74 FLORIDA GEOLOGICAL SURVEY-SEVENTH ANNUAL REPORT. 
Fig. 8 .—Tomistoma americana Sellards, a gavial found in the land pebble 
phosphate deposits. Approximately one-third natural size. Fragment of the 
lower jaw. 
mation is of interest since it affords evidence of the existence of 
gavials in North America as late as the Miocene or early Pliocene, 
although they have since disappeared from the Western Hemisphere, 
the modern gavials being found in Asia and Africa. That the spe¬ 
cies found in the pebble phosphate beds is to be placed with the 
gavials rather than with the crocodiles is indicated not only by the 
long narrow snout, but also by the fact that the first mandibular 
tooth bites on the outside and not in the inside of the upper jaw. 
The fish remains in the phosphate bed include chiefly teeth of 
sharks and rays. Sharks’ teeth in particular are extremely abund¬ 
ant. It is difficult, however, to determine whether the teeth are 
from sharks that were living at the time the phosphate pebble ac¬ 
cumulated, or represent teeth residual from the marl beneath. Since 
the sharks’ teeth are highly resistant they would readily withstand 
the slight amount of erosion incident to their reaccumulation in the 
phosphate beds without showing any appreciable attrition, and it 
seems probable that most of these teeth have been washed in from 
the “bed rock.” The range of the species of sharks as identified by 
their teeth is considerable, and it is doubtful if it can be definitely 
determined whether the teeth in this formation are those of Oligo- 
cene, Miocene or Pliocene sharks. Plates from the teeth of the 
rays are also found both in the “bed rock” and in the phosphate 
beds. It is very probable that the teeth of sharks and rays taken 
from these beds represent a mixture of Oligocene and Pliocene 
forms. 
