JUHASSIO DINOSAUHS 205 



in the Como beds in Wyoming. We have the same succession in both 

 localities of marine beds containing belemnites, followed by fluviatile or 

 estuarine beds, composed of compacted sand, gravel, and clays, containing 

 the remains of Brontosaurus, Diplodocus, Stegosaurus, and other dino-. 

 saurs, both carnivorous and herbivorous, immediately above these estua- 

 rine deposits the Cretaceous reveals itself. If similarity in the physical 

 structure of deposits and the presence in them of the same genera and 

 species prove anything, it is undoubtedly true that the beds which have 

 been recently exploited in Utah were synchronous in their development 

 with the Como beds of Wyoming, and that they therefore belong to the 

 Jurassic. 



After this passing reference to the stratigrapliy of these formations, I 

 desire to speak briefly of the numerous discoveries throwing light on the 

 Dinosauiia which have occurred within the last ten or twelve years. Dur- 

 ing this time large collections have been made by the American Museum 

 of Natural History, the Field Museum in Chicago, and the Carnegie 

 Museum in Pittsburgh. The collections in the Peabody Museum at Yale 

 and in the United States National Museum at Washington have been 

 made accessible to students and have received careful study by competent 

 investigators. The material at Yale was mainly collected by the late 

 Prof. 0. C. Marsh, as was that in Washington. The more recent addi- 

 tions to the splendid collection in the American Museum of Natural 

 History, which is enriched by the possession of the great collection of 

 Professor Cope, have been principally taken from the Como beds, at a 

 locality to which Prof. Henry Fairfield Osborn has given the name of the 

 "Bone Cabin Quarry." The collections from Wyoming in the Carnegie 

 Museum were derived from a locality about 13 miles north of the quarry 

 exploited by the American Museum of Natural History ; from the quarry 

 at Canon Cit}^, Colorado, originally opened by Professor Marsh and then 

 abandoned, but reopened and worked for two years under the direction 

 of Prof. J. B. Hatcher, and from a very extensive quarry opened in 1909 

 in Uinta County, Utah, by Mr. Earl Douglass, under the direction of the 

 writer. The collections in the Field Museum obtained by Professor 

 Riggs represent explorations made by him in western Colorado and in 

 eastern Wyoming. 



The result of the acquisition of these collections by the institutions 

 named, as well as the study of the older collections, has been a great ad- 

 vance in our knowledge of the osteological structure of the sauropod 

 dinosaurs. 



Professor Osborn's paper, published in the year 1899, on the pelvis and 

 caudal vertebrae of Diplodocus, was followed in the year 1901 by a paper 



