Actinomma livae

Taxonomy

Catalog entries: Actinomma livae

Original description: Diagnosis: A species of Actinomma characterized by a small, sphaerical, well-defined outer medullary shell joined to the large multi-layered cortical shell by numerous stout, bladed radial beams; some of which penetrate the outer cortical shell as short spines.

Description: Skeleton consists of three or four spherical concentric lattice shells configured as inner and outer medullary shells and one or two cortical shells. The diameters of the three inner shells have an approximate ratio of 1:2:5. The structure of the inner medullary shell is obscured by the cortical shells and can not be observed on complete specimens. The outer medullary shell is relatively thick walled and clearly defined as a regular lattice shell, perforated by small, round, densely-spaced pores. On many specimens, fine lattice spines project radially from the outer medullary shell and may have a length approximately one-half the distance to the inner margin of the cortical shell. Additionally, numerous prominent, bladed, irregularly disposed radial beams project from the medullary shell and are joined to the robust, inflated and loosely perforated cortical shell, which may be single or paired. The two cortical shells have similar composition. On specimens with two cortical shells, the major radial beams penetrate the inner cortical shell and are joined to the inner wall of the outer cortical shell. Some of these primary radial beams penetrate the outer cortical shell as short, stout lattice spines. A multitude of secondary radial beams span the space between the cortical shells. The distance between the inner and outer cortical shells varies considerably. The ratio of these two diameters ranges from 1:3 to 1:7.

Description

Biogeography and Palaeobiology

Biostratigraphic distribution

Geological Range:
Last occurrence (top): within Neogene Period (2.59-23.03Ma, top in Piacenzian stage). Data source: Lazarus et al. 2015 - "N age group"
First occurrence (base): within Neogene Period (2.59-23.03Ma, base in Aquitanian stage). Data source: Lazarus et al. 2015 - "N age group"

Plot of occurrence data:

• Range-bar - range as quoted above, pink interval top occurs in, green interval base occurs in.
• Triangles indicate an event for which a precise placement has been suggested
• Histogram - Neptune occurrence data from DSDP and ODP proceedings. Pale shading <50 samples in time bin. Interpret with caution & read these notes
• Taxon plotted: Actinomma livae, synonyms included - Actinomma livae;
• See also space-time plot :: Samples map :: Parent: Actinomma

Actinomma livae compiled by the radiolaria@mikrotax project team viewed: 20-9-2024 Taxon Search: Advanced Search Short stable page link: https://mikrotax.org/radiolaria/index.php?id=203024 Go to Archive.is to create a permanent copy of this page - citation notes

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