sentences:  Genera making up the Falcitornoceratinae form an evolutionary series, "Phoenixites", "Falcitornoceras", "Gundolficeras", "Exotornoceras", leading up to "Posttornoceras", type genus of the Posttornoceratidae.The Tornoceratidae probably gave rise to the Cheiloceratidae (Miller et al.1964, fig 12, L27) but though which genus is unspecified (Saunders et al.