radiolaria - rads_cenozoic - Tholoma


Classification: rads_cenozoic -> Tholoniidae -> Tholoniidae inc sed -> Tholoma
Sister taxa: Amphitholus, Cubotholus, Tholoma
Daughter taxa (time control age-window is: 0-800Ma)
Tholoma metallasson

neptune records:
Tholoma sp.

neptune records:


Citation: Tholoma Haeckel 1887
Rank: genus
Basionym: Tholoma

Catalog entries: Tholoma

Original description: Tholonida with double cortical shell (with external veil), composed of four hemispherical cupolas in cross-form, opposite in pairs on the poles of two axes perpendicular one to another; central chamber simple (without medullary shell).

The genus Tholoma (Pl. 10, figs. 10, 13) differs from the preceding Tholostaurus (its probable ancestral form) only in the duplication of the shell. The outer (secondary) shell has the same cross-form as the inner (primary) shell. In the two observed species the growth seems to be different, in the first species all four cupolas of each cross being of the same size, form, and age; in the second two opposite cupolas, larger and apparently older than the other two. Tholoma is possibly the offspring of Staurotholonium, from which it may have been produced by loss of the medullary shell.


Biogeography and Palaeobiology

Biostratigraphic distribution

Geological Range:
Last occurrence (top): Extant Data source: Total of range of species in this database
First occurrence (base): at base of Gelasian Stage (0% up, 2.6Ma, in Piacenzian stage). Data source: Total of range of species in this database

Plot of occurrence data:


Haeckel, E (1887). Report on the Radiolaria collected by H.M.S. Challenger during the years 1873-1876. Report on the Scientific Results of the Voyage of H.M.S. Challenger during the year 1873-1876, Zoology. 18: 1-1803. gs


Tholoma compiled by the radiolaria@mikrotax project team viewed: 24-9-2021

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