40 



r EXO20IC MAMMAL HORIZONS 



tien) age. The supposed "americoids," Calamodon, Phenacodus, 

 Ev. protononia , Hyopsodus. Pelycodus. etc.. are all European animals. 



FAUXA.^ 



The TTasatch fauna consists of a nearly equal or half-and-half min- 

 gling of (\) archaic mammals, including 9 families which evolved 

 from the Puerco-Torrejon fauna, vrixh. (2) ancestors of the modern- 

 ized mammals, including 1 1 families. From this stage onward we 

 have to consider these two great elements in the fauna separatelv. 



Summary of genera. 



Persistent Triassic mammals 

 Other archaic f> mammal?. . . 

 Mrjflernizecl mammals 



38 



There is thus at this period a slight predominance in numher of 

 the archaic mammals over the modernized, hut the individual 

 archaic mammals greatly predominate in size. 



TJie surviving arcTiaic or Puerco-Torrejon manunals. — Some of 

 these mammals, such as CorypJiodon. are of large size. The Multi- 

 tuberculata disappear. Of the Edentata-Teeniodonta. 3 genera of 

 the Stylinodontidse. Of the archaic ungulates, 2 orders and 3 families 

 are represented: (1) Amblypoda-Ooryphodontidae, as successors to the 

 Pantolambdidae : (2) Condylarthra-Phenacodontidse : (3) Condylarthra- 

 Meniscotheriid^e. Of the Creodonta-Camivora there occur o families, 

 namely, Palaeonictidae, Oxyaenidae, Hyaenodontid^e. Mesonvchidae, 

 and Arctocyonidae : 4 of these famihes also occur in France. 



TJie Tertiary or modernizea mammals. — These mammals are mostly 

 of small size, including the successors of the supposed Torrejon pro- 

 Carnivora-Miacidae. a family which now branches out into several 

 genera. Xo other Camivora. True Primates, 2 families. Rodentia, 

 1 genus, Paramys with sciuroid teeth. Insectivora, 2 or 3 families, 

 one of doubtful affinity. Among Ungulata-Perissodactyla. 3 families, 

 Equid^. Tapiridfe, Lophiodontidie. Among Ungulata-Artiodactyla, 

 1 family. There are thus 11 families among the modernized mammals, 

 only two of which (Equidae and Tapiridae ) persist to the present time. 



n Osbom H. F., and Wortman. J. L.. Fossil mammals of the Wasatch and Wind River beds: Bull. 

 Am. Mus- Nat. Hist., vol. A. I'm. pp. Sl-1-17. 



Loomis, F. B., Origm of the Wasatch deposits: Am. Jour. Sci., May, 1907, 4th sen, vol. 23, pp. 356-364. 

 See Appendix, p. 91. 



t> See footnote, p. 33. 



