NO. 6 PALEOCENE FAUNAS OF BISON BASIN — GAZIN 3 



locality by Dr. Hough and Mr. DeMar of the U. S. Geological Survey 

 and by Dr. McGrew and his party of students from the University. 

 The combined efforts of the group were largely concentrated in a 

 search of the vicinity of the small saddle or discovery locality below 

 the south rim of the basin, and a site found by Mr. Bell in the south- 

 western part of the basin. Later, a third fossiliferous site was en- 

 countered by Dr. Brown, Mr. Pearce, and myself at the western ex- 

 tremity of the basin, and Pearce located a fourth along a ledge on 

 the south escarpment between the saddle and Bell's Titanoides locality. 

 All sites were revisited by Pearce and me with continued success 

 in 1954 but with diminishing returns, as it appears that the original 

 richness of the sites was due largely to a residual concentration of 

 materials, and the interval between successive field seasons is evidently 

 too short for erosion to afford profitable collecting. Moreover, there 

 seemed to be no one place where the concentration of bone might be 

 regarded as great enough to warrant quarrying operations. 



OCCURRENCE AND PRESERVATION OF MATERIAL 



The four principal fossil occurrences (see pis. 15 and 16) are re- 

 ferred to in the following discussion as the saddle or discovery lo- 

 cality, the ledge locality, Bell's or the Titanoides locality, and the 

 west-end locality. The small badland saddle where Brown and others 

 of the Geological Survey first encountered bone is located about mid- 

 way north and south in the eastern half of sec. 28, T. 27 N., R. 95 W., 

 according to information from Bell's mapping furnished me by Mc- 

 Grew. The richest concentration of the smaller forms was in the 

 saddle, determined by means of a hand level to be about 58 feet below 

 the rim or top of the escarpment immediately to the south. The beds 

 here have a dip of approximately 9° southward. Fossils were found 

 scattered for about a couple of hundred feet in either direction from the 

 saddle and stratigraphically near the same level, although a couple of 

 specimens of Plesiadapis jepseni in the University of Wyoming col- 

 lections came from possibly 50 feet higher. The material rather gen- 

 erally consists of incomplete jaws and maxillae and a good number of 

 isolated teeth. A single skull, that of the new pantodont Caenolambda 

 pattersoni, was encountered in a nodule a little distance away but at 

 about the stratigraphic level of the saddle. 



Approximately a quarter of a mile or more to the west, apparently 

 in the western half of section 28, a northwest-facing exposure ex- 

 hibits a prominent ledge about 25 or 30 feet below the rim. A fair 

 concentration of jaw and maxillary portions and isolated teeth was 

 found for a hundred feet or less along the ledge and in the soft clay 



