CEPHALOPOD ADAPTATIONS 



PLATE i 



Diagram Illustrating the Phylogenetic Relationships of the Various Cephalopod Types, 

 their Range in Time, and Relative Representation in the Past 

 At the left is the life-line of the relatively modern Octopoda; the next life-line is that of the somewhat more 

 ancient and less specialized Decapoda; the next is that of the Belemnoidea, which reached their maximum during 

 the Mesozoic and are represented in existing seas by Sprula; the next is that of the Nautiloidea, which reached 

 their maximum in the earlier Paleozoic. The right hand life-line is that of the Ammonoidea, which appeared 

 in the record in the late Silurian, reached an early maximum of differentiation in the Triassic, became nearly 

 extinct in the late Triassic, rapidly attained a second maximum in the Jurassic and became extinct with the 

 Upper Cretaceous. 





