Anaspida

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A branching diagram shows the evolutionary relationships among fossil and modern jawless fishes (Agnatha), with illustrations of Petromyzon, Myxine, Pharyngolepis, Pteraspis, Hemicyclaspis, and Drepanaspis along a timeline from the Ordovician period to the present.

Anaspida

fossil vertebrate order

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agnathan
Annotated classification
†Order Anaspida Small streamlined fishes, body and head covered with elongate scales, nostril between eyes, gill openings lateral and arranged in slanting line, hypocercal tail bent downward. 3 families. Early Silurian to Late Devonian (443.8–358.9 million years ago). †Order Thelodonti A little-known group of unknown affinities.…
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†Order Anaspida Small streamlined fishes, body and head covered with elongate scales, nostril between eyes, gill openings lateral and arranged in slanting line, hypocercal tail bent downward. 3 families. Early Silurian to Late Devonian (443.8–358.9 million years ago). †Order Thelodonti A little-known group of unknown affinities.…
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