270 INTRODUCTION TO EVOLUTION 



forefoot, three on each hindfoot, being reminiscent of the Eocene peris- 

 sodactyl Hyracotherium in that respect. In general appearance they some- 

 what resemble very large pigs. Their most unusual feature is a nose and 

 upper lip drawn out into a short, flexible proboscis, a sort of incipient ele- 

 phant's trunk (Fig. 12.1). But perhaps the most remarkable thing about 

 them is their distribution. They live in only two regions: ( 1 ) Central and 

 South America and (2) the Malay Peninsula and adjacent islands such 

 as Sumatra and Borneo. Fig. 12.4 reminds us that these areas, shown in 

 solid black, are about as distant from each other as two points on this 

 earth can be. How does it happen that tapirs are found in these two widely 

 separated areas? 



If we are not satisfied with the explanation that the tapirs were created 

 in the two regions mentioned, and not elsewhere, we find no clue to the an- 

 swer to our question in the living animals themselves. When we turn to the 

 fossil record, however, the explanation becomes clear. As indicated by the 

 diagonally shaded portions of the map, during Pleistocene times tapirs 

 ranged all over North and South America, and through considerable por- 

 tions of Europe and Asia. In preceding Cenozoic periods ancestral tapirs 

 lived in Europe and North America, where they were found as long ago as 

 the Oligocene. Interestingly enough, tapirs did not reach one of their two 

 modern havens. South America, until the Pleistocene. This fact correlates 

 well with the isolation of that continent from North America during long 

 periods of the Tertiary. Tapirs apparently never reached Africa. 



Evidently, then, the present widely separated regions inhabited by tapirs 

 represent isolated portions of a once widespread range. For some reason 

 tapirs disappeared from the intervening regions. Doubtless changing en- 

 vironmental conditions, coupled with competition from animals better 

 fitted for them, were factors in causing this disappearance. 



Camels 



Camels and their South American relatives supply another example of 

 discontinuity in modern range, explicable by reference to the fossil record. 



Of the camel-like inhabitants of South America, the llama and alpaca 

 are domesticated animals derived originally from wild, camel-like forms 

 inhabiting the continent before the coming of man. The llama (cf. 

 guanaco, Fig. 12.1) is smaller than a camel and lacks the characteristic 

 hump of the latter, but its undoubted relationship to camels is revealed by 

 many anatomical features. The limbs of the camel family are character- 

 istic, being elongated and having two equally developed toes. All traces of 



