Pteraspis

Pteraspis (from 'wing' or 'fin' and 'shield') is an extinct genus of pteraspidid heterostracan jawless fish. It existed from the Lochkovian to Eifelian epochs of the Devonian period in areas that are now the Americas and Europe.

== Description == left|thumb|P. rostrata cast of a specimen from England, next to a 1953 plaster model. Like other heterostracan fishes, Pteraspis had a protective armored plating covering the front of its body, and no fins other than a lobed tail. Despite this, Pteraspis had two wing-like protrusions derived from the armoured plates over its gills, and a single protrusion in the center of its back. This, along with its horn-like rostrum, possibly indicates good swimming ability. Pteraspis also has a series of stiff spines on its back, possibly as a form of protection against predators. It is thought to have fed from shoals of plankton just under the ocean surface. Some records are found in association with marine fossils, while some others are found in freshwater environments.