The genus is known from multiple parts of the skull roof, the suborbital, endocranium, and trunk shield.

[2] It is one of the commonest fishes found at the Beartooth Butte Formation.

It was found at the Utah-Idaho border, specifically in the Grassy Flat Member of the Water Canyon Formation, Green Canyon, northern Utah, and St. Charles, southern Idaho.

The specific epithet, williamsi, honors paleontologist Michael E. Williams (1940-2003).

[2] The placement of Bryantolepis within Arthrodira can be shown in the cladogram below:[2] antarctaspids Wuttagoonaspidae Lehmanosteus Kujdanowiaspis Proaethaspis ohioensis Phyllolepida Actinolepidae Bryantolepis williamsi Bryantolepis brachycephala Phlyctaeniidae Coccosteus Buchanosteus Errolosteus