Hanburia gloriosa: Rare trilobite from the Middle Cambrian, Stephen Formation, British Columbia, Canada

Hanburia gloriosa is probably blind, the smaller specimens having a forwardly expanding glabella with lateral lobes, and six (rarely five) thoracic segments; larger specimens have a parallel-sided glabella with faint traces of lateral lobes, and six, in one case seven, thoracic segments; pygidium equal in size to the cephalon. All specimens may be holaspid, the larger corynexochoid-like; however, the smaller ones are not like any known corynexochoid. Hanburia gloriosa is the rarest trilobite from the Stephen Formation. This species, and other rare but widely distributed Lower and Middle Cambrian species from deeper water faunas are all of uncertain affinities. They do not fit into the general picture of trilobite evolution, nor appear likely ancestors of shallow water species.