(Foreman, 1973, emend. Foreman, 1975)
The top of the zone is defined by the morphotypic first appearance of Theocorys anaclasta and is coincident with the lower limit of the Phormocyrtis striata striata Zone.
Events included in the zone are:
- Tm Pterocodon ampla; Tm Bekoma bidartensis; Tm Buryella tetradica; Tm Thyrsocyrtis tarsipes
- Bm Lithocyclia ocellus group; Bm Thyrsocyrtis tensa; Theocotylissa alpha -> Theocotylissa ficus
- Bm Calocyclas hispida
- The lower limit of the zone is approximately synchronous with Bm Spongatractus balbis; Bm Lamptonium sanfilippoae; Bm Theocotyle nigriniae; Bm Thyrsocyrtis hirsuta
The base of the zone is defined by the evolutionary transition from Pterocodon? anteclinata to Buryella clinata and is coincident with the upper limit of the Bekoma bidartensis Zone.
Reference slides R 47.1, R 47.2 and R 47.3 from Sample 143-384-6-3, 102-109 cm.