402 ORIGIN OF LIFE IN AMEEICA 



at that time must have had a direct land connection with 

 western North America almost independently of tlie rest of 

 South America (Pig. 14). At a still earlier stage there was 

 even a more marked affinity between Patagonia and south- 

 western North America ; and from this Professor Osborn con- 

 cluded that the northern and southern continents were con- 

 nected by land. But the points of resemblance are not alone 

 with Patagonia arid south-western North America. Professor 

 Gaudry * expressed his astonishment at the striking faunistio 

 relationship between the Patagonian Notostylops fauna on the 

 one hand, and the faunas of the Torrejon in New Mexico and 

 Cemey in Prance on the other. That a land bridge, discon- 

 nected at certain intervals, extended between western North 

 America and southern Europe I have urged again and again 

 in the preceding chapters ; and it should be borne in mind 

 how, even in these remote times, special facilities existed for 

 the passage of species from Europe to the extreme south of 

 South America, which no doubt were taken advantage of by 

 several groups then inhabiting the Old World. 



Until recently it was thought that North and South America 

 could have had no land connection subsequently to these early 

 events until the end of the Miocene or the beginning of the 

 Pliocene Periods. Professor Osborn, f however, has shown 

 that there is now evidence for the existence of true edentates 

 of the Megalonyx type in the Mascall beds of Oregon, which 

 are of Middle Miocene age. During the Miocene Period 

 Central America in its present shape had not yet come into 

 existence. Hence we may assume that even in Miocene times 

 there was a land connection between western North America 

 and some portion of South America by means of a route 

 which, as I argued, lay to the west of that continent. 



The rodents of the Santa Cruz fauna, as previously men- 

 tioned, all belong to the section Hystricomorpha. They are 

 very closely allied, according to Professor Scott, to recent 

 South American genera. Yet all are extinct and many of 

 them have left no successors. Nevertheless, though the Santa 

 Cruz rodents are more primitive, the skull structure is nearly 



* Gaudry, A., " Possiles de Patagonie," p. 105. 

 t Ostorn, H. F.,,, " The Age of Mammals," p. 289. 



