. Bulletin of the Department of Geology. Geology. 7(1 University of California Publications in Geology LVo1- 10 These jaw fragments now seem to me to be somewhat less enig- matical, since Merriam has pointed out that they do not belong to an Ichthyosaurian. In 1906 Merriam9 described a reptile, widely dif- ferent from the ichthyosaurians but with a still uncertain systematic position, Omphalosaurus. It is found in the Middle Triassic of Nevada, and is thus approximately in the same horizon as Pessopteryx. The reproductions of the teeth of Omphalosaurus that are found in this work did not sugge
. Bulletin of the Department of Geology. Geology. 7(1 University of California Publications in Geology LVo1- 10 These jaw fragments now seem to me to be somewhat less enig- matical, since Merriam has pointed out that they do not belong to an Ichthyosaurian. In 1906 Merriam9 described a reptile, widely dif- ferent from the ichthyosaurians but with a still uncertain systematic position, Omphalosaurus. It is found in the Middle Triassic of Nevada, and is thus approximately in the same horizon as Pessopteryx. The reproductions of the teeth of Omphalosaurus that are found in this work did not suggest to me any thought of the enigmatical teeth of Spitzbergen. Merriam, however, in 1911,13 has shown the great similarity between the Omphalosaurus teeth and the teeth referred by me to Pessopteryx, and since Merriam and Bryant14 the same year prod viced new figures of Omphalosaurus teeth I can myself Fig. 5.—Phalanges from the Lower Saurian horizon on Spitzbergen, X % (after Wiman). state the identity. But seeing that the teeth are identical, in what relation do then Omphalosaurus and Pessopteryx stand to each other? Of the former only parts of the cranium with teeth and biconcave, iehthyosaur-like cervical vertebrae are known, and, again, of the latter vertebrae, extremity and girdle bones are found. Therefore a com- parison cannot be made. One can, however, think of two possibilities. The one is, that all of the material represents Omphalosaurus. Mer- riam seems to be inclined to this interpretation. One would then have to imagine a reptile with a relatively short head and a body that in detail had developed on the same line as Ichthyosaurus. Such a paral- lelism is of course not inconceivable, but less probable. The other probability is that an ichthyosaurian Pessopteryx is before us, but that, together with its bones, jaw fragments of Omphalosaurus occur. It is easily possible that these very jaw bones have constituted the most lasting part of the skeleton. In favor of a
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