124 ANIMALS OF THE PAST 
small in comparison with the other bones, it 
would obviously mean that their owner passec 
his life in the water. Fora 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 » 
a given mode of life. ‘Thus the skeleton varie | 
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, 
