Fig. 85.—Sphenodon punctatum, or tuatera.
(From specimen in the Yale University museum.)
With these living tuateras we have nothing further to do, since they are land animals, living about the beaches of the New Zealand islands, and only occasionally venturing into the water, hiding from their enemies in the holes in the rocks. But, from some of their antecedents, from some of their direct forbears perhaps, there have gone off at different times various branches, whose descendants wandered into foreign lands or into foreign places, and lived and flourished for a brief time and then became extinct. Some of these went down into the water and became more or less aquatic in habit; some, indeed, changed their forms and habits so greatly that they are often, perhaps rightly, segregated into different orders. Whether or not they should be called Rhynchocephalia matters little, however. It is merely a matter of opinion as to how great the changes should be in order to entitle the offspring to a genealogical tree all its own. Of these branches there are two, whose relationships seem to be definite, the Choristodera and Thalattosauria, though there is more doubt about the latter than the former. A third group, that included Pleurosaurus, seems, from more recent discoveries, to belong to a different line of descent and has been described under the Protorosauria.
In the direct line of ancestry there is no known form that was distinctly aquatic. The oldest known of these, perhaps, is that shown in [Fig. 86], Sapheosaurus from the Jurassic of Solenhofen. Its resemblance to the modern tuatera is great, and doubtless its habits were very similar, though its rather long tail and rather short neck possibly indicate subaquatic habits.
Fig. 86.—Sapheosaurus,
an Upper Jurassic rhynchocephalian.
(After Lortet.)
CHORISTODERA
Among the many reptiles of the past which have sought a more congenial or a safer home in the water few have had a more interesting history, or a briefer one, than those to which the late Professor Cope gave the name Choristodera in 1876. Many students of repute consider the group an order, others a suborder of the Rhynchocephalia. The group, whether order or suborder, are interesting because of their long and devious migrations from western North America to Europe, or vice versa, through rivers and ponds; interesting also because of the persistence of certain old-fashioned traits that clung to them long after their disappearance in other animals. Perhaps these traits were among the causes of their merely moderate success as animals of the water, traits that led to their early dissolution. Like the proganosaurs, which they must have resembled in external appearance not a little, they wandered from their birthplace in the western continent, to perish in the eastern; and like them their span of existence was short.
Their history among mankind, too, is brief. The first known specimens, from western North America, were described by Professor Cope in 1876, under the name Champsosaurus. In the following year Professor Gervais of Paris made known another form from Rheims, which he called Simoedosaurus, so closely allied to the American that even yet they have not been sharply distinguished. Some years later these European specimens were more fully described by the well-known Belgian paleontologist, Dr. Dollo, but it has been only within the past few years that our knowledge of the animals has been made at all complete by the discovery and description of several excellent skeletons of Champsosaurus by Mr. Barnum Brown of New York.
Fig. 87.—Champsosaurus; skeleton,
as mounted in American Museum. (Brown.)