﻿Coccosteus 



Blastoid 

 (Eleacrinus) 



Ostraco- 



derm 



(Drepanas- 



pis) 



Terataspis 



_ J 



Proetus 

 DEVONIAN PERIOD 



Pephricaris 



Coccosteus 



Ammonoid 



(Gephyro- 



ceras) 



Pterichthys 



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