i dont think they can be called primitive ,they are old, not dumb, and many are much more efficient hunters then some of the more 'modern' fish out there
Alot about ploypterus is primitive like said they have changed little for millions of years and have takein on simple designs like there simple lung enableing them to gulp air for example
prim·i·tive (prm-tv)
adj.
1. Not derived from something else; primary or basic.
2.
a. Of or relating to an earliest or original stage or state; primeval.
b.Being little evolved from an early ancestral type.
3. Characterized by simplicity or ....