questioned Dr. Dawson's assignment of greater age to the Belly River series, holding that 

 the vertebrates were similar to those of the Laramie. C. A. White* takes a similar 

 view : " "What gives this (Belly River) formation especial interest is the intimate relation 

 of its fauna and flora to those of the Laramie, although these two non-marine formations 

 are, in the district within which both are known to occur, sepai-ated by a great thickness 

 of strata which are unmistakably of marine origin." Whitman Cross** places the 

 Judith River beds even higher : " Without reviewing in detail the literature of these 

 beds, it is desired to point out the fact that the Judith River strata may perhaps repre- 

 sent the Arahapahoe or some other post-Laramie formation and not the true Laramie of 

 Colorado and Wyoming." 



Other observations, however, point to the presence of older fresh-water beds in Mon- 

 tana, which may have been more or less confused by collectors with the Judith River 

 beds. White, remarks, (op. cit. p. 174) : " Certain observed conditions of strata exposed 

 along the Missouri river in northern Montana apparently indicate its [i. e. Belly River 

 formation] presence there. It also seems not improbable that some of the strata in the 

 upper part of the valley of the Musselshell river, in Montana, which have been referred 

 to the Laramie, really belonged to the Belly River formation. If strata of this formation 

 really exist there they probably were originally continuous with those of the Belly River 

 valley." More recently Earl Douglas *** has observed Mid-Cretaceous dinosaurs below 

 the Ft. Pierre beds, in Sweet-grass county, Missouri. 



In the records as they stand, therefore, there is evidence, first, of fresh- water dinosaur- 

 bearing beds in Montana older than the Laramie ; and this suggests the possibility, not 

 to say probability, of confusion in the collections ; that is some of the vertebrates already 

 described from Montana may be of Belly River age. 



Neither in the writings of Cope nor Marsh is the fact recognized that some of the 

 Montana vertebrates are of different and perhaps more ancient character. Even in their 

 latest contributions **** to the subject, Montana and Wyoming vertebrates are discus- 

 sed as of the same age, and as if the question were one of priority of nomenclature rather 

 than the more important one of priority of structure and time. Marsh (op. cit., p. 145) 

 places the " Ceratops Beds of Laramie Series " above the Fox Hills group, as the summit 

 of the Cretaceous. He defines (op. cit., p. 207) these beds as follows : — 



(p. 207). " The definite horizon in which these strange reptiles occur has been called by the 

 writers the Ceratops beds, from the type genus Ceratops, and its position is shown in the section on page 

 145 .... This geological horizon is a distinct one in the upper Cretaceous, and is indicated for more 

 than 800 miles along the eastern flank of the Rocky Mountains. It is marked at nearly every outcrop 

 by remains of these reptiles, and hence the strata containing them have been called the Ceratops beds. 

 They are fresh-water or brackish deposits which form a part of the so-called Laramie, but are below the 

 uppermost beds referred to that gi-oup. In some places, at least, they rest upon marine beds, which 

 contain invertebrate fossils characteristic of the Fox Hills deposits The most important localities in the 

 Ceratops beds are in Wyoming, especially in Converse County .... The fossils associated with the 

 Ceratopsidre are mainly dinosaurs, representing one or two orders and several families. Plesiosaurs, 

 crocodiles, and turtles, of Cretaceous types, and many smaller reptiles, have left their remains in the 



* U. S. Geological Survey, Correlation Papers, Cretaceous, 1891, p. 173. 



*♦ Geology of the Denver Basin in Colorado. Monographs of the U. S. Geological Survey, Vol. XXVU, p. 239. 

 Science, Jaauary 3, 1902, p. 31, "Dinosaurs in the Ft. Pierre shales and underlying beds in Montana." 



•* Cope, " The Horned Dinosauria of the Laramie ", Ameiican Naiuraiisl, 1889, p. 715. 



Marsh, "Dinosaurs of North America," 1895. 



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