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Mechanisms for Increasing Respiratory Capacity Through Ontogeny in the Blastoid Genus Pentremites

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Mechanisms for Increasing Respiratory Capacity Through Ontogeny in the Blastoid Genus Pentremites University of Tennessee, Knoxville TRACE: Tennessee Research and Creative Exchange Masters Theses Graduate School 8-2006 Mechanisms for Increasing Respiratory Capacity through Ontogeny in the Blastoid Genus Pentremites Troy A. Dexter University of Tennessee - Knoxville Follow this and additional works at: https://trace.tennessee.edu/utk_gradthes Part of the Geology Commons Recommended Citation Dexter, Troy A., "Mechanisms for Increasing Respiratory Capacity through Ontogeny in the Blastoid Genus Pentremites. " Master's Thesis, University of Tennessee, 2006. https://trace.tennessee.edu/utk_gradthes/1540 This Thesis is brought to you for free and open access by the Graduate School at TRACE: Tennessee Research and Creative Exchange. It has been accepted for inclusion in Masters Theses by an authorized administrator of TRACE: Tennessee Research and Creative Exchange. For more information, please contact [email protected]. To the Graduate Council: I am submitting herewith a thesis written by Troy A. Dexter entitled "Mechanisms for Increasing Respiratory Capacity through Ontogeny in the Blastoid Genus Pentremites." I have examined the final electronic copy of this thesis for form and content and recommend that it be accepted in partial fulfillment of the equirr ements for the degree of Master of Science, with a major in Geology. Michael L. McKinney, Major Professor We have read this thesis and recommend its acceptance: Colin D. Sumrall, Edmund Perfect Accepted for the Council: Carolyn R. Hodges Vice Provost and Dean of the Graduate School (Original signatures are on file with official studentecor r ds.) To the Graduate Council: I am submitting herewith a thesis written by Troy A. Dexter entitled “Mechanisms for Increasing Respiratory Capacity through Ontogeny in the Blastoid Genus Pentremites.” I have examined the final electronic copy of this thesis for form and content and recommend that it be accepted in partial fulfillment of the requirements for the degree of Master of Science, with a major in Geology. Michael L. McKinney Major Professor We have read this thesis and recommend its acceptance: Colin D. Sumrall Edmund Perfect Accepted for the Council: Anne Mayhew Vice Chancellor and Dean of Graduate Studies (Original signatures are on file with official student records.) MECHANISMS FOR INCREASING RESPIRATORY CAPACITY THROUGH ONTOGENY IN THE BLASTOID GENUS PENTREMITES A Thesis Presented for the Master of Science Degree The University of Tennessee, Knoxville Troy A. Dexter August 2006 Acknowledgements I would like to thank Dr. Colin Sumrall for creating this project and for all the help and guidance he has given throughout the process, including traveling into the field, sample collection, sample preparation, interpretation of results, expanding the project beyond the blastoid clade, and revising the first few poorly written drafts of this thesis. He has coerced me to present my research a number of times and has introduced me to other researchers in my field whose help has significantly benefited this project. Beyond this project, he is responsible for my education in geology field methods, scientific principles, how to excel at teaching, and just about everything I know in paleontology. Dr. Colin Sumrall has ensured that I am prepared for my upcoming PhD work as well as my future career. I would like to thank my committee for their advice on this project and their hasty revisions of this thesis. Dr. Michael McKinney was essential for the morphometric interpretations and statistical methods used on this project. Dr. Michael McKinney is also responsible for my original application into this department all those years ago, and without his counsel I would never have come to the University of Tennessee and would likely never have returned to academia. Dr. Ed Perfect not only helped with the revisions of this thesis, but also assisted in shaping the project and its direction in the early stages of its proposal. Dr. Ed Perfect’s knowledge of hydrodynamics was necessary for the interpretation of hydrospire biomechanics. There are a number of people who I would like to thank for their involvement in this project. Dr. Kula Misra allowed the use of his thin bladed Buehler® rock saw, which ii I proceeded to break. Dr. Claudia Mora and Dr. Zheng-Hua Li graciously allowed the use of their microtome which was originally to be used on the small samples and which I also proceeded to break. Bill Deane helped me track down and run equipment. Dr. Lawrence Taylor allowed me to use his thin bladed rock saw and Allan Patchen helped me with any issues I had with the saw and was considerate enough to try to fix Kula’s rock saw. Dr. Linda Kah was essential in kicking my ass into gear any time I started to slack on the writing of this thesis. Dr. Jonathon Evenick’s assistance was essential for the formatting of this thesis and for help with general Microsoft Word© issues (of which there are many). Jeff Nettles helped expand the possible methods I could use for this project and gave much of his time working through methodological issues with me. My personal secretary, Whitney Kocis, read over anything I had written and gave valuable advice for the clarity of my writing. Beyond the department, I had numerous talks with Dr. Johnny Waters and Dr. James Sprinkle about my project focus and what difficulties I would have to address during my research. Paleontology is not the most economic of geologic disciplines and requires a great deal of begging and borrowing. I would like to thank those organizations who have assisted this degree monetarily. The Geological Society of America provided me with a 2005 Student Grant and the Paleontological Society provided me with a Stephen Jay Gould Grant. This money was invaluable for conducting this research project. I also greatly appreciate scholarship money that I have received from the Mayo Foundation and from the Department of Earth and Planetary Sciences at the University of Tennessee. That money helped offset the great expense of attaining an advanced degree. iii Abstract This study was conducted to determine how the hydrospires in blastoids (the respiratory channels through which blastoids respire) change in shape and capacity during ontogeny. As the volume of a blastoid increases ontogenetically, the respiratory capacity of the hydrospires must increase to match the additional respiratory requirements. Ontogenetically, volume increases at a cubic rate, therefore the surface area of the respiratory structures should increase at a similar rate. Using transverse cross sections of the theca through an ontogenetic series in two species of the blastoid Pentremites, the surface area and volume of the hydrospires was quantified. The data demonstrated that the hydrospires increased surface area with increasing volume to maintain respiratory capacity and that this was accomplished using different mechanisms depending upon the species. In the species Pentremites godoni, increased hydrospire surface area was developed through increased length of the hydrospires through ontogeny. In the species Pentremites pyriformis, increased surface area of the hydrospires was accomplished by increasing the number of hydrospire folds within the body through ontogeny. iv Table of Contents 1. INTRODUCTION ........................................................................................................... 1 2. BACKGROUND ............................................................................................................. 3 Morphology................................................................................................................. 3 Phylogeny and Development..................................................................................... 10 3. CURRENT STUDY ...................................................................................................... 12 Hypothesis................................................................................................................. 12 Localities................................................................................................................... 15 Species Description................................................................................................... 16 4. METHODOLOGY........................................................................................................ 21 Sample Collection ..................................................................................................... 21 Morphometric Analysis............................................................................................. 22 Large Sample Sectioning .......................................................................................... 27 Small Sample Sectioning........................................................................................... 29 Photographic Measurements .................................................................................... 31 Calculating Surface Area.......................................................................................... 32 Calculating Visceral Volume .................................................................................... 35 Data Analysis............................................................................................................ 38 Discussion of Procedures ......................................................................................... 39 5. RESULTS...................................................................................................................
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