Representatives of the Prodromitidae are characterized by relatively large (up to 150 mm diameter) lenticular conchs with acute ventral keels and complex multilobate sutural configurations. The systematic position of the Prodromitidae has been the subject of considerable speculation (see Work et al., 1988 for review). The nominate genus, Prodromites Smith and Weller, 1901 (type species, Goniatites gorbyi Miller, 1891), is not typical and represents the culmination of the lineage, showing characters which have led authors to refer it to both the Gephuroceratina (Ruzhencev, 1960, 1962, 1965; Bogoslovsky, 1969; Ruzhencev and Bogoslovskaya, 1978) and the Prolecanitina (Miller and Collinson, 1951; Weyer, 1972; Furnish and Manger, 1973; Kullmann, 1981; Bartzsch and Weyer, 1988; Kullmann et al., 1991). Discovery of an ancestral prodromitid genus, Eoprodromites Work, Mapes, and Thompson, 1988 (type species, E. kinderhooki), in the Hannibal Shale of northeastern Missouri provided clarification on the derivation of Prodromites and provided a link to yet a third enigmatic genus, Qiannanites Ruan, 1981 (type species, Q. acutus). Work et al. (1988) concluded that the Prodromitidae were prolecanitid offshoots that appeared in the early Tournaisian with Qiannanites, progressed through Eoprodromites, and climaxed with Prodromites early in the late Tournaisian. Although aspects of sutural ontogenesis, conch morphology, and stratigraphic distribution unite these genera, subsequently obtained specimens of Eoprodromites kinderhooki provide additional sutural and morphological details (Figs. 1, 2) that support derivation from the prionoceratacean subfamily Pseudarietitinae Bartzsch and Weyer, 1987, as more recently suggested by Becker (1993a, p. 471).