Discoscaphites binodosus Subzone

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This subzone is only currently used in northern England (Whitham, 1993).

Base: The base of the subzone is the base of the Sewerby Steps Marl (Whitham, 1993).

Top: The subzone equates with the youngest exposed chalk in northern England, and so its top is undefined.

Range of index species: The index ranges from a short distance above the base of the nominate subzone to the top of the exposed subzone (Whitham, 1993).

Key fauna:

Bivalvia: Inoceramus lobatus
Sphenoceramus patootensis
S. steenstrupi
Belemnoidea: Gonioteuthis quadrata
Ammonoidea: Baculites sp.
Discoscaphites binodosus
Scaphites spp.
Echinoidea: Echinocorys spp.
Micraster glyphus
M. schroederi

Faunal abundance & preservation: The subzone is quite fossiliferous, with a diverse fauna.

Bio-markers: Rare Offaster pilula occur at the base of the subzone, and several elements of the fauna have acmes in the top of the subzone, including: Sphenoceramus steenstrupi, Echinocorys spp. (tall, conical & large globose forms) and Baculites (Whitham, 1993).

Age: Campanian