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.
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Osteostraci , Osteostraci(Cephalaspida; osteostracans; superclass Agnatha) Order of extinct, fish-like, jawless vertebrates, ranging from the Silurian to the Devon… Scale (zoology) , scales The small bony or horny plates forming the body covering of fish and reptiles. The wings of some insects, notably the Lepidoptera (butterflies… Tench , tench •Romansh •blanch, Blanche, branch, ranch, tranche •avalanche •backbench, bench, blench, clench, Dench, drench, entrench, French, frontbench, qu… Heterostraci , Heterostraci (Pteraspida; heterostracans; superclass Agnatha) Oldest known vertebrate order of jawless, heavily armoured fish-like forms, ranging fro… Teleosts , Teleostei (teleost, teleostean) Somewhat loosely defined term (an infraclass or super-order according to some authors) that includes all the living b… Fossil fishes , Acanthodii (acanthodians) Class of primitive, fossil fish, characterized by the presence of a true bony skeleton (see BONE), a heterocercal tail fin,…
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