Fig. 9

Box-and-whiskers diagrams showing the size distribution of Prolobites and species of co-occurring ammonoid genera. a–b Size distribution of Prolobites delphinus (Sandberger & Sandberger 1851) and Sporadoceras bidens (Sandberger & Sandberger 1851) within the seven successive horizons of the Prolobites delphinus Zone of the Enkeberg locality. c Size distribution of the four species Prolobites aktubensis Bogoslovsky1969, Prionoceras divisum (Münster1832), Platyclymenia annulata (Münster1832), and Platyclymenia subnautilina (Sandberger1855) within the Platyclymenia annulata Zone of the Kattensiepen locality. d Size distribution of the four species Prolobites inops Korn2002, Prionoceras divisum (Münster1832), Platyclymenia annulata (Münster1832), and Platyclymenia subnautilina (Sandberger1855) within the Platyclymenia annulata Zone of the Ense locality