''Procephalaspis'' is an extinct genus of

jawless fish Agnatha (, Ancient Greek 'without jaws') is an infraphylum of jawless fish in the phylum Chordata, subphylum Vertebrata, consisting of both present (Cyclostomata, cyclostomes) and extinct (conodonts and ostracoderms) species. Among recent animal ...

References

* Telling the Evolutionary Time: Molecular Clocks and the Fossil Record (Systematics Association Special Volume) by Philip C J Donoghue and M. Paul Smith (page 227) Osteostraci genera Silurian jawless fish {{silurian-animal-stub