Doryaspis

Science Name
Nathorsti
Description
Doryaspis is an extinct genus of primitive jawless fish that lived in the Devonian period. Fossils have been discovered in Spitsbergen.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.
Habitat
The animals had a canteen-shaped body armor, and had large branchial plates that extended out and curved downward in a triangular shape, very similar to those of the pycnosteids.
Behaviour
Doryaspis had unusually long, lateral keels growing from the back of the head shield.Their leading edges were armed with tooth like 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.
Life History
This strange appendage must have had a hydrodynamic function,since the shape of Doryaspis suggests it was an active swimmer, prob- ably feeding on plankton.
Region Found
Spitsbergen