Nannotax3 - ntax_mesozoic - Lapideacassaceae

Lapideacassaceae


Classification: ntax_mesozoic -> Nannoliths inc sedis -> Lapideacassaceae
Sister taxa: Goniolithaceae, Eoconusphaeraceae, Lapideacassaceae, Microrhabdulaceae, Nannoliths inc sed - radiate multielement, Nannoliths inc sed - other

Distinguishing features:
Parent taxon (Nannoliths inc sedis): Nannofossils not obviously homologous with heterococcoliths, holococcoliths, or braarudosphaeralids
This taxon: Hemispherical to tall cylindrical nannoliths, with narrow walls constructed from one to several cycles of thin elements, enclosing a hollow central space; the nannolith tapers distally, and may have apical spines or processes.


Daughter taxa (time control age-window is: 0-800Ma)Granddaughter taxa
Lapideacassis
Large hemispherical to tall cylindrical nannoliths with narrow walls constructed from one to several cycles of thin elements, enclosing a hollow central space; the nannolith tapers distally, and may have apical spines or processes. Protruding ledges often mark the junction of different cycles in the wall.
L. asymmetrica
L. bispinosa
L. cornuta
L. glans
L. magnifica
L. mariae
L. tricornus
L. trispina
L. sp.

Taxonomy:

Citation: Lapideacassaceae Black, 1971
Rank: Family
Type species: Lapideacassis Black, 1971.

Farinacci & Howe catalog pages: Lapideacassaceae [no catalog entry yet]

Distinguishing features:
Parent taxon (Nannoliths inc sedis): Nannofossils not obviously homologous with heterococcoliths, holococcoliths, or braarudosphaeralids
This taxon: Hemispherical to tall cylindrical nannoliths, with narrow walls constructed from one to several cycles of thin elements, enclosing a hollow central space; the nannolith tapers distally, and may have apical spines or processes.


Morphology: Rare and sporadic stratigraphical distribution, but a K/T boundary survivor.

Crystallographic orientations: The entire nannolith is formed of R-units, in side view the c-axes are inclined upward slightly (so with gypsum plate when vertical the left hand side is blue and the right hand side yellow). In apical view the c-axes are slightly oblique from radial. [JRY 2017 my obs, and interpretation of published micrographs] 


Phylogenetic relations: Forchheimer & Stradner (1973) suggested L. cornuta might be a holococcolith based on TEM images of their paratype specimen which showed a rhombohedral ultrastructure. However, this has not been supported by any other observations and they show much better developed cycles of plates than s normal in holococcoliths. Re-examination of their micrographs shows that the rhombohedra are more variable in size than is normal in holococcoliths, so they may be a diagenetic fabric [my interpretation - JRY 2015]. So, they appear more likely to be heterococcoliths.
The group does not seem to have ben affected by the K/Pg extinctions, with most species also occurring the Paleogene.

Search data:
TagsLITHS: nannolith-radiate, circular, cylindrical, hollow, CA: process, closed, CROSS-POLARS: R-prominent,
MetricsLith size: 0->0µm;
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Notes: The groups is always rare.
Last occurrence (top): at top of Priabonian Stage (100% up, 33.9Ma, in Priabonian stage). Data source: Total of range of species in this database
First occurrence (base): at base of Aptian Stage (0% up, 126.3Ma, in Aptian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:

Black, M. (1971b). Problematical Microfossils from the Gault Clay. Geological Magazine. 108(4): 325-327. gs

Forchheimer, S. & Stradner, H. (1973). Scampanella, a new genus of Cretaceous nannofossils. Verhandlungen der Geologischen Bundesanstalt (Wien). 2: 286-289. gs V O


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Lapideacassaceae compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 9-12-2021

Taxon Search:
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Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=10554 Go to Archive.is to create a permanent copy of this page - citation notes



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