The top of the zone is defined by the morphotypic first occurrence of Dictyoprora mongolfieri and is coincident with the lower limit of the Dictyoprora mongolfieri Zone.
Events included in the zone are:
- Podocyrtis acalles -> Podocyrtis sinuosa
- The lower limit of the zone is approximately synchronous with Tm Buryella clinata
The base of the zone is defined by the evolutionary transition from Theocotyle nigriniae to Theocotyle cryptocephala and is coincident with the upper limit of the Phormocyrtis striata striata Zone.
Reference slides R 45.1, R 45.2 and R 45.3 from Sample 10-94-25-3, 95-102 cm.