Doryaspis

This pterapsid (also called Lyktaspis) had much longer snout or rostrum than that of its relatives. There were bony spines set along its length (rather like the "saw" of a modern sawfish), and the mouth opened above, rather than below, the rostrum.

This strange appendage must have had a hydrodynamic function, since the shape of Doryapsis suggest it was an active swimmer, probably feeding on plankton.

Doryaspis

An additional function of thr rostrum among pteraspids could have been to stir up the bottom mud or sand and to root out crustacean prey.

Doryaspis had unusually long, lateral keels growing from the back of the head shield. Their leading edges were armed with toothlike spines. These may have acted as gliding planes and together with the rostrum and downturned tail, would have elevated the front of the body during swimming.

Doryaspis facts:

Name Doryaspis
Time Early Devonian
Locality Spitsbergen
Size 6in/15cm long