XVI. HEADS AND TAILS; A FEW NOTES RELATING TO 

 THE STRUCTURE OF THE SAUROPOD DINOSAURS.^ 



By \V. J. Holland. 

 (Plate LIX.) 



For several years past, under the oversight of Mr. Earl Douglass, 

 the Carnegie Museum has been carrying on extensive excavations in 

 Uinta County, Utah. The result of this work has been the discovery 

 of a very large number of skeletons, principally of sauropod dinosaurs, 

 although there have also been uncovered more or less imperfect skele- 

 tons of several Stegosaurs, and recently the skeleton of an Allosanrus, 

 or closely related theropod dinosaur, which promises to be sufficiently 

 perfect to permit a restoration to be made, the skull, the vertebrae, 

 and limb bones of the specimen seeming to be, according to reports 

 received from Mr, Douglass, quite well preserved, and not much 

 dislocated. One of the remarkable features of this deposit of bones 

 is the fact that in the majority of cases the skeletons of the animals 

 have been but slightly disturbed in position since having been laid 

 down. In several instances the entire vertebral series has been found 

 articulated, or but little displaced, so that it is possible to reach correct 

 conclusions as to the number of vertebrae entering into the compo- 

 sition of the skeleton. 



The deposit appears to represent a section of the bed of a small 

 stream or river. At the bottom is a layer of cobblestones and coarse 

 gravel more or less firmly cemented together by lime. Superin- 

 cumbent upon this are sandstones, the material composing which 

 varies from coarse sand in some places to finer sand in other places. 

 The sandstones composing the matrix when exposed to the weather 

 rapidly disintegrate, especially the layers which are composed of the 

 finer materials, which after a few weeks become soft and resolve them- 

 selves into loose sand. There are several layers represented in this 

 quarry lying more or less conformably in relation to each other, but 

 disclosing pockets and irregularities which naturally would occur in 

 the bed of a small stream subject to the action of drouth succeeded 



1 Read before the meeting of the Paleontological Society of America, at the 

 meeting held in Philadelphia, December 31, 1914. 



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