ILLUSTRATIONS 



FIGURES 



1. Diagram to illustrate common descriptive terras applied to the mammalian mandible. 6 



2. Diagrams to illustrate terms applied to molar cusps and their abbreviations. 7 



3. Diagram illustrating evolution of plagiaulacoid molars. 14 



4. Ctenacodon and Plagiaulax. 16 



5. Ctenacodon. Diagrammatic internal view of right lower jaw. 17 



6. Upper premolars of American plagiaulacids. 21 



7. Ctenacodon. Diagram of upper and lower molars in occlusion. 24 



8. Morrison Amphilestinae. External views of penultimate lower molars. 32 



9. Cynodonts and triconodonts. Internal views of lower molars. 32 



10. Portions of right lower jaw of Dasyurus maculatus and Trioracodon bisulcus. 34 



11. /'r«actf(^«. Diagrammatic internal view of right lower jaw. 35 



12. Occlusion in triconodonts. 35 



13. Skull and jaws of /'«ar<7^«, seen from the right side. 36 



14. Palate of Priacodon, seen from below. 37 



15. Tinodon. Diagrammatical internal view of right lower jaw. 39 



16. Tinodon bellus Marsh. 39 



17. Amfhidon swperstes. 40 



18. Morrison mammals. Internal, crown, and external views of typical right lower molars. 41 



19. Morrison mammals. External, crown, and anterior views of typical right upper molars. 42 



20. Mesozoic mammals. Last lower premolars. 43 



21. Mesozoic mammals. Last upper premolars. 44 



22. Morrison pantotheres. Typical lower molars. 46 



23. Paurodon. Diagrammatic internal view of right lower jaw. 49 



24. Diagrams of dryolestid lower molar, essentially Amblotherium. 55 



25. Laolestes. Diagrammatic internal view of right lower jaw. 61 



26. Amblotherium. Diagrammatic internal view of right lower jaw. 65 



27. Diagrams of occlusal relationships in triconodonts and pantotheres. 71 



28. Herfetairus arcuatus. Right upper molars, crown view, type. 73 



29. Comparison of upper molars of Herfetairus and Melanodon. 75 



30. Melanodon oweni. Right upper crown view. 76 



31. Melanodon. Diagram of typical left upper molar, from all aspects. 76 



32. Euthlastus cordiformis. 79 



33. Miccylotyrans minimus. 81 



34. Malthacolestes osborni. Right crown view, type. 82 



35. Pelicofsis dubius. Last three right upper molars, crown view, type. 83 



36. Premolar-molar transition in pantothere upper teeth. 85 



37. Docodon. Diagrammatic internal view of right lower jaw. 87 



38. Docodon. Diagrams of lower premolars in nine different specimens. 88 



39. Docodon. Crown view of typical right lower molar. 91 



