XXVII 



CARNIVORES 



1. Affinities of carnivores and ungulates : Cohort Ferungulata 



The union of the modern carnivores and hoofed animals in a single 

 cohort Ferungulata is based on palaeontological work that has shown 

 how both groups, together with some isolated surviving types such 

 as the elephants and sea-cows, and many other forms now extinct, 

 all arose from a common population in Palaeocene times. The 

 ungulates have been grouped together for a long time because of their 

 obvious common characteristics of herbivorous diet and hoofed feet, 

 but it is clear that 'ungulates' include two very different sorts of 

 creature, the even-toed artiodactyls, such as the pigs, sheep, and cows, 

 and the uneven-toed perissodactyls, the rhinoceroses and horses. 

 The latter can be traced backwards to a very ancient group, the 

 Condylarthra of the Palaeocene and Eocene, and they were therefore 

 for some time placed rather widely apart from the Artiodactyla, whose 

 origin was mysterious. It has now been shown, however, that there 

 is a resemblance between the Eocene artiodactyls and some of the 

 creodonts, animals that were also the ancestors of the modern Car- 

 nivora. The creodonts and condylarths are in many ways alike, and it 

 now seems probable that the whole group makes a single unit, diverging 

 first from the insectivorous eutherian ancestral population in the late 

 Cretaceous or Palaeocene, probably as a carnivorous stock. Some 

 members then diverged almost at once to make the condylarths, 

 perhaps from a stock that already possessed hoofs and then proceeded 

 later to produce the Artiodactyla (Fig. 446). 



It is a convenience to use these relationships as a basis for classifica- 

 tion, but it must be recognized that modern carnivores have little 

 more in common with ruminants than with, say, monkeys or rats. 

 The three great groups that make up the Ferungulata diverged from 

 each other only a short time after their common stock had diverged 

 from that of the other mammals; at that time all eutherians were so 

 alike that we should probably place them in a single order if they had 

 left no descendants. 



The Ferungulata have become much more diversified than the 

 other cohorts into which we have divided the Eutheria and we have 

 to recognize no fewer than fifteen orders in the group. It is therefore 



