468 CHARLES C. MOOK 
and carnivores were almost exclusively terrestrial and the sauropods 
largely aquatic in habit, the latter might escape the carnivores much 
more frequently than if the predentates were not present. 
4. Amphibia.—The known amphibian fauna of the Morrison 
consists of one frog or toad. A fauna of this nature could scarcely 
have had any effect upon the lives or development of the Sauropoda. 
5. Pisces.—The only fishes known to have existed along with the 
American Sauropoda were a few species of Ceratodus. These could 
hardly have furnished food for the sauropods, or have had any 
direct effect upon the security of the latter. 
II. INVERTEBRATES 
The known invertebrate fauna of the Morrison is neither very 
large nor varied. It consists of a number of fresh-water pelecypods 
and gastropods, together with a few ostracods. None of these were 
large enough nor abundant enough to have served as an essential 
part of the diet of the sauropods, but they may have served as 
accessories, to a very small extent, to the normal sauropod diet. 
II. FLORA 
The known flora consisted almost entirely of cycads. These 
might also have comprised an accessory portion of the sauropod 
diet, but probably not much more. The remainder of the Morrison 
flora is very little known.  Silicified wood is found occasionally, 
and rarely some imperfect reeds. The Kootenie formation contains 
leaves of deciduous trees, but few if any sauropods. The Arundel 
formation of Maryland contains both sauropod bones and deciduous 
leaves. The latter also might have formed an accessory part of the 
food of the sauropods, but could scarcely have been abundant 
enough to have sustained their huge bulk. In a region such as 
the one described above there might have been a considerable 
amount of soft vegetation which would not be easily preserved. 
In the interstream areas, especially where considerable amounts of 
windblown sands were being deposited, little vegetation may have 
been present, certain areas being semiarid. Other areas were 
probably well covered with vegetation. The character of the 
known flora suggests a rather warm climate, and the physical 
