A NEW CERATOPSIAN DINOSAUR FROM THE UPPER 



CRETACEOUS OF MONTANA, WITH NOTE 



ON HYPACROSAURUS ' 



By CHARLES W. GILMORE 



assistant curator of fo.ssii, reptiles, u. s. national museum. 



(With Two Plates) 



INTRODUCTION 



The fossil remains upon which the present communication is 

 l)ased were collected by the writ^er during the summer of 1913 

 while working under the auspices of the U. S. Geological Survey 

 on the lUackfeet Indian Reservation in northwestern Montana. The 

 partial skeletons of five individuals were found and these supple- 

 ment one another to such an extent that nearly all parts of the skele- 

 ton are represented. The skull presents some anatomical features 

 not heretofore known in the Ceratopsia and the new genus and spe- 

 cies Brachyccratops iiiontancnsis is here proposed. 



This new form is the smallest known re]>resentative among the 

 Ceratopsian dinosaurs and in several respects strikingly different 

 from any of its allied contemporaries. 



The present paper is preliminary. Upon the completion of the 

 preparatory work now in progress a more detailed account of the 

 skeletal anatomy and a discussion of its affinities will be given. 



BRACHYCERATOPS MONTANENSIS, new genus and species 

 Type. — Cat. No. 7951 U. S. Xat. Mus. A considerable portion 

 of a disarticulated skull ii. e., nasals, prefrontals, postfrontals, 

 ])Ostorbitals, premaxillaries, maxillaries, alisphenoid), with which is 

 provisionally associated a fragmentary part of the frill and a right 

 dentary and a predentary. 



Type locality.— N. E. >4 Sec. 16, T 37 N, R 8 W. Milk River, 

 Ijlackfeet Indian Reservation, Teton County, Montana. 



Paratypes. — Cat. No. 7952, U. S. Nat. ^lus. Rostral and portions 

 of the premaxillaries; Cat. No. 7953 U. S. Nat. Mus. Sacrum, 



' Published by ])ermission of the Director of the U. S. Geological Survey. 

 Smithsonian Miscellaneous Collections. Vol. 63, No. 3 



