[1] It is common in and limited to the Lower Cambrian (Upper Olenellus-zone) shelf deposits across the southwestern US, which constitutes part of the former paleocontinent of Laurentia.

[2] Bristolia can be separated into two distinct groups: one consisting of B. insolens and B. anteros,[1] the other comprising a gradual spectrum of morphologies including B. mohavensis, B. harringtoni, and B. bristolensis morphotypes.

From the oldest species B. mohavensis, the lineage undergoes gradational increase in intergenal angle and advancement of the genal spines, progressing through B. harringtoni, culminating in B. bristolensis.

Younger specimens show a trend back to more acute intergenal angles and less advanced genal spines typical of B.

Bristolia insolens represents an extreme extrapolation of the earlier trend and is restricted to a narrow stratigraphic interval at maximal flooding.

Like all other members of the Olenelloidea superfamily, the eye-ridges spring from the back of the frontal lobe (L4) of the central area of the cephalon, that is called glabella.