The Cleveland Shale fauna represents a unique view of the time after a major Devonian extinction event
(Frasnian–Famenian) with the recovery of arthrodires (Placodermi) best represented by this most specious
North American fauna. This time was followed by an additional event (Hangenberg Biocrisis) leading to the
extinction of arthrodires (and all other placoderms). An understanding of the diversity and interrelationships of
North American arthrodires can aid our understanding of this critical time in vertebrate evolution. A new aspinothoracid
arthrodire Hlavinichthys jacksoni gen. et sp. nov. is described from the Late Devonian of northern
Ohio, U.S.A., which adds to our knowledge of this group. It provides a point of comparison to other members
of the fauna whose interrelationships are poorly known. A phylogenetic analysis supports an assignment of
Hlavinichthys jacksoni gen. et sp. nov. among the aspinothoracid arthrodires. This work has drawn attention to
the continued need for descriptive and phylogenetic analyses of this unique fauna. Decades old species descriptions
need revision along with preparation and description of new taxa. The work on Hlavinichthys jacksoni
gen. et sp. nov. here is one step in that process.