The Dunkleosteidae were a family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 of placoderms, armored fish most diverse during the Devonian

Devonian

The Devonian is a geologic period and system of the Paleozoic Era spanning from the end of the Silurian Period, about 416.0 ± 2.8 Mya , to the beginning of the Carboniferous Period, about 359.2 ± 2.5 Mya...

. The gigantic apex predator

Apex predator

Apex predators are predators that have no predators of their own, residing at the top of their food chain. Zoologists define predation as the killing and consumption of another organism...

 Dunkleosteus terrelli is the most well-known member of this group. While they were previously thought to be close relatives of the genus Dinichthys

Dinichthys

Dinichthys herzeri is an extinct, giant, marine arthrodire placoderm from the Late Devonian of Ohio and Tennessee. It was comparable in size, shape and ecological role to the better known Dunkleosteus...

and grouped together in the family Dinichthyidae, more recent studies have shown that they represent a distinct clade

Clade

A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...

.