DINOSAURS. 
33 
The Extinct Dinosaurs. 
Order Dinosauria. 
Nearly allied to crocodiles are those remarkable extinct reptiles from the rocks 
of the Secondary period, which include amongst their number the most gigantic 
of all land animals, and likewise those members of the reptilian class which make 
the nearest approximation in their organisation to birds. During that epoch of the 
earth’s history in which the Chalk and underlying Oolitic rocks were deposited, 
when mammals were represented by a few small forms of lowly type, these strange 
reptiles were the dominant animals on land; some progressing in the ordinary 
lizard-like manner, while others stalked on their hind-limbs like birds. To give 
some idea of the enormous dimensions attained by some of these creatures, it may 
be mentioned that the thigh-bone of one species measures 64 inches, while the total 
vol. v .—3 
