Akmonistion
Akmonistion is an extinct genus of holocephalian that lived in the Early Carboniferous. The genus contains a single species, A. zangerli. It is distinguished by an unusual enlarged formation of the dorsal fin, called a "spine-brush complex", of unknown function. This is also found in the better known genus Stethacanthus. Remains have only been found near Bearsden in Scotland.
