(Nigrini, 1971, who termed it a 'Concurrent Range Zone')
The top of the zone is defined by the morphotypic last appearance of Anthocyrtidium angulare and is coincident with the lower limit of the Amphirhopalum ypsilon Zone.
Events included in the zone are:
- Tm Lamprocyrtis neoheteroporos
The base of the zone is defined by the morphotypic last appearance of Pterocanium prismatium and is coincident with the upper limit of the Pterocanium prismatium Zone.
Reference slides R 4.1, R 4.2 and R 4.3 from Sample 85-573-3-CC.