IGO ylAW.lL/S' NEW YORK ACADEMY OF SCIENCE.'^ 



adaptations^, but they also possess adaptations for walking on land, in 

 some forms at least. The crocodiles were amphibious and probably the 

 turtles as well. The theropod and predentate dinosaurs were terrestrial^ 

 and probably the mammals as well. No marine vertebrates hav6 been 

 found in beds which have been definitely identified as Morrison. 



20). The skeletons of the large dinosaurs often indicate, to a certain 

 extent, by their preservation, some of the physical processes connected 

 with their burial. In some cases, of which the Bone Cabin Quarry near 

 Medicine Bow, Wyoming, is an example, the bones of many individuals 

 and species are found mixed up in an intricate manner, so that anything 

 like a complete skeleton is rare. In other cases complete or nearly com- 

 plete skeletons are found in position. In still other eases a skeleton will 

 be found complete up to a certain point and then end suddenly, with not 

 a bone to be found beyond in any direction. 



The mixed-up bones indicate that they were gathered together from 

 their original resting-places by current action, in a restricted area, such 

 as one individual stream. The complete skeletons indicate swift burial 

 in relatively quiet waters or by wind action. The partial skeletons point 

 toward erosion of the beds they were deposited with, after their burial. 



21). The Morrison is more closelv related to the overlving t^ian to the 

 underlying formations. 



22 ) . The contact with the overlying beds is sharp in places, and indi- 

 cates a change of depositional conditions. There may have been a small 

 amount of erosion of Morrison beds prior to the deposition of the over- 

 lying beds in places, but if so it was probably slight. 



23). In Texas, where the Morrison is absent, its place in the sti'ati- 

 graphic column is occupied by great thicknesses of marine Comanchean 

 beds. 



24). In the north the Morrison is overlain conformably by tlie fvoo- 

 tenie formation. The Kootenie is similar in character to the Morrison, 

 and part of it, at least, may belong to the Morrison. The flora of the 

 Kootenie and Potomac formations have a bearing on this question, which 

 has been discussed in the section on the age of the Morrison. 



25). The formation lies on beds of various ages, from Archean to 

 upper Jurassic. 



26). There is a widespread erosion plane beneath the Morrison over 

 most of its area. The relation to the Sundance Avill be discussed later. 



27). The formation is present in isolated areas in the Eocky Moun- 

 tains in Colorado, about midway between the eastern and western Colo- 

 rado areas. 



