《Evolution Of Mammalian Molar Teeth》

INTRODUCTION1

CLASSIFICATION OF THE MAMMALIA ADOPTED IN THIS BOOK11

CHAPTER Ⅰ．THE TRANSITION FROM THE REPTILIAN TO THE MOST PRIMITIVE MAMMALIAN TEETH18

1．The Upper Triassic Mammals Dromatherium and Microcondon18

2．A new classification of the Mesozoic Mammals21

3．Illustrations of the chief Triconodonta and Trituberculata24

4．The origin of the tritubercular type sought in 1888 among the Mesozoic Mammalia31

CHAPTER Ⅱ．FIRST OUTLINE OF TRITUBERCULAR EVOLUTION IN MAMMALS36

CHAPTER Ⅲ．TRITUBERCULY IN RELATION TO THE HUMAN MOLAR TEETH AND THE PRIMATES48

1．Ontogenetic development of the teeth48

2．＂The history of the cusps of the human molar teeth＂55

The concresence theory57

Mechanical relations of the upper and lower teeth60

Evidence that the upper human molars were triangular62

CHAPTER Ⅳ．TRITUBERCULY IN ITS APPLICATION TO THE MOLAR TEETH OF THE UNGULATES OR HOOFED MAMMALS．COMPLETION OF THE NOMENCLATURE66

1．Disadvantages of previous systems of nomenclature of the molar cusps66

2．Methods of analysis of molar elements．Nomenclature of the molars of Ungulates66

3．Application of the theory of trituberculy to the Perissodactyla72

The horse molar72

The rhinoceros molar72

CHAPTER Ⅴ．TRITUBERCULY：A REVIEW DEDICATED TO THE LATE PROFESSOR COPE74

Polybuny74

Comparison of nomenclatures76

Tritubercular homologies77

The early stages of sexituberculy80

Lower molars80

The nomenclature of the molar cusps and crests82

The evolution of the Ungulate molar83

CHAPTER Ⅵ．CHRONOLOGICAL OR GEOLOGICAL SUCCESSION OF MOLAR TYPES91

1．Reptilian Ancestors of Mammals in the Trias91

2．The Triassic Mammals94

3．Mammals of the Jurassic94

4．Upper Cretaceous Mammals95

5．Basal Eocene Mammals98

6．Lower Eocene Mammals98

Résumé of Geological Succession of Types99

CHAPTER Ⅶ．THE ORIGINAL OR PRIMITIVE STRUCTURE OF THE MOLAR TEETH IN THE DIFFERENT ORDERS OF MAMMALS100

The major classification of the Mammalia100

Protodonta101

Allotheria or Multituberculata101

Monotremata105

Marsupialia108

Molar teeth of Multituberculates，Marsupials(？)，and Placentals in the Upper Cretaceous115

Insectivora117

Cheiroptera129

Carnivora131

Evolution of carnasial teeth in Creodonta and Fissipedia135

Convergence of upper carnassials in Creodonta and Fissipedia138

Fissipedia142

Rodentia144

Simplicidentata145

Duplicidentata148

Tillodontia151

Superorder Ungulata163

Amblypoda164

Condylarthra168

Artiodactyla171

Perissodactyla174

Chalicotheroidea or Ancylopoda184

Hyracoidea185

Proboscidea186

Sirenia188

South American Ungulates189

Cetacea190

Zeuglodontia191

CHAPTER Ⅷ．EVOLUTION OF THE PREMOLARS193

Premolars in primitive Mammals193

Adaptation of premolars194

Various upper premolar types194

Cusp addition in the premolars195

Superior premolars195

Inferior premolars198

CHAPTER Ⅸ．OBJECTIONS AND DIFFICULTIES，AND OTHER THEORIES201

Ⅰ．That the tritubercular type is not primitive201

1．The plexodont or progressive simplification theory of Ameghino201

2．Objections by Fleischmann and Mahn answered by Scott204

3．The primitive polybuny theory205

Ⅱ．That the Cope-Osborn theory of the origin of the superior molars in incorrect208

1．Cusp homologies founded on embryogeny208

Order of embryonic cusp-development in Insectivora210

Summary of Woodward＇s conclusion212

Ontogenetic order according to Marett Tims213

The premolar analogy theory215

Palaeontological difficulties in the premolar analogy theory217

Gidley＇s restudy(1906)of Jurassic-Mammals supports embryogeny and the premolar analogy theory219

Addendum：the＂trituberculy＂of Zalambdodonts a secondary acquirement or＂pseudo-trituberculy＂225

Conclusion227

CHAPTER Ⅹ．RECTIGRADATIONS IN THE TEETH229

Homoplasy as a law of latent or potential homology229

Homology237

Lankester＇s reply to the preceding article238

BIBLIOGRAPHY240