THE HORNED DINOSAURS. 



By Charles W. Gilmore, 

 Associate Paleontologist, Division of Paleontology, U. 8. National Museum. 



[With S plates.] 



The suborder of extinct reptiles known collectively as the Cera- 

 topsia, or as they are more popularly called the horned dinosaurs, is 

 one of the most remarkable of the many groups of extinct animals 

 known from North America. All the more interesting perhaps, 

 since they are, so far as known at this time, a strictly American 

 product. 



Their fossil remains are confined to a narrow belt along the eastern 

 uplift of the Rocky Mountains, ranging from Alberta, Canada, on 

 the north to the Big Bend of the Rio Grande on the south. Geo- 

 logically they are found only in the latter half of the Upper Creta- 

 ceous, appearing suddenly in the Judith River formation (Belly 

 River of Canada), again in the Edmonton formation, where cera- 

 topsian remains are less common, and continuing through to the close 

 of the Lance, where they are the most abundant vertebrate fossils 

 found. In seven years exploratory work in the Lance formation 

 (Hell Creek Beds) of Montana, Mr. Barnum Brown says: "I identi- 

 fied no less than 500 fragmentary skulls and innumerable bones 

 referable to this genus" (Triceratops) . The geological continuity 

 of their course is, however, incomplete, owing to the intervention of 

 marine deposits of considerable thickness, in which from the nature 

 of things few remains of land animals are found. 



There are in the United States National Museum a pair of horn 

 cores (see pi. 3, upper figure) that were discovered in 1887 in the 

 suburbs of Denver, Colorado, by Prof. George I. Cannon, of the 

 Denver high schools. These were submitted to Prof. O. C. Marsh, 

 and he published a brief account of what he then supposed to be the 

 horns of an extinct buffalo, giving the specimen the name Bison 

 alticornis, and it was not until the discovery two years later of com- 

 plete skulls in Wyoming having similar horn cores that it was found 

 to be a large reptile instead of a bison. This error does not reflect 

 on the sagacity of Professor Marsh, for up to that time such extraor- 

 dinary creatures were unknown, and it was perfectly natural that 



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