160 PROCEEDINGS OF THE NATIONAL MUSEUM vol 8:; 



DISCUSSION OF GENERA AND SPECIES 



Order DINOSAURIA 



Since I reviewed the fauna of the Kirtland in 1920, notable ad- 

 vances have been made in our knowledge of the Dinosauria of this 

 period. The discovery of well-preserved specimens has shown the 

 presence of a new genus of the Ceratopsia, of which two species, 

 Pentaceratops sternbergii Osborn and P. fenestratus Wiman, have 

 been named. The presence of a chasmosaurid ceratopsian appears 

 to be indicated by a fragmentary specimen. The genera Ceratops 

 and Monoclonius^ to which fragmentary specimens have previously 

 been referred as occurring in this formation, should now be dropped 

 from further consideration in that connection. Although it is quite 

 evident that unrecognized ceratopsian genera are present here, better- 

 preserved specimens are necessary before their affinities can be deter- 

 mined. At this time those specimens referred to Ceratops and Mono- 

 clonius have no significance except to indicate the presence of a 

 ceratopsian with fenestrated frills. It is quite possible that some 

 of the specimens so referred in the past may pertain to Pentaceratops. 

 The family Hadrosauridae is represented by the two genera Krito- 

 saurus and Para^wu/rolophus ; the latter is of especial interest, as 

 its first occurrence outside of the Belly River of Canada is now 

 recorded. 



The discovery of ParasauroJophus., Gorgosaur-us^ and a chasmosau- 

 rid dinosaur in the Kirtland formation known elscAvhere only in the 

 Belly River is strong evidence in support of the idea of the equiva- 

 lence in age of these widely separated geological formations. 



Family DEINODONTIDAE 



GORGOSAURUS species 



A specimen (U.S.N.M. no. 834G) collected by Dr. J. B. Reeside, Jr., 

 in 1915, consisting of a left dentary, I described in a previous paper 

 (Gilmore, 1916), but at that time I was unable to identify it. Com- 

 parison of this bone directly with a dentary of Gorgosaurus lihratus 

 Lambe from the Belly River of Canada now shows such close re- 

 semblances in size, shape, and other characteristics down to the small- 

 est details as to leave little doubt of their being congeneric. Likewise, 

 the number of alveoli (13) is in agreement with Lambe's (1917) de- 

 termination from a numl^er of specimens that the dentary in this 

 genus bears 13 or 14 teeth. 



