"CERATOPS beds" OF WYOMING AND MONTANA 283 



Williston" states that this fauna has in some respects a startling 

 resemblance to the Judith River fauna and argues that they were 

 really contemporaneous. Perhaps the best general statement of the 

 close relationship between these two faunas is that of Hatcher when 

 he was bringing forward all the arguments he could find for their 

 distinctness. The following quotations'* indicate his views, when it is 

 remembered that he uses " Laramie" for the beds in Converse County. 



"When considered in its entirety, the vertebrate fauna of these 

 (Judith River) beds is remarkably similar to, though distinctly more 

 primitive than, that of the Laramie. Almost or quite all of the Lar- 

 amie types of vertebrates are present, though, as a rule, they are repre- 

 sented by smaller and more primitive forms. The similarity between 

 this fauna and that of the Laramie contrasts strongly with the great 

 dissimilarity between the vertebrates of the Judith River and those of 

 the Atlantosaurus beds, the next older fresh-water horizon in this 

 region, containing also a rich and varied fauna, but quite distinct 

 from that of the beds in question. 



" Briefly, the Judith fauna, it is clear, is descended from the Juras- 

 sic and is the direct ancestor of the Laramie. Its relations with the 

 former are not close, and several groups are absent in the one which 

 are present in the other. Its relations with the Laramie are much 

 closer, as should be expected, considering the stratigraphic position. 

 With one or two possible exceptions all the families represented in 

 either of these two later deposits are present also in the other. 

 Although several genera and species now appear to be common to 

 both these formations, it is probable that when more perfect material 

 is available they will be found, in most instances, to be quite distinct, 

 though some pertaining to more persistent types may prove to be 

 identical." 



Only two mammals have been reported from the Judith River for- 

 mation and none from any other Upper Cretaceous horizon below the 

 "Ceratops beds," and both of these according to Hatcher are closely 

 related to forms in the "Laramie." According to Gidley there are 

 two or three mammal genera in the " Cera tops beds" that range up into 

 the Torrejon fauna of the Fort Union at Bear Butte, Montana, and one 

 of these is represented by two species that may possibly be identical 

 in both horizons. The turtles, rhynchocephalians, and crocodiles of 

 the " Ceratops beds" may also be pretty closely related to those of the 

 Fort Union, Puerco, and Torrejon, but the faunas are generally very 

 distinct. Brown states''^ that the difference between the Puerco mam- 



" Bull. U. S. Geol. Survey, No. 257, 1905, pp. 101-103. 

 " Op. cit., p. 840. 



