Supplementary Fig 6

Ontogenetic trajectories of the conch width index, umbilical width index and whorl expansion rate, as well as the two new parameters, apertural surface area index and buccal mass area index, of two ammonoid species and a *Nautilus* species: A – *Macrocephalites macrocephalus *(Schlotheim, 1813), specimen MB.C.26518 (Middle Jurassic, Westphalia), B – *Choffatia isabellae* Bonnot et al., 2008, specimen MB.C.26550 (Middle Jurassic, Normandy) and C – *Nautilus pompilius* Linnaeus, 1758, specimen GPI Tübingen 1431-K1