THE EOCENE OF EUROPE AND NORTH AMERICA 111 



It should be noted that there are no lemurs or other primates certainly 

 recognized in this fauna. Several of the animals which were regarded as 

 lemuroid by Cope are now placed near the insectivores (Matthew, 1909). 



Prevailing The ancient Carnivora (Creodonta) are either richer 



Mammals or more fully known in this phase than in the Puerco, 



Plagiaulacids since they are represented by four families, Arcto- 



Periptycliids cyonidae {Clcenodon), Mesonychidae (Dissacus), Triiso- 



Pantolambdids dontidae (Sarcothraustes), Oxyclaenidae (Chriacus, Tri- 



Phenacodonts centes, Deltatherium) . These creodonts are partly 



Taeniodonts provided with tubercular teeth, partly with sub- 



IMixodectids trenchant or cutting teeth. It is important to observe 



Insectivores (?) that no well-developed sectorial teeth have as yet 



Pro-Carnivores evolved in this phase; in other words, the Creodonta 



(or Creodonts) * are not yet perfected as flesh eaters. 

 Triisodonts The first rudiments of modernism are seen in the 



Oxyclaenids genus Didymidis, a member of the family Miacida>, 



Arctocyonids which may be considered one of the true pro-Carnivora 



because in the disposition of its carnassial or sectorial 

 teeth it agrees with dog-like and civet-like forms of the higher Wasatch 

 and Bridger Formations. 



II. THE LOWER EOCENE LIFE OF EUROPE AND AMERICA 



We now enter the life or faunal zone of Coryphodon, the bulky succes- 

 sor of Pantolambda, an animal known both in Europe and North America; 

 also of Hyracotherium and Eohippus, the first representatives of the horses 

 (Equidae). Deperet (see p. 100) was of the opinion (1905) that Cory- 

 phodon and Hyracotherium appear earlier in Europe than in America, 

 namely, in the Lower Landenian of Belgium, which he synchronizes with 

 the Cernaysian ^ or Thanetian ; the evidence for this correlation does not 

 appear conclusive. It is quite possible, however, that both Coryphodon 

 and the primitive horses may be found at an earlier geological phase in the 

 Old than in the New World. In whichever continent the coryphodons 

 and horses did originate, there is no doubt as to the occurrence of a sudden 

 modernization, through the appearance both in Europe and North America 

 of an assemblage of mammals, unheralded by ancestral forms, which in- 

 cludes ancestors of four or five modern orders and embraces eleven new 

 families, two of which persist to the present time and none of which have 

 been observed in the Torrejon or Puerco phases. We are thus in another 

 of the great successive faunal phases, namely, the Second, as follows: 



' Dep6ret, C, L'^volution des Mammifferes tertiaires; importance des migrations (Eocene). 

 C. R. Acad. Sci. Paris, Vol. CXLI, sea. Nov. 6, 1905, p. 702. 



