Anaspida

Encyclopedia : A : AN : ANA : Anaspida

The Anaspida are stem gnathostomes. This extinct marine subgroup in Superclass Agnatha, the jawless fish, were similar to the Osteostraci, but had unpaired fins. These small fishes flourished in the Early Silurian to Late Devonian, and then became extinct except for their modern-day relatives the Lampreys and Hagfishes. The gills opened as a row of holes along the side of the animal that typically numbered from 6-15.

From Wikipedia, the Free Encyclopedia. Original article here. Support Wikipedia by contributing or donating.
All text is available under the terms of the GNU Free Documentation License See Wikipedia Copyrights for details.