ABT. 18 



ON A NEW SKELETON OF DIPLODOCUS GILMORE 



17 



cast from the above-mentioned specimen, which were used to replace 

 those missing, seems to show that the originals had been somewhat 

 straightened, probably to conform to some preconceived notion. This 

 backward curvature of the heavier ribs is not a feature new to sauro- 

 podous dinosaurs, as evidenced by mounted skeletons of Apafosaurus 

 (Brontosaurus) in the Field Museum of Natural History, Chicago, 

 and the American Museum of Natural History, New York. It there- 

 fore should occasion no especial comment that a somewhat similar 

 condition is now found to exist in Diplodocus. 



The body proper is short and deep as indicated by the ribs, some 

 of which are more than 5 feet in length. The five posterior ribs, 

 however, all of which are completely preserved, have a decided in- 

 ward curvature beginning a foot or more above their distal ends. 

 This inward deflection outlines the body as passing smoothly inward 

 to form the flank, which in turn coincides with the form of the lower 

 pelvic bones. 



As mentioned previously the tenth rib was fully coalesced with the 

 diapophyses, and it shows this rib as bending forward from the 

 transverse process far enough to clear fully the anterior end of the 

 ilium. In the Pittsburgh and American Museum specimens as 

 articulated it extends downward inside the blade of the ilium. 

 From the evidence of the present specimen it would seem that the 

 position of this rib varies with the individual. 



The position of the scapula along the anterior ribs seems to be 

 indicated by a flattening of their upper halves on the outside, which 

 could be of no other use than that mentioned. 



Measured over the curve, the complete ribs of this specimen have 

 the lengths given in Table 3. 



Table 3. — Comparative trieasurements of ribs of Diplodocus 



1 Estimated. 



/Scapula. — There has been the greatest diversity of opinion among 

 paleontologists as to the proper position of the scapula in the skele- 

 tons of sauropodous dinosaurs. 



Scapulae have been articulated high up on the ribs, in an inclined 

 position, nearly vertical, and low down in a horizontal pose. Per- 



