Wednesday, October 13, 2010

Pteraspis is an extinct genus of primitive jawless fish that lived in the Devonian period. This fish is a typical of the pteraspid family of heterostracans, means an extinct jawless fish with the anterior part of its body covered with bony plates; which became very large in number and diverse during the Late Silurian and Early Devonian.

Pteraspis was a good and a powerful swimmer, bony outgrowths from the back of the head shield provides stability. Though Pteraspis lacked fins a large spine acted as a kind of dorsal fin and two rigid wings or keels functioned as pectoral hydrofoils.

The long flexible tail was hydrodynamic with the lower lobe elongated to provide lift at the front of the body during swimming.The elongated snout provide the additional lift, which was drawn out into a bladelike rostrum below which the mouth opened.

Pteraspis retained the armored plating of its prehistoric fish ancestors, but its body was more hydrodynamic, and it had strange, winglike structures that helped it to swim faster than other fish of its time. It is thought to have fed from shoals of plankton just under the ocean surface.

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