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Captorhinus After Heaton & Reisz (1980); D: Milleretta After Gow (1972); E: Pareiasaurus After Gregory (1946)

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Captorhinus After Heaton & Reisz (1980); D: Milleretta After Gow (1972); E: Pareiasaurus After Gregory (1946) National Library Bibliothèque nationale 1+1 01 Canada du Canada Acquisitions and Direction des acquisitions et Bibliographie services Branch des services bibliographiques 39S Wellington Slrecl 395. rue Wellington Ottawa.Onlano Onaw3 (Onl<1OO) K1AON4 K1AON4 NOTICE AVIS The quality of this microform is La qualité de cette microforme heavily dependent upon the dépend grandement de la qualité quality of the original thesis de la thèse soumise au submitted for microfilming. microfilmage. Nous avons tout Every effort has been made to fait pour assurer une qualité ensure the highest quality of supérieure de reproduction. reproduction possible. If pages are missing, contact the S'il manque des pages, veuillez university which granted the communiquer avec l'université degree. qui a conféré le grade. Sorne pages may have indistinct La qualité d'impression de print especially if the original certaines pages peut laisser à pages were typad with a poor désirer, surtout si les pages typewriter ribbon or if the ·originalos ont été university sent us an inferior dactylographiées à l'aide d'un photocopy. ruban usé ou si l'université nous a fait parvenir une photocopie de qualité inférieure. Reproduction in full or in part of La reproduction, même partielle, this microform is governed by de cette microforme est soumise the Canadian Copyright Act, à la Loi canadienne sur le droit R.S.C. 1970, c. C-30, and d'auteur, SRC 1970, c. C·30, et subsequent amendments. ses amendements subséquents. Canada • THE PROCOLOPHONIDBARASAURUS AND THE PHYLOGENY OF EARLYAMNIOTES DIRK MECKERT BIOLOGY DEPARTMENT McGILL UNIVERSITY, MONTREAL QUEBEC,CANADA A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Doctor of Philosophy. • © DIRK MECKERT, 1995. National Ubra:y Bibliothèque nationale 1+1 of Canada du Canada Acquisitions and Direction des acquisitions et Bibliographie Services Branch des services bibliographiques 395 Wellington Street 395. rue Wellington Ottawa, Qnlario Ottawa (Ontario) K1A QN4 K1A QN4 The author has granted an L'auteur a accordé une licence irrevocable non·exclusive licence irrévocable et non exclusive allowing the National Library of permettant à la Bibliothèque Canada to reproduce, loan, nationale du Canada de distribute or sell copies of reproduire, prêter, distribuer ou hisjher thesis by any means and vendre des copies de sa thèse in any form or format, making de quelque manière et sous this thesis available to interested quelque forme que ce soit pour persons. mettre des exemplaires de cette thèse à la disposition des personnes intéressées. The author retains ownership of L'auteur conserve la propriété du the copyright in hisjher thesis, droit d'auteur qui protège sa Neither the thesis nor substantial thèse. Ni la thèse ni des extraits extracts from it may be printed or substantiels de celle-ci ne otherwise reproduced without doivent être imprimés ou hisjher permission. autrement reproduits sans son autorisation. ISBN 0-612-12435-5 Canada • PREFACE This thesis is centered around an anatomicai study of the osteoiogy of Barasaurus besairiei, a procoiophonoid from the Upper Permian of Madagascar. Barasaurus had been described in a preiiminary fashion in 191)5 hy Piveteau. This study is hased on the original material as weil as a large number of new specimens. 1 examined ail the specimens. My description is ail original and presents for the l'irst time a complete picture of the anatomy of Barasaurus in ail aspects. With this wealth in information 1 reconstructed the skull as weil as the postcranial skeleton. This provided me with a sound hasis for further study and comparison with other genera. My detailed description ofB(zrasaurus permitted the compilation of a data matrix that 1 used in a large scale analysis of amniote relationships. My analysis led to a reassessment of the phylogeny of sorne major lineages of early amniotes. 1 demonstrated Amniota to he a mOl1ophyletic group. Sauropsida, which can he divided into Palaeosauropsida and Eusauropsida, was introduced to replace Reptilia. Turtles were found to he the sister-group of pareiasaurs, refuting the hypothesis of procolophonids (Laurin & Reisz 1995) as the sister-group. Although the pareiasaur-turtle sister-group relationship was proposed by Lee (1995) my result differs significantly. This difference is due to my focus on procolophonoids rather than pareiasaurs. Although 1 made use of the literature to ohtain background data, ail conclusions drawn are original unless explicitly stated otherwise. • 1 • ACKNOWLEDGME."ITS This study owes its existence to the su?ervision of Dr. Robert L. Carroll who critically read and edited several drnfts of this manuscript. 1 am greatly indebted for his interest, encouragement, suggestions and his unlimited patiel1ce. Furthermore it is a pleasure to acknowledge Dr. R. Bolmes, Dr. D. Dilkes, Dr. Kebang Lin, Dr. J. Boy (Mainz, Germanyl, Dr. D. Goujet (Paris, France), Dr. P.Y. Gagnier (Paris, France), Victor Reynoso and Ed Hitchcock for stimulating discussion concerning the origin and interrelationships of early amniotps and turtles. 1 have particularly benefitted l'rom Victor Reynoso's and Dr. David Dilkes' knowledge of PAUP and McClade software packages. My thanks are also due to Pamela Gaskill for drawing most of the specimens; Dr. R. Reisz (University of Toronto) for letting me study material in his lab; Dr. E.S. Gaffney for lending a specimen of Owenetta; Dr. M. S. Lee for providing manuscripts of his work and vital information about pareiasaurs. In addition, 1 have received considerable assistance trom Ingrid Birker and my "accountant" Marie La Ricca, both part of the staff at the Redpath Museum. Finally 1 would like to thank Mark Bendit, Hans Feve Beckmann and Thomas Lindenbaum for being friends; my wife Barbara Kelly for the French translation of the abstract, editing, accepting my many moods and taking care of our sons Caddaric (who still believes 1 am playing "Prince of Persia" ail night) and Sheridan ( who is most intrigued by my screensaver • II programJ. • This research was made possible by financial support from the Natural Sciences and Engineering Research Council of Canada Grants ta Dr. R. L. CarroI!. • III • TABLE OF CONTENTS Preface................................................................................ 1 Acknowledgments................................................................ II List of Illustrations............................................................... VI List of Tables.................................................... ...... ....... ....... VII Abstract.............................................................................. VIII Résumé............................................................................... X Introduction...... 1 History of the Classification of "Reptiles" 3 Materials and Methods................ 20 List of specimens................................................................. 23 Barasaurus besairiei............................................................ 25 8ystematic Palaeontology.................................................. 25 Description..................................................................... 27 8kull.............................................................................. 27 Braincase 40 Vertebrae....................................................................... 41 Ribs............................................................................... 51 Pectoral girdle 53 Pelvic girdle................................................................... 71 Analysis............................................................................. 84 Results............................................................................... 102 Discussion.......................................................................... 120 Conclusions........................................................................ 128 References.......................................................................... 129 • IV Appendix 1: List of characters............................................... 141 • Appendix II: Data matrix.. 144 Appendix III: Shortest tree and apomorphy list.................... 145 Appendix IV: List of abbreviations......................................... 148 • V • LIST OF ILLUSTRATIONS Figure Page 1 Skeletal reconstructions of early amniotes................. 5 2 Temporal distribution of early amniotes.................... 14 3 Cladograms illustrating possible sister-group relationships of turtles............................................ 17 4 Map of Madagascar and map of the Ranohira region showing the distribution of the Lower Sakamena Formation......... 22 5 Barasaurus besairiei, composite reconstruction of the entire skeleton........... 26 6 Reconstructed skulls of owenettids, dorsal view......... 28 7 Reconstructed skulls of owenettids, lateral view........ 29 8 Reconstructed skulls of owenettids, ventral view....... 30 9 Reconstructed skulls of owenettids, occipital view..... 31 10 Barasaurus besairiei, Holotype specimen P 1, dorsal. 34 11 Barasaurus besairiei, Holotype specimen P 1, ventral 35 12 Barasaurus besairiei, specimen P 8, dorsal view....... 36 13 Barasaurus besairiei, specimen P 6, ventral view...... 37 14 Barasaurus besairiei, specimen P 9, dorsal view....... 38 15 The atlas-axis complex ofBarasaurus besairiei, in comparison with the atlas-axis complex in other tetrapods.............................................................. 42 16 Barasaurus
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