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Discoaster quinqueramus

Mon, 24/03/2008 - 00:37 — Jeremy Young
quinqueramus.jpg
Citation: 
Discoaster quinqueramus Gartner 1969

Description: Symettrical 5-rayed discoaster; central-area, with prominent distal sutural ridges and large proximal boss; rays concavo-convex, with rounded tips. Central area width less than free ray length.

Remarks: D. bergenii, D. bergrennii and D. quinqueramus form an anagenetic lineage, with central area size deceasing and free ray length increasing. Distinguishing them is useful for determining position within the early part of zone NN11.

Range: Confined to NN11 (zone defining species). Virtually absent from the Mediterranean and Para-Tethys.

8-13quinqueramus.JPG 8-14quinqueramus.JPG 8-15quinqueramus.JPGDquinq263-14NN11.JPG

Size: Highly variable, c.5-15microns.

Synonym: D. quintatus Bukry & Bramlette 1969

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