66 | EXTINCT MONSTERS. 
divide them into three groups—taking the names given by Pro- 
fessor Marsh, only running together some which he would 
separate. 
We shall first consider the very interesting and huge forms in- 
cluded in his sub-order the Sauropoda, or lizard-footed Dinosaurs. 
Various parts of the skeletons, such as vertebrz, leg-bones, etc., 
of these cumbrous beasts have long been known in this country ; 
but Professor Marsh was the first person to discover a complete 
skeleton. 
We shall, therefore, now turn our attention to the bony frame- 
work of the huge Brontosaurus (Fig. 9), a vegetable-feeding 
lizard. But it will be necessary to completely lay aside all our 
previous notions taken from lizards of the present day, with their 
short legs and snake-like scaly bodies, before we can come to 
any fair conclusion with regard to this monstrous beast. 
It was nearly sixty feet long, and probably when alive weighed 
more than twenty tons! that it was a stupid, slow-moving reptile, 
may be inferred from its very small brain and slender spinal 
cord. By taking casts of the brain-cavities in the skulls of 
extinct animals, anatomists can obtain a very good idea of the 
nature and capacity of their brains ; and in this way important 
evidence is obtained, and such as helps to throw light upon their 
habits and general intelligence. No bony plates or spines have 
been discovered with the remains of this monster ; so that we are 
driven to conclude that it was wholly without armour : and, more- 
over, there seem to be no signs of offensive weapons of any kind. 
Professor Marsh concludes that it was more or less amphibious 
in its habits, and that it fed upon aquatic plants and other 
succulent vegetation. Its remains, he says, are generally found 
in localities where the animal had evidently become mired, just 
as cattle at the present day sometimes become hopelessly fixed 
in a swampy place on the margin of a lake or river (see p. 19). 
Each track made by the creature in walking occupied one 
square yard in extent! 
