Acanthodii

views updated May 08 2018

Acanthodii (acanthodians) Class of primitive, fossil fish, characterized by the presence of a true bony skeleton (see BONE), a heterocercal tail fin, a persistent notochord, ganoid scales, and stout spines in front of the fins. The acanthodians lived from the Silurian to the Permian Period and may be related to ancestors of the more modern bony fish.

Acanthodii

views updated Jun 08 2018

Acanthodii Class of primitive, fossil fish that had a true bony skeleton, a heterocercal tail fin, a persistent notochord, ganoid scales, and stout spines in front of the fins. The acanthodians lived from the Silurian Period to the Permian Period and may be related to ancestors of the more modern bony fish.

acanthodians

views updated May 08 2018

acanthodians See ACANTHODII.