NO. I LOWER EOCENE MAMMALIAN FAUNAS — GAZIN I3 



exposures very low in the Knight have yielded remains of a fauna 

 of considerable size. Collecting here was done by University of Cali- 

 fornia parties and the collections, made largely by a washing technique, 

 were described in detail by McKenna (i960). The localities from 

 which these materials were obtained are shown in a map accompanying 

 his report. 



The Four Mile fauna is equivalent in age to the early part of the 

 Gray Bull beds, or essentially the Sand Coulee level, in the Bighorn 

 Basin. These collections have not been examined by me, and no direct 

 comparison of the materials with, for example, those from Bitter 

 Creek has been made, so that a comparative listing here seemed inad- 

 visable. 



West of Elk Mountain. — Exploration of the Knight was extended 

 to include a variety of localities in the Fossil Basin along the western 

 margin of the State in Lincoln and Uinta Counties. Newly discovered 

 localities in the valley of North Bridger Creek to the west of Elk 

 Mountain, however, while only sparsely fossiliferous, have produced 

 as representative a collection as that obtained at Fossil Butte. The 

 localities are low on a west-facing escarpment that is capped with 

 Green River beds west and southwest of Elk Mountain. The occur- 

 rences are scattered along exposures due west of Elk Mountain, where 

 remains were found near the base of the sequence, to about three or 

 four miles farther south, in or near sec. 30, T. 20 N., R. 119 W., 

 where collecting was done at a somewhat higher level. In this area, 

 as near Fossil Station, the Knight is resting directly on the Evanston 

 formation. 



About 13 genera of mammals are recognized and remains of one 

 species, Haplomylus speirianus, suggesting early Gray Bull although 

 not necessarily Sand Coulee, were found at the locality near the base 

 of the section due west of Elk Mountain. Vassacyon, cf. promicrodon, 

 found a couple of miles farther south near a specimen of Phenacodus, 

 cf. vortmani, may also be indicative of Gray Bull time, but not neces- 

 sarily the earliest part. Although the remaining forms for the most 

 part do not seem to be critical as to horizon, they are, except for a 

 recently discovered specimen of Meniscotherium, cf. rohustum, forms 

 to be expected in levels of Gray Bull equivalence. It may be further 

 noted that Coryphodon is more than usually abundant along the lower 

 slopes of the escarpment and some rather good skull and jaw material 

 was obtained. 



Fossil Butte. — Fossil Butte derives its name from the well-known 

 fossil fish quarries in the Green River formation that caps this butte 



