Fig. 13

Bivariate plots of phragmocone diameter and septal distance in the late Givetian assemblage of Hassi Nebech (grey background dots represent the entire sample). A, D, G, J Septal spaces of all septa in the last half volution. B, E, H, K septal distances of the last three septa. C, F, I, L Difference in the septal spaces of the last three septa all septa in the last half volution. A–C Complete assemblage. D–F Suborder Gephuroceratina. G–I Suborder Pharciceratina. J–L Suborder Tornoceratina