UNIVERSITY OF CALIFORNIA PUBLICATIONS 



BULLETIN OF THE DEPARTMENT OF 



GEOLOGY 



Vol. 6, No. 14, pp. 329-332 Issued October 28, 1911 



NOTES ON THE DENTITION OF 

 OMPHALOSAURUS 



BY 



JOHN C. MEERIAM and HAROLD C. BRYANT 



INTRODUCTION 



In the saurian collections which have been obtained in the 

 marine Middle Triassic of Nevada during the last ten years a 

 number of specimens have appeared which represent a form 

 apparently differing from all known reptilian types. A portion 

 of a skull representing this group was described by Merriam 1 

 in 1906 as the type of the genus Omphalosaurvs. In the absence 

 of complete material it was not possible to determine definitely 

 the relationships of the genus, and it may be placed tentatively 

 in a distinct order, the Omphalosauria. So far as known the 

 animal is a short-headed form, presumably of the synapsidan 

 type. The structure of the palate and the mandible are not unlike 

 that in the plesiosaurs, while other characteristics point toward 

 the rhynchocephalian type. One of the remarkable features of 

 this specimen is found in the nature of the dentition. The 

 dentary elements are set with several rows of teeth, the crowns of 

 which are nearly circular in cross-section, and dome-like in eleva- 

 tion. There are at least three rows of teeth on the dentary, with 

 the presumption that many more rows may have been present. 

 The surface of the dentigerous area of the mandible was evi- 

 dently strongly convex. The nature of the dentition suggests 



i Merriam, J. O, Univ. Calif. Publ. Bull. Dept. Geol., vol 5, p. 76, 1906. 



