Gonioteuthis quadrata Zone
This zone should not be confused with the 'Gonioteuthis Zone' of East Anglia, which although similar in name, is conceptually different. In northern England, part of the zone might be represented by the highest part of the exposed succession, but this forms part of the Sphenoceramus (Inoceramus) lingua Zone (Whitham, 1993).
Base: In southern England, the base of the zone is placed at Telscombe Marl 4 (Mortimore, 1986; Young & Lake, 1988), and in Northern Ireland is coincident with the top of the Creggan Chalk.
Top: In southern England, the top of the zone is placed at the Farlington Marls (Wood, 1995), and in Northern Ireland is coincident with the Whitehead Flint (Wilson & Manning, 1978).
Range of index species: In southern England, the index ranges from within the lower part of the O. pilula Zone to the top of the nominate zone (Mortimore, 1986). In Northern Ireland, the index species does not appear to range below the base of the zone, and its highest occurrence is at the Whitehead Flint, marking the top of the zone (Wilson & Manning, 1978).
|Bryozoa:||locally abundant bryozoans|
|Isocrania egnabergensis (large)|
|Echinoidea:||Cidaris subvesiculosa sensu Gaster (1924)|
|E. sp. (large form of Gaster, 1924)|
|E. sp. (small form of Gaster, 1924)|
|E. sp. (rounded forms)|
|E. sp. (depressed forms)*|
|Offaster pilula nana|
(*: occurs in the zone in Northern Ireland)
Faunal abundance & preservation: Although the zone has quite a diverse fauna, it is generally sparsely fossiliferous, except at particular horizons of faunal abundance, and many of the fossils are small. The extreme hardness of the Northern Ireland Chalk Group means that many fossils are difficult to collect, and some have been reworked at hardground surfaces.
Bio-markers: In southern England, the lower part of the zone contains an acme of Hagenowia blackmorei, Retispinopora lancingensis, large Isocrania egnabergensis and distinctive morphotypes of Echinocorys (large and small forms of Gaster, 1924) (Mortimore, 1986; Young & Lake, 1988). Medium-sized, rounded Echinocorys occur at this level in Northern Ireland, and there is an acme of Belemnitella, which is also very locally represented in southern England (Salisbury area) (Bailey et al., 1983; Wilson & Manning, 1978). In the middle of the zone in southern England, bryozoans and the Conorca turbinella are locally abundant, and occur with Cretirhynchia limbata sensu Gaster (1924), Applinocrinus cretaceus, Cidaris subvesiculosa (sensu Gaster, 1924) and Offaster pilula nana (Gaster, 1924; Young & Lake, 1988). A. cretaceus also occurs locally at this level in Northern Ireland, together with an acme of Orbirhynchia bella (Wilson & Manning, 1978). In the upper part of the zone in Northern Ireland there are acmes of Galeola papillosa, depressed forms of Echinocorys, and a further acme of Belemnitella which is similarly well developed in southern England, where Echinocorys brydonei also occurs (Bailey et al., 1983; Wilson & Manning, 1978; Wood, 1995).
|Applinocrinus cretaceus Subzone|
|'post A. cretaceus beds'|