Deiracephalus aster (Walcott, 1916)


Species of Deiracephalus Resser, 1935, are rare elements in most Guzhangian (upper Marjuman) trilobite faunas of Laurentian North America, and are characterized by striking cephalic spinosity that includes very long genal and occipital or preoccipital glabellar spines. Almost all previous reports of the genus have assigned sclerites to two species, Deiracephalus aster (Walcott, 1916) and Deiracephalus unicornis Palmer, 1962.

They usually range up to at least 20mm in length, has a large occipital spine and a medial spine of siilar size on each of 10 thoracic segements. Large, outwardly and backwardly directed genal spines are unusual in arsing from just inside the cephalic border rather than from the outer border surface, as in most polymerid trilobites.