Lapideacassis


Classification: Mesozoic -> Nannoliths inc sedis -> Lapideacassaceae -> Lapideacassis
Sister taxa: Lapideacassis,

Distinguishing features: 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.


Daughter taxa: (blue => in age window 0-800Ma)
Single spine, offset from centre  (hence asymmetrica)
Lapideacassis with two apical spines, one near-vertically orientated and one at 45 degress.
Lapideacassis with two, apical spines at about 45 degrees.
Squat, dome shaped Lapideacassis with protruding ledge just above the base.

Tall, cylindrical Lapideacassis with tapering, curved upper part. Two or three cycles and ledges are typically present.
Lapideacassis with three, near-vertically orientated, tapering apical spines.
Lapideacassis with three, near-horizontally orientated, tapering apical spines.
Specimens not identified to species level

Taxonomy:

Citation: Lapideacassis Black, 1971
Rank: Genus
Type species: Lapideacassis glans Black, 1971
Synonyms: Scampanella Forchheimer and Stradner, 1973, Pervilithus Crux, 1981.

Farinacci & Howe catalog pages: Lapideacassis * , Scampanella + * , Pervilithus *

Distinguishing features: 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.


Morphology remarks: The genus name Scampanella Forchheimer and Stradner, 1973 has been used for Lapideacassis forms with a single wall cycle, but is regarded here as a junior synonym of Lapideacassis following Burnett (1997). The group in general has had many species named, based on the number of spines present, but this may be strongly influenced by preservation, rather than representing any real taxonomic significance. The L. mariae (tall) and L. glans (domed) types are most easily recognised.

Geological Range:
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: 325-327. gs

Burnett, J. A. (1997c). New species and new combinations of Cretaceous nannofossils and a note on the origin of Petrarhabdus (Deflandre) Wise & Wind. Journal of Nannoplankton Research. 19(2): 133-146. gs

Crux, J. A. (1981). New calcareous nannofossil taxa from the Cretaceous of South East England. Neues Jahrbuch für Geologie und Paläontologie Monatshefte. 1981: 633-640. gs

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


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Lapideacassis compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 18-10-2019

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