The top of the zone is defined by the evolutionary transition from Dorcadospyris dentata to Dorcadospyris alata and is coincident with the lower limit of the Dorcadospyris alata Zone.
Events included in the zone are:
- Liriospyris stauropora -> Liriospyris parkerae
- Tm Carpocanopsis cingulata; Bm Carpocanopsis cristata
- The lower limit of the zone is approximately synchronous with Tm Lychnocanoma elongata
The base of the zone is defined by the morphotypic first appearance of Calocycletta costata and is coincident with the upper limit of the Stichocorys wolffii Zone.
Reference slides R 20.1, R 20.2 and R 20.3 from Sample 85-573B-123, 61-63 cm.; R 21.1, R 21.2 and R 21.3 from Sample 85-573B-13-CC.