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Anaspida (anaspids; superclass Agnatha) Extinct order of fish-like vertebrates. The body, including the head region, was covered in dermal scales (see DERMAL BONE), and was less flattened than in the Osteostraci. The tail was hypocercal (tilting downwards). Anaspids were small (up to 15 cm in length). Genera included Jaymoytius, Pharyngolepis, and Pterygolepis. Anaspids ranged from the Late Silurian to the Late Devonian.