XXXI. io 



PECORA 



755 



retention of an ancient organization, and fossil forms similar to them 

 are found in the Pliocene. Animals not very different (*Archaeo- 

 meryx) are found back to the Eocene and were then like the early 

 camels or palaeodonts; they may well be close to the ancestry of all 

 ruminants. Several similar types and lines can be recognized. Evi- 

 dently the group represents a population persisting with rather little 

 change since the Eocene, and this status is represented bv recognizing 

 an infraorder Tragulina of the Ruminantia, contrasting with the 

 Pecora, which includes all the higher ruminants. 



9. Pecora 



The true ruminants show the full development of artiodactyl 

 characteristics. They have been an 

 actively expanding group since the 

 Miocene and are now the most success- 

 ful of the ungulates, existing in vast 

 herds in Africa and to a lesser extent 

 in Asia and North America, though 

 strangely enough hardly penetrating to 

 South America. The modern and fossil 

 forms are of three types. The deer 

 (Cervidae), browsing creatures with 

 bony deciduous antlers, are closest to the 

 central stock, from which have been derived on the one hand the 

 giraffes and on the other the great groups of grazing ruminants or 

 Bovidae, including the primitive prong-buck and the host of sheep, 

 goats, cattle, and antelopes. 



10. Cervidae 



The ancestral population from which these forms arose must have 

 been quite similar to the Eocene traguline *Archaeomeryx, but the 

 group does not become distinctly recognizable until the Oligocene. 

 The early members either had large canines and no antlers, as in 

 *Blastomcryx of the Miocene of North America, or, as in *Palaeo- 

 meryx of the Miocene of Europe, they possessed a bony outgrowth 

 covered with skin and not shed. Moschus, the musk-deer (Fig. 501) 

 of central Asia, also has large permanently growing canines and no 

 antlers and is probably a survivor of this Miocene stage of evolution. 

 It is intermediate in many respects between Traguhis and the Cer- 

 vidae and some classify it with the former. Musk-deer are about 2 ft 

 high and the individuals live alone in mountain forests. The much- 



Fig. 501. Musk-deer, Moschus. 



(After Beddard, Cambridge Natural 



History, Macmillan & Co.) 



