EXTINCT FAUNAS OF THE MOHAVE DESERT 245 



EXTIXCT FAUNAS OF THE MOHAVE DESERT, THEIR SIG- 

 NIFICANCE IN A STUDY OF THE ORIGIN AND 

 EVOLUTION OF LIFE IN AMERICA 



By Pkofessok JOHN C. MERRIAM 



Intkoduction 



IT is almost a rule that features of the natural world which have 

 exerted an unusual influence in developing our emotional, poetic 

 and religious natures, when brought within the range of scientific inquiry 

 seem only more deeply to excite our wonder and respect. Thus, it has 

 happened that the deserts of the world, having furnished the stimulus 

 for some of our earliest poetic and religious literature, appear to the 

 scientist of to-day as places in which nature meets us with unusual 

 frankness, and where her wonders almost clamor to be understood. 



In those fields of history covering the development or evolution of. 

 the external form of the earth and of the life upon it, deserts have been 

 very significant sources of information, and the so-called bad-land 

 formations in the arid or semi-arid regions of western North America 

 have been recognized as playing a very important part. As the wide- 

 spread exposures of these formations have elsewhere in America proved 

 veritable museums of wonderfully preserved remains, it has seemed 

 worthy of remark that the extensive bad-lands in the Great Basin region 

 of America have with few exceptions furnished almost nothing bearing 

 on the history of life. The early geologic explorers in Nevada and 

 California found little bearing on the paleontologic story of the area 

 they examined. Later investigators in the bad-lands of these regions 

 have generally failed to report determinable vertebrate remains, and the 

 life record has until recently remained practically a closed book. It has 

 been with much interest, therefore, that those concerned with the history 

 of western North America, and with its bearing on the whole story of 

 life growth or evolution, have seen coming to light with the past decade 

 chapter after chapter of this missing record. 



With the exception of the John Day region of eastern Oregon, which 

 supplies an important geologic and paleontologic record, the largest part 

 of our knowledge of the history of mammalian life west of the Wasatch 

 is obtained in the heretofore unexplored deposits of the Mohave Desert. 

 At the present time there are available from the Mohave at least three 

 extinct mammalian faunas previously unknown, or only imperfectly 

 known, in the Great Basin. The life record given us by these faunas, 

 the evolutionary series to which they contribute, and the suggestions 



