Fig. 10

Boxplot comparing the ratio of the eye diameter on the carapace length (CL) in five different groups of fossil polychelidans: Col = Coleiidae, Ery = Eryonidae, Pal = Palaeopentacheles (only species of Palaeopentachelidae), Pol = fossil species closely related to Polychelidae, Ros = Rosenfeldia oppeli. *, Welch test, P-value < 0,01. Abbreviations