http://earthwise-staging.bgs.ac.uk/index.php?action=history&feed=atom&title=Holaster_trecensis_Zone 2026-04-16T21:28:24Z Revision history for this page on the wiki MediaWiki 1.42.3 http://earthwise-staging.bgs.ac.uk/index.php?title=Holaster_trecensis_Zone&diff=1467&oldid=prev 2013-09-26T14:02:18Z

<p>Created page with &quot;This zone is only currently used in northern England (Whitham, 1991), and in some areas has been replaced by the standard ammonite zonal equivalent (= &#039;&#039;C. guerangeri&#039;&#039; Zone) ...&quot;</p> <p><b>New page</b></p><div>This zone is only currently used in northern England (Whitham, 1991), and in some areas has been replaced by the standard ammonite zonal equivalent (= &#039;&#039;C. guerangeri&#039;&#039; Zone) used for this part of the Cenomanian (Gaunt &#039;&#039;et al&#039;&#039;., 1992).<br /> <br /> &#039;&#039;&#039;Base&#039;&#039;&#039;: The base of the zone is the top of the Nettleton Stone (Whitham, 1991; Gaunt &#039;&#039;et al&#039;&#039;., 1992)<br /> <br /> &#039;&#039;&#039;Top&#039;&#039;&#039;: The top of the zone is the sub-Black Band (s.l.) erosion surface (Whitham, 1991; Gaunt &#039;&#039;et al&#039;&#039;., 1992).<br /> <br /> &#039;&#039;&#039;Range of index species&#039;&#039;&#039;: The index ranges from the middle of the nominate zone into the overlying &#039;&#039;Sciponoceras gracile&#039;&#039; Zone (Whitham, 1991).<br /> <br /> &#039;&#039;&#039;Key fauna&#039;&#039;&#039;:<br /> {| class=&quot;Wikitable&quot;<br /> | Annelida: || &#039;&#039;Rotularia umbonata&#039;&#039;<br /> |-<br /> | Brachiopoda: || &#039;&#039;Gibbithyris&#039;&#039; spp.<br /> |-<br /> | ||&#039;&#039;Ornatothyris sulcifera&#039;&#039;<br /> |-<br /> | Bivalvia: || &#039;&#039;Inoceramus pictus&#039;&#039;<br /> |-<br /> | Echinoidea: || &#039;&#039;Camerogalerus cylindricus&#039;&#039;<br /> |-<br /> | ||&#039;&#039;Echinocorys sphaerica&#039;&#039;<br /> |-<br /> | ||&#039;&#039;Holaster trecensis&#039;&#039;<br /> |-<br /> | Nautiloidea: || nautiloids<br /> |}<br /> &#039;&#039;&#039;Faunal abundance &amp; preservation&#039;&#039;&#039;: The zone is rather poorly fossiliferous compared to the underlying &#039;&#039;H. subglobosus&#039;&#039; Zone, although there are some local faunal acmes. Crushed specimens are not infrequent.<br /> <br /> &#039;&#039;&#039;Bio-markers&#039;&#039;&#039;: In the lower part of the zone, &#039;&#039;Ornatothyris sulcifera&#039;&#039;, &#039;&#039;Gibbithyris&#039;&#039; spp. and &#039;&#039;Rotularia umbonata&#039;&#039; co-occur (Whitham, 1991). There is an acme of &#039;&#039;Holaster trecensis&#039;&#039; in the top of the zone, associated with &#039;&#039;Camerogalerus cylindricus&#039;&#039; and &#039;&#039;Ornatothyris&#039;&#039; (Whitham, 1991).<br /> <br /> &#039;&#039;&#039;Age&#039;&#039;&#039;: Late Cenomanian<br /> <br /> [[category:Standard zonation | 033]]</div>

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