Pteraspis (Greek for "wing shield"); pronounced teh-RASS-pis
Shallow waters of North America and Western Europe
Early Devonian (420-400 million years ago)
Size and Weight:
About one foot long and less than a pound
Small marine organisms
Sleek body; armored head; stiff protrusions over gills
For all practical purposes, Pteraspis displays the evolutionary improvements made by the "-aspis" fishes of the Ordovician period (Astraspis, Arandaspis, etc.) as they swam their way into the Devonian. This prehistoric fish retained the armored plating of its ancestors, but its body was significantly more hydrodynamic, and it had strange, winglike structures jutting out of the back of its gills that probably helped it to swim farther and faster than most fish of the time. It's unknown whether Pteraspis was a bottom-feeder like its ancestors; it may well have subsisted on plankton hovering near the water's surface.