OSTEOLOGY OF THE ABMOEED DINOSAURIA. 107 



one of the dermal spines are scattered about beyond the last of the articulated 

 series. (See pi. 2.) 



The presacral vertebrae, with the exception of the mid-dorsal region, retain 

 their relative positions. In the middle of the series three vertebrae have been 

 pushed up and out of position, but the combined length of these vertebrae is suffi- 

 cient to fill the gap between the posterior and anterior articulated series. This 

 would appear to indicate that none are missing. The head and neck are articulated 

 and curve backward toward the fore feet, lying ventral side up in a death-like 

 attitude. The femora are nearly in place in the acetabulum with their distal ends 

 wide apart as if at the end of a long stride. The tibia and fibula of the right leg is 

 doubled back along the front of the femur, but the foot as well as the lower limb 

 bones of the left leg are missing. Both articulated fore limbs, with considerable 

 portions of both fore feet, occupy their relative positions, one lying on top of the 

 other. The thoracic ribs of the right side have been pushed up into a heap along 

 the front of the right ilium and above the posterior portion of the vertebral column. 

 Those of the opposite side are largely retained in their relative positions, their free 

 ends curving upward and to some extent showing the natural curve of this portion 

 of the body cavity. 



The pelvic bones are all present, though slightly disarranged; the ilia, however, 

 remain firmly coossified with the sacral vertebrae and show plainly the great breadth 

 of the hips. ' 



The dermal plates, which in life stood erect along the back, are present to a 

 point back of the pelvis and are retained in the rock in their mutual relationships. 

 The eleven plates forming the armor of the anterior part of the animal are turned 

 back in under the body and neck, forming a continuous sheet of bone upon which 

 the anterior parts of the skeleton lay. Three large plates over and back of the 

 sacral region occupy much the same position as during the life of the animal, their 

 bases being just above the spinous processes of the associated vertebrae. There are 

 three other plates present from the caudal region, as mentioned above, and although 

 disarranged they show the relative decrease in size posteriorly. The little dis- 

 turbed condition of the specimen appears to indicate that it was found in a place 

 not far removed from where the animal died. The position is that of an animal 

 which died a natural death, for such disarrangement as exists can be attributed 

 to the natural shifting of the bones rather than to their having been torn apart 

 by any of the contemporary carnivora. 



Theory offossilization. — The story of the entombment of this specimen, as read 

 from the position of the various parts of the skeleton, would appear to be as follows: 



The animal died in the water or along the banks of one of the large streams that 

 traversed that portion of Colorado in those ancient days. In the event of death 

 having occurred along the banks, before decomposition had set in a freshet floated the 

 carcass and it was carried downstream, and, as the water subsided was stranded upon 

 an old river bar. Before reaching the bar the soft tissues commenced to relax and 

 allowed the projecting plates along the top of the back to droop, and upon coming 

 into shallow water their points were caught in the sand and the current acting 

 against the carcass forced it over and upon the plates, folding them back underneath 

 the ribs of the lower side. The larger plates of the series, those above the hips 



