somite VII and/or its appendages Arthropoda into the prosoma. Euchelicerata can be defined on having plate-like opisthosomal appendages, further Chelicerata fi Tagmosis modi ed within Arachnida. Total somite counts for Chelicerata range from a maximum of nineteen in Prosoma groups like Scorpiones and the extinct Eurypterida down to seven in modern Pycnogonida. Mites may Opisthosoma also show reduced somite counts, but reconstructing segmentation in these animals remains chal- lenging. Several innovations relating to tagmosis or the appendages borne on particular somites are summarised here as putative apomorphies of individual higher taxa. -
Geological History and Phylogeny of Chelicerata
Arthropod Structure & Development 39 (2010) 124–142 Contents lists available at ScienceDirect Arthropod Structure & Development journal homepage: www.elsevier.com/locate/asd Review Article Geological history and phylogeny of Chelicerata Jason A. Dunlop* Museum fu¨r Naturkunde, Leibniz Institute for Research on Evolution and Biodiversity at the Humboldt University Berlin, Invalidenstraße 43, D-10115 Berlin, Germany article info abstract Article history: Chelicerata probably appeared during the Cambrian period. Their precise origins remain unclear, but may Received 1 December 2009 lie among the so-called great appendage arthropods. By the late Cambrian there is evidence for both Accepted 13 January 2010 Pycnogonida and Euchelicerata. Relationships between the principal euchelicerate lineages are unre- solved, but Xiphosura, Eurypterida and Chasmataspidida (the last two extinct), are all known as body Keywords: fossils from the Ordovician. The fourth group, Arachnida, was found monophyletic in most recent studies. Arachnida Arachnids are known unequivocally from the Silurian (a putative Ordovician mite remains controversial), Fossil record and the balance of evidence favours a common, terrestrial ancestor. Recent work recognises four prin- Phylogeny Evolutionary tree cipal arachnid clades: Stethostomata, Haplocnemata, Acaromorpha and Pantetrapulmonata, of which the pantetrapulmonates (spiders and their relatives) are probably the most robust grouping. Stethostomata includes Scorpiones (Silurian–Recent) and Opiliones (Devonian–Recent), while -
Phylum Arthropoda*
Zootaxa 3703 (1): 017–026 ISSN 1175-5326 (print edition) www.mapress.com/zootaxa/ Correspondence ZOOTAXA Copyright © 2013 Magnolia Press ISSN 1175-5334 (online edition) http://dx.doi.org/10.11646/zootaxa.3703.1.6 http://zoobank.org/urn:lsid:zoobank.org:pub:FBDB78E3-21AB-46E6-BD4F-A4ADBB940DCC Phylum Arthropoda* ZHI-QIANG ZHANG New Zealand Arthropod Collection, Landcare Research, Private Bag 92170, Auckland, New Zealand; [email protected] * In: Zhang, Z.-Q. (Ed.) Animal Biodiversity: An Outline of Higher-level Classification and Survey of Taxonomic Richness (Addenda 2013). Zootaxa, 3703, 1–82. Abstract The Arthropoda is here estimated to have 1,302,809 described species, including 45,769 fossil species (the diversity of fossil taxa is here underestimated for many taxa of the Arthropoda). The Insecta (1,070,781 species) is the most successful group, and it alone accounts for over 80% of all arthropods. The most successful insect order, Coleoptera (392,415 species), represents over one-third of all species in 39 insect orders. Another major group in Arthropoda is the class Arachnida (114,275 species), which is dominated by the Acari (55,214 mite and tick species) and Araneae (44,863 spider species). Other diverse arthropod groups include Crustacea (73,141 species), Trilobitomorpha (20,906 species) and Myriapoda (12,010 species). Key words: Classification, diversity, Arthropoda Introduction The Arthropoda, with over 1.5 million described species, is the largest animal phylum, and it alone accounts for about 80% of the total number of species in the animal kingdom (Zhang 2011a). In the last volume on animal higher-level classification and survey of taxonomic richness, 28 chapters by numerous teams of specialists were published on various taxa of the Arthropoda, but there were many gaps to be filled (Zhang 2011b). -
Paleontological Contributions
THE UNIVERSITY OF KANSAS PALEONTOLOGICAL CONTRIBUTIONS July 24, 1984 Paper 111 EXCEPTIONALLY PRESERVED NONTRILOBITE ARTHROPODS AND ANOMALOCARIS FROM THE MIDDLE CAMBRIAN OF UTAH' D. E. G. BRIGGS and R. A. ROBISON Department of Geology, Goldsmiths' College, University of London, Creek Road, London SE8 3BU, and Department of Geology, University of Kansas, Lawrence, Kansas 66045 Abstract—For the first time arthropods with preserved soft parts and appendages are recorded from Middle Cambrian strata in Utah. Occurrences of four nontrilobite taxa are described, including Branchiocaris pretiosa (Resser) and Emeraldella? sp. from the Marjum Formation, Sidneyia? sp. from the Wheeler Formation, and Leanchoilia? hanceyi, n. sp., from the Spence Shale. A small specimen of the giant predator Anomalocaris nathorsti (Walcott) also is described from the Marjum Formation. These occurrences extend upward the observed stratigraphie ranges of Anomalocaris, Branchiocaris, and questionably Emeraldella and Sidneyia. Emeraldella, Leanchoilia, and Sidneyia hitherto have been recorded from only the Stephen Formation in British Columbia. Further evaluation indicates that Dicerocaris opisthoeces Robison and Rich- ards, 1981, is a junior synonym of Pseudoarctolepis sharpi Brooks and Caster, 1956. DURING RECENT years, intensive collecting has 1983). Although providing little new morpho- produced rare but diverse, soft-bodied or scler- logic data, the Utah specimens are important otized Middle Cambrian fossils from several because of new information they provide about -
Darwin's Doubt
Debating Darwin’s Doubt A Scientific Controversy that Can No Longer Be Denied DAVID KLINGHOFFER, EDITOR DISCOVERY INSTITUTE PRESS SEATTLE 2015 Description This book contains essays responding to criticism of Darwin’s Doubt: The Explosive Origin of Animal Life and the Case for Intelligent Design by Stephen Meyer. The book explores topics such as orphan genes, cladistics, small shelly fossils, protein evolution, the length of the Cambrian explosion, the God-of-the-Gaps objection to intelligent design, and criticisms raised by proponents of theistic evolution. Contributors include Stephen Meyer, Douglas Axe, David Berlinski, William Dembski, Ann Gauger, Casey Luskin, and Paul Nelson. Edited by David Klinghoffer. Copyright Notice Copyright © 2015 by Discovery Institute. All Rights Reserved. Publisher’s Note This book is part of a series published by the Center for Science & Culture at Discovery Institute in Seattle. Previous books include Signature of Controversy: Responses to CritiCs of Signature in the Cell, edited by David Klinghoffer; The Myth of Junk DNA by Jonathan Wells; The Deniable Darwin & Other Essays by David Berlinski; and DisCovering Intelligent Design: A Journey into the SCientifiC EvidenCe by Gary Kemper, Hallie Kemper, and Casey Luskin. Library Cataloging Data Debating Darwin’s Doubt: A SCientifiC Controversy that Can No Longer Be Denied Edited by David Klinghoffer. BISAC Subject: SCI027000 SCIENCE / Life Sciences / Evolution BISAC Subject: SCI080000 SCIENCE / Essays BISAC Subject: SCI034000 SCIENCE / History ISBN-13: 978-1-936599-30-1 (Kindle) 978-1-936599-31-8 (EPUB) 978-1-936599-28-8 (paperback) Publisher Information Discovery Institute Press, 208 Columbia Street, Seattle, WA 98101 Internet: http://www.discoveryinstitutepress.com/ First Edition. -
Annual Meeting 2011
The Palaeontological Association 55th Annual Meeting 17th–20th December 2011 Plymouth University PROGRAMME and ABSTRACTS Palaeontological Association 2 ANNUAL MEETING ANNUAL MEETING Palaeontological Association 1 The Palaeontological Association 55th Annual Meeting 17th–20th December 2011 School of Geography, Earth and Environmental Sciences, Plymouth University The programme and abstracts for the 55th Annual Meeting of the Palaeontological Association are outlined after the following summary of the meeting. Venue The meeting will take place on the campus of Plymouth University. Directions to the University and a campus map can be found at <http://www.plymouth.ac.uk/location>. The opening symposium and the main oral sessions will be held in the Sherwell Centre, located on North Hill, on the east side of campus. Accommodation Delegates need to make their own arrangements for accommodation. Plymouth has a large number of hotels, guesthouses and hostels at a variety of prices, most of which are within ~1km of the University campus (hotels with PL1 or PL4 postcodes are closest). More information on these can be found through the usual channels, and a useful starting point is the website <http://www.visitplymouth.co.uk/site/where-to-stay>. In addition, we have organised discount rates at the Jury’s Inn, Exeter Street, which is located ~500m from the conference venue. A maximum of 100 rooms have been reserved, and will be allocated on a first-come-first-served basis. Further information can be found on the Association’s website. Travel Transport into Plymouth can be achieved via a variety of means. Travel by train from London Paddington to Plymouth takes between three and four hours depending on the time of day and the number of stops. -
Arthropod Fossil Data Increase Congruence of Morphological and Molecular Phylogenies
ARTICLE Received 14 Jan 2013 | Accepted 21 Aug 2013 | Published 30 Sep 2013 DOI: 10.1038/ncomms3485 Arthropod fossil data increase congruence of morphological and molecular phylogenies David A. Legg1,2,3, Mark D. Sutton1 & Gregory D. Edgecombe2 The relationships of major arthropod clades have long been contentious, but refinements in molecular phylogenetics underpin an emerging consensus. Nevertheless, molecular phylogenies have recovered topologies that morphological phylogenies have not, including the placement of hexapods within a paraphyletic Crustacea, and an alliance between myriapods and chelicerates. Here we show enhanced congruence between molecular and morphological phylogenies based on 753 morphological characters for 309 fossil and Recent panarthropods. We resolve hexapods within Crustacea, with remipedes as their closest extant relatives, and show that the traditionally close relationship between myriapods and hexapods is an artefact of convergent character acquisition during terrestrialisation. The inclusion of fossil morphology mitigates long-branch artefacts as exemplified by pycnogonids: when fossils are included, they resolve with euchelicerates rather than as a sister taxon to all other euarthropods. 1 Department of Earth Sciences and Engineering, Royal School of Mines, Imperial College London, London SW7 2AZ, UK. 2 Department of Earth Sciences, The Natural History Museum, London SW7 5BD, UK. 3 Oxford University Museum of Natural History, Oxford OX1 3PW, UK. Correspondence and requests for materials should be addressed to D.A.L. (email: [email protected]). NATURE COMMUNICATIONS | 4:2485 | DOI: 10.1038/ncomms3485 | www.nature.com/naturecommunications 1 & 2013 Macmillan Publishers Limited. All rights reserved. ARTICLE NATURE COMMUNICATIONS | DOI: 10.1038/ncomms3485 rthropods are diverse, disparate, abundant and ubiqui- including all major extinct and extant panarthropod groups. -
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. -
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.