Calycoceras guerangeri Zone

Base: The base of the zone is immediately below the first appearance of the index species (Gale, 1995).

Top: The top of the zone is immediately above the last occurrence of the index species (Gale, 1995).

Range of index species: The zone is coincident with the total range of the index species (Gale, 1995).

Key fauna:

Bivalvia:	Amphidonte obliquatum (locally abundant)
	Inoceramus pictus
Ammonoidea:	Calycoceras guerangeri
	C. spp.
	Eucalycoceras pentagonum
	Thomelites spp.
Echinoidea:	Holaster spp. (thin-shelled, fragmentary species)

Faunal abundance & preservation: The zone is typically sparsely fossiliferous, and the fauna often fragmentary and poorly preserved.

Bio-markers: The middle of the zone contains a widely developed acme of the oyster Amphidonte obliquatum (Gale et al., 1999).

Age: Late Cenomanian.