64 
EXTINCT MONSTERS. 
by anatomists ; some concluding, with Professor Huxley, that 
birds are descended from Dinosaurs ; while others, with Professor 
Owen, consider the resemblance accidental, and in no way 
implying relationship. Huxley has proposed the name Ornitho- 
scelida, or bird-legged, for these remarkable reptiles. 
Dinosaurs must have formerly inhabited a large part of the 
primaeval world ; for their remains are found, not only in Europe, 
but in Africa, India, America, and even in Australia ; and the 
geologist finds that they reigned supreme on the earth throughout 
the whole of the great Mesozoic era. 
Their bodies were, in some cases, defended by a formidable 
coat of armour, consisting of bony plates and spines, as illustrated 
by the case of Scelidosaurus (p. 105), thus giving them a 
decidedly dragon-like appearance. The vertebrae, or bony seg- 
ments of the back-bone, generally have their centra hollow on 
both sides, as in the Ichthyosaurus ; but in the neck and tail they 
are not unfrequently hollow on one side and convex on the 
other. In some of the largest forms the vertebrae are excavated 
into hollow chambers. This is apparently for the sake of 
lightness ; for a very large animal with heavy solid bones would 
find it difficult to move freely. In this way strength was combined 
with lightness. 
All the Dinosaurs had four limbs, and in many cases the hind 
pair were very large compared to the fore limbs. They varied 
enormously in size, as well as in appearance. Thus certain of 
the smaller families were only two feet long and lightly built ; 
while others were truly colossal in size, far out-rivalling our 
modern rhinoceroses and elephants. 
The limbs of Cetiosaurus, for example, or of Stegosaurus, 
remind us strikingly of those of elephants. The celebrated Von 
Meyer was so struck with this likeness that he proposed the name 
Pachypoda for them, which means thick-footed. Professor Owen 
opposed this name ; for it was misleading, and only applied to 
a few of them. He therefore proposed the name we have already 
