68 EXTINCT MONSTERS. 



The remarkably small head is one of the most striking features 

 of this Dinosaur, and presents a curious contrast to the large and 

 formidable skulls possessed by some other forms to be described 

 further on. But it is clear that no animal with such a long neck 

 as this creature had could have borne the weight of a heavy skull. 

 Short thick necks and heavy skulls always go together. Indeed, the 

 weight of the long neck itself would have been serious had it not 

 been for the fact that the vertebrae in this part of the skeleton, and 

 as far as the region of the tail, have large cavities in the sides of 



I. 2. 



FlG. 10. Neck vertebrae of Brontosaurus. 

 I. Front view. 2. Back view. 



the centra. This cavernous structure of the vertebrae gradually 

 decreases towards the tail. The cavities communicated with a 

 series of internal cavities which give a kind of honeycombed 

 structure to the whole vertebra. This arrangement affords a 

 combination of strength and lightness in the massive supports 

 required for the huge ribs, limbs, and muscles, such as could not 

 have been provided by any other plan. (See Fig. 10.) 



The body of the Brontosaur was comparatively short, with a fairly 

 large paunch (see restoration, Plate IV.). The legs and feet were 



