2 PROCEEDINGS OF THE NATIONAL MUSEV.M vol. 91 



HISTORY OF THE INVESTIGATION 



The occurrence of fossil vertebrates in tliis region was first recog- 

 nized in 1935 with the discovery, by Dr. J. B, Reeside, Jr., and Dr. 

 E. M. Spieker, of the U. S. Geological Survey, of fragmentary dino- 

 saur remains in exposures around North Horn Mountain and of incom- 

 plete mammalian remains at a locality high on Wagon Road Ridge 

 across the Dragon depression, to the west of North Horn Mountain. 

 These materials were all from beds that had been earlier regarded 

 as "Wasatch" in geological investigations pertaining to coal resources 

 of the region. 



In 1937 a Smithsonian Institution expedition under the direction of 

 C. W. Gilmore, and with the aid of Dr. Spieker, made a collection of 

 dinosaurian remains from the Cretaceous of the region, and was also 

 Buccessful, through the particular efforts of George B. Pearce, a 

 member of the party, in discovering a fruitful locality for Paleocene 

 mammals in lower Dragon Canyon. A popular account of this ex- 

 pedition by C. W. Gilmore and a description of the Paleocene fossils 

 by the writer were published in 1938. 



During the summer season of 1938 a Smithsonian party under the 

 writer's direction further investigated Paleocene and Cretacoous de- 

 posits and was successful in considerably enlarging the fauna Iniown 

 from the previously described Dragon Canyon locality. A popular 

 description of the 1938 expedition and descriptions of the Paleocene 

 collections by the writer were published in 1939. 



The success of the parties in the 1937 and 1938 expeditions, and 

 at the same time the fragmentary nature of many of the new finds 

 discovered during these seasons, made it imperative that further work 

 be done at these localities; hence, the 1939 and 1940 expeditions 

 undertook more thorough investigations of both the Cretaceous and 

 Paleocene. Accounts by the writer of the 1939 and 1940 expeditions 

 were published in 1940 and 1941, respectively. 



FAUNAL RELATIONS 



Contributory to the more outstanding results of further investiga- 

 tion of the Paleocene in 1939 was the finding of a new fossiliferous 

 locality in the upper portion of the North Horn series. The new 

 locality is in a patch of exposures in the western half of section 7, 

 T. 19 S., R. 6 E., about a mile nearly due west of the previously 

 described Dragon Canyon locality, which is in the northwest portion 

 of section 8. Fossils were found to occur at two levels in the new 

 locality, the upper of which, though relatively less productive, is 

 believed to represent the same stage as that at the old Dragon Canyon 

 locality, the Dragon horizon, as indicated by the occurrence there of 



