THE RESTORATION OF EXTINCT ANIMALS. 489 



must not be so placed as to be in the way, and that while there would 

 be a possibility— one might even sa}' probability— of the great, short- 

 headed, iguana-like Dinosaurs having dewlaps, that there would be no 

 great likelihood of them possessing ruffs, such as that of the Austra- 

 lian ChUmydosaurus (mantled lizard), to flap about their ears; even 

 Stegosaurus, 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 quicklv 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 proliabilities 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 ma}^ be pretty cer- 

 tain what should not. 



For example, to depict a Dinosaur with smooth, rubbery hide, walk- 

 ing about on dry land, would be to violate the probabilities, for only 

 such exclusively aquatic creatures as the whales among mammals and 

 the salamanders among batrachians are clothed in smooth, shiny 

 skin. There might, however, be reason to suspect that a creature 

 largely aquatic in its habits did occasionally venture on land; as, for 

 instance, when vertebrae that seem illy adapted for carrying the weight 

 of a land animal are found in company with huge limb bones and 

 massive feet, we may feel reasonably certain that their owner passed 

 at least a portion of his time on terra tirma. 



So much for the probabilities as to the covering of animals known to 

 us only by their fossil remains, but it is often possible to go beyond 

 this and to state certainly hoAV they were clad; for while the chances 

 are small that any trace of the covering of an extinct animal, other than 

 bony plates, will be preserved, nature does now and then seeni to have 

 relented, and occasionally some animal settled to rest where it was so 

 quickly and quietly covered with tine mud that the impression of small 

 scales, feathers, or even smooth skin was preserved. Curiously enough, 

 there seems to be no record of the imprint of hair having been found. 

 Then, too, it is to be remembered that while the chances were very 

 much against such preservation, in the thousands or millions of tmies 

 creatures died the millionth chance might come uppermost. 



The imprints of ichthyosaurs have already been mentioned, and 

 these are probably due to the slow carbonization of animal matter, 

 leaving a dark silhouette of the animal printed on the smooth rock. 



