108 ANIMALS OF THE PAST 



beauty, are but skin deep, and, being thus superficial, 

 ordinarily leave no trace of their former presence, and in 

 respect to them the reconstructor must trust to his 

 imagination, with the law of probabilities as a check rein 

 to his fancy. This law would tell us that such orna- 

 ments must not be so placed as to be in the way, and 

 that while there would be a possibility — one might 

 even say probabihty — of the great, short-headed, 

 iguana-like Dinosaurs having dewlaps, that there 

 would be no great likelihood of their possessing ruffs 

 such as that of the Australian Chlamydosaurus 

 (mantled lizard) to flap about their ears. Even Stego- 

 saurus, with his bizarre array of great plates and spines, 

 kept them on his back, out of the way. Such festal 

 ornamentation would, however, more likely be found in 

 small, active creatures, the larger beasts contenting 

 themselves with plates and folds. 



Spines and plates usually leave some trace of their 

 existence, for they consist of a superstructure of skin or 

 horn, built on a foundation of bone; and while even 

 horn decomposes too quickly to "petrify," the bone will 

 become fossilized and changed into enduring stone. 

 But while this affords a pretty sure guide to the general 

 shape of the investing horn, it does not give all the 

 details, and there may have been ridges and furrows and 

 sculpturing that we know not of. 



Knowing, then, what the probabilities are, we have 

 some guide to the character of the covering that should 

 be placed on an animal, and if we may not be sure as to 

 what should be done, we may be pretty certain what 

 should not. 



For example, to depict a Dinosaur with smooth, 

 rubbery hide walking about on dry land would be to 

 violate the probabilities, for only such exclusively 

 aquatic creatures as the whales among mammals, and 



