28 



LARAMIE FLORA OF THE DENVER BASIN. 



Hatcher concluded, however, that the " Cera- 

 tops beds" should be referred to the Laramie 

 for the following reasons : 



1. They conformably overlie the Fox Hills sandstones 

 and contain both a reptilian and a mammal fauna, with 

 decided Mesozoic affinities. * * * 



2. They contain an invertebrate fauna comprising many 

 forms identical with those already described from the 

 typical Laramie, some of which are unknown except in 

 the Laramie. 



3. They immediately and conformably overlie the Fox 

 Hills and show evidence of a continuous deposition 

 through both series. 



In 1896 Hatcher 1 published another paper 

 dealing with the Converse County area, in 

 which he criticized in the severest manner 

 Marsh's statement that the "Ceratops beds" 

 had been traced some 800 miles along the east- 

 ern flank of the Rocky Mountains. Hatcher 

 showed that, with the exception of a single 

 specimen from a doubtful locality, all the 

 material studied by Marsh had been found in 

 the Denver Basin, in Converse County, or in 

 the Judith River area. He said: 



The3e are very widely separated localities, and no 

 attempt has ever been made to trace the continuity of the 

 strata from one to the other, nor is it at all probable that 

 such an attempt would meet with success. 



Hatcher also questioned Marsh's statements 

 that the " Geratops beds" are below the upper- 

 most beds referred to the Laramie and that 

 they rest on marine beds which contain in- 

 vertebrate fossils characteristic of the Fox 

 Hills deposits. Although his comments were 

 somewhat at variance with his former state- 

 ment, Hatcher continued as follows : 



At.no place in the Converse County region do the true 

 Ceratops beds, with the remains of horned dinosaurs, rest 

 upon true marine Fox Hills sediments; nor are the Ceratops 

 beds in this region overlain by strata which could be re- 

 ferred without doubt to the Laramie. The writer has, in a 

 paper published in the American Journal of Science of 

 February, 1893, stated that the Ceratops beds rest directly 

 upon the Fox Hills series and has provisionally referred 

 the very similar series of sandstones and shales conform- 

 ably overlying the Ceratops beds to the upper Laramie; but 

 it would doubtless be better to restrict the limits of the 

 Ceratops beds to those strata in which horned dinosaurs 

 occur, and to consider the underlying 400 feet of barren 

 sandstones as the equivalent of the Judith River beds. 

 Future investigations will doubtless show that the sand- 

 stones, shales, and lignites overlying the typical Ceratops 

 beds in Converse County should be referred to the Fort 

 Union beds and not to the Laramie, as, according to Knowl- 

 ton, the limited flora sent him now indicates. 



1 Hatcher, J. B., Some localities for Laramie mammals and horned 

 dinosaurs: Am. Naturalist., vol. 30, pp. 112-120, 1896. 



In 1896 T. W. Stanton and 1 2 spent several 

 weeks in Converse County and also visited 

 numerous localities in Colorado, Wyoming, and 

 Utah, in a study whose object was stated as 

 follows : 



As many of the supposed typical Laramie localities had 

 been visited and studied by the various investigators 

 some years ago, before the recognition of the Arapahoe, 

 Denver, and Livingston formations, it became a matter of 

 interest and importance to revisit these places and ascer- 

 tain, if possible, the bearing of the new data on the ques- 

 tions of their distribution, life, etc. 



In the discussion of the Converse County 

 area in this paper several sections were given 

 showing especially the Fox Hills and overlying 

 " Ceratops beds." No fossils of any kind were 

 detected in the 400 feet of sandstones men- 

 tioned by Hatcher as occurring above the 

 highest Fox Hills horizon, but just above these 

 sandstones, in the basal portion of the "Ceratops 

 beds, " though apparently below any remains of 

 dinosaurs, a few brackish-water invertebrates 

 were detected. Particular attention was de- 

 voted to the " Geratops beds," and numerous 

 collections of invertebrates and plants were 

 listed. 



Regarding the interpretation of the inverte- 

 brate fauna, the following statement was made : 



Of the 18 identified species in the above list just half 

 occur at Black Buttes, Wyo., in or very near the bed that 

 has yielded the saurian Agathaumas sylvestris Cope. The 

 large proportion of identical forms and the general resem- 

 blance of the entire faunas, especially in the large number 

 and great differentiation of species of Unio, makes it 

 reasonably certain that the Converse County and Black 

 Buttes beds are on nearly the same horizon. The evidence 

 of the vertebrate fossils seemB to trend in the same direc- 

 tion. It will be shown later that the Black Buttes bed 

 should be regarded as true Laramie, and consequently 

 the series now under consideration is placed in the same 

 category. 



The plants, of which 25 forms were listed, 

 were compared with the floras of various 

 localities then supposed to be of Laramie age, 

 and the conclusion was reached that "as 

 nearly as can be made out, the plants confirm 

 the Laramie age of the Ceratops beds." 



From the beds conformably overlying the 

 highest dinosaur-bearing stratum 18 species of 

 plants were obtained, and of the 10 named 

 species 9 proved to be typical Fort Union 



* Stanton, T. W., and Knowlton, F. H., Stratigraphy and paleontology 

 of the Laramie and related formations in Wyoming: Geol. Soc. America 

 Bull., vol. 8, pp. 127-156, 1907. 



