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Biomechanical Reconstruction of the Appendicular Skeleton in Three

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Biomechanical Reconstruction of the Appendicular Skeleton in Three Louisiana State University LSU Digital Commons LSU Doctoral Dissertations Graduate School 2003 Biomechanical reconstruction of the appendicular skeleton in three North American Jurassic sauropods Ray Wilhite Louisiana State University and Agricultural and Mechanical College, [email protected] Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_dissertations Part of the Earth Sciences Commons Recommended Citation Wilhite, Ray, "Biomechanical reconstruction of the appendicular skeleton in three North American Jurassic sauropods" (2003). LSU Doctoral Dissertations. 2677. https://digitalcommons.lsu.edu/gradschool_dissertations/2677 This Dissertation is brought to you for free and open access by the Graduate School at LSU Digital Commons. It has been accepted for inclusion in LSU Doctoral Dissertations by an authorized graduate school editor of LSU Digital Commons. For more information, please [email protected]. BIOMECHANICAL RECONSTRUCTION OF THE APPENDICULAR SKELETON IN THREE NORTH AMERICAN JURASSIC SAUROPODS A Dissertation Submitted to the Graduate Faculty of the Louisiana State University and Agricultural and Mechanical College In partial fulfillment of the Requirements for the degree of Doctor of Philosophy in The Department of Geology an Geophysics by Ray Wilhite B.S., University of Alabama at Birmingham, 1995 M.S., Brigham Young University, 1999 May 2003 ACKNOWLEDGEMENTS I would like to thank the Jurassic Foundation, the LSU chapter of Sigma Xi, and the LSU Museum of Natural Science for their support of this project. I am also grateful to Art Andersen of Virtual Surfaces for the use of the Microscribe digitizer as well as for editing of data for the project. I would like to thank Ruth Elsey of the Rockefeller Wildlife Refuge for supplying all the Alligator specimens dissected for this paper. I am grateful to Dan Hillmann of the LSU School of Veterinary Medicine for supplying lab space for dissections, profusing specimens, and for all his help with the anatomy of the vertebrate musculoskeletal system. Lindsay Pierce, Stacey Fossey, and Jeff Shoemaker aided in the preparation of Alligator specimens (and provided much needed comic relief). Thanks also go to the collection managers and curators of the many institutions where I have worked over the years, including: Dan Chure, Dinosaur National Monument; Ken Stadtman, Brigham Young University Earth Science Museum; Don Burge, College of Eastern Utah, Burkhard Pohl, Wyoming Dinosaur Center; David Brown, Tate Geological Museum; John Foster and Rod Sheetz, Museum of Western Colorado; Larry Martin and Dave Burnam, University of Kansas; Ken Carpenter and Virginia Tidwell, Denver Museum of Natural History; Pete Reeser, New Mexico Museum of Natural History; Jack Horner and David Vericchio, Montana State University; Peter Dodson, Matt Lamana, and Josh Smith, Philadelphia Academy of Natural Science; David Berman and Betty Hill, Carnegie Museum; Mike Brett-Surman, National Museum of Natural History; Mark Norell, American Museum of Natural History; Vicki Yarborough, Yale Peabody Museum; Bill Simpson, Chicago field ii Museum of Natural History; and Matt Wedel, Sam Noble Oklahoma Museum of Natural History. I am most grateful to my advisor, Judith Schiebout, for keeping me focused on the task at hand. I would also like to thank the rest of my dissertation committee: John Wrenn, Laurie Anderson, Barbara Dutrow, Paul Farnsworth, and Dan Hillmann for their time, patience, and many suggestions and comments which have helped to improve this work greatly. I would like to thank my mentor and friend, Jack McIntosh, for nurturing my initial interest in sauropods and for always being willing to discuss perplexing aspects of sauropod anatomy. I would also like to thank Matt Bonnan and Brian Curtice for their many helpful conversations and suggestions regarding sauropod biology and morphology. I would most certainly not be at this point without the loving support of my family. My mom, dad and grandparents have always been supportive of my interest in dinosaurs. Finally, I am most grateful to my wife, Angela, who supported me through all the long hours and sleepless nights. iii TABLE OF CONTENTS ACKNOWLEDGEMENTS……………………………………………………..ii ABSTRACT……………………………………………………………………..v INTRODUCTION……………………………………………………………….1 CHAPTER 1. DIGITIZING LARGE FOSSIL SKELETAL ELEMENTS FOR THREE-DIMENSIONAL APPLICATIONS………………3 CHAPTER 2. QUALITATIVE MORPHOLOGICAL VARIATION IN THE APPENDICULAR SKELETON OF NORTH AMERICAN SAUROPOD DINOSAURS……………………………………...16 CHAPTER 3. THE APPENDICUALR MUSCULATURE OF THE AMERICAN ALLIGATOR, ALLIGATOR MISSISSIPPIENSIS…….................68 CHAPTER 4. FUNCTIONAL MORPHOLOGY OF THE FORELIMB IN THREE NORTH AMERICAN JURASSIC SAUROPODS…......95 CHAPTER 5. FUNCTIONAL MORPHOLOGY OF THE HINDLIMB IN THREE NORTH AMERICAN JURASSIC SAUROPODS…....145 CONCLUSIONS………………………………………………………………..186 APPENDIX A: DIGITIZING PROCEDURE…………………………………..189 APPENDIX B: DIGITIZED AND MEASURED SPECIMENS..……………...199 VITA……………………………………………………………………………..225 iv ABSTRACT Forelimb and hindlimb articulation, reconstructed musculature, and function were examined in Apatosaurus, Diplodocus, and Camarasaurus. A technique was developed using a Microscribe three-dimensional digitizer to capture external morphological data for skeletal reconstruction and determination of taxonomically useful features. The appendicular musculature of Alligator mississippiensis was dissected to determine form, function, origin, and insertion of muscles to aid in reconstruction of sauropod musculature. Contrary to the literature, M. caudofemoralis longus was found to originate primarily from the lateral surfaces of the proximal chevrons instead of the bodies and transverse processes of the caudals, demonstrating that chevron morphology is indicative of the size, shape, and extent of M. caudofemoralis longus in fossil archosaurs. Apatosurus and Diplodocus were found to have narrower chests than Camarasaurus with forelimbs situated directly under their bodies. Forelimb posture differences between taxa were indicated by the position of the humeral head, morphology of the distal humeral condyles, and the orientation of the posterior process of the ulna. The scapulae in all three taxa were oriented subhorizontally. Hindlimb articulation was found to be related to the shape of the femur and pelvis width. The medial condyles of the femur were longer than the lateral condyles in diplodocids, producing a narrow stance, while the femoral condyles of Camarasaurus were coequal in length, producing a relatively wide stance. This stance would have resulted in wider Camarasaurus trackways than those of diplodocids. Limb motion was restricted to a single plane. Rotation of the brachial and antebrachial joint was constrained by osteology with the brachial joint limited to between v 33º and 40º of rotation, and the antebrachial joint limited to no more than 55º of rotation. Femoral joint rotation was limited to between 30º and 37º based on changes in the length of M. caudofemoralis longus, and rotation of the femerotibial joint was restricted by osteology to between 47º and 55º. M. caudofemoralis longus was relatively larger in Diplodocus than in either Camarasaurus or Apatosaurus based on chevron morphology. These results indicate that tripodal rearing, as sometimes proposed for diplodocids, was not common, based on stance and M. caudofemoralis longus contraction length. vi INTRODUCTION Sauropod dinosaurs were the largest terrestrial animals and their biological and morphological design represents an extreme of terrestrial vertebrate evolution. The study of these immense animals is greatly hindered by the unwieldy nature of their remains. The purpose of this study was to investigate a new approach to sauropod studies using three-dimensional digitized external morphological data, muscular data from extant crocodilians, and observations and measurements of numerous sauropod specimens to produce a comprehensive picture of the appendicular skeleton’s form and function in the three most common North American Jurassic sauropod taxa, Apatosaurus, Diplodocus, and Camarasaurus. The first chapter of this study describes the techniques that were used to gather three-dimensional data for this project. Because the current study focuses exclusively on the external morphology of the appendicular skeleton, a three-dimensional point digitizer was used to gather three-dimensional morphological data for constructing biomechanical models of the sauropod appendicular skeleton. The benefits, as well as the shortcomings, of the point digitizer method are also addressed in this chapter. The second chapter focuses on qualitative morphological variation in the appendicular skeleton of North American Jurassic sauropods. This paper describes, in detail, the morphology of the sauropod appendicular skeleton as well as the morphological differences between the most common North American sauropod genera. Whereas morphological variation among numerous sauropod genera is examined, it is clear that sufficient material for meaningful morphological comparisons is only available 1 for Apatosaurus, Diplodocus, and Camarasaurus. Therefore, these taxa were chosen for the remainder of the study. The third chapter focuses on the pectoral, brachial, pelvic, and thigh musculature in Alligator mississippiensis. The origin, insertion, form, and function of the muscles are described and compared with the literature. Structures not mentioned in the literature are described here for the first
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