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SMITHSONIAN MISCELLANEOUS COLLECTIONS 



[vol. 45 



these regions of the body. Similar ossitied tendons are found in 

 many diving birds, such as auks and loons, the object being to brace 

 the body against the strain it is called upon to undergo when a fish 

 is caught and is carried in the beak. In the case of Trachodon 

 the strain was due to the weight of the tail, which was, as we shall 

 see, held clear of the ground in walking. 



The final preparation of the skeleton, its mounting, and the re- 

 storation of the missing or damaged parts was most skilfully per- 

 formed by Mr. Alban Stewart, of the U. S. National Museum, who 

 devoted to it many months of patient work. 



Trachodon is a typical example of that group of dinosaurs called 

 Predentata because the front of the lower jaw is formed by a bone 

 preceding the tooth-bearing portion, and therefore termed the pre- 

 dentary bone. This was probably encased in horn, like the beak of 



Fig. 40. — Skull of Trachodon, showing the predentary bone. 



a turtle, and served for nipping off the branches or herbage on which 

 these animals fed. As the members of the Predentata had but three 

 well-developed toes on the hind feet, and often no more, so that their 

 feet resembled those of birds, the group has also received the name 

 of Ornithopoda, or bird-footed. The animals of this division were 

 all herbivorous and were probably preyed upon by their carnivorous 

 relatives. The particular subdivision, or family, of which Tracho- 

 don is a member is called the Iguanodontidse (iguana-toothed), from 

 the name Iguanodon bestowed by Mantell on the first species found 

 in England, the name being given because the teeth were attached 

 to the inner side of the jaw as in iguanas. In the case of Trachodon 

 there were several series of teeth placed one above the other, the 

 entire series moving slowly upward, new teeth forming at the base 

 to supply the place of those worn away at the top. This arrange- 

 ment greatly increased the number of teeth, there being over two 



