338 E. W. BERRY A(JE OF THE MORRISON FORMATION 



liorizou uuder consideration. In Europe tlie record, tliougli still meager, is 

 more complete ; but it represents in every instance more primitive types than 

 those of the Arundel Jnid the Morrison. 



"The character of these dinosaurs, and of the crocodile as well, correlates 

 the beds wherein they are found absolutely with the Morrison (Como) of the 

 West. An accurate comparison with European formations is more difficult, as 

 the faunas have fewer forms in common. Pleurocalus is reported from the 

 Kimmeridgian as well as from the Wealden. but that from the former horizon 

 may readily ha^•e been ancestral to the Arundel type, although the European 

 material is too fragmentary to admit of a just comparison. Of the other 

 dinosaurs, the affinities seem to be entirely with Wealden forms, Gcrlurus 

 being found therein, while AUosaiirus compares in point of size and dentition 

 witli the Wealden Mcfjiilosaurus. DnjosaurUH has its nearest European ally 

 ill Hjii)Hiloph()(l(nt, again a Wealden type, and the ci'ocodile, GonioplioUs, is 

 i-eported from the Wealden and its marine eciuivalent, the Purbeckian, not 

 from the older Jurassic levels. 



"The weiglit of this evidence would seem to place this fauna beyond tlie 

 Jurassic into the beginning of Cretaceous times." 



Age of the Wealden 



Whatever the present analysis of the Morrison faunas may indicate 

 their relationships to be, it is an indisputable fact that the current tra- 

 dition that the Morrison formation is of Jurassic age has had no other 

 basis in fact than the late Professor Marsh's lifelong opinion that the 

 European Wealden was UiDper Jurassic. Possibly the last word has not 

 yet been said regarding the age of the Wealden, but the consensus of 

 opinion of those best able to form a reliable judgment — that is, European 

 students of the Wealden stratigraphy — seems to be that the Wealden is 

 of Lower Cretaceous age, and for the following reasons: 



1. Where the Wealden is present, the oldest marine. Lower Cretaceous, 

 is absent, and the Wealden may lie with a marked unconformity on the 

 Upper Jtuassic, as in the Boulnmiais. 



2. Its tioiu is similar to the older Potomac flora (Patuxent and 

 Arundel), and likewise similar to Neocomian and Barremian floras of 

 known age, as determined by invertebrate paleontologists in Portugal, 

 Japan, and Peru. 



The faunas of the AVealden offer little satisfactoiy evidence, since if 

 Lower Cretaceous they represent survivals from the late Jurassic, and 

 the comparable N'eocomian deposits contain marine faunas and lack both 

 terrestrial vertebrates and plants. 



Age of the Kootenai 



Turning now to a consideration of the Kootenai flora of the Eockv 

 Mountain jirovince, it may be noted that the flora of the Kootenai, as 



