260 EXTINCT "MONSTERS 
Marsh for so liberally devoting his time and his private resources 
in order to advance the science of Paleontology. 
In the country east of the Rocky Mountains, including the 
states of Dakota, Nebraska, Wyoming, and part of Colorado, 
Professor Marsh has discovered the remains of yet another 
strange group of large quadrupeds. The best known of these is 
Brontops, of which the skeleton is seen in Fig. 97. These animals 
lived after the Dinocerata, namely, in the Miocene period, and 
Fic. 97.—Skeleton of Brontops robustus. (After Marsh.) 
were the largest American mammals of that period. They 
constitute a distinct family more nearly allied to the rhinoceros 
than to any other living form. The skeleton on which Fig. 97 
is founded was the most complete of any yet discovered by 
Professor Marsh. Portions of it were exhumed at different times, 
but it was first found in 1874. Our artist has made the restora- 
tion seen in Plate XLII. from this skeleton, as figured by Professor 
Marsh. 
This strange group of creatures flourished in great numbers on 
