Dinichthys was originally
described in 1868 by
John Newberry on the basis of an incomplete skull roof and mandibles (
holotype AMNH 81). Subsequently, many unrelated large arthrodires were originally classified together within this genus, including species now assigned to
Dunkleosteus,
Eastmanosteus, and
Titanichthys. Notably, the
type species of
Dunkleosteus was originally described as
Dinichthys terrelli by Newberry in 1873, and was later separated into
Dunkleosteus by
Jean-Pierre Lehman in 1956.
Dunkleosteus was still thought to be closely related to
Dinichthys, and they were grouped together in the
family Dinichthyidae. However, in the 2010 Carr & Hlavin
phylogenetic study,
Dunkleosteus and
Dinichthys were found to belong to two separate
clades. Carr & Hlavin resurrected the family
Dunkleosteidae and placed
Dunkleosteus,
Eastmanosteus, and a few other genera from Dinichthyidae within it. Dinichthyidae, in turn, is left a
monospecific family and dismissed as a family grouping, and the genus
Dinichthys is now considered a
monotypic genus, containing only the
type species,
D. herzeri. ==Phylogeny==