38 



DINOSAURS. 



resulted. These trachodons were all much inferior in size to the gigantic 

 iguanodons. The American claosaur (Claosaurus), of which the skeleton is figured 

 on p. 36, differs from the iguanodons in having the fore-paw of normal structure. 

 Nearly allied to the iguanodons are the remarkable armoured and horned dinosaurs, 

 which constitute a subgroup characterised by their solid limb-bones, the presence 

 of some kind of bony armour, the short foot -bones, frequently terminating in 



hoof-like toes, and the 

 habitually quadrupedal 

 gait. Commencing in 

 the British Lias, these 

 extraordinary reptiles 

 i-i !m continued throughout 



the Secondary period, 

 and seem to have at- 

 tained their maximum 

 development at the close 

 of the Cretaceous epoch 

 in the United States. Of 

 the armoured forms, the 

 huge stegosaur of the 

 English Oxford, and 

 Kimeridge Clays, and 

 the corresponding rocks 

 of the United States, was 

 characterised by the 

 possession of large quad- 

 rangular bones, which 

 are believed to have been 

 arranged in a vertical 

 position down the middle 

 of the back, while the tail 

 was protected by some 

 formidable spines, as 

 shown in the greatly 

 reduced restoration of 

 the skeleton given on 

 p. 4. Still more strange 

 were the somewhat later 

 horned dinosaurs (Ceratops, etc.), of which two views of the skull and a more 

 reduced restoration of the skeleton are here given. In these extraordinary 

 creatures the hinder part of the head was provided with a pair of bony horn- 

 like projections, which were doubtless ensheathed during life with hollow horns, 

 like those of oxen; and there was also a single horn of variable size on the 

 nose. The skull was further remarkable for the expansion of its hinder extremity 

 into a fan-like shield overhanging and protecting the vertebrae of the neck. Some 

 idea of the huge dimensions attained by these dinosaurs will be conveyed by the 



UPPER AND SIDE VIEWS OF THE SKULL OP A HORNED DINOSAUR. 



a, nostrils ; /, brain ; h, horn ; n , nasal bones ; p, chin-bone ; r, extremity 

 of upper jaw. — After Marsh. 



