Daughter taxa (time control age-window is: 0-800Ma) | ||||
Tholoma metallasson neptune records: | ||||
Tholoma sp. neptune records: |
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.
Geological Range:
Last occurrence (top): Extant. Data source: Total of ranges of the species in this database
First occurrence (base): within Quaternary Period (0.00-2.59Ma, base in Gelasian stage). Data source: Total of ranges of species in this database
Plot of occurrence data:
Tholoma compiled by the radiolaria@mikrotax project team viewed: 9-9-2024
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