Fig. 95.—Scapula and
coracoid of Rutiodon carolinensis,
an American phytosaur.
(After McGregor.)
Fig. 96.—Belodon; restoration of head,
from above.
Fig. 97.—Mystriosuchus: restoration of head,
from above.
In Belodon ([Fig. 96]), the earliest known and most typical genus, perhaps, the moderately elongated face has a high crest reaching nearly to its front end, and this type is known both from Europe and from New Mexico. Others have the face long and slender, even longer and more slender than in the ancient teleosaur crocodiles or the modern gavials. In some forms the teeth are cylindrical and slender throughout, and there may be as many as fifty on each jaw, or two hundred in all; while in others only the anterior teeth are cylindrical and the posterior teeth are flattened and serrate along their cutting edges. In the body not very great differences have been observed. Some are more slender than others, and there are minor differences in the shapes and sizes and numbers of the bony scutes along the back and on the throat.
But they are all alike in their essential characters, a very long beak with numerous teeth; the foremost ones on the expanded, more or less spoon-shaped front extremity, are more or less, sometimes greatly, elongated. The jaws may be likened to a long and slender pair of tongs with nipping teeth at the front end. The strong, long, and flattened tail is sufficient evidence that the phytosaurs were excellent swimmers, but, aside from that and the posterior location of the external nostrils, directly over the internal, few other aquatic adaptations are observed in the skeleton. There are no sclerotic bony plates about the eyes, or at least none have so far been discovered, although among the numerous known specimens they would confidently be expected were they really present in the skeleton; and the presence of bony armor negatives markedly aquatic habits.
Doubtless on the whole the habits of the phytosaurs were not very unlike those of the modern gavials, which they so strongly resemble in form, size, and general characters. But they differ very greatly from the gavials in the extreme posterior position of the nostrils, and in the greatly elongated teeth of the front end of the beak, teeth which must have had some especial and peculiar use. Nor is the position of the nares to be accounted for satisfactorily by reference to aquatic habits. It has been suggested that the creatures used the very long and slender beak in prodding and probing in the sand and mud for soft-bodied invertebrates, worms and the like, for which the teeth would be especially fitted; and that the posterior position of the nostrils may be in part, perhaps wholly, accounted for by this habit, which permitted the reptiles to breathe without extricating the beak from the mud or shallow waters. That the animals were wholly and intensely carnivorous in habit is attested by their teeth; although they are called “plant saurians,” they never had anything to do with plants in the way of food. Unfortunately so far no specimens have ever been found showing the remains of stomach contents, nor have any been found showing impressions of the form of the body or of any of its parts. Until such specimens are found, as they doubtless will be eventually, one can be less sure of the precise details in their life reconstructions. However, the skeleton is now known nearly completely, and this suffices to give a very approximately correct idea of what the animals were like when alive.
CHAPTER XV
CROCODILIA
The order of reptiles to which the name Crocodilia is technically applied comprises less than twenty-five living species, popularly known as crocodiles, alligators, caimans, and gavials. They are often of great size, ugly and repulsive in appearance, cruel and vicious in habit, wholly carnivorous, and denizens, almost exclusively, of fresh-water lakes or rivers in tropical and subtropical regions; a few only venture into the sea near the shores. They are all excellent and powerful swimmers, but are by no means exclusively aquatic in habit, many of them spending a large part of the time on the shores; and they invariably seek the land for the deposition and hatching of their eggs. In size they are the largest of living reptiles, some of the existing species reaching a length of twenty-five feet, while some extinct species were probably fully twice that length.