[1] It is phylogenetically defined as a stem-based taxon including Pelorocephalus and all taxa closer to it than to Rhytidosteus.

In contrast, Brachyopoidea is defined as a node-based taxon including Brachyops and Pelorocephalus and all descendants of their most recent common ancestor.

Because Bothriceps is not thought to be a descendant of that recent common ancestor and would be more basal than it, the genus is placed just outside Brachyopoidea and is considered to be a sister taxon to the clade.

The probable presence of a tabular horn in Bothriceps also suggests that it is a basal brachyopomorph rather than a brachyopid.

[1] Keratobrachyops, once assigned to Chigutisauridae, is now thought to be a basal brachyopomorph closely related to Bothriceps.