Amphiaspis argo is the type species of the cyathaspidid taxon Amphiaspidida, and of the family Amphiaspididae.Novitskaya, Larisse. Les amphiaspides (Heterostraci) du Devonien de la Siberie. Éditions du Centre national de la recherche scientifique, 1971. Its fossils are restricted to early Emsian-aged marine strata of the Taimyr Peninsula, Early Devonian Siberia. A. argo, as with all other amphiaspidids, is thought to have been a benthic filter feeder that lived on top of, or buried just below the surface of the substrate of hypersaline lagoon-bottoms.
Anatomy So far, A. argos is known from at least one, incomplete cephalothoracic armor that is shaped vaguely like a pillow and is, from anterior to posterior, 24 centimeters long. The armor has a pattern of lateral sensory line canals. There is a prominent dorsal spine on the dorsoposterior end of the cephalothoracic armor. The animal had small, possibly degenerate eyes that were flanked laterally by a small, crescent-shaped preorbital opening at the anterior end of the armor. The small eyes, in turn, laterally flank a small, slit-shaped mouth at the center of the anterior-most end of the cephalothorax.
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