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 
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 OP THE SKULL OF A HORNED DINOSAUR. 
a, nostrils ; f, brain ; h, liorn ; n, nasal bones ; p, chin-bone ; r, extremity 
of upper jaw.—After Marsh. 
