Dbk: Created page with "This zone is only currently used in northern England (Whitham, 1991), and in some areas has been replaced by the standard ammonite zonation used in the Cenomanian (Gaunt ''et ..."

2013-09-26T14:00:31Z

Created page with "This zone is only currently used in northern England (Whitham, 1991), and in some areas has been replaced by the standard ammonite zonation used in the Cenomanian (Gaunt ''et ..."

New page

This zone is only currently used in northern England (Whitham, 1991), and in some areas has been replaced by the standard ammonite zonation used in the Cenomanian (Gaunt ''et al''., 1992).

'''Base''': The base of the zone is the top of the Hunstanton Formation ('Red Chalk', Albian), at the base of the Chalk Group (Whitham, 1991, Gaunt ''et al''., 1992).

'''Top''': The top of the zone is the top of the Nettleton Stone (Whitham, 1991; Gaunt ''et al''., 1992).

'''Range of index species''': The index ranges from a short distance above the base of the nominate zone to the lower part of the overlying ''H. trecensis'' Zone (Whitham, 1991).

'''Key fauna''':
{| class="Wikitable"
| Brachiopoda: ||''Concinnithyris subundata''
|-
| ||''Grasirhynchia martini''
|-
| ||''Monticlarella rectifrons''
|-
| ||''Orbirhynchia mantelliana''
|-
| Bivalvia: || ''Aucellina''
|-
| ||''Entolium orbiculare''
|-
| ||''Inoceramus crippsi''
|-
| ||'' I. schoendorfi''
|-
| ||''Lyropecten'' (''Aequipecten'') ''arlesiensis''
|-
| ||''Oxytoma'' sp.
|-
| ||''Pycnodonte vesiculare''
|-
| Belemnoidea: || ''Actinocamax primus''
|-
| ||''Belemnocamax boweri''
|-
| Ammonoidea:|| ''Acanthoceras jukesbrownei''
|-
| ||''A. rhotomagense''
|-
| || ''Hypoturrilites'' sp.
|-
| ||''Parapuzosia'' (''Austiniceras'') ''austeni''
|-
| ||''Schloenbachia'' sp.
|-
| ||''Turrilites'' sp.
|-
| Echinoidea: || ''Echinocorys sphaerica''
|-
| ||''Holaster subglobosus''
|}
'''Faunal abundance & preservation''': The zone is locally very fossiliferous, with the fauna concentrated into acmes at some levels.

'''Bio-horizons''': ''Aucellina'' is common in the lower part of the zone, overlain by shell-rich horizons with common ''Inoceramus crippsi'' and ''Inoceramus schoendorfi'' (Whitham, 1991). Higher in the zone there is an acme of ''Orbirhynchia mantelliana'', overlain by the fossiliferous Totternhoe Stone, with a fauna that includes characteristic elements such as ''Lyropecten'' (''Aequipecten'') ''arlesiensis'', ''Oxytoma'', ''Entolium'' ''orbiculare'',''Grasirhynchia'' ''martini'' and ''Actinocamax primus'' (Whitham, 1991). In the upper part of the zone, ''Concinnithyris'', ''Echinocorys sphaerica'' and ''Acanthoceras'' are common, and just below the top of the zone is an acme of ''Pycnodonte vesiculare'' (Whitham, 1991).

'''Age''': Early to Mid Cenomanian

[[category:Standard zonation | 032]]

Holaster subglobosus Zone - Revision history

Dbk: Created page with "This zone is only currently used in northern England (Whitham, 1991), and in some areas has been replaced by the standard ammonite zonation used in the Cenomanian (Gaunt ''et ..."