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Cycladophora robusta Lombari and Lazarus, 1988

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Cycladophora robusta
Description: Medium-sized subspherical cephalis with 2 short 3-bladed apical horns, and scattered small circular pores. Conical upper thorax with small irregularly spaced subcircular pores. Juncture with lower thorax marked by prominent sharp shoulder, with a near doubling of shell diameter. Small, weakly flared lower thorax with large irregular pores, thick, circular bars. Nodes smooth. Strong internal septum marks base of thorax. Abdomen is variably developed on different specimens, generally moderately flared and irregularly terminated. Lattice wall of abdomen similar to lower thorax.
Type: DSDP Site 173-14-2, 71 cm. England finder number VI5/4.
Origin of name: In reference to the robust lattice-wall bars of this heavily silicificd species.
Comments: Distinguished from all other species of Miocene age by its prominent shoulder, small lower thorax, and heavy circular lattice-wall bars. C. robusta is very similar in morphology to C. davisiana davisiana, an important species of the mid-Pliocene to Recent. C. robusta has a somewhat larger lower thorax and a better developed abdomen than does C. davisiana, but the two species are otherwise quite similar. C. davsiana sensu stricto first appears in the mid-Pliocene, according to Hays (pers. comm.), who has studied the evolutionary history of this latter species on a global basis.
Occurrence: Found in early Pliocene North Pacific DSDP Site 173, cores 14 through 12-CC, and late Miocene Antarctic Site 278, cores 12 through 9; Site 266, core 12.
Lombari and Lazarus 1988











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