Heterosteidae

Heterosteidae (also known as Heterostiidae^[1][2]) is an extinct family of moderately large to giant, flattened, benthic arthrodire placoderms with distinctive, flattened, triangular skulls that are extremely broad posteriorly, but become very narrow anteriorly.^[3]

Heterosteidae Temporal range: Devonian: Emsian to Givetian, 407.6–382.7 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Comparison of genera
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	†Placodermi
Order:	†Arthrodira
Suborder:	†Brachythoraci
Clade:	†Eubrachythoraci
Clade:	†Pachyosteomorphi
Superfamily:	†Dunkleosteoidea
Family:	†Heterosteidae Jaekel, 1903
Genera
Herasmius Heterosteus Yinostius

Heterosteidae belongs to the superfamily Dunkleosteoidea, a relative of the giant Dunkleosteus, as shown in the cladogram below:^[1]

Dunkleosteoidea	Eastmanosteus calliaspis Eastmanosteus pustulosus Kiangyousteus yohii Golshanichthys asiatica Westralichthys uwagedensis Dunkleosteus raveri Dunkleosteus terrelli Dunkleosteus amblyodoratus Heterostiidae Heterosteus ingens Yinosteus major

Genera

Herasmius Orvig, 1969

Heterosteus Asmuss, 1856

Yinostius J. Wang & N. Wang, 1984