Pteraspidomorphs are characterized by their massive dermal head armour having large, median, ventral and dorsal plates or shields.

Many had hypocercal tails in order to generate lift to increase ease of movement through the water for their armoured bodies, which were covered in dermal bone.

This last theory was based on the fact that they seem to have a paired olfactory organ and a sensory-line pattern which is quite similar to that of the gnathostomes.

Current phylogenetic analysis using a large number of characteristics now place pteraspidomorphs as the sister-group of all other ostracoderms and the gnathostomes.

[3] Anatolepis Arandaspidiformes Astraspidiformes Tesakoviaspidiformes Eriptychiiformes Tesseraspidiformes †Traquairaspidiformes Tolypelepidiformes Cyathaspidiformes Pteraspidiformes