Fig. 4

Proleymeriella schrammeni, NE-Germany, early Albian, RUB-Pal 11285 a 3D empirical model in lateral view showing the suture lines and morphology of the internal mould for all hollow chambers, b same model and orientation in a semi-transparent appearance showing the shape of the septa and septal spacing for all hollow chambers, c Virtual longitudinal cross section showing 57 preserved chambers (not filled/filled) including the initial chamber (ic—see Fig. 8 for a close up), and the ventral position of the siphuncle. The chambers were labeled following the occurrence during ontogeny, ts tubular structure, stw siphuncular tube wall, note: grey scale values inverted