Memoir cover 0.tif - Ohio University College of Osteopathic Medicine

TABLE OF CONTENTS
ABSTRACT ................................... 1 Crocodylomorpha ......................... 35
INTRODUCTION ............................... 1 Conclusions ................................ 40
SOFT-TISSUE INFERENCE AND THE EXTANT
ACCESSORY CAVITIES AS COMPELLING
PHYLOGENETIC BRACKET .................. 2 MORPHOLOGICAL EVIDENCE FOR PARANASAL
The Significance of Soft Tissues ................... 2 PNEUMATICITY .......................... 40
The Extant Phylogenetic Bracket Approach ........... 4 The Diversity of Accessory Cavities ............... 42
MATERIALS ................................. 10 Theropoda ................................ 42
HYPOTHESIS 1: THE ANTORBITAL CAVITY HOUSES Maxillary Recesses ........................ 42
A GLAND ............................... 10 Lacrimal Recesses ........................ 45
Historical Development ........................ 10 Jugal Recesses ........................... 45
The Extant Phylogenetic Bracket .................. 10 Nasal Recesses ........................... 45
Extant Crocodilians ......................... 11 Palatine Recesses ......................... 46
Extant Birds .............................. 11 Sauropodornorpha .......................... 46
Osteological Correlates ....................... 11 Ornithischia ............................... 46
The Hypothesis .............................. 11 Pterosauria ............................... 46
Testing the Hypothesis ......................... 11 Parasuchia ................................ 48
Suchia ................................... 11 Non-crocodylomorph Suchia ................... 48
Dinosauria ................................ 11 Crocodylomorpha ........................... 48
Conclusions ................................ 12 Summary ................................ 49
HYPOTHESIS 2: THE ANTORBITAL CAVITY HOUSES
Presence of a Bird-like Suborbital Air Sac in Fossil
AMUSCLE .............................. 12 Archosaurs .............................. 49
Historical Development ........................ 12 Squamosal Recess .......................... 49
Implications of the Muscular Hypothesis ............ 13 Ectopterygoid Recess ........................ 49
The Extant Phylogenetic Bracket .................. 13 Orbital Recess within Lacrimal Bone ............. 51
Extant Crocodilians ......................... 13 Summary ................................ 52
Extant Birds .............................. l3 summary .................................. 52
Osteological Correlates ....................... l5 ORIGIN OF THE ANTORBITAL CAVITY: BASAL
The Hypothesis .............................. 16 ARCHOSAURIFORMS ...................... 52
Testing the Hypothesis ......................... l6 Application of the Extant Phylogenetic Bracket Approach . . 52
Crocodylomorpha ........................... 16 Glandular Hypothesis ........................ 52
Other Crurotarsi ............................ 16 Muscular Hypothesis ........................ 52
Dinosauria ................................ 18 Pneumatic Hypothesis ........................ 52
Conclusions ................................ 22 The Origin of the Antorbital Fenestra and Cavity ...... 53
HYPOTHESIS 3: THE ANTORBITAL CAVITY HOUSES
THE FUNCTION OF PNEUMATIC SINUSES: A NEW
AN AIR SAC ............................. 23
PERSPECTIVE AND ITS IMPACT ON ANALYSIS
Historical Development ........................ 23
OF SOME TRENDS IN FACIAL EVOLUTION ..... 53
The Extant Phylogenetic Bracket ..................
The Enigmatic Biological Role of Pneumaticity ....... 53
Extant Birds .............................. %
Paranasal Pneumaticity ....................... 54
Extant Crocodilians ......................... 24
Paratympanic Pneumaticity .................... 56
Osteological Correlates ....................... 24
Pulmonary Pneumaticity ...................... 57
The Hypothesis .............................. 25
25 A New Perspective ........................... 57
Testing the Hypothesis .........................
Empty Space is a Red Herring
................................
................. 57
Dinosauria 25
The Epithelial Hypothesis for Pneumatic Function .... 57
Theropoda .............................. 25
Sauropodomorpha ......................... 27
Supporting Evidence ......................... 58
Lesorhosaurus and Ornithopoda ............... 28 Trends in the Evolution of the Facial Skeleton ........ 59
Thyreophora ............................. 29 Crocodylomorpha ........................... 59
Ceratopsia .............................. 30 Ornithopoda .............................. 61
Pachycephalosauria ........................ 32 Theropoda ................................ 63
Pterosauria ............................... 32 Summary .................................. 64
Cmrotarsi ................................ 33 SUMMARY .................................. 64
Parasuchia .............................. 33 ACKNOWLEDGMENTS ......................... 65
Ornithosuchidae .......................... 33 LITERATURE CITED ........................... 65
Non-crocodylornorph Suchia ................. 33 ABBREVIATIONS ........................... foldout