THE 



GEOLOGICAL MAGAZINE. 



NEW SERIES. DECADE III. VOL. VII. 



No. I.— JANUARY, 1890. 



OEIG-IUAL AETICLBS. 



I. — The Skull of the Gigantic Ceratopsid^;. 1 



By Prof. 0. C. Marsh, Ph.D., LL.D., F.G.S. 



(PLATE I.) 



THE huge horned Dinosaurs, from the Cretaceous, recently 

 described by the writer, 2 have now been investigated with some 

 care, and much additional light has been thrown upon their struc- 

 ture aud affinities. A large amount of new material has been 

 secured, including several skulls, nearly complete, as well as various 

 portions of the skeleton. 



The geological deposits, also, in which their remains are found, 

 have been carefully explored during the past season, and the known 

 localities of importance examined by the writer, to ascertain what 

 other fossils occur in them, and what were the special conditions 

 which preserved so many relics of this unique fauna. 



The geological horizon of these strange reptiles is a distinct one 

 in the Upper Cretaceous, and has now been traced nearly eight 

 hundred miles along the eastern flank of the Rocky Mountains. It 

 is marked almost everywhere by remains of these reptiles, and 

 hence the strata containing them may be called the Ceratops beds. 

 They are freshwater or brackish deposits, which form a part of the 

 so-called Laramie, but are below the uppermost beds referred to that 

 group. In some places, at least, they rest upon marine beds which 

 contain invertebrate fossils characteristic of the Eox Hills deposits. 



The fossils associated with the Ceratopsidce ai - e mainly Dinosaurs, 

 representing two or three orders, and several families. Plesiosaurs, 

 Crocodiles and Turtles of Cretaceous types, and many smaller 

 reptiles, have left their remains in the same deposits. Numerous 

 small mammals, also of ancient types, a few birds, and many fishes, 

 are likewise entombed in this formation. Invertebrate fossils and 

 plants are not uncommon in the same horizon. 



The Ceratopsidce, as the most important of this assemblage, will 

 be first described fully by the writer, under the auspices of the 

 United States Geological Survey. In the present paper, the skull 

 of one of these gigantic reptiles is briefly described, and figured, as 

 a typical example of the group. 



1 Abstract of a paper read before the National Academy of Sciences, Philadelphia, 

 November 14, 1889. 



2 American Journal of Science, vol. xxxvi. p. 477, December, 1888 ; vol. xxxvii. 

 p. 334, April, 1889; and vol. xxxviii. p. 173, August, 1889. 



DECADE III. VOL. VII. — NO. I. 1 



