254 



ANNALS NEW YORK ACADEMY OF SCIENCES 



States in the beginiiing of the Oligoeene, without direct ancestry in either 

 continent, and is regarded by Peterson*^* as probably from an Asiatic 

 source. 



NON - RUM I N A N T 5 



PECCARIES- PIGSHIPPOPOT<^WI 



ANTF L Of t S CAr T L L 



PROCRESSIVC EI/OLUTION 



OF THE 

 HIGHER CROUPS OF RUMINANTS 



NEOTROPIC/^L 



NE /ARCTIC 



PfiUtARCT/C ETM'OPIAnWoK/FNTAL 



Fig. 27. — Phylogeiiy and distributjon of the Artiodactyla 



Most of the families appear to liave originated in the Nearctic or Pala?arctic region 

 and spread thence outwardly to the more peripheral regions. The higher types are of 

 more recent origin and are still dominant in the Holarctica. 



TROBOSCIDEA 



The later Tertiary and Quaternary history of the mastodons and ele- 

 phants agrees with the various groups that we have been considering in 

 indicating Asia as the center of distribution of the race. Elephants are 

 now limited to the Ethiopian and Oriental regions, but in the Pleisto- 

 cene their range was over the whole of Europe, Asia and North America, 

 as well as Africa. The northern species, although of smaller size, are 

 more progressive than the southern species in the specialization of the 

 teeth, proportionate length of tusks, shortening of skull with concomitant 

 elongation of trunk. The more primitive mastodons first appear in India 

 in the Oligoeene, in Europe in the lower Miocene, in North America in 

 the middle Miocene. The intermediate stages leading to the mammoths 

 and elephants are best shown in the Pliocene and Pleistocene of India ; a 

 less exact series may be found in N orth America. The mastodons reached 

 South America in the Pleistocene; the mammoths and elephants never 

 reached that continent. The earlier stages in the phylogeny of the Pro- 



** O. A. Peter.sox : Mem. Carn. Mus., vol. iv, pp. 145-148. 1909. 



