Diplognathus

Diplognathus is a genus of arthrodire placoderm from the Late Famennian Cleveland Shale of Late Devonian Ohio, known only from incomplete fragments of jaws and skulls.^[1] What fragments are known suggest that the living animals were large-eyed piscivores with weak, but widely gaping jaws. D. mirabilis is thought to be fairly large, with infragnathals up to 45 centimeters in length. The second species, D. larfargei, was much smaller, with inferognathals averaging about 4 centimeters in length.^[2]

Life restoration of D. mirabilis

Diplognathus Temporal range: Late Famennian
Reconstructed as hadrosteids
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Placodermi
Order:	Arthrodira
Suborder:	Brachythoraci
Infraorder:	Coccosteina
Superfamily:	Dinichthyloidea
Family:	?Hadrosteidae
Genus:	Diplognathus Newberry, 1878
Type species
Diplognathus mirabilis Newberry, 1878
Species
D. mirabilis Newberry, 1878 D. larfargei Carr, 2005

In 1967, Obruchev placed this genus within Hadrosteidae, on the basis of how the two genera have similar denticle ("teeth") patterns of the inferognathals, though Denison (1978) contested this placement, preferring to leave the taxon as Arthrodira incertae sedis.