File:Image from page 183 of "Water reptiles of the past and present" (1914) (14586406749).jpg

Identifier: waterreptilesofp1914will Title: Water reptiles of the past and present Year: 1914 (1910s) Authors: Williston, Samuel Wendell, 1851-1918 Subjects: Aquatic reptiles Publisher: Chicago, Ill., The University of Chicago Press Contributing Library: Boston Public Library Digitizing Sponsor: Boston Public Library

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Text Appearing Before Image: iam thinks that they were related most closely with 171 172 WATER REPTILES OF THE PAST AND PRESENT the Rhynchocephalia (p. 176) of which the Sphenodon, or tua-tera, of New Zealand is the only living representative, but whosedirect genealogical history runs back nearly or quite to the timein which the thalattosaurs lived. On the other hand, there are somany resemblances to the mosasaurs shown in the remains thathave been discovered, that it is possible the thalattosaurs were onlya short-lived branch of the primitive lizards, which we also knowwere in existence at the time when the thalattosaurs lived. How-ever, even though they resembled the mosasaurs, there could havebeen no direct genealogical relationships between them, for it isquite certain that the thalattosaurs very soon went out of exist-ence, leaving no descendants. But it matters little which werethe land forbears of the thalattosaurs; they present such distinctadaptations to water life—characters all their own—that their

Text Appearing After Image: Fig. 82.—Skull of Thalattosaurus. (After Merriam) ancestral kinship may well be left to the future researches of thecurious paleontologist. For the present, at least, they may wellbe placed in an order of reptiles all their own, as Professor Merriamhas proposed—the Thalattosauria. No thalattosaurs were large animals. If they had the sameproportions between the lengths of head, body, and tail as themosasaurs, none exceeded seven feet in length, and they may havebeen even shorter, though probably not much. The figure of theskull, as restored by Professor Merriam, shows many strikingaquatic adaptations, in the elongated, pointed muzzle, in the largeexternal nostrils, situated far back toward the eyes, and in the well-ossified ring of bones surrounding the eyeball. There is a parietalopening in the roof of the skull, as in the modern lizards andtuatera; but it is not known for certainty whether there were two THALATTOSAURIA 173 openings on each side in the roof of the skull, as in the

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