Phylum Chordata 569 



branches from this line developed as lungfishes and as coelacanths. 

 The latter were thought to have become extinct during the Cretaceous. 

 In 1937, however, a living specimen of the genus Latimeria was caught 

 at a great depth off the coast of South Africa. The other subclass, the 

 Actinopterygii, developed into three groups which may be considered 



Lower teleosts 

 TELEOSTEI 



Gar pike 



. .^-w^IJ^yr^ .^J^ 



^--■ > -^- .-J .-<^\^^ 



sturgeon 

 Poddlefish 



Primitive omphibions 



Coelacanths 

 Typical 

 Crossopterygians .^rj^^^ 



Ancient palaeoniscids 



CHONDROSTEI 

 ACTINOPTERYGII CHOANICHTHYES 



Lungfishes 



Fig. 190. — A simplified family tree of the bony fish. (From Romer: 

 The Vertebrate Body, W. B. Saunders Company.) 



as superorders. One of these, the Chondrostei, first appeared in the 

 Paleozoic as the small, almost sharklike palaeoniscids. These gave 

 rise to the modern sturgeons, Aclpenser, the paddlefish Polyodon, and 

 the African Polypterus. In the middle Mesozoic, the Holostei became 

 most abundant and at present are represented by the gars Lepisosteus 

 and the bowfin Amia. The Teleostei apparently arose during the Meso- 



