Type
Zone
Age range
257.2–256.5 Ma
Lopingian
Wuchiapingian
Clarkina transcaucasica
Clarkina guangyuanensis
Clarkina leveni
257.2257.1257.1257.1257.0256.9256.9256.9256.8256.8256.7256.6256.6256.6256.5