THE ANCESTRY OF VERTEBRATES 



431 



THREADWORM 

 1600 SR 



A PHYLOGENETIC TREE OF THE ANIMAL KINGDOM. 



Fig. 378. — A diagram of the phylogenesis of man, based on the assumption that the 

 Protochordates resemble vertebrate ancestors more closely than do the annelids. 

 Annelids and other Proterostomians have, it is assumed, diverged from the main line 

 of vertebrate ancestry very early in animal phylogenesis. Before man emerged in the 

 late Tertiary, transitional forms between man and the lower Primates made their 

 appearance. Among these the best known are Propliopithecus, Dryopithecus and 

 Australopithecus, which are true "connecting links." 



