MATTHEW, CLIMATE AND EVOLUTION 



241 



^VETIODACTYLA 



The great and diverse order of artiodactyla can fairly be regarded as 

 of Holarctic origin as a whole. Its distribution can most readily be con- 

 sidered group by group. 



Pigs and Peccaries. — These two groups are characteristic of the Old 

 and Xew World respectively. The pigs are now chiefly Ethiopian and 

 Oriental, the peccaries Neotropical in distribution. The peccaries first 

 reached South America in the Pleistocene and ranged throughout the 



ances 



Tertiaru 

 of peccariesi 



No peccaries Ltnti'/ 

 'Plei'stocei-ie. 



?l77tro£^ucec( 



■y 



Fig. 21. — Distribution of pigs and peccaries 



In Old World, broken shading Siis only ; full shading, other genera. In New World, 

 full shading Dicotyies. The dispersal center of Dicotylidse was Nearctic, of SuidiP Palae- 

 arctic. The living South American genus is more primitive than the Pleistocene genera 

 of North America, Platiifjoniis and Mylohyus (the Pleistocene North American species 

 referred to Ditotyles are all lliilohyiis) . 



United States from the Oligocene to as late as the Pleistocene. Pigs 

 Avere common in the Oligocene and later Tertiary in Europe and were 

 present in India in the Miocene, probably earlier. The Tertiary ancestry 

 of the pigs in Europe can be traced back to a common ancestral group 

 in the Eocene^ and the same is true of the peccaries in the western United 

 States. 



