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Revision of D. pentaradiatus group from Mon, 14/01/2008 - 12:25

Mon, 14/01/2008 - 12:37 — Jeremy Young
Citation: 
Discoaster pentaradiatus group

This is an informal grouping for symmetric 5-rayed discoasters. These species probably do not form a clade but are a characteristic component of Late Miocene and Pliocene assemblages, including several important marker species.

Taxa included

quinqueramus.jpg

D. bergenii - D. berggrenii - D. quinqueramus lineage (NN11)

- non-bifurcate rays, concavo-convex, large proximal boss

pentaradiatus.jpg

D. pentaradiatus (NN10B-NN17)

- bifurcate rays, concavo-convex, each ray behaves as separate crystal

prepentaradiatus.jpg

D. prepentaradiatus (NN9-10A)

- bifircate ray tips, complanate, whole disc behaves optically as single crystal

hamatus.jpg

D. hamatus (NN9)

- asymetric & downward deflected ray tips

bellus.jpg

D. bellus (NN8-11)

- simple ray tips, more or les planar

 

 

 

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