Figure 6. Evolution of lateral plate morphology, dorsal side: A–E, Amigdoscalpellum truncatum (Hoek, 1883); F–J, Arcoscalpellum sociabile (Annandale, 1905); K–O, Arcoscalpellum michelottianum (Seguenza, 1876); P–T, Regioscalpellum regium (Thomson, 1873); U–Y, Diotascalpellum rubrum (Hoek, 1883). External aspect of carinolatus (A, F, K, P, U); interior of carinolatus (B, G, L, Q, V); external view of inframedian latus (C, H, M, R, W), interior of inframedian latus (D, I, N, S, X); dorsal (carinal) view of capitulum (E, J, O, T, Y). See Table 1 for details of localities. Note the migration of the position of the carinolatus umbo from apical to nearly basal, the progressive incurvature of the umbo, and the development of an upper latus surface. The lower four species are assigned to the Scalpellinae, the uppermost one to the Amigdaloscalpellinae. Scale bars: A–E, J, K–T, Y, 1 mm; F–I, U–X, 0.5 mm.