106 



EVOLUTION OF MAMMALIAN MOLAR TEETH 



- in* - 



">' 



-/n'- 



-m- 



m- 



FIG. 55. Dentition of North American Upper Cretaceous Plagiaulacidse (Ptilodus) and Polj T - 



mastodontidse (Meniscoessus). 



1. Ptilmlvs. First and second inferior molars ; on left side in situ, 011 right side reversed. 

 These teeth belong to two individuals. 



