Fig. 7 in Size-shape relationships in the Mesozoic planispiral ammonites

Fig. 7. Plot of W/D versus U/D for the whole large sample (gray points), n = 1222. Three samples are selected to show the almost invariable relative umbilical width along significant variation of relative width of whorl section. White squares: Poecilomorphus cycloides (Middle Jurassic) modified from Sturani (1971: pl. 8); black circles: Quenstedtoceras lamberti (Middle Jurassic) modified from Callomon (1985: fig. 5b); and white triangles: Dactylioceras clevelandicum (Early Jurassic) modified from Howarth (1973: pls. 3, 4).