NO. 2 A STUDY OF MENISCOTHERIUM — GAZIN 1 5 



The regional environment revealed from detailed study of Green 

 River sediments by Bradley (1929) and of the Green River plants 

 by Brown (1929, 1934) was previously summarized (Gazin, 1953, 

 1958) as it pertained to studies of tillodonts and primates. While 

 much of this may bear more directly on the middle Eocene, it does of 

 course include later Wasatchian time during which Menisc other ium 

 flourished in the Green River Basin. Bradley in studies of the physi- 

 cal characters of the lake in comparison with other large lakes con- 

 cluded that the climate, interpreted particularly for the Gosiute Lake 

 region, was characterized by cool, moist winters and relatively long, 

 warm summers. The temperature probably fluctuated widely from a 

 mean annual temperature of the order of 65° F. The rainfall is 

 described as varying with the seasons and fluctuating widely from a 

 mean annual figure somewhere between 30 and 43 inches. He also 

 pointed out that the relief, as it pertains to the height of the rim of 

 the Gosiute drainage basin relative to the floor, was probably greater 

 than now, although the floor of the basin was likely less than 1,000 

 feet above sea level. 



From the paleobotanical evidence for the regional environment 

 Brown has described "a broad, low-lying warm inland region, with 

 shallow ponds, lakes, and marshes, fed by slow streams, which 

 meandered through muddy and sandy swamps as they flowed out of 

 the distant cooler foothills and surrounding mountains." In this 

 connection Bradley (1929), in discussing topography of the ancient 

 Green River basin, observed, "most of the streams within the Gosiute 

 hydrographic basin were apparently rather short and flowed directly 

 into the lake, but those in the eastern part were longer and may have 

 had considerable volume." It is possible that these statements are 

 not truly at variance, since both are of such general application. 

 Moreover, Brown has noted for the entire area of Green River 

 deposits, "that local conditions of climate, influenced in part by 

 mountains that flanked the basin in the north, east and west, might 

 vary considerably in such a basin." Nevertheless, it is in the part of 

 the Gosiute Lake basin where the streams were evidently shorter that 

 Menisc otherium most recently flourished. As discussed above, it 

 does not seem to have been present in the eastern part of the basin 

 during later Wasatchian time. 



In attempting to understand the differences between Wasatchian 

 faunal assemblages including or not including Meniscotherium, there 

 is, unfortunately, no adequate paleobotanical evidence that might be 

 correlated, so that information on possible local differences in the 



