Pteraspis
provided by EOL authors
Pteraspis means 'Wing shield,' from the growths on the sides of the main body 'shield’. The fish was named by Agassiz in 1835. It belonged to the family Pteraspidae in the Order Pteraspidifomes of the Class Heterostraci. It was a primitive jawless fish @ 20 cm (8 inches) long and lived from the Lochkovian to Emsian of the Devonian in Belgium, Britain and other parts of Europe.
It had a protective armoured plating covering the front of its body. It lacked fins other than its lobed tail, but is thought to have been a good swimmer due to the stiff, wing-like protrusions derived from the armoured plates over its gills. These served as hydrofoils; this job is usually done by pectoral fins in other fish. This, along with the horn-like rostrum, which projected forward, made Pteraspis very streamlined in shape, aiding swimming. The lower lobe of the tail was larger than the upper lobe, which would provide upwards lift. The spine rising up from the back of the shield served the purpose of a dorsal fin and potentially provided protection from predators; stiff spikes on its back possibly protected it from predators. These adaptations suggest that the fish probably swam upwards into open water rather than cruising around the bottom. It probably ate shrimp and other small open water animals from shoals of plankton just under the ocean surface,[1] . It is found in association with marine fossils [2,[3]. Species included P. crouchi, P. rostratus and P. stensioei.
