NO. 2 A STUDY OF MENISCOTHERIUM — GAZIN II 



at Tipton Butte, and an undetermined species is reported (Henry 

 W. Roehler, personal communication) from a semifluviatile facies 

 of the Tipton tongue on nearby Table Mountain. Thorpe's species 

 is especially characteristic of the La Barge fauna, but a smaller form 

 which may well be M. chamense is abundant in the New Fork in the 

 northern part of the Green River Basin, both faunas being included 

 in Lostcabinian time. Farther east, however, although in the same 

 general basin of deposition for the Wasatch formation, no material of 

 Meniscotherium has been reported for the Four Mile, Dad, and 

 typical Cathedral Bluffs faunas. In the Fossil Basin sparse remains 

 have been found on Fossil Butte and in the Gray Bull equivalent 

 west of Elk Mountain, but not in type Knight near Evanston, nor in 

 the Gray Bull equivalent (type Almy) in Red Canyon. 



The undescribed collections from the valley of the Colorado River, 

 within the structural basin of Tertiary sediments often referred to as 

 the Piceance Creek Basin in western Colorado, are reported by Van 

 Houten (1945) to include Meniscotherium, abundantly in the lower 

 fossiliferous level of about mid-Wasatchian age and sparingly in the 

 late Wasatchian upper level. Examination of the materials in the 

 Chicago Natural History Museum, however, has revealed that the 

 information furnished Van Houten for the presence of Meniscother- 

 ium in the late Wasatchian level was based on a jaw fragment with a 

 single premolar belonging to Lambdotherium rather than Menisco- 

 therium. In the list of materials in the Carnegie Museum from the 

 Piceance Creek Basin the species of Meniscotherium given is M. 

 tapiacitis. Two species, however, are represented in both the Car- 

 negie Museum and the Chicago Natural History Museum collections. 

 In the better documented, more recently collected Chicago materials 

 it is clear that the two species, which may well be M. chamense and 

 M. tapiacitis, do not occur together but in rather widely separated 

 areas. M. chamense occurs to the northwest of the Colorado River 

 in the Roan Cliffs area, whereas all the M. tapiacitus specimens 

 were found to the southeast of the river in the general area of Mam 

 Creek. Nevertheless, there is no evidence that the horizons repre- 

 sented are significantly different and may well be mid-Wasatchian. 



The rather sporadic distribution of Meniscotherium outlined here 

 is summarized in the accompanying chart, and explanation of these 

 apparent nomalies is attempted in the following section concerning 

 environment. 



