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February 2001
"Cycladophorids" are common and diverse in the Paleocene of ODP Site 1121, Campbell Plateau, SE of New Zealand. The taxon described and illustrated here is the most common, especially in the Late Paleocene (RP5-6). For expediency it is treated as a single species although it is quite conceivable that the range encompasses several species.

Cycladophora aff. cosma Lombari and Lazarus
aff. Cycladophora cosma cosma Lombari and Lazarus 1988, p. 104, pl. 1, fig. 1-6
aff. Clathrocycloma parcum Foreman 1973, p. 434, pl. 2, fig. 13; pl. 11, fig. 12.
Diplocyclas pseudobicorona pseudobicorona Nishimura, 1992 (in part), p. 340, pl. 4, fig. 5.

Description: Conical test of 2 segments. Small spheroidal cephalis has divergent apical and vertical horns; vertical horn is the same size or smaller than apical horn. Dorsal and lateral bars may emerge from upper thorax as short radially disposed spines. Thorax has a weak shoulder proximally, at level at which spines emerge, remainder being variable in shape from evenly conical to campanulate. Distal margin typically flared with ragged termination. Simple circular pores increase gradually in size from cephalis to basal margin.

Remarks: Distinguished from C. cosma cosma by absence of thorns on the apical spine and the tendency towards a campanulate outline. In this latter respect this species resembles Clathrocycloma parcum Foreman which is distinguished by having a vertical tube (cephalopyle of Pessagno, 1969) rather than a vertical spine. Rare variants in which the vertical spine is missing (as in Nishimura's specimen) are included.

Occurrence: ODP Site 1121, Campbell Plateau, rare in RP4, common in RP5-6; DSDP Site 208, Lord Howe Rise, rare from RP4 to RP5.

Chris Hollis 2001/01/31

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Pictures 2-3

Chris Hollis (2001/01/31)

Pictures 4-5

Chris Hollis (2001/01/31)

Most of specimens of Diplocyclas pseudobicorona pseudobicorona are
constructed by smaller and and less stout skeletons than those of
Clathrocycloma parcum at DSDP Site 384.

Akiko Nishimura (2001/02/01)

First - I don't know what it is. Sorry! Chris points out that there are a couple subtle differences between the Paleocene form and the Neogene species. Thus I would agree it is not C.cosma, altho if I were scanning a Neogene slide for strat work (ie not looking too closely at taxa with no known strat value) I might well identify such Paleocene specimens as C.cosma by mistake. In hunting thru the older literature for possible equivalents, given the limitations of older illustrations, I would suggest that the geologic age of the material be taken into account (and also not forget that many of the old age estimates were seriously wrong). And, I would recommend if possible a reexamination of the type material. Good luck! - dave

Dave Lazarus (2001/02/02)

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