Dunkleosteidae

Dunkleosteidae Temporal range: Late Emsian to Late Famennian
Dunkleosteus terrelli skull, Queensland Museum
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	†Placodermi
Order:	†Arthrodira
Suborder:	†Brachythoraci
Clade:	†Eubrachythoraci
Clade:	†Pachyosteomorphi
Superfamily:	†Dunkleosteoidea
Family:	†Dunkleosteidae Stensiö, 1963
Type species
Dinichthys terrelli Newberry, 1873
Genera
Dunkleosteus Eastmanosteus Kiangyousteus Xiangshuiosteus Holdenius

Dunkleosteidae is an extinct family of arthrodire placoderms. The gigantic apex predator Dunkleosteus terrelli is the best known member of this group. While they were previously thought to be close relatives of the genus Dinichthys (when they were not synonymized as each other) and grouped together in the family Dinichthyidae, more recent studies have shown that the two taxa represent two very distinct clades within Arthrodira.^[1] The reappraisal of Kiangyousteus lead to a restructuring of the family, with the inclusions of the benthic, aberrant Heterosteus (and the other members of Heterosteidae) as the sister taxon of Dunkleosteus, and the Late Emsian Xiangshuiosteus as the sister taxon of Eastmanosteus calliaspis (with the direct implication that E. calliaspis does not belong in Eastmaneosteus), and the removal of from the family (now thought to be the most basal member of the superfamily Dunkleosteoidea, and sister taxon of and Dunkleosteidae).^[2]

Genera[]

Dunkleosteus[]

Restoration of D. terrelli

The type genus, Dunkleosteus, is known from Late Frasnian and Famennian-aged marine strata from Europe, Morocco, and North America. The best known species, D. terrelli, is famous as the "world's first vertebrate apex predator," and is estimated to be up to 6 m (20 ft) in length: other species, however, such as D. raveri, are estimated to be 1 m (3.3 ft) in length.

Eastmanosteus[]

Eastmanosteous is a diverse genus of medium to somewhat large predatory arthrodires very similar in anatomy to the species of Dunkleosteus. Eastmanosteus differs from Dunkleosteus in having a unique tubercle-ornamentation on the dermal surfaces of the plates, a distinctively shaped nuchal plate, and sutures that are more zigzagging. The best studied species, E. calliaspis may not be of this genus due to its recently appreciated relationship to the Emsian-aged genus Xiangshuiosteus.

Golshanichthys[]

Fossils of Golshanichthys are found in Frasnian-aged marine strata near Kerman, Iran.

Kiangyousteus[]

Kiangyousteus yohii

This Middle Devonian genus represents the first arthrodire described from China. Fossils are known from the Late Givetian to Early Frasnian-aged Guanwu Formation in Sichuan.

Xiangshuiosteus[]

Xiangshuiosteus was originally described as an arthrodire incertae sedis with anatomical features suggestive of both buchanosteids and coccosteids. With the reappraisal of Kiangyousteus, it is now thought to be a dunkleosteid most closely related to Eastmanosteus calliaspis.

Holdenius[]

Holdenius is a monospecific genus with only one specimen ever discovered. It was preserved next to its last meal, a Ctenacanth chondrichthyan over half its size, cleaved in two. An anterior dorsal spine from its prey was found lodged in the palate and extending into the braincase of the Holdenius, likely killing it instantly.

References[]