DOCSLIB.ORG

Lead Article New Fossil Exploration in the Charnwood Forest, Leicestershire

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Lead Article New Fossil Exploration in the Charnwood Forest, Leicestershire Author: Aron Bowers lead article New fossil exploration in the Charnwood Forest, Leicestershire There was a time when everyone thought that rocks of Precambrian age contained no fossil remains, believing that the base of the Cambrian marked the ‘dawn of life’. All that changed for ever when, in 1956/7, a schoolgirl called Tina and a schoolboy called Roger found the very first specimen of what was later named Charnia masoni in an old quarry in Charnwood Forest, Leicestershire. In the intervening years, a number of workers, both academics and amateurs, have continued to find more examples of life in what we now call the Ediacaran at new sites in and around Charnwood Forest. Veterinary surgeon Aron Bowers, share some of his recent discoveries with Down to Earth readers... Discoid fossil form, with zig-zagged stem emerging and attached 'mop- headed' frond form. Total length 15cm. (Photo: Aron Bowers) A news item in Down to Earth 87, May 2014, suggested a completely new Precambrian location had been discovered. This is not so. I discovered it two years ago and it has been written up as a scientific paper in the Mercian Geologist, last year. Of interest is that there are two significant fossil planes nearby in the same area. I have discovered several new species not known from type locations previously (Primocandelabrum sp., Hiemalora aff. stellaris, etc) and have discovered specimens of a species Hadrynichorde aff. catalinensis, not recorded previously from the UK or Europe. I have had the luck of describing thirty-five new specimens of juvenile fossil forms, many of known species, Charnia, Charniodiscus sp., and many show no correlation with known UK species, and are reminiscent of the species Charniodiscus spinosus and Trepassia sp, akin to the Newfoundland biota in Canada. Roger Mason with the original specimen that he and Tina Negus found in 1956/57. Over fifty years later, new and exciting finds are still being made in Charnwood Forest There are few incidences where amateurs can really make a difference in the field of geology. Palaeontology is the exception. Being a keen amateur geologist with a passion for palaeontology, my fossil collecting has led me to search all over the UK. My passion at the moment is for the Precambrian period. Few exposures of Precambrian rocks reach the surface in England, but fossiliferous horizons in the Charnwood Forest area of Leicestershire have been known since Tina Negus (nee Batty) and Roger Mason discovered the iconic fossil Charnia masoni in 1956/7. Prior to 2012 only six fossil locations for Precambrian fossils were known in Leicestershire. In the last two years I have been lucky Small area of fossil plane 20 x 30cm, in which twenty-seven fossil enough to discover twenty-one new fossiliferous bedding planes, discs, large and small have been discovered (small discs evident in similar locations to those known, and have also discovered three with casting of the area). (Photo: Aron Bowers) completely new locations, quite separate from those known. 10 Down to Earth 88 Discoid fossil form, likely holdfast 30 x 35mm (Photo: Aron Bowers) Several specimens look like multi-branched algal forms and parallel multi- filamentous forms seem to be of species not recorded previously. Recently, I have discovered a large fossil plane which at a preliminary, rough count has 265 discal holdfast fossils upon it, and several small Charnia/Charniodiscus forms. There is a likely total tally of circa 400 discs upon the plane, in effect this is the densest concentration of Precambrian fossils to have been discovered in Britain so far. This fossil plane is currently being written up and will appear as a scientific paper shortly. It is important to note, these fossil forms are incredibly rare finds, and are in effect national treasures. They should never be hammered or collected, as the fractured nature of the rock often means that extraction attempts destroys the fossil itself. There have been attempted fossil extractions of disc forms from classic locations in the past twenty years. It is for this reason that I have been careful not to give localities for the fossils shown in this article. The Charnia Research Group, has been set up to further research and also to protect the finds that have already been made. It comprises of like-minded geologists, Natural England representatives, land owners, conservation managers and amateurs who gather at bi-yearly meetings to discuss the protection of the fossil sites. The author would like to ask if any DtoE readers, whilst walking within the Charnwood Forest of Leicestershire, discover any potential fossil discs or unusual, presumed fossil forms - to record the locations, and take photographs and to contact me to investigate the locations further. If I can discover twnety-one new fossil-planes in two years, there is still a lot of scope for future fossil discoveries! Many Down to Earth readers are incredibly observant and it may be that these pictures inspire you to look for more in and around Charnwood Forest. If you can help Aron with this information, please contact him by email at: [email protected] .
Load more

Recommended publications
  • Ediacaran Developmental Biology
    Dunn, F., Liu, A., & Donoghue, P. (2017). Ediacaran developmental biology. Biological Reviews. https://doi.org/10.1111/brv.12379 Publisher's PDF, also known as Version of record License (if available): CC BY Link to published version (if available): 10.1111/brv.12379 Link to publication record in Explore Bristol Research PDF-document 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/ Biol. Rev. (2017), pp. 000–000. 1 doi: 10.1111/brv.12379 Ediacaran developmental biology Frances S. Dunn1,2,∗, Alexander G. Liu1,† and Philip C. J. Donoghue1 1School of Earth Sciences, University of Bristol, Life Sciences Building, 24 Tyndall Avenue, Bristol, BS8 1TQ, U.K. 2British Geological Survey, Nicker Hill, Keyworth, Nottingham, NG12 5GG, U.K. ABSTRACT Rocks of the Ediacaran System (635–541 Ma) preserve fossil evidence of some of the earliest complex macroscopic organisms, many of which have been interpreted as animals. However, the unusual morphologies of some of these organisms have made it difficult to resolve their biological relationships to modern metazoan groups. Alternative competing phylogenetic interpretations have been proposed for Ediacaran taxa, including algae, fungi, lichens, rhizoid protists, and even an extinct higher-order group (Vendobionta). If a metazoan affinity can be demonstrated for these organisms, as advocated by many researchers, they could prove informative in debates concerning the evolution of the metazoan body axis, the making and breaking of axial symmetries, and the appearance of a metameric body plan.
    [Show full text]
  • The Ediacaran Frondose Fossil Arborea from the Shibantan Limestone of South China
    Journal of Paleontology, 94(6), 2020, p. 1034–1050 Copyright © 2020, The Paleontological Society. This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/ licenses/by/4.0/), which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited. 0022-3360/20/1937-2337 doi: 10.1017/jpa.2020.43 The Ediacaran frondose fossil Arborea from the Shibantan limestone of South China Xiaopeng Wang,1,3 Ke Pang,1,4* Zhe Chen,1,4* Bin Wan,1,4 Shuhai Xiao,2 Chuanming Zhou,1,4 and Xunlai Yuan1,4,5 1State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology and Center for Excellence in Life and Palaeoenvironment, Chinese Academy of Sciences, Nanjing 210008, China <[email protected]><[email protected]> <[email protected]><[email protected]><[email protected]><[email protected]> 2Department of Geosciences, Virginia Tech, Blacksburg, Virginia 24061, USA <[email protected]> 3University of Science and Technology of China, Hefei 230026, China 4University of Chinese Academy of Sciences, Beijing 100049, China 5Center for Research and Education on Biological Evolution and Environment, Nanjing University, Nanjing 210023, China Abstract.—Bituminous limestone of the Ediacaran Shibantan Member of the Dengying Formation (551–539 Ma) in the Yangtze Gorges area contains a rare carbonate-hosted Ediacara-type macrofossil assemblage. This assemblage is domi- nated by the tubular fossil Wutubus Chen et al., 2014 and discoidal fossils, e.g., Hiemalora Fedonkin, 1982 and Aspidella Billings, 1872, but frondose organisms such as Charnia Ford, 1958, Rangea Gürich, 1929, and Arborea Glaessner and Wade, 1966 are also present.
    [Show full text]
  • What Came Before the Cambrian Explosion
    What Came Before the Cambrian? Advanced Reading The Cambrian Explosion was an era of significant evolution of animal life. What came before the Cambrian era that, in a sense, opened the door for the new body forms to evolve? The geologic era before the Cambrian was called the Ediacran, lasting from about 635 to 542 million years ago. Scientists often characterize this era as an “experimental” phase in the evolution of animals. By this time unicellular life had been around for millions of years and a mat of microbes covered parts of the seafloor. The first multicellular animals that evolved could have grazed on those microbes. The fossils from the Ediacran mostly show soft-bodied organisms. Some of these fossils look like fronds, discs and blobs, and aren’t easy to identify. Others seem to be related to Cnidarians or to be soft-bodied relatives of arthropods or perhaps Echinoderms. In addition, there are trace fossils, probably made by worm-like creatures. Many of the fossil animals remain mysterious and may represent lines of animals that no longer exist. But fossils are not the only evidence of animal life in the Ediacran. In fact the first evidence of sponges is not a body fossil but rather a biochemical fossil. When an animal dies, some of its molecules break down into a stable form that can last in rocks for millions of years just like body fossils. These are biochemical fossils. Scientists have found an Ediacran biochemical fossil of a fat molecule found today only in sponges. The name Ediacran comes from the Ediacra Hills of South Australia, the most famous location of these fossils.
    [Show full text]
  • The Ediacaran Frondose Fossil Arborea from the Shibantan Limestone of South China
    Journal of Paleontology, 94(6), 2020, p. 1034–1050 Copyright © 2020, The Paleontological Society. This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/ licenses/by/4.0/), which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited. 0022-3360/20/1937-2337 doi: 10.1017/jpa.2020.43 The Ediacaran frondose fossil Arborea from the Shibantan limestone of South China Xiaopeng Wang,1,3 Ke Pang,1,4* Zhe Chen,1,4* Bin Wan,1,4 Shuhai Xiao,2 Chuanming Zhou,1,4 and Xunlai Yuan1,4,5 1State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology and Center for Excellence in Life and Palaeoenvironment, Chinese Academy of Sciences, Nanjing 210008, China <[email protected]><[email protected]> <[email protected]><[email protected]><[email protected]><[email protected]> 2Department of Geosciences, Virginia Tech, Blacksburg, Virginia 24061, USA <[email protected]> 3University of Science and Technology of China, Hefei 230026, China 4University of Chinese Academy of Sciences, Beijing 100049, China 5Center for Research and Education on Biological Evolution and Environment, Nanjing University, Nanjing 210023, China Abstract.—Bituminous limestone of the Ediacaran Shibantan Member of the Dengying Formation (551–539 Ma) in the Yangtze Gorges area contains a rare carbonate-hosted Ediacara-type macrofossil assemblage. This assemblage is domi- nated by the tubular fossil Wutubus Chen et al., 2014 and discoidal fossils, e.g., Hiemalora Fedonkin, 1982 and Aspidella Billings, 1872, but frondose organisms such as Charnia Ford, 1958, Rangea Gürich, 1929, and Arborea Glaessner and Wade, 1966 are also present.
    [Show full text]
  • Charnwood Forest
    Charnwood Forest: A Living Landscape An integrated wildlife and geological conservation implementation plan March 2009 Cover photograph: Warren Hills, Charnwood Lodge Nature Reserve (Michael Jeeves) 2 Charnwood Forest: A Living Landscape Contents Page 1. Executive summary 5 2. Introduction 8 3. A summary of the geological/geomorphological interest 13 4. Historical ecology since the Devensian glaciation 18 5. The main wildlife habitats 21 6. Overall evaluation 32 7. Summary of changes since the 1975 report 40 8. Review of recommendations in the 1975 report 42 9. Current threats 45 10. Existing nature conservation initiatives 47 11. New long-term objectives for nature conservation in Charnwood Forest 51 12. Action plan 54 13. Acknowledgements 56 14. References 57 Appendix – Gazeteer of key sites of ecological importance in Charnwood Forest Figures: 1. Charnwood Forest boundaries 2. Sites of Special Scientific Interest 3. Map showing SSSIs and Local Wildlife Site distribution 4. Tabulation of main geological formations and events in Charnwood 5. Regionally Important Geological Sites 6. Woodlands in order of vascular plant species-richness 7. Moth species-richness 8. Key sites for spiders 9. Key sites for dragonflies and damselflies 10. Evaluation of nature conservation features 11. Invertebrate Broad Assemblage Types in Charnwood listed by ISIS 12a Important ISIS Specific Assemblage Types in Charnwood Forest 3 12b Important habitat resources for invertebrates 12c Important sites for wood-decay invertebrate assemblages 12d Important sites for flowing water invertebrate assemblages 12e Important sites for permanent wet mire invertebrate assemblages 12f Important sites for other invertebrate assemblage types 13. Evaluation of species groups 14. Leicestershire Red Data Book plants 15.
    [Show full text]
  • Of Time and Taphonomy: Preservation in the Ediacaran
    See discussions, stats, and author profiles for this publication at: http://www.researchgate.net/publication/273127997 Of time and taphonomy: preservation in the Ediacaran CHAPTER · JANUARY 2014 READS 36 2 AUTHORS, INCLUDING: Charlotte Kenchington University of Cambridge 5 PUBLICATIONS 2 CITATIONS SEE PROFILE Available from: Charlotte Kenchington Retrieved on: 02 October 2015 ! OF TIME AND TAPHONOMY: PRESERVATION IN THE EDIACARAN CHARLOTTE G. KENCHINGTON! 1,2 AND PHILIP R. WILBY2 1Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EQ, UK <[email protected]! > 2British Geological Survey, Keyworth, Nottingham, NG12 5GG, UK ABSTRACT.—The late Neoproterozoic witnessed a revolution in the history of life: the transition from a microbial world to the one known today. The enigmatic organisms of the Ediacaran hold the key to understanding the early evolution of metazoans and their ecology, and thus the basis of Phanerozoic life. Crucial to interpreting the information they divulge is a thorough understanding of their taphonomy: what is preserved, how it is preserved, and also what is not preserved. Fortunately, this Period is also recognized for its abundance of soft-tissue preservation, which is viewed through a wide variety of taphonomic windows. Some of these, such as pyritization and carbonaceous compression, are also present throughout the Phanerozoic, but the abundance and variety of moldic preservation of body fossils in siliciclastic settings is unique to the Ediacaran. In rare cases, one organism is preserved in several preservational styles which, in conjunction with an increased understanding of the taphonomic processes involved in each style, allow confident interpretations of aspects of the biology and ecology of the organisms preserved.
    [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]
  • The Influence of Environmental Setting on the Community Ecology of Ediacaran Organisms
    bioRxiv preprint doi: https://doi.org/10.1101/861906; this version posted December 2, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. 1 The influence of environmental setting on the community ecology of Ediacaran organisms 2 3 Emily G. Mitchell1, Nikolai Bobkov2,3, Natalia Bykova2,4, Alavya Dhungana,5, Anton 4 Kolesnikov2,6, 7, Ian R. P. Hogarth8,9 Alexander G. Liu10, Tom M.R. Mustill10,11, Nikita 5 Sozonov2,3, Shuhai Xiao4 and Dmitriy V. Grazhdankin2,3 . 6 7 [email protected] 8 9 1Department of Zoology, University of Cambridge, UK. 10 2Institute of Petroleum Geology and Geophysics, Novosibirsk, Russian Federation. 11 3Novosibirsk State University, Russian Federation. 12 4Department of Geosciences, Virginia Tech, Blacksburg, VA 24061, United States. 13 5 Department of Earth Sciences, Durham University, UK. 14 6Geological Institute, Russian Academy of Sciences, Moscow, Russian Federation. 15 7Department of Geography, Moscow Pedagogical State University, Moscow, Russian 16 Federation. 17 8Department of Chemical Engineering, University of Cambridge, UK. 18 9Current address: University College London, UCL Institute for Innovation and Public 19 Purpose, UK. 20 10Department of Earth Sciences, University of Cambridge, UK. 21 11Current address: Gripping Films, St. John's Church Road, London, England, E9 6EJ. 22 23 24 1 bioRxiv preprint doi: https://doi.org/10.1101/861906; this version posted December 2, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission.
    [Show full text]
  • Guide to the Geology of Bradgate Park and Swithland Wood, Charnwood Forest
    British Geological Survey Keyworth Nottingham NG12 5GG BGS Occasional Report: OR/10/041 GUIDE TO THE GEOLOGY OF BRADGATE PARK AND SWITHLAND WOOD, CHARNWOOD FOREST J N Carney Including a provisional itinerary and details of localities Old John Tower, with south- dipping strata of the Beacon Hill Formation in the f oreground Bibliographic reference: Carney, J N, 2010. Guide to the geology of Bradgate Park and Swithland Wood, Charnwood Forest. British Geological Survey Occasional Report, 0R/10/041. Geology data, British Geological Survey © NERC PROVISIONAL ITINERARY AND NOTES Gather at Bradgate Park, Hunt’s Hill entrance (SK 5232 1167) CONTENTS A. Introduction and geological background Mode of origin of the Charnian Supergroup Charnwood Forest as a ‘young’ mountain range B. Locality descriptions 1. Beacon Hill Formation, Old John Tower 2. Bradgate Formation: Sliding Stone Slump Breccia 2a. Bradgate Formation, above Sliding Stone Breccia 3. Swithland Formation in Swithland Wood 4. Hanging Rocks Formation 5. Bradgate Formation, Coppice Plantation 6. South Charnwood Diorite, Bradgate House 7. Brand Hills Formation, Stable Pit 8. Triassic exposure, Pheasantry The fossil site References Figures (at back of this guide) 1. Geology of Charnwood Forest 2. Geological map of Bradgate Park and localities to be visited 3. Subduction zone model for Charnian magma generation 4. a) Position of England & Wales 600 million years ago b) Position of UK about 420 million years ago 5 The Soufriere Hills volcano, Montserrat 6. Cross-section through a Charnian volcano 7. Principal features of the ‘sag’ structure 8. Structural synthesis of the ‘sag’ 9. Selected Precambrian fossils from Charnwood Forest 2 Note: Due to recent vandalism and attempted theft of in situ fossils, by person(s) unknown, a protocol was established between the BGS and the Bradgate Park Trust.
    [Show full text]
  • A Unique View on the Evolution of Marine Life
    EXCEPTIONAL FOSSIL PRESERVATION: A Unique View on the Evolution of Marine Life Edited by DAVID J. BOTTJER COLUMBIA UNIVERSITY PRESS Bottjer_00FM 5/16/02 1:23 PM Page i EXCEPTIONAL FOSSIL PRESERVATION Critical Moments and Perspectives in Earth History and Paleobiology DAVID J. BOTTJER RICHARD K. BAMBACH Editors Bottjer_00FM 5/16/02 1:23 PM Page ii Critical Moments and Perspectives in Earth History and Paleobiology David J. Bottjer and Richard K. Bambach, Editors The Emergence of Animals: The Cambrian Breakthrough Mark A. S. McMenamin and Dianna L. S. McMenamin Phanerozoic Sea-Level Changes Anthony Hallam The Great Paleozoic Crisis: Life and Death in the Permian Douglas H. Erwin Tracing the History of Eukaryotic Cells: The Enigmatic Smile Betsey Dexter Dyer and Robert Alan Obar The Eocene-Oligocene Transition: Paradise Lost Donald R. Prothero The Late Devonian Mass Extinction: The Frasnian/Famennian Crisis George R. McGhee Jr. Dinosaur Extinction and the End of an Era: What the Fossils Say J. David Archibald One Long Experiment: Scale and Process in Earth History Ronald E. Martin Interpreting Pre-Quaternary Climate from the Geologic Record Judith Totman Parrish Theoretical Morphology: The Concept and Its Applications George R. McGhee Jr. Principles of Paleoclimatology Thomas M. Cronin The Ecology of the Cambrian Radiation Andrey Yu. Zhuravlev and Robert Riding, Editors Plants Invade the Land: Evolutionary and Environmental Perspectives Patricia G. Gensel and Dianne Edwards, Editors Bottjer_00FM 5/16/02 1:23 PM Page iii EXCEPTIONAL FOSSIL PRESERVATION A Unique View on the Evolution of Marine Life Edited by DAVID J. BOTTJER, WALTER ETTER, JAMES W.
    [Show full text]
  • The Palaeontology Newsletter
    The Palaeontology Newsletter Contents100 Editorial 2 Association Business 3 Annual Meeting 2019 3 Awards and Prizes AGM 2018 12 PalAss YouTube Ambassador sought 24 Association Meetings 25 News 30 From our correspondents A Palaeontologist Abroad 40 Behind the Scenes: Yorkshire Museum 44 She married a dinosaur 47 Spotlight on Diversity 52 Future meetings of other bodies 55 Meeting Reports 62 Obituary: Ralph E. Chapman 67 Grant Reports 72 Book Reviews 104 Palaeontology vol. 62 parts 1 & 2 108–109 Papers in Palaeontology vol. 5 part 1 110 Reminder: The deadline for copy for Issue no. 101 is 3rd June 2019. On the Web: <http://www.palass.org/> ISSN: 0954-9900 Newsletter 100 2 Editorial This 100th issue continues to put the “new” in Newsletter. Jo Hellawell writes about our new President Charles Wellman, and new Publicity Officer Susannah Lydon gives us her first news column. New award winners are announced, including the first ever PalAss Exceptional Lecturer (Stephan Lautenschlager). (Get your bids for Stephan’s services in now; check out pages 34 and 107.) There are also adverts – courtesy of Lucy McCobb – looking for the face of the Association’s new YouTube channel as well as a call for postgraduate volunteers to join the Association’s outreach efforts. But of course palaeontology would not be the same without the old. Behind the Scenes at the Museum returns with Sarah King’s piece on The Yorkshire Museum (York, UK). Norman MacLeod provides a comprehensive obituary of Ralph Chapman, and this issue’s palaeontologists abroad (Rebecca Bennion, Nicolás Campione and Paige dePolo) give their accounts of life in Belgium, Australia and the UK, respectively.
    [Show full text]
  • Experimental Fluid Mechanics of an Ediacaran Frond
    Palaeontologia Electronica palaeo-electronica.org Experimental fluid mechanics of an Ediacaran frond Amy Singer, Roy Plotnick, and Marc Laflamme ABSTRACT Ediacaran fronds are iconic members of the soft-bodied Ediacara biota, character- ized by disparate morphologies and wide stratigraphic and environmental ranges. As is the case with nearly all Ediacaran forms, views of their phylogenetic position and ecol- ogy are equally diverse, with most frond species considered as sharing a similar eco- logical guild rather than life history. Experimental biomechanics can potentially constrain these interpretations and suggest new approaches to understanding frond life habits. We examined the behavior in flow of two well-know species of Charniodiscus from the Mistaken Point Formation of Newfoundland, Canada (Avalon assemblage): Charniodiscus spinosus and C. procerus. Models reflecting alternative interpretations of surface morphology and structural rigidity were subjected to qualitative and quantita- tive studies of flow behavior in a recirculating flow tank. At the same velocities and orientations, model C. procerus and C. spinosus expe- rienced similar drag forces; the drag coefficient of C. procerus was smaller, but it is taller and thus experiences higher ambient flow velocities. Reorientation to become parallel to flow dramatically reduces drag in both forms. Models further demonstrated that C. procerus (and to a lesser extent C. spinosus) behaved as self exciting oscilla- tors, which would have increased gas exchange rates at the surface of the fronds and is consistent with an osmotrophic life habit. Amy Singer. Geosciences Department, The University of Montana, 32 Campus Drive #1296, Missoula, MT 59812-1296; [email protected] Roy Plotnick (correspondence author).
    [Show full text]