124 ANIMALS OF THE PAST 



small in comparison with the other bones, it 

 would obviously mean that their owner passed 

 his life in the water. For a skeleton has a two- 

 fold meaning, it is the best, the most enduring, 

 testimony we have as to an animal's place in 

 nature and the relationships it sustains to the 

 creatures that lived with it, before it, and after 

 it. More than this, a skeleton is the solution 

 of a problem in mechanics, the problem of 

 carrying a given weight and of adaptation to 

 a given mode of life. Thus the skeleton varies 

 according as a creature dwells on land, in the 

 water, or in the air, and according as it feeds 

 on grass or preys upon its fellows. 



And so the mechanics of a skeleton afford 

 us a clew to the habits of the living animal. 

 Something, too, may be gathered from the 

 structure of the leg-bones, for solid bones mean 

 either a sluggish animal or a creature of more 

 or less aquatic habits, while hollow bones em- 

 phatically declare a land animal, and an active 

 one at that; and this, in the case of the Dino- 

 saurs, hints at predatory habits, the ability to 

 catch and eat their defenceless and more slug- 

 gish brethren. A claw, or, better yet, a tooth, 



