Implications of Airflow Dynamics and Soft-Tissue Reconstructions for the Heat Exchange Potential of Dinosaur Nasal Passages A dissertation presented to the faculty of the College of Arts and Sciences of Ohio University In partial fulfillment of the requirements for the degree Doctor of Philosophy Jason Michael Bourke December 2015 © 2015 Jason Michael Bourke. All Rights Reserved. 2 This dissertation titled Implications of Airflow Dynamics and Soft-Tissue Reconstructions for the Heat Exchange Potential of Dinosaur Nasal Passages by JASON MICHAEL BOURKE has been approved for the Department of Biological Sciences and the College of Arts and Sciences by Lawrence M. Witmer Professor of Biomedical Sciences Robert Frank Dean, College of Arts and Sciences 3 ABSTRACT BOURKE, JASON MICHAEL, Ph.D., December 2015, Biological Sciences Implications of Airflow Dynamics and Soft-Tissue Reconstructions for the Heat Exchange Potential of Dinosaur Nasal Passages Director of Dissertation: Lawrence M. Witmer This study seeks to restore the internal anatomy within the nasal passages of dinosaurs via the use of comparative anatomical methods along with computational fluid dynamic simulations. Nasal airway descriptions and airflow simulations are described for extant birds, crocodylians, and lizards. These descriptions served as a baseline for airflow within the nasal passages of diapsids. The presence of shared airflow and soft-tissue properties found in the nasal passages of extant diapsids, were used to restore soft tissues within the airways of dinosaurs, under the assumption that biologically unfeasible airflow patterns (e.g., lack of air movement in olfactory recess) can serve as signals for missing soft tissues. This methodology was tested on several dinosaur taxa. Restored airways in some taxa, revealed the potential presence and likely shape of nasal turbinates. Heat transfer efficiency was tested in two dinosaur species with elaborated nasal passages. Results of that analysis revealed that dinosaur noses were efficient heat exchangers that likely played an integral role in maintaining cephalic thermoregulation. Brain cooling via nasal expansion appears to have been necessary for dinosaurs to have achieved their immense body sizes without overheating their brains. 4 DEDICATION This work is dedicated to my love, Sydney, who supported and encouraged me through the most difficult parts of this endeavour. To my mother, Joan Page, and the rest of my family who always encouraged me to fulfill my dream. Lastly to Chip, who has shared in this adventure from the start. 5 ACKNOWLEDGMENTS This work would not have been possible without the wisdom, guidance and generosity of my advisor and friend, Larry Witmer. He took a chance on me despite the non-traditional way in which I joined the lab. His support and attention to detail—both on the page and in the images—helped make me into the professional that I am today. Thanks to my dissertation committee members: Larry Witmer, Patrick O’Connor, Steve Reilly, and John Cotton for ushering me through the dissertation process. For donation of specimens I would like to thank S. Reilly, P. O’Connor, W. Roosenburg, S. Montuelle, E. Schachner, T. Lyson, P. Bell, and C.G. Farmer. Many thanks to the Rockefeller Wildlife Refuge and Miami Metro Zoo for donations of specimens. I wish to extend thanks to the many collections managers and curators who provided access to fossils and wet specimens, all of which were invaluable to this study. P. Sereno, R. Masek (U. Chicago), M. Norell, and C. Mehling (AMNH), D. Berman and A. Henrichi (CM), K. Padian and P. Holroyd (UCMP), J. Gauthier and D. Brinkman (YPM), G. Watkin-Colwell (YPM), W. Simpson (FMNH), M. Carrano and M.K. Brett-Surman (NMNH), R. Irmis (NHMU), and K. Seymour and D. Evans (ROM). Special thanks to H. Rockhold (Ohio Health O’Blenness) and R. Ridgely (OUμCT) for access to and help with CT scanning. Thanks to WitmerLab members: D. Dufeau, W.R. Porter, E. Snively, A. Morhardt, C. Early, D. Cerio, J. Nassif. for useful discussions and help with hypothesis testing and synthesizing. Thanks to D. Harper for helping with some equations. Thanks to E. Gorscak, R. Felice, H. O’Brien and the rest of the BIOS graduate students for providing useful discussions and a welcoming atmosphere of collaboration and comradery. Funding for this project 6 was provided by a National Science Foundation Graduate Research Fellowship, Jurassic Foundation Grant, Welles Fund, Ohio University Student Enhancement Award, and Original Work Grants. 7 TABLE OF CONTENTS Page Abstract ............................................................................................................................... 3 Dedication ........................................................................................................................... 4 Acknowledgments............................................................................................................... 5 List of Tables .................................................................................................................... 12 List of Figures ................................................................................................................... 14 Chapter 1 : Reconstructing Dinosaur Nasal Airflow and Testing its Efficacy at Heat Transfer During Respiration ............................................................................................. 24 Abstract ......................................................................................................................... 24 Glossary ........................................................................................................................ 25 Introduction ................................................................................................................... 27 The Problem of Restoring Airflow…and a Solution .................................................... 30 Analyzing the Extant .................................................................................................... 33 Shared Airflow Patterns Among Extant Diapsids ........................................................ 35 Soft-Tissue Correction .................................................................................................. 38 Breathing Life into a Dinosaur ..................................................................................... 41 Heat Transfer in the Nasal Passages of Large Dinosaurs ............................................. 43 Physiological Effects of Nasal Passage Enhancement in Dinosaurs ............................ 45 Acknowledgments ........................................................................................................ 50 References ..................................................................................................................... 50 Chapter 2 : The Impact of Soft Tissues on Nasal Airflow in Diapsids: Implications for Dinosaurs .......................................................................................................................... 63 Abstract ......................................................................................................................... 63 Abbreviations ................................................................................................................ 64 Introduction ................................................................................................................... 64 Anatomy and Terminology ........................................................................................... 67 Materials and Methods .................................................................................................. 71 Study Taxa ................................................................................................................ 71 Dissections ................................................................................................................ 72 Computed Tomography ............................................................................................ 73 8 Model Reconstruction ............................................................................................... 73 Physiological Parameters .......................................................................................... 74 Fluid Dynamic Analysis ........................................................................................... 75 Results ........................................................................................................................... 79 Grid Independence .................................................................................................... 79 Morphological Comparisons of the Soft-Tissue Airways ........................................ 80 Soft-Tissue and Bony-Bounded Nasal Capsule Morphology ................................... 83 Airflow in Soft-Tissue Nasal Capsules ..................................................................... 84 Airflow in Bony-Bounded Nasal Capsules ............................................................... 90 Discussion ..................................................................................................................... 92 Accounting for Missing Soft Tissue ......................................................................... 99 Conclusions ................................................................................................................. 102 Acknowledgments .....................................................................................................