CHAPTER III 



THE SKELETON OF REPTILES 



The bony framework, or skeleton, that which gives form and 

 stature to the body, and which serves for the support of the soft 

 parts and the attachment of muscles, is, with rare exceptions, all 

 that is ever preserved of fossil animals. Because, therefore, 

 students of extinct animals must rely so much, if not exclusively, 

 upon the skeleton much attention has been given to the study of 

 comparative osteology, the science of bones. Not only are most 

 of the bones of the skeleton characteristic of the genus to which 

 they belong, but the more general plan of the skeleton, or parts 

 of the skeleton, is likewise characteristic of the larger groups. The 

 paleontologist may become so expert in deciphering the characters 

 of single bones, or even parts of bones — often all that are known 

 of animals new to science — that he is able to hazard guesses as to 

 the general structure of the skeleton to which they belong. But 

 such guesses usually will approximate the real truth only in the 

 degree that the bones upon which they are based approximate 

 like bones of other animals that are better known. Not all parts 

 of the skeleton are equally characteristic of the type of animal which 

 possessed them. A tooth of a mammal may positively determine 

 the species to which it belongs, while the toe bone of the same 

 animal might not enable one to guess at its family, even. As a 

 rule one can seldom be quite sure of the species of a reptile unless 

 the larger part of the skeleton, or at least the skull, is available, 

 although almost any bone of the skeleton, if one is expert, will 

 permit a decision as to the family, if not the genus. 



One must often depend upon the positions and relations of the 

 bones, as found in the rocky matrix, for the final determination 

 of many characters. One can, for instance, never be sure of the 

 number of bones in the neck, trunk, tail, or feet of a reptile, until 

 specimens have been found with all such bones in position. It 

 is for this reason that much care is exercised in the collection of 



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