SYNOPSIS OF THE VERTEBRATE FAUNA OF THE I'UEIICO t^EKllJrf. 299 



The character of the vertebrate fauna is indicated by the following table : 



Reptilia 12 



Crocodilia 3 



Testudinata 5 



Rhynchoct'phalia • ;! 



Ophidia 1 



Avcs , 1 



Mammalia 93 



? 3Iarsupialia 11 



Bunotheria 53 



Tivniodonta 3 



Creodouta 49 



Taxeopoda 28 



Quadrumana ?4 



Condylartlira 24 



Amblypoda 2 



Total 10(1 



In 1874 the wi-itei* advanced the proposition that the ancestors of modern pla- 

 cental Mammalia would be found to be " plantigrade pentadactyle bunodouts." This 

 anticipation was partly realized in the fauna of the "Wasatch epoch subsequently dis- 

 covered, but is completely so in the characters of the Mammalia of the Puerco epoch. 

 All the placentals, and probably the implacentals also, were " plantigrade pentadactyle 

 bunodouts."' More than this the placentals nearly all present the primitive type of 

 lentition of the maxillary series, since the superior molars are nearly all of the tritu- 

 bercular type. But foui- species out of the eighty-two placentals are quadrituber- 

 cular. In the inferior molars the tubei-culo-sectorial, or quinquetuberculai- type of 

 dentition, is extensively prevalent, but not so generally so as the superior tritubercu- 

 lar. Thus of the eighty-two placentals sixty-four present the primitive type. 



Ill its relations to other fauna?, the Puerco is totally distinct as to species, No 

 determined species came to it from an earlier epoch, and none continued after i(. Ol" 

 genera not widely distributed in time, one of lizard-like Khynchocephalia, Champso- 

 saurus, comes over from the Laramie, with a genus of tortoises, Compsemys. An- 

 other genus of tortoises, Chelydra, probably commences at this epoch, to conliniic 

 through the European Miocenes to the present time, since it still exists in jMorlh 

 America. Among Mammalia, two genera only coiitinue later. Didymictis is found 

 in the Wasatch and Bridger formations, and Chriacus in the AVasatch. iS'ot only 

 this, but the entire family of tlic I'eriptychidai ceased at the close of the Puerco. 

 The same is true of the Amblypod family Pantolambdidic. One of the most import- 

 ant features of the fauna is, however, the presence of eleven siJecies of the ?Marsu- 



c: 



