THE LARAMIE FORMATION AND THE SHOSHONE GROUP 4 1 



from several formations which were clearly not synchronous 

 deposits. 



It would appear to be self-evident that the vertebrate life must 

 have undergone marked evolution during the series of orogcnic 

 disturbances characterizing the Laramie and Shoshone epochs. 

 Hatcher, who took up the study of the Ceratops fauna, after Marsh, 

 realized the importance of careful stratigraphic examination, and 

 before his lamented death laid the foundation for the phylogenetic 

 study of the "Laramie" vertebrates which alone can make them of 

 diagnostic value in determining stratigraphic relations. The inves- 

 tigation of the Judith River beds of Montana by Hatcher and Stan- 

 ton in 1903 demonstrated that they belong in the Montana Group. 

 The "Ceratops fauna" was thus carried below the Laramie, and 

 Hatcher, instituting such comparisons as were possible, announced 

 the general conclusion as regards the vertebrates, that 



In every case where any group of the fauna has been studied from suflS- 

 cient material, it has been found to be represented by distinctly older 

 and more primitive types than the related forms from the Laramie.^" 



In harmony with this view are the opinions of Stanton concerning 

 the invertebrate fauna and of Knowlton on the flora, to be found 

 in the same publication. 



Vertebrate remains have been obtained in the Laramie beds (as 

 here defined) in but very few locahties. The most important fossil 

 to be referred to here is the Agathaumas silvestris Cope from Black 

 Buttes, Wyoming. This form is represented by skeletal parts and 

 cannot therefore be satisfactorily compared with most of the other 

 Ceratops forms, which are known only from cranial parts. The 

 recent review of the phylogeny of the Ceratopsia by LulP^ places 

 Agathaumas silvestris by itself as a form much older than Tricera- 

 tops of the Converse County beds. This view agrees with the refer- 

 ence of the Black Buttes beds to the Laramie by Stanton on the 

 evidence of brackish water forms believed to occur shortly above the 

 Agathaumas horizon, but conflicts in some measure with the close 



2°T. W. Stanton and J. B. Hatcher: Geology and Paleontology of the 

 Judith River Beds with a Chapter on the Fossil Plants by F. H. Knowlton. 

 U. S. Geol. Survey, Bull. 257, 1905, p. 103. 



" The Ceratopsia, by J. B. Hatcher, Mon. XLIX, U. S.Geol. Surv., edited 

 and completed by R. S. Lull, 1907, Part II by Lull, Phyolgeny, etc., p. 161. 



