Dikelocephalus is a genus of very large trilobites of up to 50 cm (20 in) long, that lived during the last 3 million years of the Cambrian (Sunwaptan).

[1] The exoskeleton is rounded anteriorly, with the thorax and sides of the tailshield (or pygidium) slightly tapering to about 2⁄3× of the width across the base of the spines at the back of the headshield (or cephalon).

The oldest known specimens of Dikelocephalus have been found in the upper part of the Tunnel City Group.

The most common location of the species is the St. Laurence Formation, which directly overlies the deposits of the Tunnel City Group.

[2] Dikelocephalus is a very large trilobite (approximately 40 centimetres or 16 inches), slightly longer than wide (1+1⁄3×), widest across the base of the spines.

central raised area of the cephalon (or glabella) is crossed by two furrows, the most backward almost straight defining the occipital ring, and the frontal one convex towards the back.

[2] Early analysis of the large morphological diversity in Dikelocephalus resulted in splitting up the genus into many "species" during the first half of the 20th century.

The large variation in morphological characters in this early trilobite can be seen as an illustration of Rosa's Rule.

[2] The genus Dikelocephalus was established relatively early on, and as a consequence many species have since been reassigned to other genera.