Systematics of Dokimocephalus and related trilobites from the Late Cambrian (Steptoean; Millardan and Furongian Series) of Laurentian North America

Abstract

Dokimocephalidae Kobayashi, 1935, is a large group of mostly Laurentian trilobites, the majority of which are confined to the Late Cambrian (Millardian and Furongian series) Steptoean Stage. We begin a long overdue revision of the family with a critical review of a 'core group' of closely related genera: Dokimocephalus (Walcott, 1924), Iddingsia (Walcott, 1924), Plataspella (Wilson, 1949) and Burnetiella (Lochman, 1958), all of which share apomorphic character states of the librigena, anterior border and palpebral lobe. The poorly known Edithiella (Kurtz, 1975) is also included as a potential member of this group, which is referred to informally as Dokimocephalidae sensu stricto. The study includes examination of relevant types as well as new material from the Honey Creek Formation of Oklahoma and from the Orr Formation and correlatives of the Great Basin. Parsimony analysis supports monophyly of all five genera. In addition, a new genus, Stittella, is established for two species that are characterized by very short anterior borders and, consequently, frontal areas; characters of the librigena and pygidium are also diagnostic. New species named formally are Dokimocephalus stewarti, D. blacki, D. oliveri and Stittella beeae. © 2010 The Natural History Museum.