HISTORICAL REVIEW OF THE LARAMIE PROBLEM. 



9 



The reptilian remains found at Black Butte, near the 

 top of the series, have, as elsewhere stated, been investi- 

 gated by Prof. Cope and by him pronounced to be de- 

 cidedly dinosaurian and therefore indicative of Cretaceous 

 age. On the other hand, the fossil plants from the same 

 beds have been studied by Prof. Lesquereux, who informs 

 me that they are unquestionably Tertiary types. My own 

 investigations having been confined to the invertebrates, 

 it is of these chiefly that I will speak here. In the first 

 place, it will be seen that all of these yet known belong to 

 a few genera of mollusks, represented by 12 or 14 species. 

 And just here it may be stated that, although partly com- 

 mitted in favor of the opinion that this formation belongs 

 to the Cretaceous and still provisionally viewing it as 

 most probably such, I do not wish to disguise or conceal the 

 fact that the evidence favoring this conclusion to be de- 

 rived from the mollusks alone, as now known, is by no 

 means strong or convincing. The genera are probably 

 all common both to the Cretaceous and Tertiary, as well 

 as to the present epoch. * * * The entire absence 

 among the fossils yet known from this formation of Bacu- 

 lites, Scaphites, Ancyloceras, PTiychoceras, Ammonites, Gy- 

 rodes, Inoceramus, and all of the other long list of genera 

 characteristic of the Cretaceous or in part also extending 

 into older rocks, certainly leaves its molluscan fauna with 

 a strong Tertiary facies. * * * It thus becomes mani- 

 fest that the paleontological evidence bearing on the ques- 

 tion of the age of this formation, so far as yet known, is of 

 a very conflicting nature; though aside from the dino- 

 saurian, the organic remains favor the conclusion that it is 

 Tertiary. 



It is plain that Meek was very much con- 

 fused by the data then available, especially by 

 the invertebrates, for he declared in another 

 place that they might with almost equal pro- 

 priety be referred to the Tertiary or the Cre- 

 taceous, and as the vertebrate evidence was 

 interpreted to mean, undoubted Cretaceous, 

 only the fossil plants were left to sustain un- 

 falteringly the Tertiary side of the argument. 

 It was immediately pointed out, as it is oc- 

 casionally even to the present day, that the 

 error made by Oswald Heer in referring plants 

 of the Dakota "group" to the Miocene 33 

 weakened the evidence of fossil plants and gave 

 added weight to the dictum of the vertebrate 

 paleontologist, namely, that the presence of 

 dinosaurian reptiles in a formation was positive 

 proof of Cretaceous age. Thus Cope was so 

 firmly convinced that the presence of Agathaw- 



» Those who are interested in this reference of the Dakota sandstone 

 to the Miocene may be instructed by reading Lesquereux's account of the 

 conditions under which the error was made (U. S. Geol. Survey Terr. 

 Sixth Ann. Kept., for 1872, p. 343, 1873). From this account it appears 

 that Heer never saw specimens of the Dakota plants, for only outline 

 drawings of a few species were submitted to him. They were mostly 

 dicotyledonous leaves and wholly unlike any then (1857) known from 

 the Cretaceous of Europe, and the drawings were without the essential 

 details of nervation. As soon as the specimens themselves were seen by 

 Newberry he recognized their correct characters. 



mas at Black Buttes proved the Cretaceous 

 age of the "Bitter Creek series" that in 1874 

 he proceeded to refer the "Great Lignitic" 

 of the upper Missouri to the same period. 

 In discussing the age of certain vertebrate- 

 bearing beds in northern Colorado, he said : 34 



Believing, as I do, that' the evidence derived from the 

 vertebrate remains requires the reference of the Bitter 

 Creek coal series to the Cretaceous period; and having 

 pointed out on similar grounds that the horizon of the Great 

 Lignite from which vertebrate remains have been procured 

 on the Missouri River is undoubtedly Mesozoic, although 

 usually regarded as Tertiary, I suspect that the corre- 

 sponding strata in Colorado will be found to pertain to the 

 same section of geologic time. 



In another bulletin of 'this series Cope 35 

 had an extensive article on the fossil verte- 

 brates then recognized from the Cretaceous of 

 the West. In this paper vertebrates from the 

 localities on Moreau River and between Moreau 

 and Grand rivers, S. Dak.; at Long Lake, 

 N. Dak.; north of Big Horn River, Mont.; and 

 in Colorado, now mainly referred to the Lance 

 formation, he for the first time definitely 

 referred to the Cretaceous. In alluding to the 

 studies of the flora of these beds by Les- 

 quereux and Newberry, he said (p. 16) : 



They have, as is well known, pronounced this whole 

 series of formations as of Tertiary age, and some of the beds 

 to be as high as Miocene. The material on which this 

 determination is based is abundant, and the latter must be 

 accepted as demonstrated beyond all doubt. I regard 

 the evidence derived from the mollusks in the lower beds, 

 the vertebrates in the higher, as equally conclusive that 

 the beds are of Cretaceous age. There is, then, no alter- 

 native but to accept the result, that a Tertiary flora was 

 contemporaneous with a Cretaceous fauna, establishing an 

 uninterrupted succession of life across what is generally 

 regarded as one of the greatest breaks in geologic time. 



The above statement by Cope has often been 

 quoted during the 48 years since it was written, 

 and it is only recently that its converse — that 

 is, that a fauna of Cretaceous type may be 

 contemporaneous with a Tertiary flora — has 

 been admitted as even possible. 



This conclusion was further elaborated by 

 Cope in Hayden's annual report for 1873, in a 

 paper that was more or less in the nature of a 

 reply to the article by Newberry already men- 



« Cope, E. D., Report on the stratigraphy and Pliocene vertebrate 

 paleontology of northern Colorado: U. S. Geol. and Geog. Survey Terr. 

 Bull. [1st ser.], No. 1, p. 10, 1874. 



" 5 Cope, E . D ., Review of the Vertebrata of the Cretaceous period found 

 west of the Mississippi River: U. S. Geol. and Geog. Survey Terr. Bull. 

 [1st ser.], No. 2, pp. 1-51, 1874. 



