Archeognathus

Archaeognathus is a fossilized jaw apparatus from the Ordovician that has been compared to the conodonts and vertebrates, yet remains unclassified.

It is a component of a jaw apparatus that also contains the Coleodus apparatus (which is therefore assumed to be synonymous).

References 

Category:Prehistoric incertae sedis animal genera
Category:Ordovician animals
Category:Fossil taxa described in 1938